干湿循环条件下两种砂岩强度及破坏特征比较试验研究

以侏罗系地层中的长英质细砂岩和弱蚀变泥质砂岩为例，分析了两种砂岩的不同矿物成分和细观 结构特征，探讨了干湿循环作用下两种砂岩强度及破坏形式变化情况。试验结果表明，由于两种砂岩矿 物成分的不同，长英质细砂岩遇水后，强度发生大幅度劣化，在之后的干湿循环过程中劣化趋于平稳， 破坏形式几乎由单一断面剪切滑移而破坏，多次干湿循环后，岩样的破坏形式无显著变化，但在断口处 出现粉化现象；弱蚀变泥质砂岩经多次干湿循环后，强度并未发生显著劣化，由于岩样的脆性较强，破 坏形式大多沿轴向存在相当多的劈裂面，但有一个贯穿整个岩样的剪切破坏面，断口处未出现粉化现象 。

Strength and Failure Mode Contrast Experiment Research on Two Sand Rocks under Conditions of Wetting and Drying Cycle

The felsic fine grained sand rock and weak altered argillaceous sand rock that located in the Jurassic system strata are taken as the study object, the different mineral composition and mesoscopic structure characteristics of two types sand rock is analyzed. And then, the changes situation of the strength and failure mode of the two types sand rock under the conditions of wetting and drying cycle is discussed. The experimental results show as follows: as the mineral composition of two kinds of sand rock is different, the strength of the felsic fine grained sand rock becomes weaken after wetting by the water; the degradation tends to smooth in the coming wetting and drying cycle process; the failure mode of the rock samples almost change from a single cross section to shear slip; after repeated wetting and drying cycle process, the failure mode of the rock samples does not change significantly, but the fracture place appears pulverization phenomenon; the strength of the weak altered argillaceous sand rock does not appear seriously degradation after repeated wetting and drying cycle process; as the result of the brittle of the rock samples is little strong, most of the shear failure surface is distributed along the axial area, but there is a shear failure surface penetrating the whole rock samples; fracture cross section does not appears pulverization phenomenon.