Cohesive soils and organic soils can also be susceptible to a loss of shear strength during the earthquake. Examples include sensitive clays, which lose shear strength when they are strained back and
forth. When dealing with such soils, it is often desirable to limit the stress exerted by the footing during the earthquake so that it is less than the maximum past pressure s′
vm
of the cohesive or organic
soils. As discussed in Chap. 8, the maximum past pressure is the highest vertical effective stress that
the clay was subjected to and completely consolidated under. The goal in limiting the imposed footing stress to a value of s′
vm is to prevent the soil from squeezing out or deforming laterally from
underneath the footing