基于保角映射的断层影响区内隧道涌水量预测

Prediction of tunnel water inflow in fault affected area based on conformal mapping

建立了断层影响区内衬砌隧道渗流模型.在该模型中,断层被视为地下水补给边界,以隧道涌水量作为衡量依据将隧道横断面内倾斜断层等效为竖向断层.利用镜像叠加原理将有限边界渗流问题转化为半无限空间渗流模型,再通过保角坐标变换和极坐标联立求解渗流微分方程,推导富水断层影响区内地下水头半解析公式,得到了隧道涌水量计算公式.经过退化验算、数值模拟及现场实测数据对比,验证了公式的正确性.在此基础上,探讨了地层与衬砌的相对渗透系数(KS/KL)、隧道与水位线的距离(h)、隧道与断层的距离(L)对涌水量的影响:KS/KL对涌水量的影响最显著;其次为h,h也会影响L的作用效果,h越大,L的影响程度也越大.施工过程中应加强注意衬砌防水措施的施作,隧道线路的选择应尽可能考虑埋深设计,避免高水头压力.

A seepage model of lined tunnel in the fault affected area was established.The fault was regarded as the groundwater supply boundary,the inclined fault in the cross section was equivalent to the vertical fault by taking the water inflow as the measurement basis,the seepage problem of the limited boundary was transformed into a semi infinite space seepage model by using the image superposition,in order to solve the seepage differential equation,the conformal coordinate transformation and polar coordinate was used,so the semi-analytical formula of groundwater head in the area affected by water-rich fault is derived,and the calculation formula of tunnel water inflow is obtained.After degradation checking,and comparing the semi-analytical solution with numerical simulation and measurement data,the formula is correct and feasible.On this basis,the influence of the relative permeability coefficient of the stratum and lining KS/KLwas discussed,the distance h between tunnel and water level line and the distance L between tunnel and fault on the water inflow respectively.It is found that the effect of K_S/K_L has the most significant effect on water inflow,the second is h.h will also affect the effect of L,and the greater h is,the greater the effect of L will be.During the construction process,attention should be paid to the construction of lining waterproof measures,the buried depth design should be considered as much as possible to avoid high water head pressure in the route selection of the tunnel.