Soil conditioning influence on face stability of shield tunnel

EPBM excavates in gravel stratum, whose ground water level is high. The soil excavated in chamber has big permeability coefficients, and is poor in flow ability. It is difficult to apply the support earth pressure to the working face due to the permeation of groundwater. Soil conditioning is a way of adjusting the soil condition in pressure chamber and increasing support earth pressure, which can decrease the permeability and increase the flow ability. The three-dimensional fast Lagrangian differential finite element method which can reflect the large strain of material is utilized to study the contribution of soil conditioning to face stability. The relationship between soil permeability decreasing and support pressures is analyzed. Some results from simulation are given for controlling face pressure.