TECHNOLOGY A 2011

TASK 1 (LOC 1 – AC 1)

Compare the difference between the methods of site survey techniques to evaluate the site

conditions and existing buildings for the redevelopments project.

As with surveying in general, land surveying can be broken down into several susections as

Geametic surveying, Topographical surveying, Photogrammetry, Hydra graphic surveying and

Engineering surveying. However, it must be stressed that them is a consideration overlap between these

sections, particularly as regards the basic methods and instruments used. That part of land surveying

which relevant to dvil engineering and construction is engineering surveying.

Geodetic surveys cover such large areas that the curved shape of the Earth has to be taken into

account. These surveys involve advanced mathematical theory and require precise measurements to be

made to provide a framework of accurately located paints. These points can be used to map entire

continents, they can be used to measure the size and shape of the Earth or they can be used to carry out

scientific studies such as the determination of Earth magnetic field and detection of continental drift.

Position fixing by satellite and sophisticated computers and software are a feature of modem geodetic

surveys.

Topographical surveys establish the position end shape of natural and man made features cover a

given area, usually for the propose of producing a map of an area or for establishing a geographic

information system. Such surveys are usually classified according to the scale of the final amp or terrain

model formed. Small scale surveys cover large areas such an entire continent, country, and many range in

scale from 1 : 1000000 to 1: 50000 looked the familiar Ordnance Survey land ranger maps of Great

Britain. Medium scale maps range in scale from about 1: 10000 to 1: 1000 and many cover the area of a

small town. Large scale maps show detailed and present information that is not often available from a

map purchased in a shop and are therefore usually commissioned for a specific purpose. These maps

range ins scale from 1: 500 up to 1:50 or larger and are often provided to meet the needs of architects,

civil engineers, or government departments.

TECHNOLOGY A 2011

TASK 2 (LOC 1- AC 2)-M2/D2

Based on the scenario, describe at least 3 types of site investigation methods that are applicable to the project.

A site investigation is the process of collecting information and evaluating the conditions of the site for the purpose of designing and constructing the foundation for a structure, such as a building, plant or bridge. Good planning for and management of a site investigation is the key to obtaining sufficient and correct site information for designing a structure in a timely manner and with minimum cost for the effort needed.

The site investigation procedure needs to identify the potential for using types of site investigations methods and identify possible areas that may require remedial works in order to make a site suitable for use. Based on the scenario, the site were home of 7 units of abandoned shop houses in Teluk Pahang. The site investigation should be done in phases in order that resources are appropriately targeted.

Phase 1 investigation should establish whether there have been any former contaminative uses on the site or adjacent properties which could impact upon the development. The Phase 1 should include a preliminary conceptual site model.

Phase 2 investigations should determine the nature, extent and severity of contamination using risk based criteria. It should provide details of remedial options, health and safety issues, potential impacts on the environment and a detailed work plan. It should assess the risks to human health, controlled waters and the wider environment.

Phase 3 Remediation Method Statement should provide details of proposed remedial options, health and safety issues and a detailed remediation strategy.

Generally the following site investigation techniques are employed to the projects:

Trial Pitting Window Sampling and Dynamic Probe Testing Cable Percussive Boreholes Hand Augering or Rotary Augering

Trial Pitting

TECHNOLOGY A 2011

Trial pitting can be carried out by a variety of methods from hand dug pits to machine excavated trenches. Trial pits provide the best method of obtaining very detailed information on strength, stratification, pre-existing shear surfaces, and discontinuities in soil. Trial pitting is generally carried out to a maximum depth of 4.5m with standard excavation plant and, depending on soil conditions, is generally suitable for most low rise developments.

Trial pits may be excavated by either hand digging or machine excavation. In general, machine excavation is used for shallow pits, whereas hand excavation is used for deep pits which must be supported. In the limited space of a trial pit, which is often 1.5m x 3m in plan area at ground level, it is usually impossible to place supports as machine excavation proceeds. Shallow trial pits provide a cheap method of examining near-surface, but the cost increases dramatically with depth, because of the need to support.

a) Shallow Trial Pitting

Shallow trial pitting are usually dug by hand using a pick and shovel, and commonly extend to a depth of about 3m. It is essential that the pit sides are guarded against sudden collapse in order to protect personnel working in the pit. For this purpose, timber shoring is usually provided when excavation is deeper than 1.2m. The spacing of the shoring should be sufficiently wide to allow inspection of the pit sides. Shallow trial pits may also be dug by machine that is excavator is the most commonly used.

Material that has been excavated from the pits should be stockpiled in such a manner that is does not fall back in to the pits or cause instability of the pit excavation. Wooden hoardings anchored by steel bars driven into the ground are often used on steep slopes to retain spoil from falling back into the pit. The spoil should be placed and covered so as not be washed downhill during rainstorms or allowed to enter surface drainage systems.

b) Deep Trial Pitting

Figure: Example of trial pitting have been done

Resource: http://www.nicholls-colton.co.uk/110.asp

TECHNOLOGY A 2011

Deep trial pitting is normally constructed by hand excavation using various methods for supporting the sides. Temporary or permanent liners are necessary for the protection of personnel working in these excavations, but it also necessary to consider the need to expose the ground for inspection and logging. The work must done such in judgment and experience often required to establish suitable procedures for such excavations.

Working in deep shafts will be dangerous unless the appropriate safety precautions are strictly followed. Attention should be given to the possible occurrence of injurious or combustible gases or of oxygen deficiencies. Correct methods of inspections should be followed and appropriate precautions should be taken.

       Window Sampling

Window sampling is a site investigation tool that utilizes portable equipment to drill small diameter boreholes in order to take soil samples and install monitoring wells. Window sampling is carried out by hand held pneumatic samplers. The equipment is suitable for shallow soils investigations and represents a rapid and cost effective drilling method that can be used for geotechnical and environmental sampling.

Window sampling can generally be extended to depths of up to 6m although it is possible to continue the borehole using dynamic probing methods. The sampler consists of a specially constructed and strengthened metal sample tube, with side windows, of diameters ranging from 80mm to 40mm.The sample tubes come in lengths of 1.00m and 2.00m and are driven into the ground by a pneumatic kango hammer using a small portable compressor unit, or by petrol or electrical hammer.

The use of electrical equipment means that sampling can be carried out safely inside buildings and the equipment can be operated in headroom of as little as 2.2 m. The equipment is self-contained, requires a small working area and causes minimal disturbance to surfacing.

Figure: Pneumatic Kango Hammer

Resource: http://www.dynamicsampling.co.uk/services.php

Figure: Strengthened Metal Sample Tube

Resource: http://drill-pro.com/Method_satement.html

TECHNOLOGY A 2011

By using this method a continuous sample of soil can be obtained for inspection and small disturbed samples can be recovered for subsequent laboratory testing. The continuous core means that the method is particularly suited to assessing the depth of desiccation in clay soils, particularly in association with pocket penetrometer testing.

The advantages of using window sampling method:

Ideal for restricted access sites Suitable for contamination sampling No residual spoil Useful initial intrusive investigative tool Can be used to install monitoring wells The equipment is portable.

Hand Augering or Rotary Augering

Hand auger equipment is suitable for soil research based on the scenario. Almost any type of soil sets its own demands where it concerns the model of the auger to be applied. With

TECHNOLOGY A 2011

hand auger equipment a depth of 8-10 meter can realistically be achieved. The maximum boring depth strongly depends on various factors such as:

Depth of the groundwater The soil profile The characteristics of the material the auger has to pass through

The hand auger consists of extendable steel rods, rotated by a handle. A number of different steel augers can be attached at the bottom end of the drill rods. A hand auger comprises of a ‘T-Bar’ handle on a length of either 1, 2 or 3m extendable steel rods with an auger head attached to the bottom.

Figure: Example of Hand Augering Set for Site Investigation and “T-Bar” handle

Resource: http://www.acme-et.com/suppliers_Eijkelkamp.php

TECHNOLOGY A 2011

Site specific conditions should be addressed before using hand augering method for site investigations. The flow chart below determined if hand augering is a feasible investigative

TECHNOLOGY A 2011

The auger head is driven into the ground as the handle is turned in a clockwise rotation. Soil is forced into and retained in the head to be brought to the surface and identified and described. The auger is then carefully placed back in the hole commonly known as a borehole and the process is repeated until the desired depth is reached. Once the desired depth has been reached on the borehole then it is backfilled and the surface is reinstated to match the existing as closely as possible. Than a display of cross sectional profile of the borehole, including foundation details can be taken.

Hand augering are appropriate for many but not all soil ground water investigations. Potential advantages, disadvantages and limitations are listed in table below and must be considered prior to beginning on investigations.

Advantages Disadvantages LimitationsNot limited by access Allow only 2inch monitor well

completionsWater table greater than 20 ft below ground level

Minimal site disturbance Could be labor intensive Sediment clast greater than 50 millimeter

Repetitive sample profile Potential loss of surface casing Consolidated sediments or bedrock

Minimize volume of drill cuttings

Boreholes conditions prevent ability to drive surface casing

Highly cohesive sediments

Sampling sediments and completing monitor wells in unstable boreholesAllows annular materials to be completed inside surface casing

Cable Percussive Borehole

Figure: Example of Hand Augering Work and taking detail from the soil

Resource: http://www.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soil_acid_sulfate_soils

TECHNOLOGY A 2011

Cable percussive borehole the most appropriate drilling technique to suit the geological conditions and objectives of a particular projects. The equipment is simple and relatively easy to maintain and is suitable for drilling in all types of soils and weak rocks. In the hands of a competent and experienced driller the equipment provides a rapid and cost-effective method of investigation to depths of up to 50 m.

The cable percussive consists of:

1. A collapsible ‘A’ frame, with a pulley at its top;

2. A diesel engine connected via a hand-operated friction clutch

3. A winch drum which provides pulling power to the rig rope and can be held still with a

friction brake which is foot-operated.

Figure 24: Cable percussion drilling

Resources from web: http://www.prioritygeotechnical.ie

TECHNOLOGY A 2011

The following can be carried out with cable percussion drilling: -

Boreholes up to 50m depth Installation of monitoring wells up to 150mm diameter In - situ testing including : -

o Standard Penetration Testing (SPT)

o Down hole vane testing

o Permeability testing

Disturbed, undisturbed, bulk and water samples can be taken Access to restricted areas by using a cut down drilling rig Drilling diameters of 150mm, 200mm or 250mm

Cable percussive only use one engine is employed, and no water or mud is needed, yet it will perform all the tasks required to drill, place casing and develop the well.

Examples picture of workers using Cable Percussion Borehole during site Investigations

Resource: http://www.geositesurveys.co.uk/cable-percussive.html

TECHNOLOGY A 2011

TASK 3 (LOC 1- AC 3)

Analyze the soil classification and their chemical composition that are possible to be found at the developments site.

Soil research is a very important aspect in the planning and execution of site investigations as well as civil engineering and operations. In order to make the soil research as comprehensive as possible the following studies must be made with regards to:

Determining the classifications, the composition, the thickness and the position of the various strata.

The soil properties for examples measuring the permeability, the filtration capacity, the bearing capacity and their chemical compositions.

Soil in the engineering sense, is defined as “any unconsolidated material that is the product of weathering and mechanical disintegration of rocks, composed of discrete particles with gases and liquids interspersed between them. Soils are diverse as the plants and animals growing and living above them. Tropical rain forest soil is not like a prairie soil. Physical, chemical, and biological actions work together to create every soil on the planet. But there are many ingredients that can go into the basic recipe.

The formation of soil happens over a very long period of time. It can take 1000 years or more. Soil is formed from the weathering of rocks and minerals. The surface rocks break down into smaller pieces through a process of weathering and is then mixed with moss and organic matter. Over time this creates a thin layer of soil. Plants help the development of the soil. How? The plants attract animals, and when the animals die, their bodies decay. Decaying matter makes the soil thick and rich. This continues until the soil is fully formed. The soil then supports many different plants.

Weathering

Weathering is the process of the breaking down rocks. There are two different types of weathering that is physical weathering and chemical weathering. In physical weathering it breaks down the rocks, but what it's made of stays the same. In chemical weathering it still breaks down the rocks, but it may change what it's made of. For instance, a hard material may change to a soft material after chemical weathering.

TECHNOLOGY A 2011

Soils are a mixture of different things rocks, minerals, and dead, decaying plants and animals. Soil can be very different from one location to another, but generally consists of organic and inorganic materials, water and air. The inorganic materials are the rocks that have been broken down into smaller pieces. The size of the pieces varies. It may appear as pebbles, gravel, or as small as particles of sand or clay. The organic material is decaying living matter. This could be plants or animals that have died and decay until they become part of the soil. The amount of water in the soil is closely linked with the climate and other characteristics of the region. The amount of water in the soil is one thing that can affect the amount of air. Very wet soil like you would find in a wetland probably has very little air. The composition of the soil affects the plants and therefore the animals that can live there.

Soil Texture

Soil texture has an important role in nutrient management because it influences nutrient retention. For instance, finer textured soils tend to have greater ability to store soil nutrients. The mineral particles of a soil are present in a wide range of size. The fine earth fraction includes all soil particles that are less than 2

Picture: Soil Formations

Resources from http://www.colorado.edu/geography/class_homepages/geog_3251_sum08/

Chart: Soil Compositions

Resource from http://soils.missouri.edu/tutorial/page1.asp

TECHNOLOGY A 2011

mm. Soil particles within this fraction are further divided into the 3 separate size classes, which includes sand, silt, and clay. The size of sand particles range between 2.0 and 0.05 mm; silt, 0.05 mm and 0.002 mm; and clay, less than 0.002 mm. Notice that clay particles may be over one thousand times smaller than sand particles. This difference in size is largely due to the type of parent material and the degree of weathering. Sand particles are generally primary minerals that have not undergone much weathering. On the other hand, clay particles are secondary minerals that are the products of the weathering of primary minerals. As weathering continues, the soil particles break down and become smaller and smaller.

Soil texture is the relative proportions of sand, silt, or clay in a soil. The soil textural class is a grouping of soils based upon these relative proportions. Soils with the finest texture are called clay soils, while soils with the coarsest texture are called sands. However, a soil that has a relatively even mixture of sand, silt, and clay and exhibits the properties from each separate is called a loam. There are different types of loams, based upon which soil separate is most abundantly present. If the percentages of clay, silt, and sand in a soil are known, you may use the textural triangle to determine the texture class of your soil.

Figure :Textural Triangle - The textural triangle describes the relative proportions of sand, silt and clay in various types of soils.

Source: http://soils.usda.gov/technical/manual/print_version/complete.html

TECHNOLOGY A 2011

Clay particles, as well as other particles of similar size, are important components of a soil. There is a fundamental difference between soils that contain large amounts of sand particles and soils that contain large amounts of very small particles, such as clay. That difference is surface area. The total surface area of a given mass of clay is more than a thousand times the total surface area of sand particles with the same mass.

Table: soil classified

Resources from http: // environment. uwe.ac.uk/geocal/SoilMesh/ classification/default.htm

Very coarsesoils

BOULDERS > 200 mm

COBBLES 60 - 200 mm

Coarsesoils

GGRAVEL

coarse 20 - 60 mm

medium 6 - 20 mm

Fine 2 - 6 mm

SSAND

coarse 0.6 - 2.0 mm

medium 0.2 - 0.6 mm

Fine 0.06 - 0.2 mm

Finesoils

MSILT

coarse 0.02 - 0.06 mm

medium 0.006 - 0.02 mm

Fine 0.002 - 0.006 mm

C  CLAY < 0.002 mm

TECHNOLOGY A 2011

Climate Classification

Soil formation greatly depends on the climate, and soils from different climate zones show distinctive characteristics. Temperature and moisture affect weathering and leaching. Wind moves sand and other particles, especially in arid regions where there is little plant cover. The type and amount of precipitation influence soil formation by affecting the movement of ions and particles through the soil, aiding in the development of different soil profiles. Seasonal and daily temperature fluctuations affect the effectiveness of water in weathering parent rock material and affect soil dynamics. The cycle of freezing and thawing is an effective mechanism to break up rocks and other consolidated materials. Temperature and precipitation rates affect biological activity, rates of chemical reactions and types of vegetation cover.

Soil Structure

TECHNOLOGY A 2011

Soil structure is the arrangement of soil particles into groupings. These groupings are called peds or aggregates, which often form distinctive shapes typically found within certain soil horizons. For example, granular soil particles are characteristic of the surface horizon. Soil aggregation is an important indicator of the workability of the soil. Soils that are well aggregated are said to have “good soil

tilth.” The various types of soil structures are provided in table below.

TECHNOLOGY A 2011

TASK 4 ( LOC 2- AC 1)

Determine the different soil classifications and their effects onto the design of substructure of the buildings.

A proper design of a substructure of the buildings requires thorough knowledge of the subsurface conditions at the structure site. The investigation should consist of subsurface investigation, laboratory testing, geotechnical analysis of all data and design recommendations. The absence of a thorough geotechnical investigation or adequate data generally leads to:

A foundation system with a large factor of safety, which is generally moreexpensive foundation or unsafe

Construction problems, disputes and claims.

Soil structure is produced by the arrangement of soil particles and the air spaces between them.  Soil structure is dependent on the arrangement of the classifications within the soil.  Aggregates are stable clusters of soil particles bound together by organic matter. Aggregates become unstable when organic matter is low, or sodium levels on the clay particles become too high. A stable soil structure is important for build substructure. Soil structure decline refers to undesirable changes in this structure as a result of various land use practices. The degree of soil structure decline depends on both soil type and land use history.

When selecting the type of substructure, the designer must consider the existing soils found at the site.

Types of Soil Descriptions PictureBedrock The solid rock

below the overburden soil, decomposed rock fragments or other loose superficial deposits. Bedrock exposed at the surface is known as rock outcrop.

TECHNOLOGY A 2011

Boulders Rounded fragments of rock that will be retained on a 3 inch [75 mm] sieve. Isolated boulders should not be confused with bedrock.

Decomposed Rocks The upper portions of bedrock may be found in varying stages of decomposition. Decomposed rock represents the uppermost product of weathering and decomposition of bedrock in situ. In its most decomposed state, it can be compact soil that retains some of the appearance and texture of the original rock structure. Decomposed rock is not equivalent to bedrock for bearing capacity.

TECHNOLOGY A 2011

Mud Deposits of a saturated or unsaturated mixture of soils and organic matter not suitable for foundation material regardless of moisture content.

Organic Matter The more or less decomposed material of soil derived from organic sources, usually from plant remains. The term covers such material in all stages of decay.

Organic Soil Soils that contain significant amounts of muck.

TECHNOLOGY A 2011

A footing is the interfacing element between the superstructure and the underlying soil or rock. The loads transmitted from the superstructure to the underlying soil must not cause soil shear failure or damaging settlement.

Foundation Type Applicable Soils ConditionsSpread footing or wall footing Any conditions where bearing capacity

is adequate for applied load. May use on single stratum, firm layer over soft layer, or soft layer over firm layer. Check immediate, differential and consolidation settlements.

Pile foundation (friction, end bearing or combination)

Poor surface and near-surface soils. Soils of high bearing capacity 25 to 150 ft [7.5 to 45 m] below ground surface. Friction piles distribute load along pile shaft if the soil strength is adequate. End bearing piles transfer load by point bearing on dense soil or rock of high bearing capacity. Check settlement of pile groups in clay.

Caisson (drilled shaft) - generally end bearing or combination of end bearing and skin resistance

Poor surface and near-surface soils. Soil of high bearing capacity (point bearing) is 25 to 50 ft [7.5 to 15 m] below ground surface.

Table : Foundation Types and Applicable Soils Conditions

TECHNOLOGY A 2011

The designer must specify excavation into the soil to key the footing into the rock and to establish a suitable level bearing surface. The excavation in the rock can be the full width of the footing or can be benched. Any footing that exceeds 3 feet in depth must have vertical reinforcement to prevent cracking.

Pile foundations may be needed in some areas to prevent undesirable seasonal movements of the substructure. Piles under such conditions are designed to transfer foundation loads, including uplift or down drag, to a level unaffected by seasonal moisture movements. Negative skin friction occurs where the soil surrounding the pile exhibits a downward movement with respect to the pile shaft. There are various causes of the downward movement of the soil. All the causes increase the load on the pile. This is also known as down drag and is analyzed as additional axial load.

In either case the piles must be extended to develop the necessary capacity below the level of expected soil types or excavation. This will prevent costly damage and eliminate the need for future underpinning. Piles should not be used where the depth to bedrock is less than 10 feet. In these cases, it is difficult to develop adequate lateral stability.

The effects of soil liquefaction on the built environment can be extremely damaging. Buildings whose foundations bear directly on sand which liquefies will experience a sudden loss of support, which will result in drastic and irregular settlement of the building causing structural damage, including cracking of foundations and damage to the building structure itself, or may leave the structure unserviceable afterwards, even without structural damage. Where a thin crust of non-liquefied soil exists between building foundation and liquefied soil, a 'punching shear' type foundation failure may occur. The irregular settlement of ground may also break underground utility lines. The upward pressure applied by the movement of liquefied soil through the crust layer can crack weak foundation slabs and enter buildings through service ducts, and may allow water to damage the building contents and electrical services.

Figure : Example of soil liquefaction on buildings

Resource : http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/earthquake_effects.html

TECHNOLOGY A 2011

TASK 5 ( LOC 2 – AC 2 ) M3/D3

Describe the effects of the followings factors onto the design and construction of a substructure:

a) Waterb) Chemicalc) Contaminated Soils

The purpose of a substructure is to transfer the load of a structure to the ground without causing the ground to respond with uneven and excessive movement. Most building are supported on one of four types of foundations. Examples are pads, strips, rafts and piles. These may be modified and combined to form a suitable foundation or substructure for the ground conditions that exist.

Water

The movements of water levels and the ground-water are characteristics that should be studied at every site before design or construct substructure. When water levels are lowered consolidation may occurs. A shaft of an end-bearing pile can be loaded to failure by the downward drag against it of consolidating sediment. Uneven consolidation beneath a buildings will result in differential settlement and structural failure.

Tables : The hydrological cycle

Resource : http://geography.about.com/od/physicalgeography/a/hydrologiccycle.htm

TECHNOLOGY A 2011

Ground water is the fluid most commonly encountered in engineering construction. It is derived from many sources but most now comes from rainfall and melting snow and is termed meteoric ground water. The passage of water through the surface of the ground called infiltration and its downward movement to the saturated zone at depth is described as percolation. Water in the zone of saturated ground moves towards river, lakes, and the seas a process known as ground water flow, where it is evaporated and returned to the land as clouds of water vapor which may precipitate as rain or snow. The circulation of water is termed the hydrological cycle.

Effect on water to construction:

Water logging

The excavation becoming weak

Collapse of edge excavation

Temporary support will collapse

Settlement to the nearest building

CONCRETE CRACKS AND DETERIORATES

In the coastal flats and many desert areas, the ground water table is very near to the surface and salts may exist either in solution in the groundwater, or in the form of salt crusts on the surface. The salts which consist mainly of sulphates, chlorides or carbonates of calcium, magnesium and sodium, attack the concrete externally both below and up to a meter above ground level. The calcium aluminum hydrate in hardened concrete reacts with sulphate salts to produce calcium sulpho-aluminate crystals within the framework of the hydrated paste. As these crystals have a volume 227% greater than the original calcium aluminum hydrate crystals, the concrete cracks and deteriorates.

Photo: An experiments that been done to showed reactions of sulphate salts with concrete that can effect cracks and deteriorates.

Resource: http://www.shieldcrete.com/UniqueApplications5.html

TECHNOLOGY A 2011

CONSOLIDATION

Consolidation is a process by which soils decrease in volume. Consolidation is any process which involves decrease in water content of a saturated soil without replacement of water by air. In general it is the process in which reduction in volume takes place by expulsion of water under long term static loads. It occurs when stress is applied to a soil that causes the soil particles to pack together more tightly, therefore reducing its bulk volume. When this occurs in a soil that is saturated with water, water will be squeezed out of the soil.

The process of consolidation is often explained with an idealized system composed of a spring, a container with a hole in its cover, and water. In this system, the spring represents the compressibility or the structure itself of the soil, and the water which fills the container represents the pore water in the soil.

1. The container is completely filled with water, and the hole is closed. (Fully saturated soil)

2. A load is applied onto the cover, while the hole is still unopened. At this stage, only the water

Photo: Example photos of building settlement cause by ground water movements.

Resource: http://www.nd.edu/~concrete/1999_duzce_earthquake_reconnaissance/liq_set_sub.html

TECHNOLOGY A 2011

resists the applied load. (Development of excess pore water pressure)

3. As soon as the hole is opened, water starts to drain out through the hole and the spring

shortens. (Drainage of excess pore water pressure)

4. After some time, the drainage of water no longer occurs. Now, the spring alone resists the

applied load. (Full dissipation of excess pore water pressure. End of consolidation)

SOIL SHRINKAGE

Subsidence frequently causes major problems in construction of substructure, where dissolution of limestone by fluid flow in the subsurface causes the creation of voids. If the roof of these voids becomes too weak, it can collapse and the overlying rock and earth will fall into the space, causing subsidence at the surface. This type of subsidence can result in sinkholes which can be many hundreds of meters deep. This also known as soil shrinkage.

Chemical

Photo: Example photo and diagram showed of foundation failure cause by dissolution of limestone by fluid flow in the subsurface.

Resource: http://www.dep.state.pa.us/dep/deputate/minres/districts/homepage/california/Underground/Mine%20Subsidence/mine_subsidence.htm

TECHNOLOGY A 2011

Chemicals substances are often defined as any materials with definite materials composition in most introducing general chemistry textbooks. It also can we defined as the soil may contain phosphorus waste & radioactive substances. It will spontaneously ignite when exposed to atmosphere. Toxic waste is hard to remove because costly. All the materials above are not really dangerous / hazard to human but may affect to plants & building materials.

Ground waters have a concentration of sulphate that is aggressive to concrete. The sulphate comes from soluble sulphate minerals in the ground, and for this reason the sulphate minerals in the ground, and for this reason the sulphate content of both soil and water should be measured. It is useful to measure their pH at the same time. Sulphates are common in deposits of clays, evaporate and peat. Oxidation of pyrite can produce free sulphuric acid and this occurrence is indicated by a low pH for the soil and a high content of sulphate. Metal piles can corrode in saline ground and the electrical conductivity of the soil will indicate the severity of this effects.

Alkali-silica reaction can cause serious expansion and cracking in concrete, resulting in major structural problems and sometimes necessitating demolition. Alkali-silica reaction is the most common form of alkali-aggregate reaction in concrete. The other, much less common, form is alkali-carbonate reactions, alkali-silica reaction and alkali-carbonate reaction are therefore both subsets of alkali-aggregate reaction. Alkali-silica reaction is caused by a reaction between the hydroxyl ions in the alkaline cement pore solution in the concrete and reactive forms of silica in the aggregate examples chert, quartzite, opal, and strained quartz crystals.

Tables :

Corrosion of Metal piles in substructure cause by a low pH for the soil and a high content of sulphate.

Resource : http://www.corrosionist.com/picture_of_corrosion.htm

TECHNOLOGY A 2011

Contaminated Soils

March harmful waste degrades to harmless substances that eventually enter the atmosphere as a gas or the hydrosphere as a solute in ground water. Safe waste disposal ensure that dangerous products cannot travel far from their repository until they have degraded to a safe conditions. To predict the rate of migration of waste products that have been buried in the ground, it is necessary to study the geology of each disposal site or contaminated sites.

Special attention must be directed to the movements of ground water. Some contaminated soil or waste contains materials that do not degrade and do not decay. Examples are cadmium and mercury. The disposal of these wastes on the land may be achieved by burying them beyond reach of the agents of weathering and erosion. Underground disposal sites are thus an attractive location for these materials.

Building sites that may contain contaminants can be identified from planning records or local knowledge of previous uses. Sites that are likely to contain contaminants include:

Asbestos works Chemical or gas works Coal carbonisation plants and ancillary byproducts Industries making or using wood preservatives Landfill sites Waste disposals sites Metal works Munitions factories Nuclear installations

Tables : Concrete thin-section, viewed with a petrographic microscope, showing a chert aggregate particle (at the right of the image) from which alkali-silica gel has extruded into adjacent cracks.

Resource : http://www.understanding-cement.com/alkali-silica.html

TECHNOLOGY A 2011

Oil stores Paper printing works Railway land Scrap yards Sewage works Tanneries

Signs of possiblecontaminants

Possible contaminant Relevant action

No sign of vegetation, orpoor or unnatural growth

MetalsMetal compounds

None

No sign of vegetation, orpoor or unnatural growth

Organic compoundsGases

Removal

Surface colour andcontour or materials maybe unusual indicatingwaste

MetalsMetal compoundsOily and tarry wastes Asbestos (loose) Other mineral fibers Organic compoundsincluding phenolsCombustible materialincluding coal and coke dustRefuse and waste

None

Removal, filling or sealingFilling or sealingNoneRemoval or sealing

Removal or sealing

Total removal or seekspecialist advice

Fumes and odours mayindicate organicchemicals at very lowconcentrations

Flammable explosive andasphyxiating gases includingmethane and carbon dioxideCorrosive liquidsFaecal animal and vegetablematter (biologically active)

Removal

Removal, filling or sealingRemoval or sealing

Drums and containers(whether full or empty)

Various Removal with allcontaminated ground

Effects of Contaminated to environment:

Figure: Possible signs of contaminants soil and actions.

TECHNOLOGY A 2011

Sulphur dioxide and nitrogen oxides can cause acid rain which lowers the pH value of

soil.

Nitrogen oxides are removed from the air by rain and fertilise land which can change the

species composition of ecosystems.

Soil can become infertile and unsuitable for plants. This will affect other organisms in the

food web.

Smog and haze can reduce the amount of sunlight received by plants to carry out

photosynthesis and leads to the production of troposphere ozone which damages plants.

Invasive species can out compete native species and reduce biodiversity. Invasive plants

can contribute debris and bio molecules (allelopathy) that can alter soil and chemical

compositions of an environment, often reducing native species competitiveness.

Bio magnification describes situations where toxins (such as heavy metals) may pass

through tropic levels, becoming exponentially more concentrated in the process.

Carbon dioxide emissions cause ocean acidification, the ongoing decrease in the pH of

the Earth's oceans as CO2 becomes dissolved.

The emission of greenhouse gases leads to global warming which affects ecosystems in

many ways.

Contaminated to construction:

Tables : examples of contaminated soil with toxic waste that can effect substructure of ah building.

Resource : http://www.sciencedaily.com/releases/2010/06/100609201310.htm

TECHNOLOGY A 2011

If used for residential purposes, need fully investigated & assessed in order to restore the

land to a health & safety level ensured for residents

Many site contain toxic materials ( dumped illegally)

Sites contain phosphorous waste & radioactive substances will spontaneously ignite when

exposed to atmosphere.

Some sites cannot built over because cost of removing toxic waste expensive.

For pest industries site, which contain chemicals, acids or heavy metals ; not all materials

above are dangerous / hazardous to human but will effect plants or building materials.

TASK 6 (LOC2 – AC 3) - M1/D1

TECHNOLOGY A 2011

Compare and appraise the various types of substructure and their associated temporary works to be used for the buildings in the redevelopments projects.

Newsday in construction world, managing the weight of these vertically constructed works of architecture is one of their major technical concerns. The construction of a steel or concrete building's substructure enables them to handle their considerable weight. "Substructure" refers strictly to the foundation and will not address the rest of the skeleton that undergirds the building. The foundation is the part of the structure that contacts the earth. It must be capable of holding the structure, and prevent excessive settlement. Foundations today are generally made of concrete, or CMU (cement masonry units or cement blocks). Almost all foundations are reinforced with steel bar called rebar. Chart below showed types of substructure and foundations.

Shallow Foundation

Substructures

Foundation

Shallow Foundation

Slab

Pad

Strips

Raft

Deep foundation

Pile

TECHNOLOGY A 2011

Shallow foundations represent the simplest form of load transfer from a structure to the ground beneath. They are typically constructed with generally small excavations into the ground, do not require specialized construction equipment or tools, and are relatively inexpensive. In most cases, shallow foundations are the most cost-effective choice for support of a structure.

SLAB FOUNDATION

The slab foundation is the easiest foundation to build, because it takes very little site preparation, less labor and less concrete form work. The slab is a ground supported foundation. A slab may be reinforced with wire mesh to prevent settlement and shrinkage. Slabs are generally 4 to 6 thick and vary in their construction. There are methods offering additional support for load-bearing walls, chimneys and fireplaces, that can offer vary in style from traditional to contemporary foundations. Slab foundations come in four basic variations.

1. Floating or pinned:

This variety is most commonly used for garage floors. The floor, itself, is poured onto a bed of gravel and floats between two walls and the footings. It is free standing, in that it is not supported by some form of support at its edges. Some floating floors are pinned at the edges to tie the walls and floor together.

2. Monolithic:

The slab floor, and foundation are poured as one piece with mesh and a steel bar to add reinforcement and strength. With the monolithic floor, the edges are also thicker to offer support to the load bearing walls.

3. Supported, footed, or concrete-block supported:

These are variations of the same basic concept. They are comprised of a slab resting at its edges, where vertical support is needed for the framing, or on a direct footing such as the basement variety. They can also be constructed on footing and a few courses/layers of concrete blocks and footing where the soil grading is not leveled, but pitched. Another variety has a shoulder cut at the top of the foundation for the edge of the slab to rest on.

TECHNOLOGY A 2011

It is not uncommon for water supply and waste lines, heating ducts, or hot water heat plumbing to be located below the slab. When building a slab, it is required that all these systems be installed, before the concrete is poured.

Figure: various types of slab foundation use in substructure

Resource: http://www.bettergazebos.com/foundation.htm

Figure: Picture of slab foundation been done

Resource: http://www.homesfromthegroundup.com/creative_concrete_stamped_concrete_drives_walkways_Ge

orgia/Concrete_Basements_Slabs_Mono_Slabs_Raised_Slabs_in_Georgia_Communities.shtml

TECHNOLOGY A 2011

PAD FOUNDATION

Pad foundation is isolated foundations which may be of reinforced or unreinforced concrete. The minimum thickness of the foundation should not be less than 150mm.These foundations are normally used for structures which are framed with steel or concrete columns. This type of foundation will also be used to provide a foundation for isolated piers, but it is important to ensure that the scar cement still remains the same as any other type of foundation.

A brick may need to be placed on a pad foundation. This will support the piers that carry the weight of the construction. The size of the pad foundation will be in the plans for the project. The formwork will be built in the same way as slab formwork. Pad foundations may also be below ground level. In this case the earth will act as the formwork.

The spread of the pad foundation is determined by the loads on it and the bearing capacity of the subsoil and the thickness of is either at least equal to the projection of the pad each side of the pier. The spacing of the piers or columns is determined by the most economical construction. Pad foundation to heavily loaded structural steel columns are sometimes provided with a steel grillage

The advantage of this system of foundation is that pockets of tipped stone or brick and concrete rubble that would obstruct bored piling may be removed as the pits are excavated and that the nature of the subsoil may be examined as the pits are dug to select a level of sound subsoil. This advantage may well be justification for this labor intensive and costly form of construction.

TECHNOLOGY A 2011

Figure: Example construction of pad foundation from earlier stages until ready for backfill

Stages 1 Finish Excavation Stages 2 Pad Rebar

Stages 3 Foundation Pad Form Stages 4 Foundation Pad Pour

Stages 5 Foundation Pad Pored Stages 6 Foundation Pier Ribar

Stages 7 Foundation Pier Forms Stages 8 Foundation Ready For Backfil

TECHNOLOGY A 2011

STRIP FOUNDATIONS

Strip foundations consist of a continuous strip, usually of steel reinforced concrete, formed centrally under load bearing walls. This continuous strip serves as a level base on which the wall is built and is of such a width as is necessary to spread the load on the foundations to an area of subsoil capable of supporting the load without undue compaction. The bearing capacity of the soil should be greater than the loads imposed by the buildings foundation.

In practice the concrete strip will generally be wider than the thickness of the wall for the convenience of covering the whole width of the trench and to provide a wide enough level base for bricklaying below ground. A continuous strip foundation of concrete is the most economic form of foundation for small buildings on compact soils.

The width of a concrete strip foundation depends on the bearing capacity of the subsoil and the load on the foundations: the greater the bearing capacity of the subsoil, the less the width of the foundation

Types of strip foundation:

Stepping Strip Foundation Wide Strip Foundation Narrow Strip Foundation Deep Strip Foundation

Figure: Examples of strips foundations

Resource: http://www.sierraconcretefoundations.com/information.php

TECHNOLOGY A 2011

RAFT FOUNDATION

A raft foundation consists of a raft of reinforced concrete under the whole of a building. Raft foundations may be used for buildings on compressible ground such as very soft clay, alluvial deposits and compressible fill material where strip, pad or pile foundations would not provide a stable foundation without excessive excavation.

The reinforced concrete raft is designed to transmit the load of the building and distribute the load over the whole area under the raft, reducing the load per unit area placed on the ground. The two types of raft foundation commonly used are:

Flat raft Wide toe raft.

The flat slab raft is of uniform thickness under the whole of the building and reinforced to spread the loads from the walls uniformly over the under surface to the ground. This type of raft may be used under small buildings such as bungalows and two storey houses where the comparatively small loads on foundations can be spread safely and economically under the rafts. The concrete raft is reinforced top and bottom against both upward and downward bending.

Figure : Raft foundations

Resources from http://wsuzana.wordpress.com/2010/03/14/jom-travel-to-europe/

TECHNOLOGY A 2011

The construction sequence is as follows.

1. Vegetable topsoil is removed. 2. A blinding layer of concrete is spread and leveled to provide a level base so that the steel

reinforcement cage can be constructed.3. Where the raft is not cast directly against the ground, formwork may be required to

contain any concrete up-stands.4. Once the reinforcement is correctly spaced, and tied together in position, the concrete can

be poured, vibrated and leveled.5. A waterproof membrane can be positioned either underneath the structural concrete or on

top beneath the insulation. Some architects choose to position the damp proof membrane (dpm) on top of the insulation and beneath the finish screed. Traditionally the damp proof membrane (dpm) was placed on top of the blinding; it is now more common for the dpm to sit on top of the insulation (providing the insulation is impermeable). When the dpm is positioned above the insulation it not only prevents groundwater penetration but also reduces the possibility of interstitial condensation forming.

6. Rigid insulation boards are placed on top of the structural concrete.7. Finally a 40mm sand/cement screed finish is spread and leveled on top of the raft.

Figure: Examples construction of raft foundation on sites

Resource: http://www.angliaformwork.co.uk/reinforcement.html

TECHNOLOGY A 2011

Deep Foundation

As foundation or structure becomes more structured by codes the question of axial strength definition becomes more important. Capacity is usually the basic consideration in the design of deep foundation. The basic function that is usually assigned to a deep foundation is to transfer a load to deeper, stronger soil layers or in a few cases to limit and control settlements in soft soils.

PILE

Where the subsoil is of firm, shrinkable clay, which is subject to volume change due to deep rooted vegetation for some depth below the surface and where the subsoil is of soft, or uncertain bearing capacity for a few meters below the surface, it may be economic and satisfactory to use a pile foundation as a substructure.

Piles are concrete columns, which are either precast and driven into the ground or cast in holes that are augured into the ground down to a level of a firm, stable stratum of subsoil. Pile divide by six; driven pile- concrete, driven tubular steel piles, driven cast in- place piles, jack piles, bored piles, and bored displacement piles.

Transfer of load depends on capacity of pile. There is a need that pile should be strong enough to transfer the whole load coming on it to underlying hard strata. For this purpose, pile design is usually given much consideration. Depending on the load, type of material is usually selected for the piles. Piles are usually made from following materials:

Figure: Basic principle of foundation and Isometric view

Resource: http://maitindia.blogspot.com/2010/09/typical-pile-foundation.html

TECHNOLOGY A 2011

Timber Concrete Steel Composite pile

It is understood that pile is the basis for design of deep foundation. The very first step in the design of pile foundation is selection of right type of pile. Selection of type, length, & capacity of pile depends on following parameters:

Soil condition Magnitude of load

In actual construction, first pile load test is performed on the soil to verify soil strength that whether it can take the load of pile or not. Factors which affect the selection of pile are as under:

Length of pile in relation to load and soil condition Behavior of structure Availability of material in locality of construction Type of loading Ease of maintenance Availability of funds Factors causing damage Cost of pile

Two more things which have importance in pile foundation design are:

1. Pile spacing2. Negative skin friction

Too much close spacing between the piles causes overlapping of pressure bulb. Piles should be spaced so that the bearing capacity of group is not less than bearing capacities of individual piles in group.

The fill above the original soil in which pile group is established usually settle down under its own weight. This will exert drag on pile in addition to friction between pile and soil. This adds to the load on the pile instead of resisting it. It is said to be as negative skin friction. Being the extra load it must be taken into account in design of pile foundation.

TECHNOLOGY A 2011

SHALLOW FOUNDATION DEEP FOUNDATIONA common method is to pack down the area under isolated foundations or trenches under continuous foundations with tampers. Often

Their use is recommended for weak, subsiding, swelling, and other soils having special properties and a high ground-water level. Large buildings with heavy

Figure: a hierarchical representation of pile types can be used for different conditions and situation

Resource : http://sbe.napier.ac.uk/projects/piledesign/guide/chapter1.htm

TECHNOLOGY A 2011

used for smaller buildings. loads. Sites with poor general ground conditions. Often used in cohesion less soils

Types of materials always been uses: Concrete Steel

Types of materials always been uses: Concrete Steel Timber

Generally constructed in: Excavations Trenches.

Generally constructed in: drill-filling driven piles deep piers caissons

Advantages of using shallow foundation: Affordable construction cost Simple construction procedure Mostly used concrete material Economic Shallow form requires little

excavation.Disadvantages of using shallow foundation:

Limited to dealing with point loads Potential for edge erosion of not treated

properly Can become very large if used for high

point loads. Requires specific treatment for point

loads.

Advantages of using deep foundation: In clay soils, if correctly designed, they

are not affected by clay heave or shrinkage Groundwater can percolate between piles

easily Limited tree roots have little effect as piles

continue further below the surface than any tree root system

Techniques available to overcome groundwater

Whilst piling, so dewatering not required Reduced quantity of spoil and minimal ground

disturbanceDisadvantages of using deep foundation:

Usually results in higher construction cost. Can require additional engineering design

effort than a slab-on-grade, and can result in higher engineering fees.

Extra time required to construct structurally isolated floor can lengthen overall construction schedule.

Improper carton form installation can result in void that is insufficient to provide for anticipated soil expansion.

Termites can be attracted to moist cardboard of carton forms.

Grade beams that are in contact with soil can heave due to swelling of expansive soils.

Depending on slab elevation, can allow water to collect below slab.

CONCLUSION

TECHNOLOGY A 2011

Soil classification is important not only for scientist research in soil sciences themes for many other natural, social, economic, cultural and technical sciences. The main contribution of soil classification is to allow for the defining of clusters of different soil characteristics, relevant in space and time to specify research needs in the respective field’s science. The access of nonsoil scientists to soil classification is very limited because there is not enough information available in written form to understand soil classification, which must be urgently improved. A user-friendly key to soil classification must develop as soon as possible. Then, Water, chemicals and also contaminated soils can give effect to human and also to construction. It also will affect the substructures of building if we can’t control it. So, After completing my case study assignment, my conclusion is that site and soil investigation is an important method that need to be carried out before the foundation are been selected. If using wrong foundation in wrong soil stability will make the building structure unsafe. In the other hand, during the construction stage, I can now know the basic of built the foundation and it how does it work.

REFERENCES

TECHNOLOGY A 2011

1. http://en.wikipedia.org/wiki/Pollution

2. http://books.google.com/books?

3. http://www.krishiworld.com/html/soils6.html

4. http://environment.uwe.ac.uk/geocal/SoilMech/classification/default.htm

5. http://en.wikipedia.org/wiki/Chemical_substance

6. http://images.google.com

7. http://www.answers.com/topic/stepped-foundation-1

8. diydoctor.org.uk

9. McMullan, R. Environmental Science in Building 5th Edition ( Palgrave, 2001)

10. Chudley, R. Building Construction Handbook 2nd Edition ( Butterworth- Heinemann, 1995)

11. http://en.wikipedia.org/wiki/Surveying

12. http://roger-bullivant.co.uk/products/piling.html

13. http://www.repair-home.com/how_to/home_construction_foundations.htm

14. www.woking.gov.uk/.../guidance/raft foundations

15. http://www.carshed.com/foundations.html