磁西矿超深井筒原岩地应力研究

介绍了磁西超千米井筒设计和地质条件，展示了井壁受力的实测方案以及依据包神解析公式进行地层原岩应力反演计算的原理。实测结果反演得到了井筒1 208 m深处的水平应力平均估值以及不均匀分布情况，水平应力与垂直应力之比符合自重应力场的规律，侧压力系数估值约为0.256~0.278之间。通过有限元数值模拟，图形化展示了井筒地应力分布，验证了实测反演数据的合理性，同时也反映了岩层剪切模量和构造等地质条件对水平应力不均匀分布的影响规律。结合对该矿区宏观地质构造运动演化和地质力学的定性分析原理，综合地分析了实测结果、解析反演和数值计算之间的一致性，对水平原岩应力Hoek & Brown统计规律的普适性提出了质疑，讨论了现有原岩应力解析计算方法，为采用包神公式进行井壁设计供了参考。

Study of in-situ geostress around an ultra-deep shaft in Cixi colliery

This paper reports the design of an auxiliary shaft at a depth of more than 1 000 m at Cixi colliery and its surrounding geological conditions, and addresses the scheme for monitoring the in-situ stress around the shaft and the principle of inverse calculation for the in-situ geostress using the “Baoshen” analytical solution. The average values and nonuniform distribution of horizontal stresses are actually obtained at the depth of 1 208 m through inverse calculation and analysis of field monitoring data, which reveals that the ratio of horizontal stress to vertical stress conforms to the dead weight stress field. The lateral pressure coefficient ranges from 0.256 to 0.278. The in-situ stress distribution around the shaft is illustrated based on finite element simulations; and thus the reliability of inverse data based on field measurements is corroborated. Meanwhile, it is shown that the nonuniform distribution of horizontal stress is related to some factors such as the shear modulus of rock and geological tectonic, etc. With combining the information on tectonic evolution in this area and geomechanical principles, the consistence among the results of in-situ test, analytical solution and numerical simulations is comprehensively analyzed. In this context, the universality of the Hoek & Brown statistic principle about the distribution of horizontal in-situ stress is questioned, and the existing analytical methods for calculating the in-situ horizontal stress are also discussed, laying a foundation for using the “Baoshen” solution to the shaft lining design.