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For Official Use Only

GOVERNMENT OF INDIA

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MINISTRY OF RAILWAYS

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Consultancy ReportOn

New LineBetween

Nagapattinam - Velankanni Section

Tiruchchirappalli Division : Southern Railway

Consultancy No. RDSO/2011/GE:CR-0148

May 2011

Geo-technical Engineering Directorate

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Research Designs & Standards Organisation

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Lucknow – 226011

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INDEX

SL Contents Page

Preface 2

Synopsis 3

1. Introduction 4

2. Reference 4

3. Scope Of Work 4

4. History Of Problem 4-8

5. Track Structure 9

6. Details Of Soil Samples 9

7. Bore log analysis 10

8. Site Inspection And Collection Of Field Data 11-13

9. Analysis & Discussion Of Test Results 14-25

10. Slope Stability Analysis 25

11. Causes of problem 25

12. Recommendations 25-27

13. Annexure I

Annexure IA

Annexure I B

Annexure IIA & IIB

Annexure III

Annexure IV

29-30

31

32-33

34 & 34

36-39

40

14. Figures –

(i) Index Map (Fig 1)

(ii)Existing Profiles (Fig 2 To 6)

(iii) Recommended Profile (Fig 7A &7B)

(iv) Bore log details (Fig 8)

41

42-46

47-48

49

PREFACE

This report is based on the basis of soil exploration, field investigation, and soil testing and literature survey. The views expressed are subject to modifications from time to time in the light of future developments on the subject. The views do not represent the views of Ministry of Railways (Railway Board), Government of India.

This report is the property of the RDSO and is meant essentially for officials use. It may not be loaned, reproduced in part or in full or quoted as an authority without the permission of Director General, RDSO.

(Rajesh Agarwal) (Shirish Kesarwani) Director/ Geo-tech Engg. Executive Director/Geo-tech Engg.

SYNOPSIS

The new line section between stations Nagapattinam & Velankanni, Tiruchchirappalli Division of Southern Railway was opened for traffic on 20.12.2010. CRS inspection was carried out in August-2010. CRS in his authorization letter at item no. 1.3 (a) pointed out that appropriate soil solution have not been arrived at for base soil, also used poorly graded soil for the embankment with blanket material of SC type of soil with plasticity index varying from 10 to 17 as brought out in the Report of NIT/Trichy.

On the request of Southern Railway, detailed field investigations of nine locations between stations Nagapattinam & Velankanni was carried out alongwith testing of field’s undisturbed/disturbed soil samples at GE lab/ RDSO.

Recommendations include proper re-profiling of slope duly compacted, pitching/turfing on finished slope, monitoring of settlement, Ground improvement etc.

15. INTRODUCTION

The new line between Nagapattinam & Velankanni, Tiruchchirappalli Division of Southern Railway from km. 1/355 to km.10/404 was constructed between 2007-2010. The line was inspected by CRS/Southern circle on 25.08.2010 and 26.08.2010 and opened for passenger traffic on 20.12.2010. The section was

opened with speed restriction of 10 kmph from km. 1/355-2/700 and 20kmph between km.2/700-5/500 whereas maximum section speed is 30kmph. Vide letter No. W.347/T/10/CN /Vol.II dated 11.1.2011 & dated 24-1-2011 from CE/CN/C/MS requested RDSO to investigate new line between Nagapattinam- Velankanni (10 kms.) as per CRS remarks. As such RDSO team inspected site on 1st & 2nd February 2011 alongwith XEN/Con/TPJ, Shri P.Susendran, AEN/Con/TPJ, Shri P. Jeevendran and SSE/W/GC/TPJ, Shri T. Kalyansundaram for rendering the consultancy for effected section.

SL Referred Location

Locations Selected

For Embankment

For Bore logs

Between Stations

1 Km. 1.355 to Km. 10.404

Km. 1/600, 1/800, 2/100, 2/600, 2/650, 3/900, 5/150, 5/175, 6/600 (9 nos)

km 1/800, km 2/650, km 3/900 and km 5/150 (4 nos)

Nagapattinam & Velankanni

Accordingly site observations were made & soil samples were collected from these locations.

2.0 REFERENCE

CE/CN/C/MS letter no. W.347/T/10/CN /Vol.II dated 11.1.2011

3.0 SCOPE OF WORK

Scope of work includes site inspection, soil exploration, testing for checking the stability of bank, assessment of compaction and other geotechnical aspects of the 9 locations i.e. Km. 1/600, Km. 1/800, Km. 2/100, Km. 2/600, Km. 2/650, Km. 3/900, Km. 5/150, Km. 5/175 and Km.6/600 and suggest suitable measures for the referred stretch.

4.0 HISTORY OF PROBLEM

The stretch was first referred to RDSO on 11.01.2011 by Chief Engineer/CN/C/MS Southern Railway vide letter no. W.347/T/10/CN /Vol.II dated 11.01.2011 after CRS inspection of Southern circle, findings & general recommendations of NIT/Trichy, Observations & recommendations of IIT/Chennai and observations of Principal Chief Engineer/Southern Railway.

4.1 CRS Southern Circle inspection (25.08.2010 & 26.08.2010)

CRS Southern Circle inspected the section of new BG line between Nagappattinam (km. 0.00) to Velankanni (km. 9.049) by Motor Trolly on 25.08.2010 & 26.08.2010 and observation letter sent to Southern Railway on 31.08.2010.

Interim report on inspection of new BG line from Nagapattinam to Velankanni from km 1.355 to 10.404 prior to opening for public carriage of passengers has been submitted to Railways after soil investigation by NIT/Trichy & inspection by PCE/Southern Railway. Extract of CRS Southern Circle interim report on formation chapter is placed at Annexure III. Finding and general recommendation of different individual as mentioned are as under:

4.2 FINDINGS AND GENERAL RECOMMENDATIONS BY NIT/TRICHY (24.09.2010)

a. Geotechnical Investigation on new B.G. line between NAGAPATTINAM-VELANKANNI stations has been carried out by NIT/TRICHY.

b. Investigation report No.: SRT/KMK-2010-11has been submitted by ENGINEERING CONSULTANCY CENTRE, Department of Civil Engineering, National Institute of Technology, Tiruchirappalli – 620 015 in reference to Dy. Chief Engineer, Gauge Conversion/S. Rly. Tiruchirappalli letter No. W. 148/GC/II/NGT-VLKN/7 dated: 28.08.2010

c. Abstracts of NIT/Trichy test results as brought out in Inspection note of Pr CE SR dated 26.10.2010 are placed at Annexure-IV.

Geotechnical Evaluation of NIT/Trichy

• The blanketing material is clayey sand (SC-type) with plastic fines more than 12%. The relative compactness of the blanketing is medium dense at the centre of the line and it is loose in state at the side slope.

• The formation soil is SC/CI group. The relative compactness of the formation soil is loose to medium dense.

• The subsoil of the BG, line is SM/OH/CH group. The compactness/consistency of the subsoil is very soft to very stiff/very loose to medium dense.

4.2.1 RECOMMENDATIONS

16. The embankment formation material and quality of compaction of formation is quite satisfactory in the second half of the B.G. line i.e., chainage from 5/5 to the end of the line towards Velankanni.

17. The relative compactness of the embankment formation soil from Chainage 0/9 to 5/5 is also up to the accepted range except at few locations (towards the side slope). The side slope of the formation should be stabilized with suitable materials (with geotextiles) and with suitable drainage system.

18. Construction of toe wall may be a good option to retain the slope of the formation but it may not control the subsoil settlement since the subsoil is very soft at chainage from 1/3 to 3/5.

19. The subsoil should be stabilized by any suitable ground improvement techniques. Particular, between chainage 1/3 to 3/5, the subsoil is very soft high compressible

clay with more organic matter. The combination of stone and sand lime column may be adopted.

20. Train services may be permitted with limited speed (speed about 30 Km/hrs) for a short duration to check the performance of the embankment under cyclic load. The embankment performance may be monitored during train services.

4.3 OBSERVATIONS AND RECCOMENDATION MADE BY IIT/CHENNAI (12.11.2010)

21. Note on observations are made by Prof.S.R.Gandhi and Dr.R.G.Robinson during visit to railway line from Nagapatinam to Velankanni on 28.10.10 and submitted the report on 12.11.2010.

22. The officials reported that the embankment construction was completed few years back and was left for about three to four seasons. Loaded trains were also operated few times. No significant settlement of embankment was observed during this period. However, settlement data are not available.

23. The embankment was constructed, in general on a water logged area with many creek crossings, where RCC culverts have been provided.

24. Pile foundations were used to support major bridges.

25. In general, good quality moorum was used for the construction of the embankment. However, it was noticed that local soil is used in few places.

26. The soil along the side slopes is found to have erosion cuts due to lack of erosion control measures. At places where grass has grown, erosion is negligible.

27. In order to protect the slopes, retaining walls were constructed in few places, and this has improved the stability.

28. Review of the soil investigation report suggests that formation soil is of high plastic clay with very low shear strength. However, it is necessary to evaluate the present state of the formation about the consolidation characteristics of the formation soil and undrained shear strength of the soil evaluated using undisturbed soils need to be provided.

29. It was suggested that instead of RCC wall, stone filled gabions can also be used which does not require deep foundation excavation. IIT will provide typical sections of the gabion wall. This will be more economical.

30. Final recommendations will be made once the consolidation test data is available.

4.4 PROBLEMS WITH THE CONSTRUCTED FORMATION OBSERVED BY PCE/SOUTHERN RAILWAY (26&27.10.2010)

On 26-10-2010, NGT to Km. 5/400 was trolleyed by PCE/SR with CN officers, OL officers, L&T Representative and Prof. K. Muthukkumaran of NIT/Tiruchy. On

27-10-2010, VLKN to NGT was trolleyed with CN Officers, OL Officers and L&T Representative.

4.4.1 PROBLEMS WITH THE CONSTRUCTION OF FORMATION ARE AS UNDER:

a. Too high a percentage of fines passing through 75 micron.

b. Highly compressive clay as base soil.

c. Organic clay as base soil.

d. Bearing capacity much less than actual pressure on soil.

e. NMC close to LL in some bore holes.

f. Water logged area, tidal flow.

g. Sub soil drainage problem.

h. Moderately swelling clay in base soil.

i. Likely punching shear of bank into base soil-local/general shear failures.

j. Land width limited for a desirable solution.

k. On the whole, remedial measures are needed for base soil, bank soil and blanketing soil on different aspects.

4.4.2 RECOMMENDATIONS

(a) RECOMMENDATIONS FOR BLANKET SOIL

1. It is not advisable to disturb the well compacted blanket in other stretches.

2. The most feasible solution is to improve cross drainage by cutting trenches upto 50 cm below formation top and filling up with compacted ballast. At the ends of formation, filled in ballast should not be eroded and hence to be retained with gabions.

3. The depth of trench has been arrived at based on actual condition of plastic nature of soil and entrapped water noted at different depths of blanketing soil at various sites in site inspection.

(b) RECOMMENDATIONS FOR BANK SOIL

1. For erosion control measure it is recommended that dry stone pitching up to a height of HFL + 0.3 m and for further height up to formation level, slope shall be protected with vetiver plantation. Small toe wall is required to retain the bottom most layer of pitching stones.

2. Disturbed bank slope shall be re-profiled to 3H to 1V slope with benching of parent slope and compacting with blanket soil (limiting 75 micron). This 3:1slope is to be provided from NGT to km 5/400. Beyond this up to VLKN 2:1 slope with suffice.

3. Line chutes shall be provided on slopes to drain out rain water as provided in nearby road bank.

4. The foregoing solution enables more drainage paths through dry stones, confinement of bank soil with pitching and no foundation problem with retaining wall. Punching shear of bank into base soil will be reduced.

( c) RECOMMENDATIONS FOR BASE SOIL

1. For improvement of drainage of base soil, it is recommended that verticality of deep piles, sand shall be confined by suitable casing. To permit drainage, casing shall be perforated in such a way water only will flow through surrounding soil and not fine material. Based on permeability of existing base soil, spacing of sand piles can be decided, preferably staggered spacing.

2. Lime is generally a proven solution for reducing the expansiveness, i.e. swelling/shrinkage values of expansive soils. It is also reported to reduce plasticity index of highly soils though may not be swelling type. Plasticity index reduces by 10% or more as per lime content. Even plastic fines are also changed to non-plastic fines as per lime content and lime quality. Hence, alternately lime piles are also required. Lime shall be in contact with clay soil to alter the property of clay soil by cat-ion exchange process. 50% of required piles shall be provided in one monsoon and balance 50% in next monsoon. Water is required for lime penetration into base soil and hence lime piling shall be done before monsoon to take advantage of lime penetration during monsoon. To further improve lime penetration and reduce the cost of costly lime piling, lime:sand can be mixed 50%:50%. This will give good results on flowability of lime, Casing shall not be left for lime piling as lime is to be in contact with clay.

3. Base soil requires ground improvement up to Km. 5 only. Km.5 to VLKN-no treatment is required for base soil.

4. Construction branch has stated that the formation can be kept under observation. With the existing expertise with man power, such troublesome formations cannot be qualitatively and quantitatively monitored for behavior. Hence, instrumented monitoring will be more useful. Professor/NIT has been advised to suggest and install instruments to monitor various parameters.

In the opening document, 300 mm ballast cushion is said to have been provided. As per checks done during trolley inspection, there are deficiencies in cushion at certain locations. Least value noted is 210 mm at km 9/200-300. Minimum 300 mm ballast cushion shall be ensured as per opening document and standard pressure on formation can be recalculated. If formation pressure has to be reduced further based

on bearing capacity requirements, then 350 mm cushion (one stone extra) can be thought of duly reducing dynamic augment by increased distribution.

To effect cross drainage in Km.6 and Km.7 before commencement of passenger traffic at a speed of 40 kmph and balance works to be completed covering two monsoon seasons and as per lime penetration requirements. Subject to compliance of all the listed works, train speed can be increased to 60 kmph after two monsoons. Index map showing stretch is placed at Fig.1.

5.0 TRACK STRUCTURE

Rail 52 Kg.

Sleeper PSC

Sleeper Density M+8

GMT/annum Not Available

Total GMT Not Available

Ballast cushion 200-250mm

6.0 DETAILS OF SOIL SAMPLES

From all the reports sent by Southern Railway, it is clear that formation problem appears in between Nagapattinam station to km 6. Hence locations for soil sampling have been selected from km 1 to km 6. Selected locations by the RDSO team are different from the locations selected by NIT/Trichy for soil investigation as those results are available (Annexure III). Soil sample locations are selected based on the problems observed in formation during visit such as rain cuts, cess erosion; soil erosion at slope, cracks appears etc. Location also selected where bank height is maximum. Based on the above criteria, twenty nine numbers of Disturbed/Undisturbed soil samples were collected from the locations given in Table-I.

Table-I

SL Location Disturbed Undisturbed Total1. Km 1/600 2 - 22. Km 1/800 3 1 43. Km 2/100 2 - 24. Km 2/600 1 - 15. Km 2/650 4 1 56. Km 3/900 6 1 77. Km 5/150 3 1 48. Km 5/175 2 - 29. Km.6/600 2 - 2

These soil samples were tested in Geo-technical Engineering Laboratory/ RDSO for the following tests:

31. Classification32. Natural Moisture Content (NMC)33. Natural Dry Density (NDD)34. Grain Size Analysis35. OMC & MDD36. Differential free swelling37. Shrinkage Limit38. Specific Gravity39. CBR40. UCC41. Consolidation test12. Triaxial shear test in Consolidated Undrained condition with

measurement of pore pressure (CU) & Unconsolidated Undrained test (UU)

Test results are enclosed at Annexure –I, IA & IB.

7.0 BORE LOG ANALYSIS

i) Bore logs are taken at four locations i.e. km 1/800, km 2/650, km 3/900 and km 5/150

ii) Bore log details are placed at Fig 8.

iii) Bore logs are taken upto 6m depth from the G.L. or up to Ground water Table.

iv) Disturbed soil samples are taken during the boring to know the strata met in the sub-soil.

v) In Bore log –I (km 1/800), SM & CH type of soil has been encountered.

vi) In Bore log –II,( km 2/650), , SM, SC, CL & CH type of soil has been encountered.

vii) In Bore log –III (km 3/900) , SW-SM, SC, SM & CI type of soil has been encountered.

viii) In Bore log –IV (km 5/150), Only SM type of soil has been encountered.

ix) It is concluded from the bore log details that Sandy Soil has been encountered upto 2.5m depth.

8.0 SITE INSPECTION AND COLLECTION OF FIELD DATA

8.1 Location – Km. 1/600

42. Degree of compaction was checked and found 92.2% for subgrade and 89.39% for blanket with respect to Railway MDD value.

43. Erosion on side slope has been observed.

44. Fishery is being carried out adjacent to toe of the bank.

45. Two disturbed soil sample were collected, to assess the capacity of soil to withstand the dynamic loads.

46. Toe wall constructed.

Photograph showing constructed toe wall at Km. 1/600

8.2 Location -Km 1/800

1. Erosion of side slope has been observed.

2. Cultivation of fish is being carried out adjacent to toe of bank.

3. Three disturbed and one undisturbed soil sample were collected, to assess the capacity of soil to withstand the dynamic loads.

4. Cross section taken at km 1/900 is placed at Fig. 2.


47. Degree of compaction was checked and found 89.62% for subgrade and 93% for blanket with respect to Railway MDD value.

48. Erosion of side slope has been observed.

49. Cultivation of fish is being carried out adjacent to toe of bank.

50. Two disturbed soil sample were collected, to assess the capacity of soil to withstand the dynamic loads.

8.4 Location -Km 2/600-Km 2/650

51. Degree of compaction was checked and found 96.38% for subgrade with respect to Railway MDD value.

52. Cess has been completely eroded near km. 2/650.

53. Severe erosion of side slope has been observed.

54. Turfing on the slope has been observed.


Photograph showing erosion of embankment at km. 2/650

8.5 Location- Km 3/900

56. Slope completely eroded with 1m deep and 1m wide rain cuts.

57. Turfing has not been observed.

58. Large crack at the toe of the embankment has been observed along the alignment.

59. At 6.5m below Ground Level, augring could not be done due to very stiff layer of soil has been found.

60. Degree of compaction was checked and found 95.78% for sub-grade and 96.34% for blanket with respect to Railway MDD value.


Photograph showing erosion of embankment at km. 3/900


1. Slope and cess completely eroded.

2. Construction of toe wall is in progress.

3. Cross section taken at km 5/150 is placed at Fig.5


Degree of compaction was checked and found 93.94% for sub-grade and 93.23% for blanket with respect to Railway MDD value.

Photograph showing constructed toe wall at km 5/175


1. Not a problematic section.

2. Degree of compaction was checked and found 95.99% for blanket with respect to Railway MDD value.

3. Cross section taken at km 5/150 is placed at Fig.6

9.0 ANALYSIS & DISCUSSION OF TEST RESULTS

9.1 Location – Km. 1/600

Two disturbed soil samples have been collected from this location. Test results are as under:

Soil Properties –

4. Grain size distribution & test for consistency conducted on the collected blanket and subgrade soil samples & blanket/soil classify as SC (Clayey Sand).

5. Blanket material contains fines 26.08%, plastic limit is 18 & Plasticity Index value is 21. Para 4.3.4 Guidelines for Earth work in Railway Project July 2003 clearly mentioned that Blanket material should have Non-plastic fines (particles of size less than 75 micron) are limited maximum to 12%, whereas plastic fines are limited maximum to 5%. Therefore blanket material does not satisfy the specification of blanket material.

6. Field dry density at km 1/6-7 of blanket material is 1.779 gm/cc and that of subgrade soil is 1.743 gm/cc and MDD as determined in RDSO’s GE-Lab is 2.148 gm/cc of blanket material & 2.095 gm/cc of subgrade soil. Therefore,

SL Soil Parameters Blanket (Dist.) Soil (Dist.)

1. Classification SC SC2. Grain Size Distribution :

Gravel (%) 33.15 00Sand (%) 40.77 74.48Silt (%) 16.73 20.32Clay (%) 9.35 5.20Fines passing 75µ sieve (%) 26.08 25.52

3. Consistency Limits :Liquid Limit 39 28Plastic Limit 18 16Plasticity Index 21 12SL - -DFS - -

4. OMC (%) 10.00 8.19MDD (g/cm3) 2.148 2.095NMC - -NDD - -

5. Specific Gravity - 2.516. Cu 1652.17 50.00

Cc 2.57 4.607. CBR Value 8.79 1.95

degree of compaction at km 1/6-7 of blanket material comes out as 82.82% & that of subgrade soil is 83.19% which shows less compaction. Since degree of compaction is less than the desired limit which adversely affects the strength of formation.

9.2Location – Km. 1/800

Four soil samples (3 disturbed & 1 undisturbed) have been collected from this location. Test results are as under:

Soil Properties –

SNo Soil Parameters

Sub Soilat 0.5 m

depth( UD)

Sub Soilat 0.5 m

depth(Dist.)

Sub Soilat 1.0 m

depth(Dist.)

Sub Soilat 2.5m depth(Dist.)

1 Classification SM SM CH SM

2 Particle size distributionGravel (%) 00 1.04 0.26 2.48Sand (%) 58.74 77.20 17.90 81.29Silt (%) 41.26 21.76 66.95 16.23Clay (%) 00 00 14.89 00Fines passing 75µ sieve (%)

41.26 21.76 81.84 16.23

3 Consistency limits:Liquid Limit NP NP 55 NPPlastic Limit NP NP 28 NPPlasticity Index NP NP 27 NPShrinkage limit - NP 20 NPDifferential Free Swell - 10 33 00

4. NMC (%) 33.07 - - -NDD (g/cc) 1.403 - - -

5. Cu 40.0 2.33 21.76 2.97Cc 2.95 0.62 0.19 0.74

6. Specific Gravity 2.56 - 2.35 -7. Shear Parameters

Unconfined compressive strength test (UCC), Cu (kg/cm2)

Not Possible

- - -

Tri-axial shear test (UU)C (kg/cm2) 0.08 - - -φ (degree) 06 - - -

8. Consolidation ParameterPc ((kg/cm2) 0.70 - - -Cc 0.102 - - -

e0 0.677 - - -Cv ( At 2 kg/cm2) 0.838 - - -Cv ( At 4 kg/cm2) 0.811 - - -Cv ( At 8 kg/cm2) 0.936 - - -

62. Grain size distribution & test for consistency conducted on the collected Sub soil samples classify the soil as silty sand i.e. SM (at depth 0.5 & 2.5) and clay of high compressibility i.e. CH at depth 1.0m.

63. As soil below 0.5 m is so soft that Unconfined compressive strength can not be determined.

64. Sub soil contains fines varies from 16.23% to 81.84% and plastic limit varies from NP to 28.

65. Shrinkage limit of sub soil at depth 1.0m is 20, which shows soil is not shrinkable in nature.

66. Differential free swell of subsoil varies from 10 to 33, which shows that sub soil is not of swelling type.

67. Since sub-soil is mainly SM category and soft therefore mostly elastic settlement occur.


Two disturbed soil samples have been collected from this location. Test results are as under:

Soil Properties :–

SL Soil Parameters Blanket (dist.) Sub-grade (dist.)

1. Classification SC SC2. Grain Size Distribution :

Gravel (%) 22.49 0.88Sand (%) 55.42 70.27Silt (%) 17.04 20.82Clay (%) 5.05 8.03Fines passing 75µ sieve (%) 22.09 28.85

3. Consistency Limits :Liquid Limit 43 28Plastic Limit 22 17Plasticity Index 21 11SL - 18DFS - 10


5. Specific Gravity 2.466. Cu 320 57.14

Cc 15.31 8.477. CBR Value 5.40 2.12

1. Grain size distribution & test for consistency conducted on the collected blanket and subgrade soil samples & blanket/sub-grade soil classify as Clayey Sand (SC).

2. Subgrade soil contains fines 28.85% and plastic limit is 17. The PI value is 11.

3. Blanket material contains fines 22.09% and plastic limit is 22. The PI value is 21. Para 4.3.4 Guidelines for Earth work in Railway Project July 2003 clearly mentioned that Blanket material should have Non-plastic fines (particles of size less than 75 micron) are limited maximum to 12%, whereas plastic fines are limited maximum to 5%. Therefore blanket material does not satisfy the specification of blanket material.

4. Field dry density at km 2/1-2 of blanket material is 1.860 gm/cc and that of subgrade soil is 1.685 gm/cc and MDD as determined in RDSO’s GE-Lab is 2.265 gm/cc of blanket material & 2.080 gm/cc of subgrade soil. Therefore, degree of compaction at km 2/1-2 of blanket material comes out as 82.12% & that of subgrade soil is 89.42% which shows less compaction. Since degree of compaction is less than the desired limit which adversely affects the strength of formation.

9.4 Location – Km. 2/600.

One disturbed soil sample has been collected from this location. Test results are as under:

Soil Properties:-

S.No. Soil ParametersFormation Soil

(DS)1. Classification CL

2. Grain size distribution:

Gravel (%) 0.12Sand (%) 20.65Silt (%) 70.31Clay (%) 8.92Fines passing 75µ sieve (%)

79.23

3. Consistency Limits:Liquid Limit 33Plastic Limit 17Plasticity Index 16SL -DFS -

4. OMC(%) 12.02MDD(g/cm3) 1.908NMCNDD -

5. Specific gravity 2.576. Cu 31.30

Cc 31.307. CBR Value 1.54

1. Grain size distribution & test for consistency conducted on the collected formation soil sample classify the soil as Clayey soil of low compressibility i.e. CL.

2. Subgrade soil contains fines 79.23% and plastic limit is 17. The PI value is 16.

3. Field dry density at km 2/600 of subgrade soil is 1.812 gm/cc and MDD as determined in RDSO’s GE-Lab is 1.908 gm/cc of subgrade soil. Therefore, degree of compaction at km 2/600 of subgrade soil is 94.96% which shows less compaction. Since degree of compaction is less than the desired limit which adversely affects the strength of formation.

9.5 Location – Km. 2/650.

Four disturbed and one undisturbed soil samples were collected from this location. Test results are as under:

Soil Properties:-

SNo Soil Parameters

Sub Soil

at 0.5 m

depth(D5)

Sub Soilat 1 m depth(D6)

Sub Soil

at 2.5 m

depth(D7)

Sub Soilat 6 m depth(D8)

Sub Soil

at 0.5 m

depth(UD)

1 Classification CL SC SM CH SM2 Particle size distribution

Gravel (%) 00 00 1.88 4.32 0.98Sand (%) 32.62 66.26 67.18 26.70 54.08Silt (%) 54.56 29.19 30.94 39.58 44.94Clay (%) 12.82 4.55 00 29.40 00Fines passing 75µ sieve (%)

67.38 33.74 30.94 68.98 44.94

3 Cu 48.00 13.00 7.14 - 2.50Cc 11.34 3.99 0.61 - 1.41

4 Consistency limits:Liquid Limit 30 30 NP 72 NPPlastic Limit 21 18 NP 28 NPPlasticity Index 09 12 NP 44 NPShrinkage limit 20 17 NP 10 -Differential Free Swell 20 10 00 140 -

5 NMC (%) - - - - 20.63NDD (g/cc) - - - - 1.681

6. Specific Gravity 2.63 2.567. Shear Parameters

UCC Test, Cu (kg/cm2) - - - - 0.141Triaxial Shear Test (CU)C′(kg/cm2) - - - - .006φ′ (degree) - - - - 30.92

1. Grain size distribution & test for consistency conducted on the collected Sub soil samples classify the soil as Clay of low compressibility/ Silty Sand (CL/SM) (at depth 0.5), Clayey Sand (SC) (at depth 1.0m), Silty Sand (SM) (at depth 2.5m) and clay of high compressibility (CH) (at depth 6.0m).

2. Sub soil contains fines varies from 30.94.23% to 68.98% and plastic limit varies from NP to 28. Plastic index varies from NP to 44.

3. Shrinkage limit of sub soil from depth 0.5m to 1.0m varies from 17 to 20, which shows soil is not shrinkable in nature.

4. Differential free swell of subsoil at depth 6.0m is 140, which is too high, therefore soil at this depth is highly swelling in nature.

5. Sub soil is mainly SM category the elastic settlement may occur during construction.

6. Undrained Shear strength of sub soil 14.1 kpa which is less than 25 kpa, hence the sub soil is under the category of soft soil.


Six disturbed and one undisturbed soil samples were collected from this location and tested. Test results are as under

Soil Properties:-

SNo Soil Parameters

Sub Soilat

0.5 m depth(UD)

Sub Soilat

0.5 m depth(Dist)

Sub Soilat

1 m depth(Dist)

Sub Soilat

2.5 m depth(Dist)

Sub Soilat

6 m depth(Dist)

Blanket(Dist)

Sub-grade Soil

(Dist)

1 Classification SM SC SM SW-SM CI SC SM2 Particle size distribution

Gravel (%) 00 00 0.73 17.07 00 28.14 1.71Sand (%) 54.64 55.02 85.23 77.56 6.02 46.97 73.14Silt (%) 45.36 41.68 12.01 5.37 63.32 21.43 19.62Clay (%) 00 3.30 2.03 00 30.66 3.46 5.53Fines passing 75µ sieve (%)

45.36 44.98 14.04 5.37 93.98 24.89 25.15

3 Cu 30.00 24.00 4.41 7.92 - 266.67 12.67Cc 11.41 9.38 1.42 1.20 - 1.26 2.54

4 Consistency limits:Liquid Limit NP 28 NP NP 44 39 NPPlastic Limit NP 17 NP NP 22 23 NP

Plasticity Index NP 11 NP NP 22 16 NP

Shrinkage limit - 20 NP NP 16 - NP

Differential Free Swell - 20 00 10 33 - 10

5 NMC (%) 20.51 - - - - - -NDD (g/cc) 1.725 - - - - - -OMC (%) - - - - - 9.50 9.50MDD (g/cc) - - - - - 2.130 2.010

6. Specific Gravity 2.51 2.447. CBR Value - - - - - 7.30 14.998. Shear Parameters

UCC Test, Cu (kg/cm2) 0.093 - - -Triaxial Shear Test (UU)C (kg/cm2) 0.12 - - - - - -φ (degree) 05 - - - - - -

9. Consolidation ParameterPc ((kg/cm2) 0.58 - - - - - -Cc 0.098 - - - - - -e0 0.593 - - - - - -Cv ( At 2 kg/cm2) 1.290 - - - - - -

Cv ( At 4kg/cm2) 0.939 - - - - - -

Cv ( At 8 kg/cm2) 0.903 - - - - - -

1. Grain size distribution & test for consistency conducted on the collected blanket samples classify as clayey Sand (SC). Sub-grade soil is classified as Sility Sand (SM). Sub –soil are classified as SM, SC, SM & SW-SM upto 2.5m depth and CI at 6m depth.

2. Blanket material contains fines upto 24.89% and plastic limit is 23. The PI value is 16. Para 4.3.4 Guidelines for Earth work in Railway Project July 2003 clearly mentioned that Blanket material should have Non-plastic fines (particles of size less than 75 micron) are limited maximum to 12%, whereas plastic fines are limited maximum to 5%. Therefore blanket material does not satisfy the specification of blanket material.

3. Sub-grade soil is Non-Plastic in nature.

4. Sub-Soil upto 2.5 m depth contain more than 50% sand hence elastic settlement has been occurred during construction.

5. Undrained Shear strength of sub soil 9.3 kpa which is less than 25 kpa, hence the sub soil is under the category of soft soil.

6. Field dry density at km 3/900 of blanket material is 1.946gm/cc and that of subgrade soil is 1.82 gm/cc and MDD as determined in RDSO’s GE-Lab is 2.130gm/cc of blanket material & 2.010 gm/cc of subgrade soil. Therefore, degree of compaction at km 3/900 of blanket material comes out as 91.36% & that of subgrade soil is 90.54% which shows less compaction. Since degree of compaction is less than the desired limit which adversely affects the strength of formation.


Three disturbed and one undisturbed soil have been collected from this location. Test results are as under:

Soil Properties:-

SNo Soil Parameters

Sub Soilat 0.5 m

depth(Dist)

Sub Soilat 1 m depth(Dist.)

Sub Soilat 2.5 m

depth(Dist.)

FormationSoil at Cess

(UDS)

1 Classification SM SM SM SC2 Particle size distribution

Gravel (%) 00 00 3.25 1.17Sand (%) 68.00 75.15 70.76 65.69Silt (%) 32.00 24.85 24.84 21.88Clay (%) 00 00 1.15 11.26Fines passing 75µ sieve (%)

32.00 24.85 25.99 33.14

3 Cu 5.00 10.67 9.50 121.43Cc 1.62 2.80 1.73 21.78

4 Consistency limits:Liquid Limit NP NP NP 30Plastic Limit NP NP NP 17Plasticity Index NP NP NP 13Shrinkage limit NP NP NP 20Differential Free Swell 10 10 10 10

5 NMC (%) - - - -NDD (g/cc) - - - -

6. Specific Gravity 2.517. Shear Parameters

Triaxial Shear Test (CU)C′(kg/cm2) 0.041φ′ (degree) 26.73

1. Grain size distribution & test for consistency conducted on the collected Sub soil samples classify the soil Silty Sand (SM) (at depth 0.5, 1.0 & 2.5) and formation soil as Calyey Sand (SC).

2. Sub soil contains fines varies from 24.85 to 32% and non plastic in nature.

3. Formation soil contains fines 33.14% and plastic limit is 17 and plastic index is 13.

4. Shrinkage limit of formation soil is 20, which shows soil is not shrinkable in nature

5. Differential free swell of subsoil and formation soil is 10, which shows that sub soil and formation soil is not of swelling type.


Two disturbed soil samples were collected from this location. Test results are as under:

Soil Properties:-

SL Soil Parameters Blanket (dist.) Sub-grade (dist.)

1. Classification SM SC2. Grain Size Distribution :


3. Consistency Limits :Liquid Limit NP 30Plastic Limit NP 17Plasticity Index NP 13SL - 20DFS - 10

4. OMC (%) 7.00 1O.85MDD (g/cm3) 2.260 2.018Specific Gravity 2.33

5. Cu 51.43 50.00Cc 8.00 3.46

6. CBR Value 7.69 1.51

1. Grain size distribution & test for consistency conducted on the collected blanket and subgrade soil samples classify the blanket material as Silty Sand (SM) and subgrade soil as Clayey Sand (SC).

2. Blanket material contains fines 18.06% and non plastic in nature. The PI value is 21.Para 4.3.4 Guidelines for Earth work in Railway Project July 2003 clearly mentioned that Blanket material should have Non-plastic fines (particles of size less than 75 micron) are limited maximum to 12%, whereas plastic fines are limited maximum to 5%. Therefore blanket material does not satisfy the specification.Cu value of blanket material is 51.43 and Cc value is 8.00. As per specification of blanket material Cc value should lie between 1 and 3, therefore blanket material is not as per specification of blanket material.

3. Field dry density at km 5/175 of blanket material is 1.874 gm/cc and that of subgrade soil is 1.766 gm/cc and MDD as determined in RDSO’s GE-Lab is 2.260 gm/cc of blanket material & 2.018 gm/cc of subgrade soil. Therefore, degree of compaction at km 5/175 of blanket material comes out as 82.92% & that of subgrade soil is 87.51% which shows less compaction. Since degree of compaction is less than the desired limit which adversely affects the strength of formation.


Two disturbed soil samples were collected from this location and tested. Test results are as under

SL Soil Parameters Blanket (dist.) Sub Soil (dist.)

1. Classification SM SC

2. Grain Size Distribution :


3. Consistency Limits :Liquid Limit NP 27Plastic Limit NP 18Plasticity Index NP 09SL - 21DFS - 20


5. Specific Gravity - 2.506. Cu 313.73 -

Cc 2.76 -7. CBR Value 20.34

4. Grain size distribution & test for consistency conducted on the collected blanket and subgrade soil samples classify the blanket material as Silty Sand (SM) and subgrade soil as Clayey Sand (SC).

5. Blanket material contains fines 22.87% and plastic limit is 18. The PI value is 21. Para 4.3.4 Guidelines for Earth work in Railway Project July 2003 clearly mentioned that Blanket material should have Non-plastic fines

(particles of size less than 75 micron) are limited maximum to 12%, whereas plastic fines are limited maximum to 5%.. Therefore blanket material does not satisfy the specification.

6. Field dry density at km 6/600 of blanket material is 1.874 gm/cc and MDD as determined in RDSO’s GE-Lab is 2.070 gm/cc. Therefore, degree of compaction at km 6/600 of blanket material comes out as 90.53% which shows less compaction. Since degree of compaction is less than the desired limit which adversely affects the strength of formation.

10.0 SLOPE STABILITY ANALYSIS

Slope stability analysis for designing side slope has been carried out with the help of Slope-W software for 5.3 m height of embankment near km 2/650. The design parameters have been chosen as per site conditions. The following assumptions have been made during analysis:

68. Pore water pressure ratio (ru) assumed- 0.25(formation soil) & 0.5 (sub-soil)

69. Depth factor (Dr) -1.5

With above assumptions, for height of embankments 5.3 m and side slope of 3.5:1, the factor of safety works out to be 1.476 & for height of embankments 3.5 m and side slope of 3:1, the factor of safety works out to be 1.403 which is more than minimum required factor of safety i.e 1.4 as per Para-2.1 of Annexure-III of “Guidelines For Earthwork In Railway Projects”, July 2003, hence safe. Slope stability analysis is attached as Annexure-IIA & IIB.

11.0 Causes of Problem:

1. No soil survey has been carried out before construction of embankment as mentioned in Para 3.0 Guidelines for Earth work in Railway Project July 2003.

2. No Ground improvement techniques were adopted for soft soil.

3. Blanket material does not confirm the required specification.

4. Compaction of Subgrade soil & Blanket is very less than desire limit.

12.0 RECOMMENDATIONS:

Based on details of site inspection of nine inspected problematic stretches and test results of soil samples, the following recommendations are made for all the nine locations:

12.1 Slope Stability

Slope stability analysis has been carried out near km 2/650 with effective shear parameters. The height of embankment is 5.3 m. Existing side slope of the embankment is 2H: 1V which is failing. Hence slope stability at the location has been carried out with effective shear parameters. For 5.3m height of embankment with side slope of 3.5:1, the factor of safety works out to be 1.476 & for height of embankments 3.5 m and side slope of 3:1, the factor of safety works out to be 1.403 which is more than minimum required factor of safety i.e. 1.4. Hence at this location 3.5H: 1V side slope should be provided. Recommended profile is placed at fig. 7A & 7B. At other locations in the section, slope stability should be carried out for design of safe stable slope.

• Wherever slope is re-profiled as per design slope, following should also be noted:

• Repair and re-profiling should be done with good soil duly compacted up to 98% of MDD value otherwise it will need more maintenance. The slope should be from top of retaining wall/toe wall where ever provided. If side slope will not be provided as per the designed value, embankment may fail in service.

• Erosion control measure such as turfing/pitching should be providing on the re-profiled side slope of the embankment.

• A sand layer of 30cm thick below G.L., 15 cm thick above G.L & 30 cm thick sand layer at 3m below top of formation should be provided in

widened portion for quick dissipation of pore water pressure. The sand layer provided below G.L. should be extended 50 cm from the toe of the embankment

12.2 Three bore logs locations (km 1/800, km 2/650 & km 3/900)

As the Ground water table is just below the existing ground and sub soil is soft in nature, therefore ground improvement should have been carried out. Though ground improvement is not possible at this stage, hence railway has to watch the behaviour of the embankment for two years by monitoring of settlement by providing settlement platform as mentioned in Chapter 6 (INSTRUMENTATION AND MONITORING) of “Guidelines on Soft soils-Stage Construction Method, No. GE: G-5, April-2005” and other points as follows:

• Settlement by providing settlement platform.

• Monitoring track parameters such as regular recording of track parameters, variation in cross level and undulation of the track.

• Monitoring of track attention from gang chart.

• Check of any heaving of soil between sleepers, heaving/lower of cess and cracks on cess.

If settlement occurs, then Railway should take the immediate action.

12.3 Erosion control measures on eroded slope

Erosion control measure such as turfing/pitching should be providing on the eroded side slope of the embankment wherever required. The method of erosion control should be cost effective as per site condition.

12.4 Compaction of Earthwork

Compaction of earth work & Blanket ( 6 locations between km 1 to km 6) varies from 82.12% to 94.96% which are below than the stipulated value 98%, can results settlement in the formation. Since compaction of the embankment may not feasible at this stage, hence Railway have to watch the behaviour of the embankment for one or two years by monitoring the following points-

• Monitoring track parameters such as regular recording of track parameters, variation in cross level and undulation of the track.

• Monitoring of track attention from gang chart.

• Check of any heaving of soil between sleepers, heaving/lower of cess and cracks on cess.

12.5 General Recommendations

• Minimum formation width of 6.85m with sufficient cess width (not less than 90cm) should be ensured. Low/high cess should be properly dressed.

• Cultivation of mangroves tree far away from the toe of the embankment helps to protect the embankment due to tidal water.

• Cracks developed in formation should be properly filled with sand and sealed with non expansive cohesive soil.

• Rain cuts should be properly repaired.

• All loose earth dumped on side slope of the embankment should be properly dressed up & compacted up to 98% of MDD value.

• Mainly problematic stretch exists between km 1 to km 6. Beyond km 6 up to Velankanni station there is no problem with sub soil & formation soil. Soil used in embankment construction is mostly SC & CL type whereas soil available in the non problematic stretch in nearby area (between km 6 to Velankanni station) is better soil i.e. SM soil. Hence railway should have to be used the better soil in subgrade between km 1 to km 6, which was already available.

OFFICERS AND STAFF ASSOCIATED

WITH PREPARATION OF REPORT

The report has been prepared by Geo-technical Engineering Directorate of RDSO under guidance of Shri Shirish Kesarwani, Executive Director/Geo-technical Engineering/RDSO and Shri Rajesh Agarwal, Director/ Geo-technical Engineering.

Following officials of Geo-technical Engineering Directorate of RDSO were associated in site inspection & soil exploration:

1. Shri Shiv Kumar SSRE/GE2. Shri G.P.Shukla SRE/GE

Following officials of Geo-technical Engineering Directorate of RDSO were associated in soil testing:

1. Shri D.K. Srivastava, SRE/GE2. Shri N.K. Singh, SRE/GE3. Shri S. D. Sharma, SRE/GE4. Shri Bimal Kumar Das JRE/GE

Following officials of Geo-technical Engineering Directorate of RDSO were associated in preparation of the Consultancy Report:

1. Shri S.K.Ojha ARE/GE2. Shri Shiv Kumar SSRE/GE3. Shri S.K.Gupta, SRE/GE4. Shri G.P.Shukla SRE/GE 5. Shri Mukesh Maingi, SRE/GE6. Shri Susheel Kumar, JE/D/GE

Hkkjr ljdkj & jsy ea=ky; Government of India – Ministry of Railways Annexure-I

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Research Designs & Standards Organisation Manak Nagar, Lucknow-226011.

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enk ijh{k.kksa dh fjiksVZ] Reporting of Soil testingifj;¨tuk dk fooj.k %

Name of Project

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Nagapattinam-Velankanni new BGline, Nagapattinam-Velankanni Section, Tiruchirapalli Division, Southern Railway.

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Reference No. :

RS/GE/72/SR dated : 14.02.2011. ijh{k.k fjiksVZ la[;k%

Test Report No:04/2011. Dated 25.03.2011

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0002 1/800 Sub Soil SM - - 1.04 77.20 21.76 00 21.76 2.33 0.62 NP NP NP NP 10 - -

0003 1/800 Sub Soil CH - - 0.26 17.90 66.95 14.89 81.84 21.76 0.19 55 28 27 20 33 - -


0005 1/800 Sub Soil SM 33.07 1.403 00 58.74 41.26 00 41.26 40.0 2.95 NP NP NP - - - -

0006 2/650 Sub Soil CL - - 00 32.62 54.56 12.82 67.38 48.00 11.34 30 21 09 20 20 - -

0007 2/650 Sub Soil SC - - 00 66.26 29.19 4.55 33.74 13.00 3.99 30 18 12 17 10 - -


0009 2/650 Sub Soil CH - - 4.32 26.70 39.58 29.40 68.98 - - 72 28 44 10 140 - -

0010 2/650 Sub Soil SM 20.63 1.681 0.98 54.08 44.94 00 44.94 2.50 1.41 NP NP NP - - - -

0011 3/900 Sub Soil SC - - 00 55.02 41.68 3.30 44.98 24.0 9.38 28 17 11 20 20 - -

0012 3/900 Sub Soil SM - - 0.73 85.23 12.01 2.03 14.04 4.41 1.42 NP NP NP NP 00 - -

0013 3/900 Sub Soil SW-SM - - 17.07 77.56 5.37 00 5.37 7.92 1.20 NP NP NP NP 10 - -

0014 3/900 Sub Soil CI - - 00 6.02 63.32 30.66 93.98 - - 44 22 22 16 33 - -

0015 3/900 Sub Soil SM 20.51 1.725 00 54.64 45.36 00 45.36 30.00 11.41 NP NP NP - - - -

0016 5/150 Sub Soil SM - - 00 68.00 32.00 00 32.00 5.00 1.62 NP NP NP NP 10 - -

0017 5/150 Sub Soil SM - - 00 75.15 24.85 00 24.85 10.67 2.80 NP NP NP NP 10 - -

0018 5/150 Sub Soil SM - - 3.25 70.76 24.84 1.15 25.99 9.50 1.73 NP NP NP NP 10 - -

0019 5/150 Below cess SC 18.58 1.730 1.17 65.69 21.88 11.26 33.14 121.43 21.78 30 17 13 20 10 - -

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0020 1/600 Blanket SC - - 33.15 40.77 16.73 9.35 26.08 1652.17 2.57 39 18 21 - - 10.00 2.148

0021 1/600 Soil SC - - 00 74.48 20.32 5.20 25.52 50.00 4.60 28 16 12 - - 8.19 2.095

0022 2/100 Blanket SC - - 22.49 55.42 17.04 5.05 22.09 320.0 15.31 43 22 21 - - 8.00 2.265

0023 2/100 Soil SC - - 0.88 70.27 20.82 8.03 28.85 57.14 8.47 28 17 11 18 10 9.00 2.080

0024 3/900 Blanket SC - - 28.14 46.97 21.43 3.46 24.89 266.67 1.26 39 23 16 - - 9.50 2.130

0025 3/900 Soil SM - - 1.71 73.14 19.62 5.53 25.15 12.67 2.54 NP NP NP NP 10 9.50 2.010

0026 5/175 Blanket SM - - 16.85 65.09 12.98 5.08 18.06 51.43 8.00 NP NP NP - - 7.00 2.260

0027 5/175 Soil SC - - 3.76 64.26 25.08 6.90 31.98 50.00 3.46 30 17 13 20 10 10.85 2.018

0028 2/600 Soil CL - - 0.12 20.65 70.31 8.92 79.23 31.30 31.30 33 17 16 - - 12.02 1.908

0029 6/600 Blanket SM - - 26.27 50.86 14.93 7.94 22.87 313.73 2.76 NP NP NP - - 10.00 2.070

0030 6/600 G. Soil SC - - 0.0 69.38 16.48 14.14 30.62 - - 27 18 09 21 20 9.30 2.004

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l voi

d ra

tio

(e0)

fof'k"V

ÄuR

oSpe

cific

gra

viy

laÄuu + xq.kkad

Coefficient of consolidation (Cv)

2 kg

/cm

2

4 kg

/cm

2

8 kg

/cm

2

21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

0003 1/800 Sub Soil CH - - - - - - - - - - - - 2.35 - - -

0005 1/800 Sub soil SM NP - - - - 0.08 06 - - 0.70 0.102 0.677 2.56 0.838 0.811 0.936

0007 2/650 Sub Soil SC - - - - - - - - - - - 2.63 - - -

0010 2/650 Sub soil SM 0.141 - - - - 0.006 30.92 - - - - - 2.56 - - -

0012 3/900 Sub Soil SM - - - - - - - - - - - 2.44 - - -

0015 3/900 Sub soil SM 0.093 - - - - 0.12 05 - - 0.58 0.098 0.593 2.51 1.290 0.939 0.903

0018 5/150 Sub Soil SM 2.51

0019 5/150BBelow cess SC - - - - - 0.041 26.73 - - - - - - - - -

0020 1/600 Blanket SC - - - - - - - 8.79 8.47 - - - - - - -

0021 1/600 Soil SC - - - - - - - 1.61 1.95 - - - 2.51 - - -

0022 2/100 Blanket SC - - - - - - - 4.31 5.40 - - - - - - -

0023 2/100 Soil SC - - - - - - - 2.12 2.12 - - - 2.46 - - -

0024 3/900 Blanket SC - - - - - - - 7.30 7.30 - - - - - - -

0025 3/900 Soil SM - - - - - - - 9.05 14.99 - - - - - - -

0026 5/175 Blanket SM - - - - - - - 5.69 7.69 - - - - - - -

0027 5/175 Soil SC - - - - - - - 1.47 1.51 - - - 2.33 - - -

0028 2/600 Soil CL - - - - - - - 1.54 1.17 - - - 2.57 - - -

0029 6/600 Blanket SM - - - - - - - 18.42 20.34 - - - - - - -

0030 6/600 G. Soil SC - - - - - - - - - - - - 2.50 - - -

Annexure-IIA

1.476

Slope 3.5:1

Height = 5.3 mSlope 3.5:1Factor of safety = 1.476

Em bankm ent Soil

Sub Soil

Bed Rock

Soil 1Em bankm ent SoilSoil M odel M ohr- Coulom bUnit W eight 20.77Cohesion 4.1Phi 26.73Unsaturated Phi B 0Piezom etric Line # 0Ru (added) 0.25Pore- Air Pressure 0Soil 2Sub SoilSoil M odel M ohr- Coulom bUnit W eight 20.34Cohesion 0.6Phi 30.92Unsaturated Phi B 0Piezom etric Line # 0Ru (added) 0.5Pore- Air Pressure 0Soil 3BedrockSoil M odel BedrockUnit W eight - 1Piezom etric Line # 0Ru (added) 0Pore- Air Pressure 0

Horizontal Distance (m )

3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Elevation

(m)

2

3

4

5

6

7

8

9

10

11

12

13

14

Annexure-IIB

1.403

Slope 3:1

Height = 3.5 mSlope 3:1Factor of safety = 1.403

Em bankm ent Soil

Sub Soil

Bed Rock

Soil 1Em bankm ent SoilSoil M odel M ohr- Coulom bUnit W eight 20.77Cohesion 4.1Phi 26.73Unsaturated Phi B 0Piezom etric Line # 0Ru (added) 0.25Pore- Air Pressure 0Soil 2Sub SoilSoil M odel M ohr- Coulom bUnit W eight 20.34Cohesion 0.6Phi 30.92Unsaturated Phi B 0Piezom etric Line # 0Ru (added) 0.5Pore- Air Pressure 0Soil 3BedrockSoil M odel BedrockUnit W eight - 1Piezom etric Line # 0Ru (added) 0Pore- Air Pressure 0Horizontal Distance (m )

3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39

Elevation

(m)

2

3

4

5

6

7

8

9

10

11

12

13

14

Annexure-III

V – FORMATION

5.1 Soil Exploration of the New Line in the alignment has not been carried out as laid down in para 3.4.3 of the “Guidelines for the Earthwork in Railway Projects” Guideline No. GE:G-1. (This information is being asked from Southern Railway from 22.03.2010, in spite of several rounds of correspondence and discussions with CE/CN/MS, Southern Railway is not able to submit results of Soil Explorations results carried out before starting the Earthwork.) A Soil Investigation Report carried out during the year 2009 has been furnished, this Soil exploration has been carried out almost at the completion stage of the Earthwork. The line being close to sea, Soil Exploration plays a vital role, even otherwise soil exploration plays a vital role in New Line Construction. The Report of Soil Exploration carried out during 2009 indicated only silty clay type of soil existing whereas between Kms 1 to 5 clayey soil was found as could be seen from the soil excavated for providing retaining wall at the toe of the embankment recently.

5.2 The condition of embankment is not in an acceptable manner. The extent of erosion of the slopes of embankment found during Inspection was very very high, burrows of width of about 50 cm to 60 cm and 50 cm to 60 cm deep were found at many locations on side slopes of embankment. These continuous Burrows on slopes of embankment (see photos) has made total embankment to look like badly melted candy and some places core of the embankment was visible (see photos), these burrows on side slopes of embankment were available continuously upto km. 5/500. Some of the stretches upto Km. 5/500, repairs have been carried out by dumping loose earth and filling these burrows, this kind of repair of filling of burrows with loose soil will not hold and stay for long, hence this kind of repair will not help at all. Railways to approach RDSO/LKO for detailed analysis and recommending solutions, further certifying the Earthwork, to salvage the situation.

5.3 The Soil used for the embankment appears to be either silty clay or clayey type highly plastic in nature of very uniform grain size making the embankment not very stable. The eroded material has collected at the toe of the bank, this eroded material deposited at toe of bank indicates that it is either very fine sand very poorly graded or clay mixed with fine sand. Both the sides surface of slopes of embankment as well as the material collected at the toe of the bank has become so slushy making the location not even fit for walking, as the shear strength of these layers seems to be almost zero. Such material cannot become proper material for embankment as per para 5.1 of RDSO’s Guidelines for Earthwork in Railway Projects, Guideline No. GE:G-1.

5.4 Railways have brought red earth mixed with gravel from outside and is being dumped into these burrows through Ballast Train, as the area is not approachable by road, being a totally water logged area and close to sea. Such dumping of earth cannot get bonded to

the embankment as no removal of loose earth nor benching has been adopted, besides this the dumped earth is not being compacted, such earth is loosely lying and can get washed away during rains. This situation exists upto km. 5.5 from km. 1.355. Even beyond km. 5.5 wherever embankment height is around one metre and above similar situation of erosion of bank was observed as brought out above.

5.5 An RCC toe wall is being constructed to retain the earth flowing away from the embankments and getting deposited at the toe. Even while constructing this wall when enquired about the foundation that is being provided, no proper soil analysis has been carried out to arrive at the foundation as per the statements of the Engineers of the Construction Department who accompanied. The toe wall by itself may prevent flowing of earth away from the embankment but cannot prevent erosion on the slopes of the bank.

5.6 Railways were advised on 31.08.2010 how they are going to mitigate the deficiencies brought out by Commission to consider the Opening of the Line. Railway’s have approached NIT/Trichy to investigate the geotechnical problems. NIT/Trichy has submitted their report on 24.9.2010, a copy of the Report is enclosed. This Report is of preliminary nature and not a detailed Report. As already brought out, the deficiencies that should have been identified before construction of embankment so that care during Construction could have been taken for the base soil as well as the embankment soil by adopting appropriate solutions arrived at based on detailed field investigations. Based on this, discussions were held with CE/Const/Southern Railway as well as PCE/Southern Railway. PCE/Southern Railway agreed to inspect to arrive at an amicable solution and inspected the Line on 26.10.2010 and 27.10.2010, a copy of Inspection Notes is enclosed herewith for ready reference. PCE/Southern Railway’s analysis and appreciation of the problem needs real appreciation. In a short period, with available data, PCE/Southern Railway tried to analyse the problems to the extent possible and correlated the situation existing on the ground during the Inspection. PCE/Southern Railway concluded based on the results of NIT/Trichy that “on the whole remedial measures are needed for base soil, bank soil and blanket soil on different aspects”. Further PCE’s conclusions are that the blanket soil is of SC type with plasticity index varying from 10 to 15, suggested only drainage improvement in km. 6 & 7, other than this remedial measure PCE felt that there was no need to disturb the blanket provided though it is of SC type with plasticity index varying from 10 to 15.

5.6.1 Regarding bank soil, PCE has observed that “Side slopes have deep erosion at numerous locations 2H:1V is not also available”.

5.6.2 Regarding base soil, PCE has conducted the Vane shear tests at several locations and recommended strongly to have ground improvements, essentially required upto KM. 5 only.

5.6.3 Regarding formation to be kept under observation, as suggested by Construction Organisation PCE was of opinion that such troublesome formations cannot be qualitatively and quantitatively monitored for behaviour”. PCE suggested for instrumented monitoring.

5.6.4 Considering the above two Reports of NIT/Trichy and PCE/Southern Railway, there is a need for proper and thorough investigation of the situation before allowing Train Services. As Commission is not equipped to carry out such investigations, Railways have to approach RDSO to analyse the problems in detail and get the Earthwork certified by RDSO before allowing Passenger Services at normal speed on such troublesome, problematic embankment which do not satisfy any of the specifications or guidelines laid down by Railways.

5.7 Enclosed is the Note on the Observations made by Professor Shri S.R.Gandhi and Dr. R.G. Robinson during visit to Railway land from Nagapattinam to Velankanni on 28.10.2010. These observations do not contain any of the remedial measures suggested as the data given to them seems to be inadequate. They are needing soil samples and further investigations for arriving at final recommendations. The above has been sent by CE/C/West/MS to Commission vide letter No. W.347/T/10/CN/Vol.II dated 26.11.2010. The second opinion from IIT/MAS which was stated to be enclosed by CE/C/West/MS do not indicate any opinion of IIT/MAS. As advised by IIT/MAS, Railways have to feed data/samples to IIT/MAS, on obtaining IIT/MAS second opinion, Railways to forward the same to Commission for consideration.

5.8 Fixing of top of Formation/Embankment Level and Rail Level : Regarding fixing Top of Formation Level and hence Rail Level particularly at the locations starting from takeoff point to km. 5 which is almost having a flat terrain and open to the sea and prone for getting affected by tidal waters, when Railways were asked to advise how rail level has been fixed at this location, they have indicated only that “standard practice” has been followed in arriving at the rail level. But when enquired to provide the 50 year tide levels in the area, Railways had not obtained the 50 year tide level data before fixing the rail level though the area is prone for tidal effect. On further insistence for the data, Railways tried to obtain data from Survey of India, Dehra Dun. Survey of India have forwarded data from the year 1971 to 1977, for 7 years and 1980 to 1990, for 11 years.

It is reliably learnt that there are accepted theories based on which methods to extrapolate highest tide levels for various periods like 50 years/100 years etc. with available data. Railway to obtain the same from Survey of India along with assessing wave heights. This aspect also has to be seen by RDSO and certify that the Formation level and rail level provided is adequate considering tidal level along with the wave action.

5.9 Velankanni Station:

Yard drainage not provided as indicated in the yard plan of VLKI, this shall be provided.

5.10 Km. 6/1-4 : Pond near the toe of the bank slopes badly eroded.

5.11 Km. 6/4-5 : Embankment at Bridge approach needs repair. Loose earth was being dumped by a contractor through labour, the way in which it is being dumped will not last even one rainy season. Appropriate method of benching compacting shall be followed instead of dumping loose earth which will again get washed away.

Annexure-IV

Abstract of NIT/Tiruchy test results

Sl Item Base soil Bank soil Blanket soil

No.

1. Classification

Out of 8 locations bore holes,CH in 4 locationsOH in 1 locationSM in 2 locationsCI in 1 location

Out of 8 locations bore holes,CI in 3 locationsSC in 4 locationsSM in 1 location

Out of 8 locations bore holes,CI in 1 locationSC in 6 locations

2. 75 micron passing

20-94% wide range of

variation

35 to 70%Wide range of

variation

27-70%Wide range of

variation

3. Plasticity Index 13-33 13-17 10-15

4. Differential free swell 40-60 13-23 Not done

5 Liquid limit 35-68 33-40 35-376 N Values 0 to 24 2 to 25 4 to 24

7.Natural

moisture content

11-62% 11-23% 6 - 14%

8 φ 43-46° 43°

9. Specific gravity 2 – 2.7 2.2 to 2.7

10.Unconfined compressive

strength4 to 11 t/sq.m

11. NIT Conclusion

SM/OH/CH group compactness – very loose to medium denseConsistency – very soft to very stiffKm. 1/3 to Km. 3/5 – sub soil very soft highly compressible clay with more organic matter.

SC/CI group – relative compactness – loose to medium dense.

Clayey sand – SC typemore than 12% plastic finesRelative compactness – medium dense at centre and loose in side slopes.

Index Plan between Nagapattinam-Velankanni stations, TiruchchirappalliDivision, Southern Railway

DRG. NO. GE/SK/SR/658/REV.0/2011

Research Designs & Standards OrganisationTO T

IRUC

HCH

IRAP

PALL

I

THANJAVUR

NOTE:- NOT TO SCALE

THIRUVARUR KM. 37.91

VELANKANNI

TO CHENNAI N

MAYILADUTURI

NAGA

PPAT

TINA

M K

M. 7

7.43

NAGORE KM. 84.74

2. D AND UD INDICATES DISTURBED AND UNDISTRBED SOIL SAMPLES RESPECTIVELY.

Cross section at Km. 1/800 (Facing Velankanni)

1. ALL DIMENSIONS ARE IN mm.NOTES:

1.75:1(Avg. Slop

e)

2100

1000

1200

2.4:1 (Avg. Slope)2400

1000Blanket

L C

Bore 1

Existing profile between Nagapattinam - Velankanni

stations, Tiruchchirapalli Division, Southern Railway

DRG. NO. GE/SK/SR/659/Rev.0/2011


NOT TO SCALE

D6000

2:1 (Avg. Slope)

2.3:1 (Avg. Slope)1000

2300 2000

4000

Toe wall

1000

2000UD

Figure 2

Blanket



2000


D

Bore 2

6000

UD

D

2000

2.14:1 (Average S

lope)

2.5:1 (Average Slope)

1400

5000 3000






NOT TO SCALE


1000

L C

2200

3450 4200

1700

Figure 3

1000




2.02:1 (Average S

lope)

1800

1400

4000 3400

1600

3000

DBlanket

L C





NOT TO SCALE

D

Bore 3

3000

D

6000

UD

D

3500


1300

2700

1700

3000

1450

Figure 4

1000


2. D AND UD INDICATES DISTURBED AND UNDISTRBED SOIL SAMPLES RESPECTIVELY.1. ALL DIMENSIONS ARE IN mm.

D

NOTES:

D6000

Bore 4

2000

1700

1.95:1 (Aver

age Slope)

UD

4000

1900

3500

Blanket

CL





NOT TO SCALE

Figure 5


3800

1800

1300

2750

Blanket

L C


2. D INDICATE DISTURBED SOIL SAMPLE.1. ALL DIMENSIONS ARE IN mm.NOTES:

2.0:1 (Average

Slope)3200

1600





NOT TO SCALE


3000

600

D 1450

D

Figure 6

Proposed Profile

2. PROPOSED PROFILE IS SHOWN IN RED.1. ALL DIMENSIONS ARE IN mm.NOTES:

3425

1 IN 30

Blanket

L C

2:1

BENCHING

1000

1 IN 30

EXISTING PROFILE

3.5:1

300


LAYER OF LOCAL GRANULAR MATERIAL

Proposed profile between Nagapattinam - Velankanni



NOT TO SCALE

500

5300

30cm THICK LAYERS OFLOCAL GRANULAR MATERIAL

'X'

3000

150

Figure 7 A

EXISTING PROFILE

3:1

Proposed Profile


BENCHING

1 IN 30

Blanket

L C

1000

3425

2:1


LAYER OF LOCAL GRANULAR MATERIAL

Proposed profile between Nagapattinam - Velankanni



NOT TO SCALE

300

'X'

500

150

3500

Figure 7 B

Bore Log Detail


(2) km. 2/650

CH 3500

SM

(1) km. 1/800

CH

SM

Bore - I

CL

SC

SM1500

500

500

1500

500

500

Bore - II

Bor log details between Nagapattinam - Velankanni




NOT TO SCALE

3500

(3) km. 3/900

CI

500

500

1500SW-SM

SC

SM

SM

(4) km. 5/150

SM

SM

Bore - III Bore - IV

1500

500

500

Figure 8

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