Shear Strength of Soils - Elements of Soil Mechanics - page 112

Fig. 4.24 Example 4.7.

4.10 The pore pressure coefficients A and B

These coefficients were proposed by Skempton in 1954 and are now almost universally accepted. The
relevant theory is set out below.

Change in volume
Original volume

= −∆

V

Volumetric strain =

V

( Δ V is negative when dealing with compressive stresses as is the general case in soil mechanics.)
Consider an elemental cube of unit dimensions and acted upon by compressive principal stresses σ 1 ,
σ 2 and σ 3 (Fig. 4.25) .
On horizontal plane (2,3):

= σ 1 Compressive strain

E

µσ µσ

2 3

Lateral strain from stresses σ and σ =− + 2 3

E E

Fig. 4.25 Compressive principal stresses.