冻融循环条件下粗砂岩物理力学性质变化规律

Variation of physical and mechanical characteristics of coarse sandstone during freezing and thawing cycles

岩体经受自然冻融循环过程后,其物理力学性质的劣化是引起岩石工程灾害的主要原因。借助于MTS815液伺服岩石试验系统对经历不同冻融循环次数的粗砂岩进行三轴压缩试验,研究经历不同冻融循环次数后岩石在不同围压下的强度和变形特性,分析冻融循环次数和围压对岩石强度和变形的影响规律。研究结果表明,在冻融循环次数一定的条件下,随着围压的增加,岩石的三轴抗压强度、弹性模量和峰值轴向应变逐渐增加,表明粗砂岩的破坏逐渐由脆性破坏向塑形破坏变化;在围压相同的情况下,随着冻融循环次数的增加,岩石的三轴抗压强度、弹性模量逐渐减小,峰值应力对应的轴向应变逐渐增加;随着冻融循环次数的增加,粗砂岩的黏聚力均呈指数衰减形式降低,内摩擦角变化很小。

Subjected to freezing and thawing cycles, the deformation of rock’s physical and mechanical properties is the main causeof engineering disasters. Based on the analysis on different freezing and thawing cycles of triaxial compression test of sandstone,conclusions are drawn that under conditions of certain freezing and thawing cycles, with the increase of confining pressure, the triaxialcompressive strength, the elastic modulus and the axial strain increase gradually, indicating that the failure of rock changesfrom brittle failure to plastic failure; in the case of same confining pressure, with the increase of the number of freezing and thawingcycles, the triaxial compressive strength, the elastic modulus of rock decrease and the axial strain corresponding to peak stress increasesgradually. With the increase of the number of freezing and thawing cycles, the cohesion of coarse sandstone and fine sandstonedecreases exponentially, the internal friction angle changes very little.