3Ground Stability and Foundations

The foundation of a building is that part of walls, piers and columns in direct contact with, and transmitting loads to, the ground. Early buildings were founded on rock or firm ground, and it is not unusual to find buildings without foundations when carrying out work on older properties. It was not until the beginning of the twentieth century that concrete was increasingly used as a foundation for loadbearing walls. With the introduction of local and then national building regulations, standard forms of concrete foundations have become accepted practice in the UK. This has been accompanied by more rigorous investigation of the nature and bearing capacity of soils and bedrock to inform foundation design. In this chapter, we start by looking at the nature of rocks and soils, and the stability of soils, before moving onto foundation design and a description of the four typical types of foundations: strip, pad, raft and piled. Piled foundations are usually associated with framed buildings and are described in further detail in Barry’s Advanced Construction of Buildings.

3.1 Bedrock and soil types

‘Ground’ is the term used for the Earth’s surface, which varies in composition within the following five groups: rocks, non‐cohesive soils, cohesive soils, peat and organic soils, and made‐up ground and fill. Rocks include the hard, rigid, strongly cemented geological deposits such as granite, sandstone and limestone, and soils include the comparatively ...

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