三轴条件下岩石抗剪强度参数线性回归法的修正

岩石三轴强度包络线通常为非线性，通过线性回归法（LRM）获得的抗剪强度参数对围压的变化具有很高的敏感性。为使 LRM能够考虑围压对抗剪强度参数估计的影响，定义了岩石三轴强度围压效应系数，构造一个指数函数表示该系数与围压的关系，并将其引入到 LRM 的修正中，提出考虑围压效应的线性回归分析法（CCPE-LRM）。同时，提出了CCPE-LRM 的合理性检验方法，并定义了距离系数作为指标来表征抗剪强度参数估计值与参数实际值的差异。通过以公开发表文献中多种类型岩石的三轴强度数据为例进行验证分析，结果显示各种岩石的距离系数均较小，CCPE-LRM 获得的抗剪强度包络线紧贴摩尔圆，且近似相切状态。表明通过CCPE-LRM 获得的抗剪强度包络线在一定程度上可以代替理想抗剪强度包络线，该方法估计的抗剪强度参数与理论抗剪强度参数的一致性较高，证明CCPE-LRM 具有较好的适用性。

Modification of linear regression method for rock shear strength parameters under triaxial condition

The triaxial strength envelope of rocks is usually nonlinear, and the shear strength parameters obtained by the linear regression method (LRM) are highly sensitive to confining pressure. In order to enable LRM to consider the influence of confining pressure on the estimation of shear strength parameters, the confining pressure effect coefficient of triaxial strength of rocks is defined. An exponential function is constructed to express the relationship between the coefficient and confining pressure, which is also introduced into the correction of LRM. A linear regression method considering confining pressure effects (CCPE-LRM) is proposed. At the same time, a rationality test method is proposed, and a distance coefficient is defined as an index to characterize the difference between the estimated and actual values of shear strength parameters. Through the verification and analysis of the triaxial strength data of various types of rocks in the published literature, the results show that the distance coefficients of various rocks are small, and the shear strength envelopes obtained by CCPE-LRM are all close to the Mohr circles in an approximately tangent state. It indicates that the shear strength envelope obtained by CCPE-LRM can replace the ideal shear strength envelope to a certain extent, and the shear strength parameters estimated by this method are in good agreement with the theoretical shear strength parameters. These prove that CCPE-LRM LRM has a good applicability.