隧道在低渗透性土壤中掘进,盾构掘进速度的改变将引起作用在掘进面上支护压力的显著变化。考虑盾构掘进速度以及土体的渗透系数的影响,通过伽辽金有限元法推导三维稳态渗流有限元方程,使用FORTRAN代码编制数值分析程序计算稳态地下水流条件下隧道掘进面附近水头分布。维持掘进面稳定极限支护压力由有效支护压力和渗透力共同构成,前者基于土体稳定的极限平衡理论计算结果,后者通过隧道掘进面附近水头分布推导得出。结果发现,低渗透性土层中进行隧道掘进,盾构掘进速度的改变对隧道掘进面附近水头分布产生很大影响,掘进速度的增加将引起作用在隧道掘进面上支护力的显著增加。理论分析结果与实验数据取得较好的一致,验证了该理论与方法的合理性和有效性。 Tunnels are drilled in low permeability so that a change in the shield tunneling speed will cause a significant change in the supporting pressure acting on the heading surface. Considering the influence of shield tunneling speed and soil permeability coefficient, the three-dimensional steady-state seepage finite element equation was deduced by using Galerkin finite element method. The numerical analysis program was used to calculate the head distribution near the tunnel heading face under steady state groundwater flow . Maintaining the stability limit of driving surface The supporting pressure is composed of effective supporting pressure and seepage force. The former is based on the limit equilibrium theory of soil stability and the latter is derived from the distribution of water head near tunnel boring surface. The results show that tunneling in low permeability soil layer has a great influence on the distribution of water head near the excavation face. The increase of the excavation speed will cause the significant increase of the supporting force on the excavation face of the tunnel. The result of theoretical analysis is in good agreement with the experimental data, which verifies the rationality and effectiveness of this theory and method.