岩石非均质程度对水压致裂地应力测试方法影响的分析与讨论  

Influence of rock inhomogeneity degree on the crustal stress results measured by hydraulic fracturing method

作　　者：陈东升 纪洪广[1,2] 袁永忠 李芹涛 CHEN Dongsheng;JI Hongguang;YUAN Yongzhong;LI Qintao(School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China;Beijing Key Laboratory of Urban Underground Space Engineering,University of Science and Technology Beijing,Beijing 100083,China;LaizhouHuijin Mining Investment Co.,Ltd.,Yantai 261400,Shandong,China)

机构地区：[1]北京科技大学土木与资源工程学院,北京100083 [2]北京科技大学城市地下空间工程北京市重点实验室,北京100083 [3]莱州汇金矿业投资有限公司,山东烟台261400

出　　处：《地质力学学报》2023年第3期365-374,共10页Journal of Geomechanics

基　　金：山东省重大科技创新工程项目(2019SDZY02,2019SDYZ05)。

摘　　要：准确揭示原位地应力状态,对地下工程开挖支护设计和长期稳定性分析等具有十分重要的意义。利用水压致裂技术开展了纱岭金矿主竖井地应力测试工作,获得了20个测段地应力状态;室内进行了主竖井测试孔岩芯的岩石力学试验,包括巴西劈裂试验、单轴压缩试验及声发射监测试验,获得了岩石空间非均质度和强度分布特征,并分析了岩石非均质度与水压致裂测试结果的关系。结果表明:主应力大小随测量深度近似呈线性增大,测试孔的最大水平主应力值为20.78~45.20 MPa,最小水平主应力值为14.94~35.33 MPa,平均最大水平主应力方向为NW65°;测试孔岩芯各层位非均质度不同,变辉长岩非均质度系数为0.1~0.3,且岩石不同强度条件下声发射信号数量变化不显著,岩石离散度较小,花岗岩非均质度系数最高,可达1.0,以加载后期强相破裂产生的声发射信号为主;岩石非均质度影响水压致裂裂纹的扩展方向,扩展方向和最大水平主应力方向的夹角φ影响着最大、最小水平主应力的测量结果,且对最小水平主应力的影响尤为显著。分析水压致裂测量结果与岩石性质之间的关系,对精确探测非均质地层的地应力场分布规律具有一定的指导作用。Accurate in-situ crustal stress data are essential for excavation support design and long-term stability analysis of underground projects.We tested the main shaft of the Shaling Gold Mine for crustal stress using hydraulic fracturing technology,and the crustal stress state of 20 measurement points was obtained.The Brazilian test,uniaxial compression test,and acoustic emission test of the cores were conducted indoors to obtain the rock’s spatial inhomogeneity and strength distribution.We analyzed the relationship between the inhomogeneity of the rock and the hydraulic fracturing results.The analysis results show that the magnitude of the principal stress increases nearly linearly with the measurement depth,with the maximum horizontal principal stress value ranging from 20.78 to 45.2 MPa and the minimum principal stress value from 14.94 to 35.33 MPa.The average direction of the maximum horizontal principal stress is NW 65°.The inhomogeneity of each layer of the cores varies,and the inhomogeneity coefficient of the metagabbro is from 0.1 to 0.3.The number of acoustic emission signals under each intensity of the rock is basically the same,and the dispersion of the rock is small.The non-homogeneity coefficient of granite is up to 1.0,dominated by the acoustic emission signals generated by the intense-phase rupture at the late loading stage.The non-homogeneity of the rock affects the direction of expansion of the hydraulicφfracture,and the angle between the expansion direction and the maximum horizontal principal stress affects the measurement results of the horizontal maximum and minimum principal stresses and has a more significant effect on the horizontal minimum principal stress.The relationship between hydraulic fracture measurements and rock properties was analyzed,which is helpful for accurately detecting the distribution of stress fields in inhomogeneous strata.

关 键 词：深部地层 原位地应力 水压致裂法 岩石非均质度 岩石力学试验 

分 类 号：P553[天文地球—构造地质学]