The equivalent nodal forces *f*σ0 for the elements

for plane strain. The negative sign on the pore

pressures *p *in Equation 6 reconciles the difference

subject to the initial stresses are computed as a

between the sign conventions for soil mechanics

volume integral over the element domain

and standard solid mechanics. The pore pressures *p*

correspond to full uplift for those elements adjacent

⌠ *B *Tσ *dV*

(7)

⌡V

to the crack surfaces and vary linearly in the hori-

0

0

zontal direction from full uplift at the crack tip to

zero (empty lock chamber) at the toe of the mono-

where *B *is the strain-displacement operator.

lith. The initial stresses are constant in the vertical

Because the initial stresses are hydrostatic, the equi-

direction at a given horizontal distance from the

valent nodal forces act in both the horizontal and

toe.The pore pressure distribution over the elements

vertical directions. Elements subjected to initial

adjacent to the interface is shown in Figure A-7.

A-7