考虑走滑断裂活动影响的公路隧道初始地应力场反演分析

为了使跨活动断裂带区域地应力反演结果更加符合实际，提出了考虑走滑断裂活动影响的公路隧道初始地应力场反演思路。通过在断裂带与两侧岩体之间建立接触单元，采用边界位移荷载实现了断裂带两侧岩体的相对挤压及滑动作用。依托华坪至丽江高速公路东马场1号隧道工程，对比分析了采用常规边界荷载和考虑走滑边界荷载2种情况下隧址区地应力场的反演结果。研究结果表明:考虑走滑边界荷载反演得到的地应力场更加符合实际且精度更高；常规边界荷载的最大残差为2.29 MPa，而走滑边界荷载的最大残差仅为0.66 MPa，其残差平方和也均小于常规边界荷载；在断裂带附近，考虑走滑活动影响的最大、最小水平应力值相对常规边界均有所减小，上盘岩体垂直应力也相对减小，下盘岩体受上盘岩体的影响垂直应力相对增大，符合跨断层岩体区域实际地应力场的分布规律；隧址区整体表现为水平应力大于垂直应力，以水平构造应力为主。

Inversion Analysis of Initial Geostress Field of Highway Tunnel Considering Influence of Strike-slip Fault Activity

An inversion of the in-situ stress field considering strike-slip fault activity is proposed to make the inversion results of geostress in a region across an active fault zone more realistic. By establishing contact elements between the fault zone and rock masses on both sides and using boundary displacement loads, the relative compression and sliding effects of rock masses on both sides of the fault zone were realized. Relying on the Dongmachang No.1 tunnel project of the Huaping-Lijiang expressway, this study analyzed the active tectonic characteristics and geostress states of the Chenghai fault zone. The inversion results of the geostress field at the tunnel site under the conventional and strike-slip boundary load conditions were compared and analyzed. The results demonstrated that the geostress field under the inversion of the strike-slip boundary load was more realistic and accurate than that under the conventional boundary load. The maximum residual error of the conventional boundary load was 2.29 MPa. The maximum residual error of the strike-slip boundary load was only 0.66 MPa. The residual sum of squares of the strike-slip boundary load was smaller than that of the conventional boundary load. Near the fault zone, the maximum and minimum horizontal stress values considering the effect of strike-slip activity were reduced compared with those of the conventional boundary load, and the vertical stress of the hanging wall was relatively reduced. The vertical stress of the footwall was relatively increased under the influence of the footwall, which was owing to the distribution law of the actual in-situ stress field across the fault rock mass area. The overall performance of the tunnel site area was such that the horizontal stress was greater than the vertical stress, and the horizontal tectonic stress was dominant.