断层构造对高地应力隧道初始地应力场影响分析

Analysis of influence of fault structure on initial ground stress field of high ground stress tunnel

为减少地下工程区断层等地质构造对局部应力场的影响,以云南省红河州某高速公路隧道工程为例,分析隧道选址区域初始地应力场。首先,建立隧道选址区域三维地质模型,使用空芯包体法采集10处测点的初始地应力数据;然后,根据实测地应力数据,通过多元线性回归反演分析方法反演,得到隧道选址区岩体初始地应力场,同时,在该方法的基础上考虑区域内断层和破碎带的影响,总结断层对地应力分布状态的影响;最后,根据现场勘察所得地质构造条件(主要为断层),对断层带施加挤压力和压扭力模拟断层错动,从而进行局部地应力调整,得到符合实际的地应力场。结果表明:研究区域水平垂直隧道轴线方向的应力最大,表现为σy>σz>σx;应力值在断层内部减小,断层带边缘增大。在高地应力硬岩隧道工程中,应力集中的断层边缘存在岩爆发生概率增大的可能性,应加强防治,以保障施工过程安全。

In order to reduce the influence of geological structures such as faults on the local stress field in the underground engineering area,an expressway tunnel project in Honghe Prefecture,Yunnan Province was taken as an example to analyze the initial ground stress field in the tunnel site selection area.Firstly,a three-dimensional geological model of the tunnel site selection area was established,and the initial stress data of 10 measuring points were collected by the hollow inclusion method.Then,according to the measured in-situ stress data,the initial in-situ stress field of rock mass in the tunnel site was obtained by multiple linear regression inversion analysis.At the same time,the influence of faults and fracture zones in the area was considered on the basis of this method,and the influence of faults on the distribution of in-situ stress was summarized.Finally,according to the geological structure conditions(mainly faults)obtained from field investigation,the fault dislocation was simulated by applying compressive and torsion forces to the fault zone,so as to adjust the local in-situ stress and obtain the actual in-situ stress field.The results show that the stress in the horizontal and vertical direction of the tunnel axis in the study area is the largest,which isσy>σz>σx.The stress value decreases inside the fault and increases at the edge of the fault zone.In the high ground stress hard rock tunnel project,the edge of the fault with stress concentration has the possibility of increasing the probability of rockburst,andprevention and control should be strengthened to ensure the safety of the construction process.