基于多源应力数据的川南地区地应力特征分析  

Analysis of In-Situ Stress Characteristics in Southern Sichuan Basin Based on Multi-Source Data

作　　者：高桂云 王成虎 周昊 谷佳诚 Gao Guiyun;Wang Chenghu;Zhou Hao;Gu Jiacheng(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,P.R.China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085

出　　处：《地下空间与工程学报》2023年第2期550-559,共10页Chinese Journal of Underground Space and Engineering

基　　金：中央级公益性科研院所基本科研业务专项(ZDJ2020-07);国家自然科学基金(42174118,41574088)。

摘　　要：本文通过结合区域构造形迹分析、原地应力实测资料、震源机制数据以及钻孔破坏现象,采用基于震源机制解的应力反演及基于应力多边形与钻孔破坏指标的应力量值估算方法,对四川盆地南部地区地应力特征进行了综合分析。结果显示:四川盆地南部区域应力状态稳定,有利于逆断和走滑断层的活动,区域浅部最大水平主应力的方向有NE和NW向2个优势方位,深部最大水平主应力优势方位为NWW向;区域应力场分区特征不明显,震源机制解一致性较好,应力结构类型均为逆断型;浅部应力估算结果显示不同钻孔的侧压力系数值相对较为稳定,平均值分别为k_(Hmax)=1.72和k_(hmin)=0.99,应力积累指标μ_(m)值范围为0.15~0.5;而在埋深3207~3716 m时,最大和最小水平主应力范围分别为104.5~122.3 MPa和81.1~96.5 MPa,应力积累指标μ_(m)值在0.37~0.43,区域深部应力积累水平较低,断层易滑性较低。In situ stress states are the key to tackle the problem involving geomechanical stability.Based on the analysis of regional tectonic trace,in-situ stress measurement data,focal mechanism data and borehole failure phenomena,this study comprehensively analyzed the in-situ stress characteristics in the southern Sichuan basin.Using a stress inversion method based on focal mechanism solutions,the stress orientations were estimated,while the stress magnitudes were constrained based on the stress polygon method and borehole failure indexes.The results show that the regional stress state in the southern Sichuan Basin is stable,which straddles the boundary between reverse faulting and strike-slip faulting regimes.The orientation of the maximum horizontal principal stress at shallower depth has two preferred directions,NE and NW,while it turns to NWW in deep depth.The zonal characteristics of regional stress fields are not obvious,where the focal mechanism solutions are in consistent and the stress fields are relatively uniform.The estimation of the stress magnitude in the shallow region show that the lateral stress coefficients of different drilling holes are relatively stable,with an average value of k_(Hmax)=1.72 and k_(hmin)=0.99,respectively.The stress accumulation index valueμ_(m)ranges from 0.15 to 0.5.When the buried depth is 3207~3716 m,the magnitudes of the maximum and minimum horizontal principal stresses in Weiyuan area are in ranges of 104.5~122.3 MPa and 81.1~96.5 MPa,respectively,while the vertical stresses range from 83.3 MPa to 96.5 MPa.The values of stress accumulation indexμ_(m)are in range of 0.37~0.43,indicating that the regional stress accumulation level is low.This stress estimation and analysis method based on multi-source stress data could lead to a comprehensive understanding of regional stress in southern Sichuan Basin and provide a possible method for stress analysis especially for that lack of in-situ measurement data.

关 键 词：地应力 应力积累 钻孔崩落 四川盆地南部 

分 类 号：P315.72[天文地球—地震学]