Fundamentals of Soil Mechanics for Sedimentary and Residual Soils (Wesley/Fundamentals Soil Mechanics) || Stresses in the Ground from Applied Loads

✍ Scribed by Wesley, Laurence D.

• Publisher: John Wiley & Sons, Inc.
• Year: 2009
• Tongue: English
• Weight: 329 KB
• Edition: 1
• Category: Article
• ISBN: 0470376260
• DOI: 10.1002/9780470549056.ch5

✦ Synopsis

We now move on to look at stresses in the ground arising from applied loads, in particular loads from buildings or other structures at the ground surface. Such structures are often supported on surface foundations, commonly known as spread footings or "shallow foundations." Our interest in knowing the stress in the soil caused by such loads is primarily so that we can estimate the likely settlement of the foundation. Any increase in vertical stress in the ground will result in compression of the soil layer in accordance with the laws that govern the compressibility of the soil, covered in later chapters.

Figure 5.1 shows a surface foundation. The load on the foundation applies a stress to the soil at the surface. This stress "spreads out" with depth, or distance from the foundation, so that as the depth increases, the load is resisted by a wider area of soil, and the resulting stress decreases with depth. In order to estimate the settlement at the surface, we need to calculate the stress change throughout the layer and apply Equation 5.1 to a series of sublayers to give us the compression of each layer. The procedure is covered in detail in Chapter 8. In this chapter we are only concerned with the stress changes caused by various shapes of surface load.