通过对直剪试件剪切面内应力集中系数分布规律的研究，结合剪应力–剪切位移变化曲线的分析，提出一种采用应力集中系数进行土体抗剪强度取值的方法。以武汉地铁六号线某区间段角砾黏土地层为研究对象，进行室内大型直剪试验，得出角砾黏土的抗剪强度参数随含石量的变化规律，与规程方法进行对比分析，探讨文中方法的可行性。结果表明，应力集中系数K0一定程度上能够反映直剪时土体剪切承载力的强弱；角砾黏土的黏聚力随着含石量的增加呈近似线性关系，与现有研究成果一致；试验结果位于规程规定合理范围内，说明基于应力集中系数的抗剪强度取值方法可作为研究土体强度特性的有效途径。

This paper proposes a method for determination of shear strength based on stress concentration factor by investigating the distribution regularity of stress concentration factor in the shear plane and analyzing the curves of shear stress-shear displacement. Laboratory large-scale direct shear tests are conducted on the specimens from clay layer with breccia along Wuhan metro line 6. the variations of shear strength parameters of the soil layer with the stone content variation are determined. Through comparing this method with procedures in codes, the feasibility of this method are discussed. The results show that the stress concentration factor K0 partly reflect the shear strength of the soil; the cohesion of clay containing breccia approximately increases linearly with the increase of stone content, which is consistent with the existing research results. This method for shear strength based on stress concentration factor, can be used as an effective way to study soil strength characteristics.