Abstract: Mohr-Coulomb criterion and the failure criterion of coarse-grained soil were expressed by p, q and b. The failure lines on π-plane of the two criterion were compared with the test results of coarse-grained soil in which both p and b kept constant. It is shown that the later criterion is closer to the test results owing to considering the influence of the intermediate principal stress ratio b. Both of the two criterion have singular points which are disadvantageous to numerical calculations. Based on the experimental results of loose sand, dense sand, gravel and coarse-grained soil, a new strength criterion is proposed whose failure line on π-plane fits for the test results.

Key words: geotechnical engineering, failure criterion；π-plane, coarse-grained soil, both p-and b-constant, true triaxial

摘要： 用p, q, b这3个变量表示Mohr-Coulomb破坏准则、粗粒土破坏准则，将这两个强度准则在π平面上的破坏线与粗粒土等p等b试验结果比较：发现后者由于考虑了中主应力系数b的影响，更接近试验结果；但这两个破坏准则都有奇异点，不利于数值计算。在松砂、紧砂、砾石料、粗粒土的等σ3等b试验结果基础上，提出了一个无奇异点的新强度准则，其在π平面上的破坏线与试验结果更加吻合。

关键词: 岩土工程, 破坏准则, π平面, 粗粒土, 等p等b, 真三轴