各向异性砂岩冻融力学特性研究

针对新疆天山公路岩质边坡的砂岩， 开展了单/三轴压缩试验和不同次数的冻融循环试验， 探讨了岩样强度和变形参数的各向异性随围压和冻融循环次数的变化规律， 分析了层理角度及冻融作用对岩样破坏模式的影响。结果表明： 岩样的弹性模量、 黏聚力、 内摩擦角和峰值强度均随着层理角度的增加呈现先减小后增加的U型发展态势， 在60°时达到最小值， 在0°或90°时其值最大； 岩样的强度以及变形参数随着冻融循环次数的增加逐渐减小， 随着围压的增加而增大； 不同层理角度岩样强度及力学参数的差异性随着围压的增加逐渐较小， 相应的岩样各向异性特性逐渐减弱； 随着冻融循环次数的增加， 岩样内部的裂纹不断扩展导致岩样各向异性程度逐渐增强； 不同层理角度岩样的破坏模式可归纳为穿越基质和层理面的竖向劈裂张拉破坏、 穿越基质和层理弱面的剪切破坏、 拉-剪混合破坏、 沿层理弱面的剪切滑移破坏、 沿层理弱面的竖向劈裂破坏等5种模式。研究成果可为寒区岩体工程相关研究提供参考和依据。

Mechanical characteristics of anisotropic sandstone under freeze-thaw cycles

In order to study anisotropic properties of sandstone in Tianshan Highway， Xinjiang， freeze-thaw cycle test， uniaxial/triaxial compressive tests were carried out. Strength and deformation parameters under different confining pressure and numbers of freeze-thaw cycles were discussed， the impact of bedding angle and failure modes was analyzed. The results show that elastic modulus， inner friction angle and cohesion of samples increase at first and then decrease with the increase of angle， and reach the minimum when the angle is 60°， reach the maximum at the angle of 0°or 90°； strength and deformation parameter decreases with numbers of freeze-thaw cycles， however， these parameters increase with the increase of confining pressure； with the increase of confining pressure， anisotropy of samples is decreasing； with numbers of freeze-thaw cycles， anisotropy of samples is increasing； the failure modes of sandstone can be summarized as splitting failure cross weak bedding face， shear failure cross weak bedding face， tension-shear failure， shearing slip damage along the weak bedding face， and splitting failure along weak bedding face. These results could be useful for engineering construction in cold regions.