盾构掘进速度对开挖面水头分布的影响

Effect of Shield Advance Velocity on the Hydraulic Head Distribution Around Tunnel Face

盾构掘进过程中隧道掘进面附近水头分布是掘进面稳定分析的重要因素.为此,基于固定在隧道开挖面上参照坐标系,推导了考虑盾构掘进速度、土体的渗透系数以及土体贮水系数的稳态地下水流动偏微分方程.通过伽辽金有限元法,推导了考虑盾构掘进速度的二维稳态渗流有限元方程,编制了有限单元数值分析程序,计算了稳态地下水流条件下,地下水参数和盾构掘进速度的变化对隧道掘进面附近水头场分布的影响.结果发现,在低渗透性土层中进行隧道开挖,掘进速度的增加导致隧道掘进面附近总水头梯度显著增加.水头场的重新分布导致了作用在隧道掘进面的渗透力增加.将考虑盾构掘进速度的数值分析结果与相关实验数据相比较,两者取得较好的一致性.

The head distribution around the tunnel face is an important factor in stability analysis of tunnel face in shield advance. Based on a frame of reference that advances together with the tunnel heading, the steady seepage flow differential equations were derived in consideration of shield advance velocity, the ground permeability and the storativity. Moreover, the finite element equation was deduced by the weighted residual-Galerkin method and the finite element numerical program was written to measure the effect of shield advance velocity and the groundwater parame- ters on the head distribution around the tunnel face. The results show that the head gradients around the tunnel face are increased greatly especially in poor permeable ground with the increase of advance velocity. The head redistribution causes the increase of the seepage force on the tunnel face. The result of numerical analysis in consideration of shield advance velocity is consistent with the experimental data.