中文摘要：

岩土工程中常用的屈服准则多以压缩剪切为其破坏机制,然而硬脆性岩体的脆性破坏包括拉伸破坏、张拉剪切破坏和压缩剪切破坏3类,且随着岩体工程向深部发展,张拉剪切破坏成为了洞壁围岩的主要破坏机制。针对此问题,开展了硬脆性大理岩的室内拉剪试验,分析了大理岩拉剪破坏特征,并结合压剪试验结果,建立了考虑张拉剪切破坏机制和应力状态影响的Mohr-Coulomb准则。研究结果表明,硬脆性大理岩破裂面在拉剪应力状态和低正应力压剪应力状态下均具有张拉剪切破坏特征,高正应力压剪应力状态下则只具有压缩剪切滑移特征;拉剪应力状态下,大理岩破裂面张拉破坏特征明显,无明显剪切痕迹,剪切力固定时,剪切位移随着轴向拉力增加而增加;凝聚力和内摩擦角受应力状态影响,凝聚力随正应力增大先减小后增大,内摩擦角则随正应力的增大而减小;凝聚力、内摩擦角随正应力的变化趋势可分为4段,拉剪段、低压应力段、中压应力段和高压应力段,每段的凝聚力、内摩擦角与正应力皆可认为是线性关系,靠近抗拉强度处,内摩擦角趋近90°,凝聚力趋于无穷大;考虑张拉剪切破坏机制和应力状态影响的Mohr-Coulomb准则曲线分为两部分,可采用二次抛物线进行拟合的拉剪段和考虑凝聚力、内摩擦角随正应力演化的压剪段,由此建立的Mohr-Coulomb准则更全面、精度也更高。

英文摘要：

The yield criterion of materials in geotechnical engineering is generally presented on the basis of the compression-shear failure type. However, brittle hard rock has three types of failure, i.e., tensile failure, tension-shear failure and compression-shear failure. With increasing the depth of rock engineering, the tension-shear failure turns into the main failure mechanism of surrounding rock. Tension-shear tests are conducted on brittle hard marble to investigate the characteristics of tension-shear failure. By analyzing tension-shear and compression-shear testing results, a modified Mohr-Coulomb criterion is established, which can consider the effect of tension-shear failure and stress state. It is noted that the failure of brittle hard marble is in tension-shear at the tension-shear stress state and at the compression-shear stress state with a low normal axial stress, but it shows compression-shear slip characteristic at the compression-shear state with a high normal stress. The failure of marble is dominated by obvious tension cracks at tension-shear stress state, while no obvious shear crack appears. The shear displacement increases with the increase of axial tensile stress when the shear stress is fixed. The cohesion and friction angle are influenced by the stress state. The cohesion decreases initially and then increases with increasing the normal stress, while it is opposite in the friction angle. The variations of the cohesion and friction angle with the normal stress can be divided into four stages： tension-shear, low compression stress, medium compression stress and high compression stress. The relationships between cohesion, friction angle of each stage and normal stress are linear, and the friction angle reaches up to 90 degrees while the cohesion approaches infinitely to tensile strength. By considering the effect of tensile shear failure and stress state, the Mohr-Coulomb criterion curve can be divided into two stages, the tension-shear stage which is fitted with a second-degree parabola and th