砂岩循环加卸载过程能量的演化与损伤特性  

Energy evolution and damage characteristics of sandstone under cyclic loading and unloading

作　　者：秦涛[1,2] 段燕伟 刘志 王磊[1] 孙洪茹 Qin Tao;Duan Yanwei;Liu Zhi;Wang Lei;Sun Hongru(Key Laboratory of Mining Engineering of Heilongjiang Province College,Heilongjiang University of Science&Technology,Harbin 150022,China;School of Resources&Civil Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]黑龙江科技大学黑龙江省普通高校采矿工程重点实验室,哈尔滨150022 [2]东北大学资源与土木工程学院,沈阳110819

出　　处：《黑龙江科技大学学报》2020年第1期8-15,共8页Journal of Heilongjiang University of Science And Technology

基　　金：国家自然科学基金项目(51774122);国家重点研发计划专项项目(2016YFC0600901)

摘　　要：为了获得岩石加卸载过程能量演化与损伤特性,开展了不同围压下砂岩循环加卸载力学特性实验。基于能量平衡理论,分析了不同围压下砂岩加卸载过程能量密度转化规律,从能量耗散角度定义损伤变量,建立了基于耗散能的损伤模型。结果表明:不同围压下砂岩循环加卸载过程能量演化趋势呈现一致性,在压密阶段和弹性变形阶段,能量消耗主要用于原生微裂隙受压闭合,加载过程中输入能量主要转化为弹性应变能;在高应力水平下的屈服阶段,耗散能密度增加速度逐渐增大,但峰值应力前仍以弹性能储存为主,围压越大岩石弹性储能极限越大;在峰后阶段以能量耗散为主,弹性应变能密度剧减,耗散能密度急增。在应力屈服点以前,各循环阶段损伤较小,累积损伤随着循环次数呈线性增大;在应力屈服点以后,岩石内部新生裂纹萌生、扩展,耗散能量加剧,绝对损伤和累积损伤均明显增大。This paper aims to identify the characteristics underlying the energy evolution and damage of the rock under loading and unloading conditions.The study involves performing tests on the mechanical characteristics of sandstone subjected to different confining pressures under cyclic loading and unloading;analyzing the law controlling energy density conversion of sandstone during loading and unloading under different confining pressures using the energy balance theory;defining the damage variable from the perspective of energy dissipation;and developing a damage model based on dissipation energy.The results show that a consistent trend exists in energy evolution during cyclic loading and unloading process of sandstone subjected to different confining pressures.The compaction stage and the elastic deformation stage see the energy consumption mainly used for the compression and closure of the primary micro-fracture and loading stage is accompanied by the transformation of the input energy mainly into elastic strain energy;a gradual increase occurs in the increasing speed of the dissipated energy density,at the yield stage at high stress levels,but the elastic energy storage is still the main factor before the peak stress.The peak stress is preceded by the dominance of elastic energy storage,suggesting that the greater the confining pressure is,the greater the elastic energy storage limit of the rock is.The post peak stage dominated by energy dissipation is followed by a sharp decrease in the energy density of elastic strain and a rapid increase in the energy density of dissipation.The stress yield point is preceded by a small damage in each cyclic stage,and a linear increase in the cumulative damage with the times of cycles.After the stress yield point come an increase in the dissipated energy due to cracks initiating and propagating in the rock and a significant increase in the absolute damage and cumulative damage.

关 键 词：砂岩 循环加卸载 能量演化 损伤特性 

分 类 号：TD31[矿业工程—矿井建设]