拉林铁路巴玉深埋隧道地应力场反演分析

Inverse Analysis of Geostress Field in Bayu Deep-buried Tunnel on Lhasa- Linzhi Railway

基于区域构造应力环境和实测地应力成果,根据拉萨—林芝铁路巴玉深埋隧道地形起伏特征将工程区划分为3个区段,利用边界荷载调整法对各区段地应力场进行了反演分析。结果表明:除隧道进出口段外,地应力场均以竖向主应力为主,在隧道最大埋深处最大主应力值达到48 MPa;在隧道进出口段应力值较低,隧道轴线与最大水平主应力方向夹角较小,有利于隧道围岩的稳定;在隧道深埋段竖向主应力与水平主应力值均较高,且隧道轴线与最大水平主应力方向近于正交,不利于隧道围岩的稳定。

With regional tectonic force environment and actual measured geostress,the project area was divided into3 sections according to the characteristics of topography of deep-buried tunnel on the Lhasa-linzhi railway.A inverse analysis was conducted on the geostress field with boundary load adjustment method.The results indicate that the vertical principle stress is the dominant geostress in the tunnel except for entrances and exits.The maximum principle stress goes up to 48 MPa at the deepest area in the tunnel.The geostress is low at entrances and exits,and the intersection angle between the tunnel axis and the maximum horizontal principle stress is small,leading to a more stable surrounding rock.By comparison,the vertical and horizontal principle stress are higher at the deeper part of the tunnel,and the tunnel axis is approximately perpendicular to the maximum horizontal principle stress,causing a stability problem of the surrounding rock.