For the design of a tunnel, the effect of pore water flow should be taken into account to predict rock deformation accurately since deformability as well as strength of the saturated rock are affected by pore pressure.
In this paper, a technique of numerical analysis on coupling problem of rock deformation and pore water flow is discussed from this point of view.Basic equations governing the mechanical interaction between rock and pore water are obtained, based on the Biot's model with additional assumptions. A numerical technique to solve these equations approximately under the arbitrary initial and boundary conditions is also proposed. To examine the validity of the basic equations and the proposed solution technique, numerical results for one-dimensional consolidation problem are compared with the analytical solution. The excavation of a circuler tunnel is also simulated in order to discuss the interaction of rock and pore water.
Conclusions are summarized as follows:
(1) Numerical technique employed to solve the equations provides the results with adequate accuracy.
(2) The intensity of interaction between rock and pore water depends on the difference of bulk modulus measured under drained and undrained conditions.
(3) When a tunnel is excavated rapidly, pore pressure can exceed the minimum compressive stress near the tunnel wall. This means that rock failure should be taken into consideration for more practical analysis.
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