尺寸效应和各向异性影响下岩体力学特性

Numerical Research of Rock Mass Mechanics Properties under the Influence of Scale Effects and Anisotropy

目的研究试样的尺寸效应和由于节理存在引起的各向异性对岩体的力学特性的影响.方法基于应变软化模型和遍布节理模型,通过多组岩体试样的单轴压缩试验和三轴试验数值模拟,对试样峰值强度和应力应变关系进行对比分析.结果岩体轴向峰值强度随岩体尺寸增大而减小,峰后残余强度却相应增大;节理倾角与45°+/2(为节理内摩擦角)越接近,岩体水平加载与竖直加载峰值强度相差越小.一组节理时,岩体节理面与加载面夹角在45°～75°,峰值强度最小,围压增加,岩体峰值强度增加,但增长速率逐渐变缓.结论岩体单轴压缩峰值强度、峰后残余强度和塑性区形态受岩体尺寸效应影响较大;在节理岩体中,岩体抗压性能受节理倾角及围压影响较大.

The paper aims to research the influences of sample size effect and rock anisotropy caused by existing joints on mechanical properties of rock mass.Based on the strain-softening model and ubiquitous-joint model,through the uniaxial compression test and the triaxial test numerical simulation,to compare and analyze the peak strength and stress-strain relationship.The results show that：the sample size is larger,the rock mass axial compressive stress peak intensity is smaller,and residual strength is bigger;The closer the joint angle is to 45°＋/2（ is the joint′s internal friction angle）,the peak intensity of level loading and vertical loading on rock mass is smaller.Under the condition of one group joints,when the angle between rock joints weak face and loading face is 45°~75°,the rock′s compressive property is the worst.As confining pressure increase,rock compression performance increase.Rock uniaxial compression peak strength,residual strength of the peak and the plastic zone size affected by Rock size effect bigger;In jointed rock masses,the rock′s compressive property by the joint Angle and confining pressure affected bigger.