单轴压缩下红砂岩能量演化试验研究

 岩石在变形至破坏过程中，伴随着能量的耗散和释放。为寻找加载过程中能量的演化规律，对红砂岩试件进行4种加载速率下单轴不断增加荷载循环加、卸载试验，得到弹性能和耗散能随应力的演化及分配规律。研究结果表明：(1) 破坏之前，试件吸收总能量、积聚弹性能、耗散能皆随应力的增大而增大，吸收总能量增加最快，弹性能次之，耗散能最慢。(2) 弹性能随轴向应力呈现非线性增长，在24%极限强度前增长速率较小，随后慢慢增大，临近破坏时又增长放缓；耗散能起初增长较缓慢，在即将破坏阶段显著大幅增加，增幅可达85%左右。(3) 整个加载过程弹性能所占比例约从60%增长到82%，增长速率逐渐变慢，而临近破坏时有小幅下降；耗散能所占比例的变化规律相反。(4) 在准静态加载范围内，大体上加载速率越小，耗散能越大；而加载速率对弹性能演化基本无影响。(5) 试件的弹性能密度–应力曲线无离散性，能够反映材料本身的固有性质。

EXPERIMENTAL RESEARCH ON ENERGY EVOLUTION OF RED SANDSTONE SAMPLES UNDER UNIAXIAL COMPRESSION

Energy dissipation and energy release appear evidently during the deformation and failure process of rock.In order to obtain the evolution and distribution laws of energy with stress in rock,tests on red sandstone samples under cyclic loading-unloading uniaxial compression with 4 different loading rates were carried out.The results show that:(1) The total absorbed energy,accumulated elastic energy and dissipated energy in rock samples all increase as the axial stress increases before failure,and the total absorbed energy grows fastest,followed by the elastic energy,and the dissipated energy grows slowest.(2) The elastic energy grows nonlinearly with the axial stress,and the increasing rate is small before 24% of ultimate strength,and then becomes larger gradually,but growth slows down when approaching destruction;and the dissipated energy grows slowly at first and increases substantially in the coming failure phase,with an increase of about 85%.(3) The proportion of elastic energy grows from 60% to 82% approximately in the whole loading process with the increasing rate slowing down gradually,and decreases slightly when approaching destruction;and the proportion of dissipated energy varies conversely.(4) In the quasi-static loading range,the smaller the loading rate,the greater the dissipated energy generally;and loading rate has no influence on the evolution of elastic energy basically.(5) The elastic energy density-stress curves of rock samples have no discreteness,and can reflect the inherent nature of the material itself.