富水深埋隧道围岩渗透扰动高度计算方法研究

Analytical Solution for Disturbance Height of Seepage Field of Surrounding Rock in Deep-Buried Tunnel with Rich Water

针对深埋富水隧道排水过程对周边围岩渗流场扰动问题,首先,采用数值模拟方法,探明隧道排水条件下围岩渗流场分布规律,提出围岩渗流扰动高度概念;同时,采用控制变量法,明确不同因素(水头高度、围岩渗透系数、隧道排水率)条件下围岩渗流扰动高度变化规律;其次,采用数理拟合方法,给出围岩渗流扰动高度分段计算方法;最后,采用室内相似试验,对所提出计算方法的合理性进行验证。研究表明:1)隧道排水后会对围岩渗流场产生扰动,但渗流场扰动范围仅在隧道拱顶以上一定高度内存在,即围岩渗流扰动高度。2)围岩渗透系数、水头高度、隧道排水率均分别与围岩渗流扰动高度呈正相关关系,且3个因素的影响程度依次降低。3)当给定渗透系数与排水率时,围岩渗流扰动高度随水头高度变化规律呈明显2段式特征。当水头高度不大于临界水头高度时,围岩渗流扰动高度随水头高度的增大呈线性增大趋势;当水头高度大于临界水头高度时,围岩渗流扰动高度为定值,为临界围岩渗流扰动高度。4)给出围岩渗流扰动高度的数学计算表达式,并将采用所提计算方法的计算结果与室内试验结果进行对比,验证所提方法的正确性及合理性。

To study the disturbance influence of drainage in the tunnel on seepage field of surrounding rock,first,the distribution laws of seepage field of tunnel surrounding rock under drainage are discussed using numerical simulation method,and the concept of disturbance height of seepage field of surrounding rock is proposed.Second,the influence of different factors on the disturbance height of the seepage field,i.e.water head,permeability coefficient,and drainage rate,is analyzed using the control variable method.Third,the sectioned calculation method for seepage disturbance height is obtained using the mathematical fitting method.Finally,the proposed calculation method is verified by a laboratory similarity experiment.The main conclusions are drawn as follows:(1)after drainage in the tunnel,the seepage field of surrounding rock is disturbed,and the disturbance range of the seepage field exists within a certain height above the tunnel crown,called the disturbance height of the seepage field of the surrounding rock;(2)the permeability coefficient,water head,and drainage rate are all positively correlated with the disturbance height,and the influence degree of the permeability coefficient is the highest,followed by that of water head,and that of drainage ratio is the lowest;(3)under a certain permeability coefficient and drainage rate,the disturbance height of the surrounding rock seepage field shows an obvious two-stage characteristic with increasing water head.When the water head is lower than the critical water head,the disturbance height linearly increases with the increasing water head height,however,the disturbance height is constant when water head is higher than critical water head;and(4)the calculation formula for disturbance height is proposed and verified by an indoor experiment,and the results show the validity and rationality of the formula.