基于水压致裂法的三山岛深竖井工程区地应力测量与反演分析

In-situ stress measurement and inversion analysis of the deep shaft project area in Sanshan Island based on hydraulic fracturing method

山东省三山岛西岭矿区拟建2000 m深副井,属于超深井建设工程。揭示建井工程区地应力场特征是开展竖井设计、建设施工的必要先决条件之一,研究中采用水压致裂法开展了深部竖井地应力现场测量工作,测量深度达到1899.00 m,通过数值仿真模拟方法反演了竖井工程区2017.56 m深的地应力场。结果表明:在水压致裂测试的钻孔357.76~1899.00 m深度范围内,最大水平主应力(SH)为23.16~70.86 MPa,最小水平主应力(Sh)为15.24~47.06 MPa;主应力随深度近于线性增加,地应力测量孔实测最大水平主应力方向分别为NW55.5°、NW60.4°、NW58.4°,为近北西方向;竖井工程区应力场主要以水平应力为主导,1200.00 m以下铅直主应力(Sv)为中间应力,SH与Sv之比平均值为1.53;通过FLAC 3D软件的反演分析获得了建井工程区内地应力场随深度、地层变化的分布规律,测试点的反演结果与实测值基本一致。近2000 m超深地层地应力状态及其分布规律,为竖井工程的井筒井壁设计和工程风险评估提供了基础科学依据。

The proposed 2000-meter-deep auxiliary shaft at the Xiling mine,Sanshan Island,Shandong Province,is an ultra-deep shaft construction project.Revealing the characteristics of the in-situ stress field in the shaft construction area is one of the necessary prerequisites for the design and construction of the shaft.We measured the in-situ stress in the deep shaft by hydraulic fracturing method to a depth of 1899.00 m and inverted the 2017.56-meter-deep in-situ stress field in the shaft construction area by numerical simulation.The results show that the maximum horizontal principal stress(SH)ranges from 23.16 to 70.86 MPa,and the minimum horizontal principal stress(Sh)from 15.24 to 47.06 MPa in the depth range from 357.76 to 1899.00 m in the borehole tested by hydraulic fracturing;the principal stress increases nearly linearly with depth,and the measured maximum horizontal principal stress directions in the measured boreholes are NW 55.5°,NW 60.4°,and NW 58.4°,respectively.Horizontal stress mainly dominates the stress field in the shaft engineering area,the vertical stress(Sv)below 1200.00 m is the intermediate stress,and the average value of the ratio of SH to Sv is 1.53.The in-situ stress field distribution pattern in the well-construction area with depth and stratigraphic changes is obtained by inversion analysis of FLAC 3D software.The inversion results are basically consistent with the measured values.It provides the fundamental scientific basis for shaft wall design and engineering risk assessment of shaft projects.