中间主应力对砂岩扩容及强度特性影响  

Influence of intermediate principal stress on dilation and strength characteristics of sandstone

作　　者：尹光志[1,2,3] 鲁俊[1,2,3] 李星[1,2,3] 边光[1,2,3] 宋真龙 刘玉冰[1,2,3] 

机构地区：[1]重庆大学煤矿灾害动力学与控制国家重点实验室,重庆400030 [2]重庆大学资源及环境科学学院,重庆400030 [3]重庆大学复杂煤气层瓦斯抽采国家地方联合工程实验室,重庆400030

出　　处：《煤炭学报》2017年第4期879-885,共7页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51434003;51374256);2016重庆市科研创新资助项目(CYS16012)

摘　　要：基于自主研发的"多功能真三轴流固耦合试验系统",进行了真三轴应力(σ1﹥σ2﹥σ3)条件下,保持体应力不变、改变中主应力系数的砂岩强度试验,探讨了不同中主应力系数条件下砂岩的变形、强度及剪切破坏特性。试验结果表明:在真三轴应力条件下,扩容起点随中主应力系数b的增大而呈递减趋势。应力加载过程中扩容存在明显的阶段性:随最大主应力的增加,稳定压缩段,体应变近似呈线性递增趋势;加速扩容段,体应变近似呈二次函数增大,且应变速率呈线性增大。保持体应力不变条件下,砂岩峰值强度随中主应力系数b的增大而逐渐降低,符合修正Lade准则。试验应力条件下,岩样主要发生双斜面对称剪切破坏,剪切破坏面倾角随b的增加呈线性增大。Based On the self-made ＂multi-functional true triaxial fluid-solid coupling experiment system＂, an experi- ment to investigate the strength of sandstone under true triaxial compression（ σ1 〉 σ2 〉 σ3 ）for different coefficients of the intermediate principal stress and maintaining the volume stress unchanged was carried out. The authors have dis- cussed the deformation, strength and shear failure plane feature of sandstone under different coefficients of intermediate principal stress. The research result shows that the starting point of dilatancy decreases with the increase of the coeffi- cient b of intermediate principal stress under true triaxial compression. The dilataney exists an obvious stage under ex- perimental conditions, with the increase of maximum principal stress, the volume strain increases linearly at the steady compressing stage and increases as a quadratic function at the accelerating stage with the strain rate increases linearly. The strength of sandstone decreases with the coefficient b increase and coincides with the Modified Lade Criterion un- der the condition of keeping volume stress unchanged. In this experimental test, the rock specimens generally devel- oped a typical type of symmetrical double shear failure and the angle of shear plane increases linearly with the coeffi- cient b increase.

关 键 词：真三轴 扩容 中主应力系数 强度 剪切破坏 

分 类 号：TD313[矿业工程—矿井建设]