桑珠岭特长隧道初始地应力场反演分析

桑珠岭隧道是拉萨-林芝铁路的控制性工程,工程区地质条件复杂,面临着深埋隧道高地应力灾害问题。因此,对其展开初始地应力场分析为保障隧道安全施工及优化结构设计具有重要意义。以现场勘察工作为基础,综合分析工程区地质资料,利用工程类比法和Anderson理论估算了隧址区主应力方向与量值范围;结合现场地应力实测数据,利用多元线性回归分析方法,进行了隧道工程区地应力场的三维反演计算分析。结果表明:测点地应力反演值与实测值在量值与方向上存在较好拟合关系;且同区域构造背景相一致,说明计算结果具有一定的合理性与可靠性。最后,通过分析桑珠岭隧道沿轴向的地应力分布规律,对隧道沿线的易发岩爆段及岩爆等级进行了初步预测,为后期隧道开挖及支护结构设计提供依据。

Regression analysis of initial geostress field of Sangzhuling super-long tunnel

SangZhuling tunnel is the controlling project of the Lasa-linzhi railway engineering, which faces the questions of high geostrss disasters of deep tunnel for the complicated geological conditions. Therefore, the analysis of initial geostress field of the engineering area has important significance to the safety of tunnel construction and the optimization of structure design. Based on the on-site inspection work, the existed geological data in the engineering area was comprehensively analyzed, the theory of Anderson and the engineering analog method were applied to analyze preliminarily the possible values and orientations of the maximum principal stress. The multivariate linear regression method is used to reverse analyze the 3-D distribution of geostress field regime of the whole project area according to the measured geostress dates. The results show that the calculation values fit well with the measured values mostly both in the magnitude and the directions, and the stress distribution is consistent with the regional tectonic background, which indicates that the geostress field obtained by the regression is of rationality and reliability. Finally, the probability and intensity of rock burst along tunnel were forecasted basing on the obtained in-situ stress distribution rule along the axis of the tunnel, so as to provide the basis for later tunnel excavation and supporting structure design.