Consider a saturated soil of initial volume V. Then volume of pore water = nV where n = porosity. Assume a change in total ambient stress = A<73.

Assume that the change in effective stress caused by this total stress increment is Acr'j and that the corresponding change in pore water pressure is Aua. Then,

Decrease in volume of soil skeleton = QVAct'j and

Decrease in volume of pore water = CvnVAua With no drainage these changes must be equal: i.e.

CcVA<t'3 - CvnVAua nCv

The compressibility of water is of the order of 1.63 x 10~7kN/m2.

Typical results from soil tests are given in Table 3.1 and show that, for all saturated soils, B can be taken as equal to 1.0 for practical purposes.

Table 3.1 Compression of saturated soils.

Soil type

Soft clay

Stiff clay

Compact silt

Loose sand

Dense sand

n (%)

0 0

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