A Trench Fill Foundation - Assignment Example

TRENCH FILL FOUNDATION The ground conditions of the site are as follows: the site has firm clay underlain by chalk, which is located at a depth of one meter below the ground level. The suitable foundation suggested for this type of site condition is trench fill foundation. A trench fill foundation is just like a deep strip foundation. However, the depth of the trench and the amount of concrete required is greater as compared to deep strip foundation. The first step is to dig the ground and after the digging process, the trench is laid, which is later packed with concrete(Cyril, 2003: 105).

The depth of the concrete has to be greater than 500 millimeter. From ground level, the depth of the concrete must be greater than 1500 millimeter (Cyril, 2003: 110). Since the ground condition has firm clay, therefore there is a need to consider the depth of foundations. Clay exhibits the property to shrink or contract depending on the moisture content present in it (Kenneth, 1993:25). At the same time, if the surrounding area has trees, there is a possibility that the trees would absorb the moisture from the clay and hence, the foundation may experience settlement to a significant level.

For this case, it is essential to consider the depth of the foundation. A trench fill foundation is thus ideal for this type of site condition. Research suggests that “trench fill foundations are quicker to prepare than deep strip foundations. This means that there is less disruption once the building work starts and not as much labour time will be needed. It is less likely that subsidence will occur in cases where there may be changes in the soil's substrata” (Mosley & Bungey, 2000, 48).

FOUNDATION FOR UNEVEN GROUND CONDITIONSThe site has different ground conditions and has different soils. Thus, it has a weak bearing capacity. For this purpose, the ideal foundation would be strip, grid or mat foundation. In this case, the suggested foundation is mat foundation. Because of varying ground conditions, majority of the isolated footings would have large areas and thus, it would become uneconomical (Terzaghi et.al, 2006, 256)l. According to the British Code, “Where the subsoil is very weak the load needs to be spread over a greater area.

This is achieved by casting a slab of concrete over the whole ground area and thickening the slab where walls are to be placed”(Perry & Perry, 2009, 118). The design of any reinforced concrete structure aims at a suitable and economical design and for this purpose, mat foundation is ideal. A mat foundation is often used by designers when isolated footings may overlap with one another (Fleming et.al, 2005: 198). A mat foundation is considered to be that type of foundation, which is placed over the entire area.

It comprises of reinforced concrete slab, which would be laid over the uneven ground and thus, it would bear the load of the entire structure. Mat foundation is also ideal for this type of ground condition because of differential settlement. The aim of the mat foundation is to minimize differential settlement (Coduto, 2001, 289). The massive loading of the structure can cause the soil to compress and thus, the structure may experience settlement. For this purpose, the mat is used as an option in order to distribute the entire loads of the buildings and to remove differential settlement.

BibliographyCyril M. Harris (2003). Design of Structures : A Guide for Architects and Engineers. Mcgraw-Hill.Mitchell, James Kenneth (1993), Fundamentals of Soil Behavior (2nd ed.), Oxford: Oxford Printing Press.Mosley W. H. & Bungey J. H.; “Reinforced Concrete Design”, 4th Edition, Macmillan Press, 2000.Perry J. H. & Perry R. H.; “Engineering Manual”, McGraw Hill, 2009.Terzaghi, Karl; Peck, Ralph Brazelton; Mesri, Gholamreza (2006), Soil mechanics in engineering practice (3rd ed.), Oxford: Oxford Printing Press.

Fleming, W. G. K. et al., 2005, Piling Engineering, Surrey University Press; Hunt, R. E., Geotechnical Engineering Analysis and Evaluation, 2006, McGraw-Hill.Coduto, Donald P. Foundation Design: Principles and Practices 2nd ed., Prentice-Hall Inc., 2001