6.5 Simulation of Excavation Sequences

The draining of zinc chloride in the rubber bag was simulated by two approaches. The first, used in the simulation of test Ts1 and Ts2, is that the removal of soil layer by layer and the rate of removal of these soil layers was the same as the discharge rate of zinc chloride solution mentioned in Chapter 3. The second approach is to remove the preload that is equivalent to the pressure of zinc chloride solution distributed on the model diaphragm wall and the bottom of excavation body. The latter is a better simulation of draining out a heavy liquid. This was used in the analysis of Ts5.

CRISP is based on a Biot¡¯s type coupled formulation and thus consolidation is included automatically. The coefficients of permeability of the upper soft soil and bottom layer were taken as 1 x 10^-8 m/s and 1 x 10^-7 m/s. In simulating the excavation, the pore water pressure boundary in the excavated area was ajusted to reflect a draining boundary.