利用孔壁竖向裂缝方位数据分析沂沭断裂带的地应力场特征  

ANALYSIS OF IN-SITU STRESS PARAMETERS OF YISHU FAULT ZONE BASED ON ORIENTATION OF DITF IN BHTV IMAGE

作　　者：王璞 王成虎[1] 王洪 陈念 周昊[1] 魏学勇[1] WANG Pu;WANG Cheng-hu;WANG Hong;CHEN Nian;ZHOU Hao;WEI Xue-yong(Key Laboratory of Crustal Dynamics,Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China)

机构地区：[1]中国地震局地壳应力研究所,地壳动力学重点实验室,北京100085

出　　处：《地震地质》2020年第6期1316-1334,共19页Seismology and Geology

基　　金：国家自然科学基金(41574088)资助。

摘　　要：区域地应力场状态的特征参数对于区域地壳稳定性分析、深部能源和资源开采以及深部基础设施建设都至关重要。主应力方向是地应力场的重要特征指标之一。在众多基于钻孔的地应力测量与估算方法中,利用钻孔孔壁诱发裂缝(DITF)确定区域应力场最大水平应力方向是最直接的方法之一。利用跨沂沭断裂带布置的3个深度约400m的钻孔,于2012—2014年开展了为期3a的高精度超声波钻孔电视重复扫描录井及水压致裂应力测量工作,以期准确确定区域的地应力场特征。通过录井图像精确识别出竖向裂缝共199组,其中包括钻孔诱发裂缝99组、水压致裂裂缝43组、后期生长裂缝57组。经循环统计方法确定的沂沭断裂带区域应力场的最大水平主应力优势方向为92.28°,并在优势方向附近首次发现竖向裂缝自然生长现象,进一步验证了利用超声波钻孔电视确定应力方向的准确性。The parameters of regional in-situ stress field are very important for the analysis of regional crustal stability,extraction of deep energy resource materials,and deep infrastructure construction.Moreover,the principal stress orientation is one of the important characteristic indicators of regional in-situ stress field.At present,there are many methods to determine the stress field,mainly including the method based on borehole(in-situ measurement)or focal mechanism solution(inversion).Comparing the way of in-situ measurement and inversion measurement,the in-situ measurement not only can measure the orientation of the in-situ stress,but also can obtain the magnitude of the in-situ stress.In the existing in-situ stress measurement and estimation methods based on borehole,the stress orientation is mainly determined by borehole induced failure structures when drilling or coring.Due to the concentration of tectonic stress in the borehole wall after drilling,the rock mass in the borehole wall area may be damaged,and borehole induced failure structures including borehole breakout(BO)and borehole-induced tensile fracture(DITF)will occur.Usually,borehole breakout occurs near the minimum principal stress orientation,and tensile cracks occur near the maximum principal stress orientation.In these two types of borehole induced failure structures,the DITF is more widely used to determine stress in-situ orientation,because DITF is the direct response of the orientation of the maximum horizontal stress in the stress field.The Yishu fault zone is the main active fault in the southern middle segment of Tan-Lu fault zone and the M_S8.5 Tancheng earthquake in 1668 occurred in this area,so determining the characteristics of the stress field in this area has important reference value for the judgment of Yishu fault stability.In order to accurately determine the orientation of the modern stress field of the Yishu fault zone,we drilled three boreholes with a depth of about 400 m in the Yishu fault zone from 2012 to 2014,the connection d

关 键 词：沂沭断裂带 地应力场 超声波钻孔电视 钻孔诱发裂缝 主应力方向 

分 类 号：P315.2[天文地球—地震学]