冻融循环层理砂岩破坏模式试验研究

Research on failure modes of stratified sandstone under freeze-thaw cycling

在西部高寒地区,冻融循环作用对岩石路基稳定性具有不可忽视的影响,易引发一系列的工程地质问题.为研究冻融循环环境下各向异性层理砂岩的损伤特性,选取路基中典型垂直、平行层理砂岩试样开展冻融循环试验研究,基于电液伺服压力试验机进行单轴压缩试验,以应力应变曲线、力学参数和压缩破坏形态为依据,探究了冻融循环损伤后层理砂岩强度、变形特征的演化规律及破坏模式.研究结果表明:随着冻融次数的增加,垂直、平行层理试样呈现出向右拉伸,向下压缩的应力应变曲线;垂直层理砂岩试样峰值点下降路径平缓,而平行层理砂岩试样则沿阶梯状路径下降;冻融损伤累积减弱了破坏模式的各向异性特征,随冻融次数的增加,垂直层理砂岩试样裂缝与加载方向趋于平行,平行层理砂岩试样则始终表现为沿层理的劈裂破坏.

In the western alpine region,freeze-thaw cycling can not be ignored on the stability of rock roadbed,which can cause a series of engineering geological problems easily.To study the damage properties of anisotropy stratified sandstone under freeze-thaw cycling,the freeze-thaw cycle tests were carried out on the vertical and parallel stratified sandstone samples on the subgrade,and the differences in the freeze-thaw damage of the two inclinations were analyzed.Single-axis compression testing was carried out based on an electro-hydraulic servo pressure tester.Based on the stress-strain curve,mechanical parameters and compression and failure modes,the evolution law of the sandstone strength and deformation characteristics of the sandstone after the freeze-thaw cycle was explored,research indicated:With the increase of freezing and thawing times,the stress-strain curves of the two kinds of bedding samples were as follows:Stretch to the right and compress down;The descending path of the peak point of the vertical stratified sandstone samples was gentle,while the parallel stratified sandstone samples descends along the stepped path;The accumulation of freeze-thaw damage weakened the anisotropic characteristics of the failure mode.With the increase of freezing and thawing times,the cracks of the vertical stratified sandstone samples were gradually parallel to the loading direction,and the parallel stratified sandstone samples was always shown as splitting damage along the bedding direction.