三轴压缩时砂岩的割线模量及其峰后损伤演化特征

Evolution Characteristics of Secant Modulus and Its Post Peak Damage in Three Axial Compression for Sandstone

基于典型岩石应力-应变曲线的分类特征,并根据割线模量衰减特征定义了损伤系数,对比围压对割线模量和损伤演化特征的影响,借助于砂岩的三轴压缩试验,对理论模型进行了验证,结果表明:基于割线模量衰减定义的损伤系数,本质上是刚度退化系数;围压通过抑制横向变形间接提高了割线模量,降低了割线模量衰减速度,延缓了损伤的发展;临界损伤系数随着围压的增大而增大,该系数可以用于定量表征材料的延性特征。

Based on classification characteristics of stress-strain curves of typical rocks,the damage coefficient was defined according to the attenuation characteristics of secant modulus,meanwhile,the influences of confining pressure on secant modulus and damage evolution characteristics was compared.Then,the theoretical model was verified by the three axis compression test of sandstone,the results show that:The damage coefficient,defined by secant modulus attenuation,is stiffness degradation coefficient essentially.Confining pressure improved secant modulus indirectly by suppressing transverse deformation,meanwhile,it reduced the decay rate of secant modulus and delayed injury development.The critical damage coefficient increased with the increases of confining pressure,and the coefficient could be used to quantitatively characterize the ductility characteristics of materials.