分析了岩（土）材料在不同应力情况下的破坏特征，指出对岩（土）结构起作用的强度指标除抗剪强度指标c、tanφ外，还应包含抗拉强度指标T，原强度折减法在强度折减过程中过高地考虑了抗拉强度，导致计算偏危险。因此，在有限元强度折减法计算岩土工程的安全系数时应保证抗拉强度指标与抗剪强度指标同等减少，即采用“抗拉剪强度折减法”。通过4个非常典型的算例模型：一般边坡、钟乳石、隧道、陡边坡验证了“抗拉剪强度折减法”提出的必要性和正确性。研究表明，改进的强度折减法在岩土工程中具有更加普遍的适用性。

The failure characteristic of geomatertials in different stress states is analyzed, and it is found that the stability of geotechnical structure depends on not only shear strength index c and tanφ, but also tensile strength index T. The overvalued of tensile strength of materials could lead to non-conservative results in the primary strength reduction method. Therefore, the FEM strength reduction method should take identical reduction of both tensile strength index and shear strength index into account. In other word, tension and shear strength reduction method (TSSR) in the process of strength reduction should be adopted. The necessity and correctness of TSSR is validated by stimulating four typical example models, i.e. the general slope, the stalactite, the tunnel and the steep slope. Studies show that the modified strength reduction method has universal applicability in geotechnical engineering.

重庆市科技攻关项目（CSTC, 2011AC6212,2009AB6194）；重庆市国土资源和房屋管理局科技计划项目（［2010］171）