喜马拉雅东构造结北缘通麦—波密段现今地应力场特征研究  

Determination of the current in- situ stress field of the Tongmai- Bomi section in the northern margin of the eastern Himalayan syntaxis

作　　者：秦向辉[1,2] 陈群策 孟文[1,2] 张重远 孙东生[1,2] 杨跃辉 陈虹[1,2] 李冉 QIN Xianghiu;CHEN Quncel;MENG Wen;ZHANG Chongyuan;SUN Dongsheng;YANG Yuehui;CHEN Hongl;LI Ran(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing 10008l,China;Key Laboratory of Active Tectonics&Geological Safety,Ministry of Natural Resources,Beijing 1oo081,China)

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]自然资源部活动构造与地质安全重点实验室,北京100081

出　　处：《地质学报》2023年第7期2126-2140,共15页Acta Geologica Sinica

基　　金：中国地质调查局项目(编号DD20211376,DD20221816);国家重大科技专项项目(编号2016ZX05034-003);国家自然科学基金项目(编号42102266)联合资助的成果。

摘　　要：喜马拉雅东构造结是青藏高原构造演化研究的关键地区,规划有川藏铁路和雅鲁藏布江下游水电开发等重大工程,受限于地质地理条件,其现今地应力场尚不完全清楚。本文利用水压致裂法地应力数据,研究了东构造结北缘通麦—波密段现今地应力场,探讨了其构造应力环境。结果表明,通麦—波密段实测主应力随深度增加而增大,1100 m深度内SH和S_(h)分别为4.87~32.47 MPa和3.05~20.07 MPa,随深度增加梯度分别为2.49 MPa/100 m和1.61 MPa/100 m,略低于青藏地块和东构造结西缘梯度水平,但地应力状态特征参数表明其水平应力作用强度总体上高于青藏地块;SH优势方向为NEE向(N69.2°±11.5°E),相比NNE—NE向区域主压应力方向表现出明显的顺时针偏转特征;现今地应力场由水平向应力作用主导,400 m以浅应力类型为逆冲型,以深转换为走滑型;水平向差应力和构造差应力在600 m深度以下显著增加,构造差应力最大为12.42 MPa,表明通麦—波密段深部存在相对较强的构造应力作用;库伦摩擦失稳准则分析表明,受地形影响较小的200 m以深实测地应力值总体低于摩擦系数取0.6时理论地应力水平,并且430 m深度以下地应力值总体在摩擦系数取0.2~0.4的理论地应力取值范围内,揭示通麦—波密段现今地壳应力强度尚未达到极限水平,目前处于相对稳定的构造应力环境。最后,讨论了现今地应力场对东构造结北缘重大铁路隧道工程的潜在影响,并提出了应对建议。The eastern Himalayan syntaxis is the key geological region to understand the tectonic evolution of the Qinghai-Tibet Plateau where major engineering projects such as the Sichuan-Tibet railway and hydropower stations in the lower Yarlung Tsangpo River have been planned.However,the current in-situ stress field of this region is still unclear yet due to the complex geological and geographical conditions.Based on in-situ stress data that were obtained recently using the hydraulic fracturing method in this region,the current in-situ stress filed of the Tongmai-Bomi section,which is located in the northern margin of the eastern Himalayan syntaxis,is determined in detail.Furthermore,the current tectonic stress environment is estimated and discussed by adopting the Coulomb frictional-failure criterion and Byerlee\s law.The results indicate that the measured principal stresses SH and Sh show increase pattern versus depths and range 4.87~32.47 MPa,and 3.05~20.07 MPa within 1000 m depth below surface,respectively.The increase gradient coefficients of S H and Sh versus depths are 2.49 MPa/100 m,and 1.61 MPa/100 m,respectively,being lower than the corresponding gradient levels of the Qinghai-Tibet block and the western margin region of the eastern Himalayan syntaxis.However,the characteristic parameters representing the in-situ stress state reveal that the horizontal stress intensity in this region is greater than that of the Qinghai-Tibet block.The orientation of SH of the Tongmai-Bomi section derived from hydraulic fracturing tests is dominantly in NEE direction,with a mathematical average magnitude N69.2°±11.5°E,showing a clockwise deflection pattern comparing with the dominant NNE-NE regional tectonic stress direction derived from other tectonic stress indicators.The measured in-situ stress data reveal that the horizontal stresses play a dominant role in the generation of the current in-situ stress field,and the stress regime is considered to be thrust faulting within depths shallower than 400 m,and strike-slip faulti

关 键 词：喜马拉雅东构造结 地应力场 水压致裂法 特征参数 构造应力环境 

分 类 号：U452.11[建筑科学—桥梁与隧道工程] P553[交通运输工程—道路与铁道工程]