围压效应对钙泥质胶结砂岩强度和变形的影响

摘要 针对西部地区侏罗系砂岩成岩年代新、胶结程度较差，以及煤矿高强度开采的特点，开展恒定围压下三轴压缩实验，不同速率卸围压，以及单块多级加载实验，研究围压路径变化效应对钙泥质胶结砂岩强度和变形特征的影响.实验表明:西部中粒砂岩峰值强度、残余强度、峰值应变、弹性模量、泊松比等力学参数均对围压依赖性较强，且由于其钙泥质胶结的细观特性使其黏聚力、内摩擦角相比其他地区、其他年代的砂岩较低.随着围压的增大，试件由简单平整破裂面向复杂非平整多破裂面破裂模式转化.变围压加载过程中，围压的变化对砂岩的承载能力和变性特征影响显著，围压主要通过束缚试件横向变形和裂纹扩展，以及增大内部摩擦的方式影响岩体的力学特征，围压卸载和加载对岩体力学参数的影响规律可为采场推进速度优化和围岩支护分析提供一定的参考.
Abstract：Considering the characteristics of short diagenetic age and high intensity mining of Jurassic weak cemented sandstone in western China， the conventional triaxial compression tests， different unloading rates of confining pressure in triaxial compression tests and multi-stage triaxial tests were conducted to study the effects of confining pressure path on the strength and deformation. The results show that: the peak strength， residual strength， peak strain， elastic modulus and Poisson ratio depend on the confining pressure strongly， and the cohesion and internal friction angle of the sandstones in western China are lower than those of other sandstones. As the confining pressure increases， the failure mode transits from single plane fracture to complex multi-fracture. During the loading process， the change of confining pressure can remarkably affect the strength and the deformation characteristic by restricting lateral dilatation and increasing the angle of internal friction. The effect of unloading and loading confining pressure path on the mechanical parameters can provide references for the optimization of mining velocity and the support design of the surrounding rock masses.