喜马拉雅东构造结西缘地应力特征及其对隧道围岩稳定性的影响  

Characteristics of in-situ stresses on the western margin of the eastern Himalayan syntaxis and its influence on stability of tunnel surrounding rock

作　　者：张重远 杜世回[4] 何满潮[1,2] 秦向辉[3] 李彬[5] 陈兴强 陈群策 孟文[3] 黄勇[4] ZHANG Chongyuan;DU Shihui;HE Manchao;QIN Xianghui;LI Bin;CHEN Xingqiang;CHEN Qunce;MENG Wen;HUANG Yong(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China;Key Laboratory of Neotectonic Movement and Geohazard,Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 100081,China;China Railway First Survey and Design Institute Group Co.,Ltd.,Xi¢an,Shaanxi 710043,China;School of Civil Engineering,Qinghai University,Xining,Qinghai 810016,China)

机构地区：[1]中国矿业大学(北京)深部岩土力学与地下工程国家重点实验室,北京100083 [2]中国矿业大学(北京)力学与建筑工程学院,北京100083 [3]中国地质科学院地质力学研究所新构造与地质灾害重点实验室,北京100081 [4]中铁第一勘察设计院集团有限公司,陕西西安710043 [5]青海大学土木工程学院,青海西宁810016

出　　处：《岩石力学与工程学报》2022年第5期954-968,共15页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(41941018);地质调查项目(DD20211376);西藏自治区科技厅重点研发项目(XZ202001ZY0011G)。

摘　　要：拟建川藏铁路林芝—通麦段位于喜马拉雅东构造结西侧,构造和应力环境非常复杂,查明其现今地应力特征对于铁路线路工程地质条件评价和隧道科学施工有重要的指导作用。采用水压致裂法在林芝—通麦段实施总计20个钻孔原地应力测量,根据实测数据对该段的现今地应力特征进行研究,并对其围岩稳定性和工程灾害效应进行评价。结果表明:(1)林芝—通麦段实测主应力随埋深的增大而增加,但整体应力积累水平相对偏低,500 m以深发育走滑型应力,表明水平主应力占主导,与区域动力学环境和主要构造活动方式相一致;(2)实测SH平均方位角为N61°~72°E,与震源机制解、GPS和壳幔各向异性资料揭示的区域构造应力方向具有较好的一致性,表明其受区域构造运动方式控制;(3)林芝—通麦段隧道Ⅱ和Ⅲ级围岩以中等~极强岩爆为主,初始岩爆埋深约为400 m,岩爆风险随埋深增加而增大,其中拉月隧道发生强烈~极强岩爆比例最高;(4)基于Hoek-Brown准则预测显示,围岩脆性破坏深度随埋深增大而线性增加,其中拉月隧道最大埋深处围岩脆性破坏深度可能将达1.4倍隧道半径。The planned Nyingchi—Tongmai section of the Sichuan—Tibet Railway,located on the west side of the eastern Himalayan syntaxis,is in a complex tectonic and stress environment.Investigating the characteristics of in-situ stresses has an important guiding role for the evaluation of the engineering geological conditions of the railway and the scientific construction of the tunnels.Hydraulic fracturing stress measurements of a total of 20boreholes were carried out in the Nyingchi—Tongmai section.Based on the measured stress data,the present-day in-situ stress characteristics of this section were studied,and the stability of the surrounding rock and the engineering hazards were evaluated.The results show that:(1)The measured principal stress of the Nyingchi—Tongmai section increases with increasing the buried depth,but the overall stress accumulation level is relatively low.Strike-slip faulting stress develops below 500 m,indicating that horizontal principal stress is dominant,which is consistent with the regional dynamic environment and the tectonic activity pattern.(2)The measured SH average azimuth angle is N61°–72°E,which is in good agreement with the direction of the regional tectonic stress revealed by the focal mechanism solution as well as GPS and crust-mantle anisotropy data,indicating that it is controlled by the mode of the regional tectonic movement.(3)The surrounding rocks of GradeⅡand GradeⅢtunnels are dominated by moderate to extremely strong rock bursts.The initial buried depth of the rock bursts is approximately 400 m.The risk of rock bursts increases with the burial depth.The Layue tunnel has the highest proportion of strong to extremely strong rock bursts.(4)The prediction based on the Hoek-Brown criterion shows that the brittle failure depth of the surrounding rock increases linearly with increasing the buried depth,and the brittle failure depth of the surrounding rock at the maximum buried depth of Layue tunnel may reach 1.4 times the tunnel radius.

关 键 词：岩石力学 川藏铁路 喜马拉雅东构造结 水压致裂法 地应力 岩爆 脆性破坏 围岩稳定性 

分 类 号：TU45[建筑科学—岩土工程]