Geotechnical Properties & Construction Methods - Coursework Example

At this stage, Engineer will be collecting data from Geological survey, topographic maps, photogeology (aerial) , digital data, borehole records, national survey, mining records in order to understand the geology, compressive soils, drift thickness, landslides, soluble rocks, made ground, etc.… The main importance of the desk study is to understand the geological condition of the site in order to analyse its implication during any stage of the planned engineering activity. This means that for a difficult ground condition, either the foundation design has to be adequate or a reduction of the actual superstructure loads has to be considered.

In the given site, the points below can be listed as evidence of desk study as an element of site investigation: Borehole data: the presence of made ground and building debris with patches of old oil spillages; this has been found at a thickness of 1m above the ground level. Soft silt up to a depth of 10m then compacted sand and gravel at 18m. This is the exact composition of the soil beneath and will allow for adequate selection of foundation design. Knowing that up to a depth of1m below the ground level, the soil has almost no strength.

This layer will have no importance in the overall bearing capacity of the soil. The Borehole data will enable Engineers to be aware of possible soil contamination of the top soil, weak soil up to a depth of 10m and that strong strata can be seen only after 18m below the ground level. One can argue that Strip foundation; defined as shallow foundation (Maheshwari, 2009) will never be ideal for this type of soil. Topographic map. For the considered site, a topographic map has been obtained. This gives the large-scale detail as well as the relief of the site.

It consists of measuring the ground level with respect to a benchmark (Mellow, 2010). On map has shown latitude, which is the level of a given point on site with respect to the ground level. For the fact that two points of the same site are not always at the same level with respect to the sea level, while a building requires a level terrain, topographic map will be important to give the ground profile, and enable engineers to quantity earthwork; this is the volume of cutting and filling in order to level the site before construction begins.

Ground water table: as an element of the site investigation, the desk study will give enable to locate the ground water. For the proposed site, this is 1.5m below the ground level. McLean and Rible (1985) explained that the water table is a very important factor influencing the overall strength of the soil. In an undrained condition, where the water pressure has been taken into account, the total strength of the soil is much higher than the drained condition, without water; keeping in mind that the latter will give the actual strength parameters of the soil.

Overestimating the strength of the soil can lead to structural failure as the foundation will not be under-designed therefore will not be able to support the imposed load from the superstructure. Also, as the required construction has taken into account a basement, deep excavation will be required. Knowing the ground water level, will be very important for the fact that, if it is above the required depth of excavation, flooding will occur and the exaction, representing the working environment will be against the health and safety.

It can be seen that the desk study wi