Environmental Statement Appendix 12.B Settlement Assessment Report · 2016-06-07 · 1 Mair, R.J.,...

Environmental Statement Appendix 12.B

Settlement Assessment Report

April 2016

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Document Reference: 6.3.12.2

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Document Reference 6.3.12.2

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Contents

List of Abbreviations ................................................................................................ 6

Glossary of Terms .................................................................................................... 7

1. INTRODUCTION ......................................................................................... 13

1.1 Scope .......................................................................................................... 13

1.2 Proposed scheme ....................................................................................... 13

2. PURPOSE OF THIS REPORT .................................................................... 15

3. SETTLEMENT RISK ASSESSMENT ......................................................... 17

3.1 General ....................................................................................................... 17

3.2 Settlement assessment process ................................................................. 19

4. GEOLOGY .................................................................................................. 21

4.1 Ground conditions ....................................................................................... 21

5. SETTLEMENT ASSESSMENT METHODOLOGY ...................................... 23

5.1 General ....................................................................................................... 23

5.2 Choice of model .......................................................................................... 23

5.3 Tunnel settlement ........................................................................................ 24

5.4 Cut-and-Cover and retained box excavation settlement ............................. 27

5.5 Subsurface settlements ............................................................................... 28

5.6 Consolidation effects ................................................................................... 29

6. BUILDINGS AND SIMILAR STRUCTURES ASSESSMENT PROCESS ... 31

6.1 General ....................................................................................................... 31

6.2 Damage Risk Assessment Method ............................................................. 31

7. PHASE I ASSESSMENT ............................................................................. 35

7.2 Settlement predictions ................................................................................. 35

8. PHASE II ASSESSMENT ............................................................................ 39

8.1 Results ........................................................................................................ 39

9. UTILITIES ASSESSMENT .......................................................................... 43

9.1 General ....................................................................................................... 43

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9.2 Assumptions ................................................................................................ 43

9.3 Results ........................................................................................................ 46

10. RECOMMENDATIONS ............................................................................... 49

10.1 General .................................................................................................... 49

10.2 Utilities ..................................................................................................... 50

10.3 Monitoring ................................................................................................ 50

11. LIMITATIONS .............................................................................................. 53

11.1 General .................................................................................................... 53

Appendix A. GEOLOGICAL LONG SECTIONS ................................................ 55

Appendix B. GENERAL SETTLEMENT CONTOUR DRAWINGS ..................... 57

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List of Tables

Table 6.1 Damage risk categories based on typical values of maximum asset slope or settlement ............................................................................................................ 31

Table 6.2 Asset damage risk categories based on Limiting Tensile Strain ............... 32

Table 7.1 Silvertown Tunnel Assets identified within the 1mm surface contour zone ................................................................................................................................. 36

Table 7.2 Silvertown Tunnel Assets requiring the Phase II Assessment. ................. 38

Table 8.1 Surface Settlement Assessment Results ................................................. 39

Table 9.1 Utilities assumptions ................................................................................. 43

Table 9.2 Assumed acceptance criteria ................................................................... 46

Table 9.3 Surface Settlement Assessment Results ................................................. 46

List of Figures

Figure 3.1 Settlement Assessment process suggested by Mair et al. (1996) ........... 18

Figure 5.1 Idealised transverse surface settlement profile with normal distribution from (O’Reilly and New: 1982) ................................................................................. 25

Figure 5.2 Scheme of notation for ribbon representation, from New & Bowers, 1994 ................................................................................................................................. 29

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List of Abbreviations

BS British Standard

CIRIA Construction Industry Research and Information Association

DCO Development Consent Order

DLR Docklands Light Railway

EAL Emirates Air Line

EIA Environmental Impact Assessment

TBM Tunnel Boring Machine

SAR Settlement Assessment Report

SCL Sprayed Concrete Lining

TfL Transport for London

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Glossary of Terms

Blackwall Tunnel An existing road tunnel underneath the River Thames in east London, linking the London Borough of Tower Hamlets with the Royal Borough of Greenwich, comprising two bores each with two lanes of traffic.

Cross Passage A small tunnel usually linking two larger tunnels.

Cut and Cover A form of construction usually involving in situ reinforced concrete, where a tunnel is built within an excavation which is undertaken from the ground surface.

Defect Survey A survey to record defects in buildings or other structures, undertaken before and after construction of the relevant parts of the Scheme.

Detailed Design A finalised design, complete in all aspects and suitable for construction of the Scheme.

Docklands Light Railway (DLR) An automated light metro system serving the Docklands and east London area. The DLR is operated under concession awarded by Transport for London to KeolisAmey Docklands, a joint venture between transport operator Keolis and infrastructure specialists Amey plc.

Emirates Air Line (EAL) A cable car service for pedestrians and cyclists across the River Thames in east London, linking the Greenwich peninsula to the Royal Victoria Dock.

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The service is managed by TfL, and is part of the TfL transport network.

Listed Buildings A listed building is a building or other structure that has been placed on the Statutory List of Buildings of Special Architectural Interest and afforded special protection under the Planning (Listed Buildings and Conservation Areas) Act 1990. Listed Buildings are separated into three categories: Grade I buildings are of exceptional interest, sometimes considered to be internationally important; Grade II* buildings are particularly important buildings of more than special interest; Grade II buildings are nationally important and of special interest. A listed building may not be demolished, extended or altered without special permission from the local planning authority.

Sheet Pile Profiled heavy duty steel elements which are installed in the ground from the surface and used to form temporary or permanent retaining structures.

Silvertown Tunnel Proposed new twin-bore road tunnels under the River Thames from the A1020 in Silvertown to the A102 on Greenwich Peninsula, East London.

The Scheme The construction of a new bored tunnel with cut and cover sections at either end under the River Thames (the Silvertown Tunnel) between the Greenwich peninsula and Silvertown, as well as necessary alterations to the connecting road network and the

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introduction of user charging at both Silvertown and Blackwall tunnels.

Tunnel Boring Machine (TBM) A machine used to excavate tunnels with a circular cross section. There are two main types of closed face TBMs: Earth Pressure Balance (EPB) and Slurry Shield (SS). Please see those terms (above) for further explanation.

Volume Loss An expression for the volume of a settlement tough arising per unit length from excavation-induced ground movement, expressed as a percentage of the excavated tunnel area.

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SUMMARY

S.1 General

S.1.1 This Settlement Assessment Report (SAR) has been prepared as part of the Reference Design for the Silvertown Tunnel to inform the Development Consent Order (DCO) application and provide a basis for the Environmental Impact Assessment. This report has been prepared in accordance with tunnelling industry practice and outlines the theoretical background to settlement damage assessment due to the proposed scheme and provides findings from combined Phase I and Phase II of the three phased assessment process suggested by Mair et al. (1996)1.

S.1.2 Settlement assessment was carried out for the entire scheme including the open-cut tunnel portal approaches, the Cut-and-Cover tunnel sections and the bored tunnel with cross passages.

S.1.3 The Oasys Xdisp 19.3 SP1 build 25 software has been used in order to model the scheme civil works and obtain the settlement profiles as well as the affected assets’ tensile strains.

S.2 Content

S.2.1 Within the document, the following information is presented:

a) Detailed information on the settlement calculation procedures for both the bored and the Cut-and-Cover tunnel sections as well as the retaining walls excavation at the approach ramps.

b) Damage risk categories based on typical values of maximum building slope or settlement and limiting tensile strain.

c) Detailed information on the predicted settlement and affected buildings & utilities.

d) Building classification to appropriate damage risk categories based on typical values of maximum building slope or settlement and limiting tensile strain.

1 Mair, R.J., Taylor, R.N. and Burland, J.B. (1996). Prediction of ground movements and assessment of building damage due to bored tunnelling. International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground. Rotterdam, The Netherlands, pp. 713-18

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e) Worksite requirements to undertake assets protective measures.

f) Limitations to this assessment (including foundation details assumptions).

S.2.2 This document will also provide the information required to determine if any of the affected structures identified within the zone of influence of the Silvertown Tunnel require Phase III assessments to be undertaken. However, no Phase III assessment has been undertaken as part of this settlement assessment completed in support of the Reference Design, where this would be completed in consideration of the Detailed Design and construction proposals.

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1. INTRODUCTION

1.1 Scope

1.1.1 The Silvertown Tunnel scheme (the Scheme) involves the construction of a twin bore road tunnel providing a new connection between the A102 Blackwall Tunnel Approach on Greenwich Peninsula (Royal Borough of Greenwich) and the Tidal Basin roundabout junction on the A1020 Lower Lea Crossing/Silvertown Way (London Borough of Newham). The Silvertown Tunnel would be approximately 1.4km long and would be able to accommodate large vehicles including double-deck buses. It would include a dedicated bus, coach and goods vehicle lane, which would enable TfL to provide additional cross-river bus routes.

1.1.2 The proposed scheme will have associated ground movements caused by deep excavations and the Tunnel Boring Machine (TBM) operations. An understanding of these movements, their distribution, and their effects on surrounding buildings is essential in order to:

confirm the technical feasibility of the works proposals;

inform subsequent impact assessment of the effects of the development on existing buildings, structures and assets;

identify the need for settlement mitigation works;

identify land requirements for above or protective measures.

1.1.3 These ground displacements and their magnitude depends on a wide range of factors, e.g. local geology, groundwater conditions, manmade underground obstructions, construction methods and construction quality. It is therefore important to understand the nature of the ground displacements in order to propose the most adequate tunnel design solutions.

1.2 Proposed scheme

1.2.1 The proposed twin bore, two lane, unidirectional Silvertown Tunnel will connect the A102 on the Greenwich Peninsula and the Tidal Basin Roundabout on Silvertown Way. The main tunnel section under the river (proposed 12.35m overall diameter) will be bored using a TBM. Cross passages between the bores are proposed, spaced at a maximum of 150m centre to centre. It has been envisaged that the 4.55m external diameter

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cross passages will be constructed using the Sprayed Concrete Lining (SCL) technique.

1.2.2 It is proposed that the descending approaches to the bored tunnels will be Cut-and-Cover, with a top down construction method being anticipated. The proposed method of construction for the TBM chambers at Greenwich and Silvertown is using the bottom-up technique. It has been currently proposed that the Cut-and-Cover tunnel, TBM chambers, and the open-cut approach walls will be constructed using the secant pile walls. For more details on construction methods please refer to the Construction Method Statement (Document Reference 6.3).

1.2.3 For the scheme layout and sections please refer to “Engineering Section Drawings and Plans” (Document Reference 2.8).

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2. PURPOSE OF THIS REPORT

2.1.1 This SAR has been produced to outline the methodology that has been used to predict the ground movement and assess possible damage caused to the third party assets by works associated with construction of the proposed Silvertown Tunnel Scheme. This report presents results of the settlement damage assessment carried out for the third party assets at Silvertown and Greenwich Peninsula, which are found to be within the possible scheme zone of influence.

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3. SETTLEMENT RISK ASSESSMENT

3.1 General

3.1.1 Ground movements are unavoidable when constructing an open excavation or a tunnel, but can be assessed using reliable empirical means and mitigated if required. It is necessary to assess if these movements will affect any surface or sub-surface structures and how intense the damage may be. The following information is required to predict the potential damage caused by an excavation:

buildings and structures characteristics, including type, size, structural form, foundation details etc;

utilities characteristics, including material, internal and external diameters, depth;

define the zone of influence of the excavations;

estimate the magnitude of ground movements and displacements within the zone of interest;

assess how those displacements will affect existing surrounding structures.

3.1.2 In this report, the three phase assessment process suggested by Mair et al. (1996)2 has been applied. This methodology has proven to be effective and was recently used in several projects in the UK, e.g. Crossrail and Jubilee Line Extension. Figure 3.1 presents how the procedure works.

2 Mair, R.J., Taylor, R.N. and Burland, J.B. (1996). Prediction of ground movements and assessment of building damage due to bored tunnelling. International Symposium on Geotechnical Aspects of Underground Construction in Soft Ground. Rotterdam, The Netherlands, pp. 713-18

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Figure 3.1 Settlement Assessment process suggested by Mair et al. (1996)

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3.2 Settlement assessment process

Phase I – Preliminary assessment

3.2.1 Based on an empirical method, a conservative estimation of the settlements has been produced assuming only “green-field” ground movements. This generated settlement contour plans indicating which structures are within the excavation’s zone of influence. This zone is generally defined as the 1mm settlement surface from “green-field” ground movements.

3.2.2 A general criterion has been then applied at this phase to define which structures require further analysis, and should be evaluated at Phase II of this procedure. Common criteria at this phase are that buildings within the 10mm settlement contour or subjected to a ground slope greater than 1:500 should be analysed in further detail.

3.2.3 The contours in this phase have not been intended to work as an exact prediction of the ground movements, but mainly as a filter to identify which structures might be endangered.

3.2.4 Utilities have been included in this assessment, however detailed information regarding their number, size, sensitivity etc. should be confirmed on later stage of the project. When a comprehensive package of utility information becomes available a further study should be undertaken to assess possible tunnelling effects.

3.2.5 Roads including pavements have been also excluded from this assessment as these assets are less sensitive than buildings to ground movements and are under a constant maintenance regime which includes resurfacing.

Phase II – Individual building/utilities assessment

3.2.6 After defining structures which have been more likely to be at ‘moderate’ or greater risk of the ground movement effects, a further examination has been carried out in order to obtain results reflecting particular building characteristics.

3.2.7 In this phase, depending on the relative position of the structure and settlement contours, zones of tensile and compressive strains could have been identified for the asset. Subsequently the maximum tensile strain in the structure can be obtained. The ’damage risk category’ has been determined for each asset. This data have been used as a basis to decide which structures should be submitted to further analysis.

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3.2.8 As part of the Phase II analysis, the foundation type of assets recognized within Phase I as being ’at risk’ has been identified (reasonable assumptions may be taken if available assets information is insufficient). Where assets are founded on a pile raft (pile toe level above the tunnel axis) then the sub-surface settlements have been assessed.

3.2.9 Known utility assets located within the zone of influence of the tunnelling works have been assessed as well, with exception of telecommunication and electricity cables.

3.2.10 Assumed acceptance criteria are consistent with values published by Attwell et al., 1986 & Bracegirdle et al. (1986)3. They represent values that have been used for initial assessment, and final acceptance criteria shall be agreed with each asset owner.

3.2.11 Where assets fail to meet the criteria further detailed evaluation might be necessary.

Phase III – Detailed evaluation

3.2.12 This phase will be undertaken exclusively for structures which have been considered to exceed a moderate risk level according to the Phase II evaluation. This assessment considers many other variables such as the current condition of the structure, the tunnelling sequence, underground man made features, three dimensional aspects and the soil-structure interaction. The use of complex models and numerical methods is applicable.

3.2.13 This assessment phase have not been conducted in this report, however information provided from Phase II will define if there are any structures which will need this evaluation.

3 Attewell, P. B., Yeates, J. & Selby, A. R. (1986). Soil movements induced by tunnelling and their effects on pipelines and structures. Balckie, Glasgow.

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4. GEOLOGY

4.1 Ground conditions

4.1.1 The general geological profile on both sides of the river comprises sequential layers, starting with made ground at the surface, followed by alluvium, river terrace deposits, London Clay, Harwich Formation, Lambeth Group, Thanet Sands and finally the underlying chalk. The bored tunnel sections will be constructed mainly between the River Terrace Deposits and Lambeth Group. The Cut-and-Cover sections and retaining wall excavations will be constructed mainly in Made Ground, Alluvium and River Terrace Deposits.

4.1.2 Geological data has been obtained from drawings A.1.1 and A.1.2 geological long sections of the tunnel and can be found in 0.

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5. SETTLEMENT ASSESSMENT METHODOLOGY

5.1 General

5.1.1 Ground displacements in soft ground can occur for several reasons when bored tunnel works are in progress. These ground movements are caused by:

ground deformation towards the tunnel face due to stress relief in the ground;

distortions on the tunnel lining as it starts to resist the ground loading;

long term consolidation of fine grained soils; AND

TBM ground overbreak required to install the tunnel lining.

5.1.2 When building retaining walls for the Cut-and-Cover sections and the tunnel approaches, ground displacements can occur during the wall installation and when the walls deflect upon taking the lateral ground loading.

5.2 Choice of model

5.2.1 The method used to calculate the tunnel surface settlement derives from the widely accepted O’Reilly and New (1982)4 empirical calculation. The sub-surface settlements were assessed using methods described in New and Bowers (1994)5. For the retaining walls and the Cut-and-Cover tunnel sections, the methodology is based on a case study presented in CIRIA C580.

5.2.2 The analysis undertaken up to and including Phase II has modelled the ground simplistically as single layer strata. The choice of soil was based upon the main layer that the tunnel runs through at particular chainage. The excavations required for the retaining walls and the Cut-and-Cover tunnel sections have been modelled as either being in low stiffness clay or sand, depending on location.

4 O’Reilly, M.P. and New, B.M. (1982) Settlements above tunnels in the United Kingdom – their magnitude and prediction; Proceedings of Tunnelling 82, Institution of mining and metallurgy, London pp 173-181 5 New and Bowers (1994) Ground movement model validation at the Heathrow Express trial tunnel 74. Transport Research Laboratory, Crowthorne, England

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5.3 Tunnel settlement

Surface settlement profile

5.3.1 Surface and sub-surface settlements due to tunnelling depend on the tunnel diameter, depth, construction method and the ground conditions above the tunnel. These settlements are manifested as a trough at the ground surface, which can be observed at any depth between the tunnel and the surface.

5.3.2 It is widely accepted that the shape of the surface settlement trough, at right angles to the tunnel axis, approximates to an inverted Gaussian distribution curve. This is discussed further in Peck’s paper (1969)6 “Deep Excavations and Tunnelling in Soft Ground” Proc 7th Int. Conf. Soil Mech. & Foundation Eng., which is based upon studies by Schmidt (1967): “Settlement and Ground Movements Associated with Tunnelling in Soil” PhD Thesis University of Illinois, Urbana. USA.

5.3.3 The shape of the trough can be calculated using the following equation, which is based upon a Gaussian distribution curve:

Equation 5.1

5.3.4 Where

5.3.5 W(y) = magnitude of settlement at distance y from the tunnel centreline,

5.3.6 Wmax = maximum settlement on the trough, which occurs directly above the tunnel centreline,

5.3.7 y = the transverse horizontal distance from the tunnel central axis to the trough,

5.3.8 i = horizontal distance from the tunnel centreline to the point of inflexion on the settlement trough;

5.3.9 From equation (5.1) the volume of the settlement trough, V, per unit length of tunnel can be calculated using:

√ Equation 5.2

6 Peck, R.B. (1969) Deep Excavations and Tunnelling in Soft Ground. Proc 7th Int. Conf. Soil Mech. & Foundation Eng.

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5.3.10 Therefore, if any two of V, i, or Wmax are known, it is possible to predict the likely settlement trough profile caused by tunnelling operations. Figure 5.1 shows an idealised surface settlement trough.

Figure 5.1 Idealised transverse surface settlement profile with normal distribution from (O’Reilly and New: 1982)

5.3.11 Horizontal displacements at the surface towards the tunnel also occur due to the ground flow towards the tunnel axis. These displacements induce horizontal tensile strains at a distance greater than i (trough width parameter) from the tunnel. Determining tensile strains is essential to assess damage risk on surrounding assets.

5.3.12 An approximation to the horizontal displacement values is made by considering a linear relation between it and the vertical settlements (O’Reilly and New, 1991)7:

7 New, B.M. and O’Reilly, M.P. (1991) Tunnelling induced ground movements: predicting their magnitude and effects; invited review paper to 4th international conference on ground movements and structures, Cardiff, Pentech press, London

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∗ Equation 5.3

5.3.13 Where

Hy is the horizontal movement,

y is the transverse distance to the tunnel axis and,

z is the depth of the tunnel axis

5.3.14 Horizontal strain is obtained deriving equation (5.3).

Trough width parameter

5.3.15 The trough width parameter depends on the ground conditions around the tunnel. The width of the ground surface settlement trough is assumed to be proportional to the depth of the tunnel and dependent on the condition of the surrounding soil. The following equation derives from the paper presented by O’Reilly and New (1982)8:

Equation 5.4

5.3.16 Where:

5.3.17 = trough width parameter at the point of inflexion on the curve, in meters;

5.3.18 K = trough width factor, an empirical constant depending on the soil type;

5.3.19 z = depth to the tunnel axis, in meters;

8 O’Reilly, M.P. and New, B.M. (1982) Settlements above tunnels in the United Kingdom – their magnitude and prediction; Proceedings of Tunnelling 82, Institution of mining and metallurgy, London pp 173-181

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5.3.20 In the Oasis X-Disp 19.3 model produced for this report, equations 5.5 and 5.6 were used in order to generate the settlement contours. These are based on Eq. 5.4 but have been adjusted to reflect field data (New and O’Reilly 1991)9.

. . Equation 5.5 For cohesive soils

. . Equation 5.6 For granular soils

Volume Loss

5.3.21 The volume loss related to the ground displacements must be estimated in order to determine the ground surface settlement profile. This volume, V, can be expressed as a percentage of the excavation volume and is referred to as the percentage volume loss.

5.3.22 The magnitude of volume loss will depend upon the construction methodology, its control and the soil type surrounding the excavation.

5.3.23 Following study of the Emirates Air Line (EAL) design documentation produced by Buro Happold it has been recorded that a volume loss figure of 1.7% was adopted in design of the assets foundation. As the EAL is one of the East London iconic landmark structures, and of significant importance to the operator (Docklands Light Railway), a project decision was taken that it would be prudent conservative to adopt the 1.7% volume loss figure for the assessment of bored tunnels and cross passages.

5.3.24 Based on the zone of influence established in Phase I, a volume loss figure of 1.7% was used again for the bored tunnels and cross passages in the Phase II assessment.

5.4 Cut-and-Cover and retained box excavation settlement

5.4.1 According to procedures from case studies presented in CIRIA C580, the ground surface settlement profile for the Cut-and-Cover and the retained box excavation techniques has been described as the hogging zone of the inverted Gaussian distribution curve.

9 New, B.M. and O’Reilly, M.P. (1991) Tunnelling induced ground movements: predicting their magnitude and effects; invited review paper to 4th international conference on ground movements and structures, Cardiff, Pentech press, London

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5.4.2 The retaining wall construction will produce the maximum settlement at the wall face, where the minimum will be found at a distance W from the wall face. The following equation is used to calculate the settlement values:

. Equation 5.7

5.4.3 Where,

5.4.4 Sv = settlement due to the box construction (m);

5.4.5 v = settlement at the retaining box face (m);

5.4.6 y = distance from the box outer wall (m);

5.4.7 W = extent of the settlement trough (m).

5.4.8 For the horizontal movements, we define the following equation:

. Equation 5.8

5.4.9 Where,

5.4.10 h = horizontal ground movement at the box wall face (m).

5.4.11 For these excavations, ground movements are dependent on the ground conditions, excavation’s depth and the support system stiffness.

5.5 Subsurface settlements

5.5.1 Similar to surface settlement, the sub-surface settlement trough takes the form of an inverted Gaussian distribution curve. However it has been observed that the improved prediction values can be obtained assuming a radial ground flow oriented toward the invert of the tunnel rather than the tunnel axis.

5.5.2 New & Bowers (1994)10 sub-surface settlement calculation method is based on the Ribbon Sink assumptions. The ground loss is assumed to occur along a line at the invert of the tunnel, at constant rate of excavation, given by the volume loss defined previously.

10 New and Bowers (1994) Ground movement model validation at the Heathrow Express trial tunnel 74. Transport Research Laboratory, Crowthorne, England

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5.5.3 Vertical and horizontal movements have been obtained by integrating the New & O’Reilly (1991)11 equations on a ribbon shaped zone of ground loss at the invert level as shown on Figure 5.2.

5.5.4 Equations for the ribbon shaped zone of ground loss calculations are given in New and Bowers (1994)12.

Figure 5.2 Scheme of notation for ribbon representation, from New & Bowers, 1994

5.6 Consolidation effects

5.6.1 The volume loss used in this assessment has been based on short‐term construction effects that are usually considered to be ‘immediate’. Consolidation settlements occur due to changes in pore water pressures around the tunnel and generally occur over a much longer period. The magnitude of this consolidation settlement is difficult to predict, but case studies indicate that this can be similar or greater than the short‐term settlement in certain ground conditions (more generally in uniformly cohesive ground conditions unlike Silvertown). However, where such settlements occur they affect a wide area and are therefore less likely to cause damage to assets by differential settlements. For this reason, consolidation effects have not been considered at this phase of the settlement assessment.

11 New, B.M. and O’Reilly, M.P. (1991) Tunnelling induced ground movements: predicting their magnitude and effects; invited review paper to 4th international conference on ground movements and structures, Cardiff, Pentech press, London 12 New and Bowers (1994) Ground movement model validation at the Heathrow Express trial tunnel 74. Transport Research Laboratory, Crowthorne, England

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6. BUILDINGS AND SIMILAR STRUCTURES ASSESSMENT PROCESS

6.1 General

6.1.1 The assessments were carried out in two phases. In the Phase I assessment, assets found within the 1mm settlement contour were identified. Of these, any structure within the 10mm settlement contour zone or exposed to a ground slope greater than 1/500 were then taken forward to Phase II where more detailed assessments of the potential damage to each asset was carried.

6.2 Damage Risk Assessment Method

6.2.1 The assets damage risk assessment was initially completed using typical values of maximum building slope and settlement based on information provided in Table 9 of CIRIA Project Report 30 (1996)13. This has been given in Table 6.1 and is applicable to all buildings (assets) under this assessment. The results were reviewed and assets categorised on a basis of higher risk category from either slope or settlement considerations. It was acknowledged that this may not apply directly to the reinforced concrete and the steel frame assets, but it gives an indication of the potential impact.

Table 6.1 Damage risk categories based on typical values of maximum asset slope or settlement

Risk Category

Maximum slope of building

Maximum settlement of building (mm)

Description of risk

1 <1/500 <10 Negligible: superficial damage unlikely

2 1/500 – 1/200 10 - 50 Slight: possible superficial damage which is unlikely to have structural significance

3 1/200 - 1/50 50 - 75 Moderate: expected superficial damage and possible structural damage to buildings and infrastructure

4 >1/50 >75 High: expected structural damage to buildings and infrastructure

13 CIRIA Project Report 30, 1996 (CIRIA 30) Prediction and effects of ground movement caused by tunnelling in soft ground beneath urban areas.

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6.2.2 In addition to the initial categorisation tool the tensile strain was also determined for the affected assets (where applicable) following the elastic beam theory developed by J.B. Burland.

6.2.3 In Phase II of the assessment process, assets were represented by an elastic, deep beam model (where applicable). The settlement calculated for the “green-field” conditions was imposed on the asset, i.e. it is assumed that the asset behaves completely flexibly and its own stiffness has no influence on the settlement behaviour. The strain developed by deformation of this beam model due to ground movements was assessed. In addition, the surface deformation due to horizontal ground movement was assumed to be transmitted completely to the building. Using the obtained tensile strain the asset was assigned to a damage risk category based upon the work of Burland, Broms and de Mello (1977) and Boscardin & Cording (1989)14. The categories and the typical damage descriptions are reproduced in Table 6.2.

Table 6.2 Asset damage risk categories based on Limiting Tensile Strain

Risk Category and Description

Max Tensile Strain (%)

Description of Typical Damage and Likely Form of Repair for Typical Masonry Buildings

Approx. Crack Width (mm)

0. Negligible 0.0 – 0.05 Hairline cracks <0.1

1. Very slight 0.05 - 0.075 Fine cracks which can easily be treated. Perhaps isolated slight fractures in buildings. Cracks in external brickwork visible on inspection.

<1

2. Slight 0.075 – 0.15 Cracks easily filled. Redecorating probably required. Several slight fractures showing inside of building. Cracks are visible externally and some repointing may be required externally to ensure weather tightness. Doors and windows may stick slightly.

<5

3. Moderate 0.15 – 0.3 The cracks require some opening up and can be patched by a mason. Recurrent cracks can be masked by suitable linings. Repointing of external brickwork and possibly a

5 to 15 or number of cracks >3

14 Burland, J.B., Broms, B.B., and de Mello, V.F. (1977) and Boscardin & Cording (1989). Building damage risk categories.

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small amount of brickwork to be replaced. Doors and windows sticking. Service pipes may fracture. Weather tightness often impaired.

4. Severe >0.3 Extensive repair work involving breaking out and replacing sections of walls, especially over doors and windows. Windows and door frames distorted, floor sloping noticeably. Walls leaning and bulging noticeably, some loss of bearing in beams. Service pipes disrupted.

15 to 25 but depends on number of cracks

5. Very Severe This requires a major repair job involving partial or complete rebuilding. Beams lose bearing, walls lean badly and require shoring. Windows broken due to distortion. Danger of instability.

>25 but depends on number of cracks

Note: Crack width is only one factor in assessing category of damage and should not be used on its own as a direct measure of it.

Note: local deviation of slope, from the horizontal or vertical, of more than 1/100 will normally be clearly visible. Overall deviations in excess of 1/150 are undesirable.

6.2.4 Assets that are assigned the damage category 3 (Moderate risk) or above will be considered in need of further investigation and should be taken forward to a Phase III assessment.

6.2.5 For every asset that would be taken into Phase III assessment, assumptions made in the Phase I and II will need to be re-examined at a Detail Design stage. If following the re-examination the asset is still found in a damage category above 3 then a detailed structural analysis of the asset should be undertaken for the predicted ground movements.

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7. PHASE I ASSESSMENT

7.1.1 The Phase I Assessment results are presented in this section. The “green-field” ground surface settlement contours are presented in Appendix B.

7.2 Settlement predictions

7.2.1 Based on the results of the Phase I Assessment, all structures within the 1mm settlement contour were identified in Table 7.1. Amongst these assets, those which are located within the 10mm settlement contour or presenting a ground slope greater than 1/500 were subjected to a Phase II Assessment and are identified in Table 7.2. This selection criterion was based on information presented in Table 6.1.

7.2.2 Approximate asset height from the underside of the foundation to the highest structural elements has been scaled from the available drawings and site photos. Where the foundation information has not been available, reasonable and conservative assumptions were taken, based on experience and engineering judgment.

7.2.3 Within the 1mm predicted settlement contour zone at Greenwich there is the Grade II listed entrance arch structure to the Blackwall Tunnel. Where at significant damage risk, normal procedure would be to assess such a building by a Heritage Building Specialist, and ensure all special and fragile features are identified, and that the building is assigned to an appropriate damage category respecting its heritage status, following initial damage risk categorisation. However, whilst the building's curtilage lies within the assessed settlement trough of surface ground movements, the expected damage risk is low because the actual ground movements are expected to be significantly lower than those conservatively predicted, due to the construction processes involved and the excavation geometry of the nearest works.

7.2.4 It is recommended that an assessment of the building be undertaken at Detail Design stage using 2d or/and 3d numerical modelling techniques in order to investigate the actual aggregate construction effects on the structure, taking into account the detailed construction sequence and construction proposals, significant damage risk is not anticipated.

7.2.5 The location of the surface structures listed in Table 7.1 and Table 7.2 is presented on drawings B.1.1 to B.1.6, which can be found in Appendix B.

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Table 7.1 Silvertown Tunnel Assets identified within the 1mm surface contour zone

Lp. Asset No.

Asset Description

Structural Form

Total Asset Height / Depth of the foundation (approximate)

Foundation type

1 B1_N Warehouse Portal frame

Assume

12.0m / 0.5m

Foundation Information Unavailable. Assume shallow pad foundation due to light weight of the building. Assume no basement

2 B2_N Warehouse Possibly steel frame

Assume

16.0m / 0.5m



Assume

12.0m / 0.5m



Assume

12.0m / 0.5m


5 B5_N Covered store area

Industrial Canopy

Assume

7.0m / 0.5m

Foundation Information Unavailable. Assume shallow pad foundation due to light weight of the building.


11.5m / 0.5m Possibly strip foundations around the building perimeter.

7 SRW South River Wall

Framingham Sheet Piles, concrete coping

10.0m The wall toe level is located approximately 4.0 above the proposed tunnel extrados (based on the available historical information)

8 NRW North River Wall

Larssen Sheet Piles,

12.5m The wall toe level is located approximately 5.0 above the proposed

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concrete coping

tunnel extrados (based on the available historical information)

9 B1_S O2 car park office

Masonry ~3.0m / 0.5m Foundation Information Unavailable. Assume 10shallow strip foundations located under the main walls. Assume no basement

10 EAL_S_1 EAL South Station

Steel Frame

15.0m AGL/ ~42m deep piles with cap

Pile raft

11 EAL_S_5 EAL SIP Pontoon B

Piles joined by steel frame

15.0m above river bed, ~12.0 to 21m deep piles below river bed

Pile Group

12 EAL_N_2 EAL North Intermediate tower

Pylon 60.0m AGL/ ~48.0m deep piles with cap

Pile group

13 Bpier_DLR_1

DLR viaduct pier No 1

Pier Assume 8m above pile cap level, piles and the pilecap depth unknown, assume 25m BGL

Pile group

14 Bpier_DLR_2


Pier Assume 8m above pile cap level, piles and the pilecap depth unknown assume 25m BGL

Pile group

7.2.6 A number of assets which following the Phase I assessment have been selected for the Phase II assessment, cannot be modelled satisfactorily as an elastic beam in line with the theory developed by J.B Burland. This is due to their complicated structure. These assets are; the Emirates Air Line (EAL) towers; the Ship Impact Protection pontoons; the Docklands Light Railway (DLR) Woolwich Branch viaduct piers; as well as the River Thames Walls. All of the assets which fall into Phase II assessment are included in Table 7.2, however the maximum tensile strain has not been presented in Table 8.1, as it is believed to not be representative.

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Table 7.2 Silvertown Tunnel Assets requiring the Phase II Assessment.

Asset No. Asset Description Structural Form

B1_N Warehouse Portal frame

B2_N Warehouse Possibly steel frame



B5_N Warehouse Industrial Canopy


SRW South River Wall Frodingham Sheet Piles, concrete coping

NRW North River Wall Larssen Sheet Piles, concrete coping

EAL_S_1 EAL South Station Steel Frame

EAL_N_2 EAL North Intermediate tower Pylon

Bpier_DLR_1 DLR viaduct pier No 1 Pier

Bpier_DLR_2 DLR viaduct pier No 2 Pier

B1_S O2 car park office Masonry

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8. PHASE II ASSESSMENT

8.1 Results

8.1.1 Surface settlement details for the third party assets located in the vicinity of the Silvertown Tunnel scheme are given in Table 8.1 below. These structures were classified to the appropriate damage category following the risk parameters presented in Table 6.2 of this report.

Table 8.1 Surface Settlement Assessment Results

Asset

Maximum vertical surface

settlement (mm)

Maximum Slope

Maximum Tensile

strain (%)

Damage risk category

B1_N 102 0.0043 0.181 Moderate (3)

B2_N 88 0.0042 0.078 Slight (2)

B3_N 100 0.0043 0.173 Moderate (3)

B4_N 100 0.0043 0.173 Moderate (3)

B5_N 26 0.0028 0.132 Slight (2)

B6_N 76 0.0038 0.118 Slight (2)

O2 car park office

116 0.0110 0.455 Severe (4)

SRW 110 0.0125 NA Moderate (3)

NRW 152 0.0250 NA Severe (4)

EAL South Station

68 0.0028 NA NA

EAL North Intermediate tower

28 0.0028 NA NA


53 0.0045 NA NA


51 0.0045 NA NA

8.1.2 The EAL South Station and the North Intermediate Tower, located within the 10mm settlement zone, are founded on deep piles in excess of 40m in depth. This is approximately 15 to 20m below the proposed tunnel invert level. Taking this into consideration the provided settlement values of 68mm and 28mm are not representative as these structures foundations extend deep below the settlement effects zone.

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8.1.3 In addition the North Intermediate Tower is constructed within the redundant Royal Victoria Dock Western Entry and separated from the tunnel by possible in-situ lock gates, left in place while the entry was decommissioned, There is a possibility of a clash between lock gates and Cut-and-Cover structure., Therefore there must be a safe procedure in place in order to cut/take out the lock gates causing as low as possible zero or very limited horizontal and vertical ground movements will that may reach the tower piles. Possible solution is to use sheet piles behind the lock gates in order to take them out.

8.1.4 A series of the Acceptance of Design documentation was prepared by Buro Happold (Emirates Air Line designer) in order to prove that the proposed scheme has met the Employer’s Requirements (TfL).

8.1.5 It was required by Buro Happold to demonstrate that construction of the Silvertown Tunnel will not affect the Cable Car operations, based upon assumption that the tunnel construction may induce a maximum volume loss of 1.7%.

8.1.6 The effect of the Silvertown Tunnel construction on the EAL assets was assessed by Buro Happold (BH) by means of a combination of semi-empirical and numerical analyses, using a combination of the software Oasys XDisp 19.2 and Plaxis v9. In the analysis, an external tunnel diameter of 14m was adopted and the most adverse alignment (provided by the previous designer) was used to obtain the worst case results.

8.1.7 The deep foundations for the EAL assets were designed for axial loads (compression & tension), bending moments and shear forces that will be induced by the superstructure loading and the proposed Silvertown Tunnel construction.

8.1.8 The South Station nearest foundation pile distance at the time of the structure design was estimated at 6.5m. As the tunnel diameter has now been reduced from 14.0m to 12.35m and the alignment offset improved, this distance has increased to 7.6m. It is therefore believed that the structure is not under threat of significant damage risk due to the tunnel construction, as the assessment factors i.e. tunnel diameter and clear distance, now work in favour of the EAL asset.

8.1.9 Taking into consideration the depth of the DLR viaduct foundation (approximately 12m below the proposed Cut-and-Cover section), it can be assumed that the effect of tunnel construction on the DLR should be negligible. However comprehensive modelling of the asset behaviour during

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the tunnelling works would need to be undertaken at the project Detailed Design stage and monitoring installed prior to the tunnel construction.

8.1.10 The sub-surface settlement assessment covered the Emirates Air Line and Ship Impact Protection Pontoon B for the South Main Tower. According to the available information the piles toe level of this structure is located just above the tunnel invert level. The assessment results indicated that the vertical ground settlements of less than 1mm are expected at the piles toe level, hence the vertical ground movement should not affect the pontoon. However at a Detail Design stage the horizontal ground movement effects acting on the SIP assets should be investigated, in order to confirm that the structure will not be subject to an unacceptable level of tilt while tunnelling progresses. Tilting of the SIP assets may affect operation of the floating pontoons that slide along the pile therefore the specified limits of deviation (by SIP designer) should be reviewed and compared with the detailed analysis results.

8.1.11 The sub-surface settlement analysis also covered the South and North River Walls. South River Walls are structurally paired walls, with the exterior wall tied to the interior buried sheet pile wall. This arrangement makes it highly unlikely that any ground disturbance will destabilize the anchors as the buried wall would also have to become unstable.

8.1.12 Due to these structures being linear assets positioned perpendicularly to the tunnel axis (approximately 5m above the tunnel extrados crown) high settlements are expected at these locations. However, it is expected that the structure will not deflect to the same extent as the “green-field” calculations show since piles are interlocked, and portions of the wall are outside the influence zone. With regards to the above the walls will have to be further assessed at the Detail Design stage.

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9. UTILITIES ASSESSMENT

9.1 General

9.1.1 With the exception of polyethylene (PE) pipes, all utilities infrastructure within the 1mm surface settlement contour were assessed and categorised using the appropriate acceptance criteria. PE pipes are more flexible and hence are considered to be more tolerant of ground movements. Therefore, only those PE pipes subjected to settlement of more than 50mm will be assessed (after Attewell et al., 1986)15.

9.1.2 Data necessary for the assessment has been collated from relevant utilities drawings. Where some aspects of information required to undertake the assessment were incomplete, necessary assumptions have been made.

9.2 Assumptions

9.2.1 List of assumptions that has been made is in below table:

Table 9.1 Utilities assumptions

Asset Name Asset Owner Assumed Size (mm)

Assumed Material

Assumed Cover (mm)

Silvertown side (Bell Lane)

250PE GAS 1 Silvertown

National Grid Gas 250 PE 800

250PE GAS 2 Silvertown

National Grid Gas 250 PE 800

Greenwich side (East Parkside)

250PE GAS 1 Southern Gas Network 250 PE 1500





125PE GAS branch 0

Southern Gas Network 125 PE

2200

15 Attewell, P. B., Yeates, J. & Selby, A. R. (1986). Soil movements induced by tunnelling and their effects on pipelines and structures. Balckie, Glasgow.

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125PE GAS branch 1


1500

125PE GAS branch 2


1500

125PE GAS branch 3


1500

125PE GAS branch 4


1500

125PE GAS branch 5


1500

125PE GAS branch 6


1500

125PE GAS branch 7


1700

180PE GAS GCG 1

GCG 180 PE 800

180PE GAS GCG 2

GCG 180 PE 800

180PE GAS GCG 3

GCG 180 PE 800

180PE GAS GCG 4

GCG 180 PE 800

180PE GAS GCG 5

GCG 180 PE 800

300 PE water 1 Thames Water 300 PE 900








300 PE water branch 1

Thames Water 300 PE

900


Thames Water 300 PE

900

300 PE water branch 3a

Thames Water 300 PE

900

300 PE water branch 3b

Thames Water 300 PE

900

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Thames Water 300 PE

900


Thames Water 300 PE

900

600 concrete drainage 1

Thames Water 600 Concrete 2500





150 VC drainage 4

Thames Water 150 Vitrified Clay

4700



225 VC drainage 1

Thames Water 225 Vitrified Clay

2500

9.2.2 All PE utilities in above table lay in the areas where calculated surface settlements exceeds 50mm. Those pipes were assessed based on Water Research Centre ‘Polyethylene Pipe systems Manual’ where following guidance was employed:

9.2.3 The bending of polyethylene is permissible and the properties of fusion jointed systems enable changes of direction. However, the pipe should not normally be cold bent to a radius of less than 25 times the outside diameter of the pipe. It should be noted that since the joints and fittings for polyethylene pipes are normally fused together, it is assumed that the response of such pipes to ground movements will not be influenced by the joints.

9.2.4 The following acceptance criteria are generally consistent with published values (after Attewell et al. (1986)16 & Bracegirdle et al. (1996)17). In table below list of assumed acceptance criteria for materials other than PE has been listed:

16 Attewell, P. B., Yeates, J. & Selby, A. R. (1986). Soil movements induced by tunnelling and their effects on pipelines and structures. Balckie, Glasgow. 17 Bracegirdle, A., Mair, R. J., Nyren, R. J., and Taylor, R. N. (1996). A methodology for evaluating potential damage to cast iron pipes induced by tunnelling. Proc. Int. Symp. on Geotechnical Aspects of Underground Construction in Soft Ground, Mair & Taylor (eds), Balkema, London, April 1996, pp 659-664.

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Table 9.2 Assumed acceptance criteria

Material Allowable Strain Rotation Pullout Young’s Modulus

Poisson’s Ratio

Axial Strain reduction factor Tension/ Compression

Tension (με)

Compression (με)

Limit (deg)

Limit (mm)

Vitrified Clay

80 400 2 12.5 5.00E+07 0.275 0.2

Concrete <750mm

40 400 1 12.5 5.00E+07 0.275 0.2

Concrete >750mm

60 400 0.5 12.5 5.00E+07 0.275 0.2

9.3 Results

9.3.1 Surface Settlement details for the third party assets located in the vicinity of the Silvertown Tunnel scheme are given in Table 9.3 below. These structures were assessed following the acceptance criteria represented above.

Table 9.3 Surface Settlement Assessment Results

Asset Name Asset Owner Site Status

Failure mode

250PE GAS 1 Silvertown National Grid

Gas Silvertown OK N/A

250PE GAS 2 Silvertown National Grid

Gas Silvertown OK N/A

250PE GAS 1 Southern Gas

Network Greenwich OK N/A









125PE GAS branch 0 Southern Gas




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180PE GAS GCG 1 GCG Greenwich OK N/A





300 PE water 1 Thames Water Greenwich OK N/A








300 PE water branch 1 Thames Water Greenwich OK N/A


300 PE water branch 3a Thames Water Greenwich OK N/A

300 PE water branch 3b Thames Water Greenwich OK N/A



600 concrete drainage 1 Thames Water Greenwich Fails Tension

1050 concrete drainage 2 Thames Water Greenwich OK N/A

1050 concrete drainage 3 Thames Water Greenwich Fails Tension/Compression

150 VC drainage 4 Thames Water Greenwich Fails Tension/Compression

675 concrete drainage 5 Thames Water Greenwich Fails Tension

225 VC drainage 1 Thames Water Greenwich OK N/A

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10. RECOMMENDATIONS

10.1 General

10.1.1 It is recommended that the proposed tunnel route is visually surveyed shortly prior to the tunnel construction in order to confirm that all the assets identified within this report are still present and that no additional structures have been constructed which have not been considered in this report.

10.1.2 A defect survey should be undertaken prior to tunnelling works for all assets listed in this report and constructed since this publication in the zone of influence.

10.1.3 Following the tunnel route pre-construction survey, the locations where existing asset demolition took place should be recorded. These sites should then be surveyed in order to ensure that all possible deep foundation piles that may obstruct the Tunnel Boring Machine operation have been removed. If residual deep obstructions that could clash with the tunnel alignment are recorded, then an extraction methodology should be developed and works completed prior to tunnelling taking place.

10.1.4 The O2 car park office has been labelled as at ‘severe’ risk of damage and should be taken to a Phase III assessment, as stated in Section 0 of this report. However taking into consideration the Greenwich Peninsula Masterplan this building is planned to be demolished.

10.1.5 The River Thames walls and the Silvertown industrial buildings No. B1_N, B3_N and B4_N have been labelled as at ‘moderate’ to ‘severe’ risk of damage and hence should be taken to a Phase III assessment at a Detail Design stage. However these industrial buildings mentioned above currently are proposed to be demolished. Depending on the Phase III assessment outcome, possible protective works may be required for some assets. The expected land required for the works has been identified as part of the design process and is presented on the settlement contour drawings.

10.1.6 The DLR Woolwich Branch viaduct and the EAL Ship Impact Protection Pontoon B should undergo a Phase III assessment at the Detailed Design stage in order to ensure that no adverse effects will be imposed on these structures during and after the Silvertown Tunnel construction.

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10.2 Utilities

10.2.1 It is recommended that the further assessment should be undertaken for the utilities in the area of tunnel construction. Based on current conservative assumptions drainage pipes laying in the area of Greenwich site are failing due to high value of tension/compression in the concrete and vitrified clay sections. Therefore appropriate mitigation measures shall be employed (i.e. replacement or by-pass).

10.2.2 Discussion shall take place with the utility companies to establish whether the methodology proposed by Bracegirdle et al. (1996)18 shall be used to assess the potential for damage to near surface utilities resulting from excavation induced ground movements.

10.2.3 The acceptance criteria shall be agreed with each asset owners. A risk-based approach should be agreed with the utility owner that takes account of the strategic nature of the asset, and the consequences of failure, including consequence of multiple asset failure following a single settlement event.

10.3 Monitoring

10.3.1 It is recommended that all the assets identified for the Phase II assessment and all utilities identified in the report have defect surveys undertaken pre and post tunnel construction. They should also be monitored before, during and after the construction of the tunnel. These assets should have monitoring installed as agreed with the asset owner. This monitoring should continue until the project manager and the asset owner is satisfied that the ground movements has stabilised.

10.3.2 The monitoring of ground movements along the tunnel (where feasible) and the open cut approaches will allow confirmation of the assessment and provide confidence in the assumptions on which the report relies, in addition to the behaviour of the above ground structures during the tunnelling.

10.3.3 It is recommended to check/monitor operations of the EAL Ship Impact Protection floating pontoons before, during and after the tunnelling works.

18 Bracegirdle, A., Mair, R. J., Nyren, R. J., and Taylor, R. N. (1996). A methodology for evaluating potential damage to cast iron pipes induced by tunnelling. Proc. Int. Symp. on Geotechnical Aspects of Underground Construction in Soft Ground, Mair & Taylor (eds), Balkema, London, April 1996, pp 659-664.

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This should be discussed and agreed with the asset operator, in order to establish monitoring requirements and schedule of the operation checks.

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11. LIMITATIONS

11.1 General

11.1.1 It should be noted that the O’Reilly and New (1982)19 methodology used in the XDisp (Oasys) analysis has only considered the ground as a single layer strata. Whilst a conservative approach has been taken, this is not a true reflection of the actual highly complex ground profile. Detail Design should consider the ground with multilayer strata where Phase III assessments are concerned. A single layer strata has also been used when analysing the tunnel approach excavations.

11.1.2 Modelling buildings as beams whose displacements are directly proportional to ground displacements is a fairly simplistic approach and suitable only for Phase I & II assessments. It can be argued that using this method to model the DLR viaduct, the River Walls and the Emirates Air Line assets is inappropriate. Further phases of analysis i.e. Phase III will more accurately model these buildings behaviour with regards to the ground settlements.

11.1.3 It is currently envisaged that the Cut-and-Cover tunnels will be constructed utilising the top-down construction method, see the Construction Method Statement (Document Reference 6.3). This method involves early installation of the cover slab which acts as high level propping, however a more conservative model has been used at this stage i.e. no high level propping. At the Detail Design stage this assumption will need to be revisited and the settlement modelling undertaken, taking into consideration the actual construction sequence adopted.

11.1.4 This report does not take into account future developments planned along the tunnel alignment due to the area Masterplan still being at a preliminary stage with no detailed information available. These developments may or may not be built before the tunnel construction commences and therefore should be reviewed yet again at the Detail Design stage.

19 O’Reilly, M.P. and New, B.M. (1982) Settlements above tunnels in the United Kingdom – their magnitude and prediction; Proceedings of Tunnelling 82, Institution of mining and metallurgy, London pp 173-181

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Appendix A. GEOLOGICAL LONG SECTIONS

Atkins drawing No. STWTN-ATK-HGT-XXXX-DR-C-0001 “Geological long section and location plan - Sheet 1”;

Atkins drawing No. STWTN-ATK-HGT-XXXX-DR-C-0002 “Geological long section and location plan - Sheet 2”;

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N

ST03

ST07

ST06ST05

ST02

ST04

BM-S

BM-N

2003-WS104B

2003-101A2003-101B

0+700

0+720

0+740

0+760

0+780

0+800

0+820

0+840

0+860

0+880

0+900

0+920

0+940

0+960

0+980

1+000

1+020

1+040

1+060

1+080

1+100

1+120

1+140

1+160

1+180

1+200

1+220

1+240

1+260

1+280

1+300

1+320

1+340

1+360

1+380

1+400

1+420

1+440

1+460

1+480

1+500

1+520

1+540

1+560

1+580 1+600 1+620 1+640 1+660 1+680 1+700 1+720 1+740 1+760 1+780 1+800

1+820

1+840

1+860

1+880

1+900

1+920

1+940

1+960

1+980

2+000

2+020

2+040

2+060

2+080

2+100

2+120

2+140

2+160

2+180

TU B

H01

Offs

et: 6

.8m

TU B

H02

Offs

et: -

0.3m

G3

Offs

et: -

9.4m

EB

1O

ffset

: 11.

3m

G5

Offs

et: 3

.6m

ET9

Offs

et: 1

1.8m

G9

Offs

et: 7

.5m

G6

Offs

et: -

2.1m

ET5

Offs

et: 0

.0m

2003

-102

Offs

et: 9

.5m

2003

-WS

106

Offs

et: -

19.0

m

2003

-106

Offs

et: 1

9.7m

2003

-WS

102

Offs

et: 1

0.9m

2003

-101

CO

ffset

: 5.7

m

G10

AO

ffset

: 9.3

m

G1B

Offs

et: 1

3.3m

Elevation (m

AO

D)

16251350 1600 1750 1775 1875-55.00

-50.00

-30.00

-40.00

-20.00

-10.00

0.00

10.00

900 925 950 975 1000 1025 1050 1075 1100 1125 1150 1175 1200 1225 1250 1275 1300 1325 1375 1400 14751425 1450 1500 1525 15751550 170016751650 18501725 1800 1825 1900 1925 1950 2000 2100 211975 20752025 21502050 2125

GEOLOGICAL SECTION LEGEND:

MADE GROUND

ALLUVIUM

RIVER TERRACE DEPOSIT

LONDON CLAY

THANET SAND

CHALK

HARWICH FORMATION

READING FORMATION LOWER MOTTLED CLAY

WOOLWICH FORMATION LAMINATED BEDS

WOOLWICH FORMATION LOWER SHELLY CLAY

UPNOR FORMATION

HARDSTANDING

EXISTING GROUND LEVEL

ROAD ALIGNMENT

ZONE OF CORE LOSS

TUNNEL OUTLINE

PLAN LEGEND:

CABLE PERCUSSION

TRIAL PIT / TRENCH

OBSERVATION PIT

ORANGE SYMBOLS DENOTE HOLESUSED ON THE LONG SECTION

LOCATIONPLAN

SAFETY, HEALTH AND ENVIRONMENTALINFORMATION

In addition to the hazards/risks normally associated with the types of workdetailed on this drawing, note the following significant residual risks(Reference shall also be made to the design hazard log).ConstructionGroundwater is contiguous with the tidal River Thames throughout thegeological sequence. High groundwater pressures may be expected at thetunnel face throughout the tunnel drive.Maintenance / CleaningNone

UseNone

Decommissioning / DemolitionNone

Date

Designed / Drawn

Revision

Scale

Drawing Number

Drawing Title

Project TitleDrawing Status

DO

NO

T S

CA

LE

Date Date Date

Checked ApprovedClient

Original Size

Suitability

Mill

imet

res

100

100

A1

Plo

tted:

Apr

26,

201

6 - 5

:48p

m b

y: B

RO

W31

84

Drawn / Des DateCheckedRev Approved

Description

Authorised

Copyright C Atkins Limited (2014)

Woodcote GroveAshley RoadEpsomSurreyKT18 5BW

www.atkinsglobal.com

Tel:Fax:

+44 (0)1372 726140+44 (0)1372 740055

SILVERTOWN TUNNELREFERENCE DESIGN

GEOLOGICAL LONG SECTIONAND LOCATION PLAN

SHEET 1 OF 2

STWTN-ATK-HGT-XXXX-DR-C-0001 P03

S2FOR INFORMATION

AS SHOWN SB

26/04/16

RS

26/04/16

SRM

26/04/16

MRM

26/04/16P03 SB RS SRM 26/04/16

For TfL Review

P02 SB MK MK 25/09/15

For TfL Review

P01 JC FR SRM 19/06/15

Draft

Scale 1:2000

50m 0m 50m 100m LONG SECTION1:2000H 1:500V

CO

NTI

NU

ATI

ON

ON

DW

G S

TWTN

-ATK

-HG

T-X

XX

X-D

R-C

-000

2C

ON

TIN

UA

TIO

N O

N D

WG

STW

TN-A

TK-H

GT-

XX

XX

-DR

-C-0

002

PLAN1:2000

NOTES:

1. THIS DRAWING IS TO BE READ IN CONJUNCTION WITH THE GROUND INVESTIGATION REPORT (GIR)STWTN-ATK-VGT-XXXX-RP-GE-0001.

2. TOPOGRAPHY IS TAKEN FROM THE TOPOGRAPHICAL SURVEY STWTN-ATK-GEN-XXXX-M3-G-0001.3. RIVER BED LEVEL IS TAKEN FROM THE BATHYMETRY SURVEY STWTN-ATK-VTO-XXXX-M3-G-0002.4. GEOLOGICAL DATA USED IN THE THREE DIMENSIONAL (3-D) MODEL (STWTN-ATK-GEN-XXXX-M3-Z-0001)

HAS BEEN SOURCED FROM A NUMBER OF GROUND INVESTIGATION REPORTS, INCLUDINGa. ATKINS, DLR LCY EXTENSION, 1998b. ATKINS, GREENWICH PENINSULA, 2003c. BURO HAPPOLD, LONDON CABLE CAR, JULY 2011d. ATKINS, SILVERTOWN TUNNEL, JUNE 2015

5. THE GEOLOGICAL SECTION SHOWN IS A SLICE THROUGH THE 3-D GROUND MODEL, USING ALL OF THEAVAILABLE DATA, AS LISTED IN NOTE 4. THE BOREHOLES SHOWN ON THE SECTION ARE A SELECTIONALONG THE LINE OF SECTION, FOR ILLUSTRATIVE PURPOSES ONLY. THEY DO NOT REPRESENT THETOTALITY OF DATA USED TO GENERATE THE SECTION.

6. THE GEOLOGICAL SECTION IS TAKEN ALONG THE CENTRE LINE OF THE NORTH TUNNEL.

CROSS PASSAGES OMITTED FOR CLARITY

THIS MAP IS REPRODUCED FROM ORDNANCE SURVEY MATERIAL WITHTHE PERMISSION OF ORDNANCE SURVEY ON BEHALF OF THECONTROLLER OF HER MAJESTY'S STATIONERY OFFICE. © CROWNCOPYRIGHT. UNAUTHORISED REPRODUCTION INFRINGES CROWNCOPYRIGHT AND MAY LEAD TO PROSECUTION OR CIVIL PROCEEDINGS.Licence No. 100018928, 2014

an High Water

y

N

G21

G27

G24ET15

ET13

ET26

ET34ET25

ET33

ET36

ET22ET21

G20

ET18

1602+180

2+200

2+220

2+240

2+260

2+300 2+320

2+360

2+420

2+480

2+500

2+560

2+580

2+600

2+620

2+640

2+660

2+680

2+700

2+720

2+7402+748

NT

DS

02F

Offs

et: -

1.4m

NIT

BH

08O

ffset

: 7.5

m

NT

DS

01O

ffset

: -19

.9m

G17

Offs

et: 1

2.7m

G15

Offs

et: -

19.5

m

EB

4O

ffset

: 8.8

m

G20

Offs

et: -

5.4m

ET1

7O

ffset

: -11

.0m

ET2

4O

ffset

: 3.3

m

ET1

8O

ffset

: -8.

6m

ET3

2O

ffset

: -0.

6m

EB

6O

ffset

: -6.

5m

Ele

vatio

n (m

AO

D)

-55.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

10.00

75 2200 2250 22752225 2300 23502325 2375 2400 2425 2450 2475 25252500 2550 2575 2600 2625 2650 2675 2700 2725 2748

GEOLOGICAL SECTION LEGEND:

MADE GROUND

ALLUVIUM

RIVER TERRACE DEPOSIT

LONDON CLAY

THANET SAND

CHALK

HARWICH FORMATION

READING FORMATION LOWER MOTTLED CLAY

WOOLWICH FORMATION LAMINATED BEDS

WOOLWICH FORMATION LOWER SHELLY CLAY

UPNOR FORMATION

HARDSTANDING

EXISTING GROUND LEVEL

ROAD ALIGNMENT

ZONE OF CORE LOSS

TUNNEL OUTLINE

PLAN LEGEND:

CABLE PERCUSSION

TRIAL PIT / TRENCH

OBSERVATION PIT

ORANGE SYMBOLS DENOTE HOLESUSED ON THE LONG SECTION

LOCATIONPLAN

Date

Designed / Drawn

Revision

Scale

Drawing Number

Drawing Title

Project TitleDrawing Status

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NO

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CA

LE

Date Date Date

Checked ApprovedClient

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res

100

100

A1

Plo

tted:

Apr

26,

201

6 - 5

:49p

m b

y: B

RO

W31

84


Description

Authorised

Copyright C Atkins Limited (2014)

Woodcote GroveAshley RoadEpsomSurreyKT18 5BW

www.atkinsglobal.com

Tel:Fax:

+44 (0)1372 726140+44 (0)1372 740055

SILVERTOWN TUNNELREFERENCE DESIGN

GEOLOGICAL LONG SECTIONAND LOCATION PLAN

SHEET 2 OF 2

STWTN-ATK-HGT-XXXX-DR-C-0002 P03

S2FOR INFORMATION

AS SHOWN SB

26/04/16

RS

26/04/16

SRM

26/04/16

MRM

26/04/16P03 SB RS SRM 26/04/16

For TfL Review

P02 SB MK MK 25/09/15

For TfL Review

P01 JC FR SRM 19/06/15

Draft

Scale 1:2000

50m 0m 50m 100m

LONG SECTION1:2000H 1:500V

CO

NTI

NU

ATI

ON

FR

OM

DW

G S

TWTN

-ATK

-HG

T-X

XX

X-D

R-C

-000

1

CONTINUATION FROM DWG STWTN-ATK-HGT-XXXX-DR-C-0001

SAFETY, HEALTH AND ENVIRONMENTALINFORMATION

In addition to the hazards/risks normally associated with the types of workdetailed on this drawing, note the following significant residual risks(Reference shall also be made to the design hazard log).ConstructionGroundwater is contiguous with the tidal River Thames throughout thegeological sequence. High groundwater pressures may be expected at thetunnel face throughout the tunnel drive.Maintenance / CleaningNone

UseNone

Decommissioning / DemolitionNone

NOTES:

1. THIS DRAWING IS TO BE READ IN CONJUNCTION WITH THE GROUND INVESTIGATION REPORT (GIR)STWTN-ATK-VGT-XXXX-RP-GE-0001.

2. TOPOGRAPHY IS TAKEN FROM THE TOPOGRAPHICAL SURVEY STWTN-ATK-GEN-XXXX-M3-G-0001.3. RIVER BED LEVEL IS TAKEN FROM THE BATHYMETRY SURVEY STWTN-ATK-VTO-XXXX-M3-G-0002.4. GEOLOGICAL DATA USED IN THE THREE DIMENSIONAL (3-D) MODEL (STWTN-ATK-GEN-XXXX-M3-Z-0001)

HAS BEEN SOURCED FROM A NUMBER OF GROUND INVESTIGATION REPORTS, INCLUDINGa. ATKINS, DLR LCY EXTENSION, 1998b. ATKINS, GREENWICH PENINSULA, 2003c. BURO HAPPOLD, LONDON CABLE CAR, JULY 2011d. ATKINS, SILVERTOWN TUNNEL, JUNE 2015

5. THE GEOLOGICAL SECTION SHOWN IS A SLICE THROUGH THE 3-D GROUND MODEL, USING ALL OF THEAVAILABLE DATA, AS LISTED IN NOTE 4. THE BOREHOLES SHOWN ON THE SECTION ARE A SELECTIONALONG THE LINE OF SECTION, FOR ILLUSTRATIVE PURPOSES ONLY. THEY DO NOT REPRESENT THETOTALITY OF DATA USED TO GENERATE THE SECTION.

6. THE GEOLOGICAL SECTION IS TAKEN ALONG THE CENTRE LINE OF THE NORTH TUNNEL.

PLAN1:2000

CROSS PASSAGES OMITTED FOR CLARITY


Silvertown Tunnel



Page 57 of 57

Appendix B. GENERAL SETTLEMENT CONTOUR DRAWINGS

ST150030-ATK-ZZZ-ZZ-DR-CE-3161, “Ground Settlement Contours, Scheme Layout”;

ST150030-ATK-ZZZ-ZZ-DR-CE-3162, “Ground Settlement Contours, Sheet 1 of 5”;




ST150030-ATK-ZZZ-ZZ-DR-CE-3166, “Ground Settlement Contours, Sheet 5 of 5”.

Mean High Water

Boro Const & Ward Bdy

PLANSCALE 1:2500

NOTES:KEY:

DRAWING No.

STWTN-ATK-STU-XXXX-DR-C-0002

DRAWING No.


DRAWING No.


DRAWING No.


DRAWING No.


EXISTING BUILDINGS

EMIRATES AIR LINE ASSETS

DOCKLANDS LIGHT RAILWAY ASSETS

LONDON UNDERGROUND LIMITED JUBILEE LINE

RIVER THAMES WALLS

NORTHGREENWICH

O2 ARENA

SILVERTOWNRIVER THAMES

NOTES:1. THIS DRAWING SHOULD BE READ IN CONJUNCTION WITH SHEETS 1 TO 5 IN

THIS SERIES.2. THE DETAILED SETTLEMENT ASSESSMENT METHODOLOGY IS PRESENTED

IN ATKINS REPORT No. STWTS-ATK-STU-TUXX-RP-C-0006 "SETTLEMENTASSESSMENT REPORT"

N

DEMOLISHED BUILDING FOOTPRINT

ROYAL VICTORIA DOCK REDUNDANT WESTERN ENTRY

GAS WORKS DEMOLISHED BUILDINGS

C:\programdata\bentley\projectwise\brow3184\dms14408\STWTN-ATK-GEN-XXXX-DR-Z-3161.dwg: Plotted by: brow3184 Date: Apr 26, 2016 - 7:12pm

Drawing Status

DO

NO

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Suitability

Mill

imet

res

100

100

Date

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Revision

Scale

Project Drawing Number

Drawing Title

Project Title

Date Date Date

Checked Approved

Original Size

A1

Authorised


DescriptionAtk

ins

Ref

.

SILVERTOWN TUNNEL

GROUND SETTLEMENT CONTOURSSCHEME LAYOUT

STW

TN-A

TK-G

EN

-XX

XX

-DR

-Z-3

161

P01

S8FOR DCO SUBMISSION

1:2500 SB

26/04/16

GR

26/04/16

RW

26/04/16

MRM

26/04/16

P01 SB GR RW 26/04/16

For DCO Submission

ST150030-ATK-ZZZ-ZZ-DR-CE-3161

Scale 1:2500

50m 0m 50m 100m 150m


ORDER LIMITS

1 mm

5 mm

10 mm

25 mm

50 mm

25 mm

10 mm

5 mm

1 mm50 mm

75 m

m

50 m

m25 m

m10 m

m5 m

m1 m

m

100

mm

25 mm

75 m

m50

mm

25 m

m

10 m

m5

mm

1 m

m

75 mm

50 mm

25 mm

10 mm

5 mm

1 mm

FOR CONTINUATION SEE SHEET 2

BLACKWALL TUNNELENTRANCE GATES(GRADE II LISTED)

PLANSCALE 1:500

N


Drawing Status

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Date

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Date Date Date

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Authorised


DescriptionAtk

ins

Ref

.

SILVERTOWN TUNNEL

GROUND SETTLEMENT CONTOURSSHEET 1 OF 5

STW

TN-A

TK-G

EN

-XX

XX

-DR

-Z-3

162

P01


1:500 SB

26/04/16

GR

26/04/16

RW

26/04/16

MRM

26/04/16

P01 SB GR RW 26/04/16

For DCO Submission


Scale 1:500

10m 0m 10m 20m 30m


NOTES:1. THIS DRAWING SHOULD BE READ IN CONJUNCTION WITH

SHEETS 1 TO 5 IN THIS SERIES AND GROUND SETTLEMENTCONTOURS SCHEME LAYOUT DRAWINGST150030-ATK-ZZZ-ZZ-DR-CE-3161.

2. ALL SETTLEMENT VALUES ARE GIVEN IN MILLIMETERS3. SETTLEMENT IS BASED ON GROUND VOLUME LOSS OF 1.7%4. DRAWING INDICATES SHORT TERM SETTLEMENT ONLY5. THE DETAILED SETTLEMENT ASSESSMENT METHODOLOGY

IS PRESENTED IN ATKINS REPORT No.STWTS-ATK-STU-TUXX-RP-C-0006 " SETTLEMENTASSESSMENT REPORT"

KEY:

EXISTING BUILDINGS


DOCKLANDS LIGHT RAILWAYASSETSLONDON UNDERGROUNDLIMITED JUBILEE LINE

RIVER THAMES WALLS

ORDER LIMITS

SETTLEMENT CONTOURS:1mm

5mm

10mm

25mm

50mm

75mm

KEY PLAN

SHEET 3

SHEET 1

SHEET 2

SHEE

T 4

SHEE

T 5

1 mm

5 mm10 mm

25 mm

50 mm

75 mm

75 mm

50 mm

25 mm

10 mm

1 mm

1 mm

5 mm

10 mm

25 mm

50 mm

75 mm50 mm

25 mm

10 mm5 mm

1 mm

100 mm

100 mm

75 mm

75 mm

75 mm

100 mm

100 mm

125 mm

125 mm150 mm

EAL SOUTH STATION

75 mm

100 mm

O2 CAR PARKOFFICE

5 mm

75 mmFOR

CO

NTI

NU

ATI

ON

SE

E S

HE

ET

1

FOR

CO

NTI

NU

ATI

ON

SE

E S

HE

ET

3

PLANSCALE 1:500


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100

100

Date

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Revision

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Drawing Title

Project Title

Date Date Date

Checked Approved

Original Size

A1

Authorised


DescriptionAtk

ins

Ref

.

SILVERTOWN TUNNEL


STW

TN-A

TK-G

EN

-XX

XX

-DR

-Z-3

163

P01


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Scale 1:500

10m 0m 10m 20m 30m






KEY:

EXISTING BUILDINGS



RIVER THAMES WALLS

ORDER LIMITS


5mm

10mm

25mm

50mm

75mm

100mm

KEY PLAN

SHEET 3

SHEET 1

SHEET 2

SHEE

T 4

SHEE

T 5

125mm

150mm

N

1 mm

5 mm

10 mm

25 mm

50 mm

75 mm

100 mm

75 mm

50 mm

25 mm

10 mm5 mm

1 mm

125 mm

125 mm

125 mm

125 mm

100 mm

100 mm

100 mm

75 mm

75 mm

50 mm

50 mm1 mm

5 mm10 mm25 mm50 mm

75 mm100 mm

75 mm50 mm25 mm10 mm5 mm

1 mm

125 mm

125 mm

125 mm

125 mm100 mm

100 mm

100 mm

75 mm

75 mm

50 mm

50 mm

150 mm

150 mm

150 mm

150 mm

25 mm25 mm

100 mm

EAL SHIP IMPACT PROTECTIONCENTRAL PONTOON

EAL SOUTHMAIN TOWER

EAL SHIP IMPACTPROTECTION PONTOON B

RIVER THAMES WALL

FOR

CO

NTI

NU

ATI

ON

SE

E S

HE

ET

4

FOR

CO

NTI

NU

ATI

ON

SE

E S

HE

ET

2

PLANSCALE 1:500


Drawing Status

DO

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T S

CA

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Mill

imet

res

100

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Date

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Revision

Scale


Drawing Title

Project Title

Date Date Date

Checked Approved

Original Size

A1

Authorised


DescriptionAtk

ins

Ref

.

SILVERTOWN TUNNEL


STW

TN-A

TK-G

EN

-XX

XX

-DR

-Z-3

164

P01


1:500 SB

26/04/16

GR

26/04/16

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Scale 1:500

10m 0m 10m 20m 30m






KEY:

EXISTING BUILDINGS



RIVER THAMES WALLS

ORDER LIMITS


5mm

10mm

25mm

50mm

75mm

100mm

125mm

150mm

KEY PLAN

SHEET 3

SHEET 1

SHEET 2

SHEE

T 4

SHEE

T 5

N

1 mm

5 mm10 mm

25 mm

50 mm

75 mm

100 mm

1 mm

5 mm10 mm

25 mm50 mm

75 mm100 mm

50 mm

75 mm50 mm

25 mm10 mm5 mm

1 mm 100 mm

125 mm

150 mm

150 mm

1 mm

5 mm10 mm

25 mm

50 mm

75 mm

100 mm

INDUSTRIAL BUILDINGNo B5-N



INDUSTRIALBUILDING No B2-N



EMIRATES AIR LINENORTH MAINTOWER

RIVER THAMESWALL

ROYAL VICTORIA DOCK RISINGMAIN (SUBJECT TO REALIGNMENTDURING THE CUT-AND-COVERTUNNEL WORKS)

DLR VIADUCT PIERNo1

DLR VIADUCT PIERNo2EMIRATES AIR LINE NORTH

INTERMEDIATE TOWER

100 mm

75 mm

100 mm

125 mm

150 mm

125 mm150 mm

100 mm

75 mm50 mm

10 mm25 mm

FOR

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NU

ATI

ON

SE

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HE

ET

5

FOR CONTINUATION SEE SHEET 3

PLANSCALE 1:500


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A1

Authorised


DescriptionAtk

ins

Ref

.

SILVERTOWN TUNNEL


STW

TN-A

TK-G

EN

-XX

XX

-DR

-Z-3

165

P01


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10m 0m 10m 20m 30m






KEY:

EXISTING BUILDINGS



RIVER THAMES WALLS

ORDER LIMITS


5mm

10mm

25mm

50mm

75mm

100mm

125mm

150mm

KEY PLAN

SHEET 3

SHEET 1

SHEET 2

SHEE

T 4

SHEE

T 5

N

1 mm

5 mm10 mm

25 mm

50 mm75 mm

1 mm

5 mm

10 mm

25 mm

50 mm

1 mm

5 mm

10 mm

STAND ALONE "L" SHAPERETAINING WALL

JUBILEE LINENORTHBOUNDTUNNEL

JUBILEE LINESOUTHBOUNDTUNNEL

DLR WOOLWICH BRANCHVIADUCT PIER No1

FOR

CO

NTI

NU

ATI

ON

SE

E S

HE

ET

4

OPEN-CUT APPROACH (SECANT PILE RETAINING WALL)

NORTHPORTAL

OPEN-CUT APPROACH (STAND

ALONE"L"SHAPE RETAINING WALLS)

CUT-AND-COVER TUNNEL(SECANT PILE SIDE WALLS)

PLANSCALE 1:500


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SILVERTOWN TUNNEL


STW

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TK-G

EN

-XX

XX

-DR

-Z-3

166

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10m 0m 10m 20m 30m






KEY:

EXISTING BUILDINGS



RIVER THAMES WALLS

ORDER LIMITS


5mm

10mm

25mm

50mm

75mm

KEY PLAN

SHEET 3

SHEET 1

SHEET 2

SHEE

T 4

SHEE

T 5

Environmental Statement Appendix 12.B Settlement Assessment Report · 2016-06-07 · 1 Mair, R.J.,...

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Transcript of Environmental Statement Appendix 12.B Settlement Assessment Report · 2016-06-07 · 1 Mair, R.J.,...