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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。
This paper introduces the design and geological conditions of wellbore of west magnetic tunnel, shows the measurement scheme of wellbore stress and the calculation principle of original rock stress according to Baochun analytical formula. The inversion of measured results obtained the average horizontal stress and uneven distribution of the depth of 1 208 m in wellbore. The ratio of horizontal stress to vertical stress accorded with the law of self-weight stress field, and the lateral pressure coefficient was estimated to be between 0.256 and 0.278 . Through the finite element numerical simulation, the distribution of wellbore stress is demonstrated graphically, and the rationality of measured inversion data is verified. At the same time, the effect of geological conditions such as shear modulus and structure on uneven horizontal stress distribution is also reflected. Combined with the principle of qualitative analysis of the macroscopic geological tectonic movement and geomechanics in this mining area, the consistency between measured results, analytical inversion and numerical calculation is comprehensively analyzed, and the universality of the Hoek & Brown statistical rule of horizontal protolith stress is put forward Questioning and discussing the existing analytical methods of stress analysis of original rock, it provides a reference for the design of wellbore wall using the Baogang formula.