盐岩变速率循环试验中的疲劳特性与声发射特征研究  

Experimental study on fatigue properties and acoustic emission characteristics of salt rock under variable cyclic rate effect

作　　者：杨镇宇[1,2] 陈结[1,2] 范金洋[1,2] 姜德义 王同涛[3] 杨春和[3] YANG Zhenyu;CHEN Jie;FAN Jinyang;JIANG Deyi;WANG Tongtao;YANG Chunhe(State Key Laboratory for the Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;School of Resources and Safety Engineering,Chongqing University,Chongqing 400044,China;Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)

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400044 [2]重庆大学资源与安全学院,重庆400044 [3]中国科学院武汉岩土力学研究所,湖北武汉430071

出　　处：《岩石力学与工程学报》2024年第4期951-963,共13页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金面上项目(52274073);国家自然科学基金重点项目(51834003);国家自然科学基金资助项目(52022014)。

摘　　要：为研究压气蓄能型盐穴注采气速率变化对围岩疲劳力学特性和细观机制的影响,在声发射监测下对盐岩开展4组变循环速率疲劳试验(加、卸载速率一致),试验中采用不同的上限应力和应力路径。分析循环内的残余应变、声发射累积振铃计数(后续简称AE计数)和峰频等与循环速率的相关性,结果表明:(1)循环残余应变和循环累积AE计数均具有明显的率相关性(即与循环速率呈明显的幂函数型关系,如ε_(ri)=mv_(i)^(-b)+ε_(l),N_(AE-i)=m'v_(i)^(-b')形式),应力等级和应力因子(幂函数的系数项m,m')正相关,应力等级和蠕变塑性的率相关性(幂函数指数项b)正相关,循环累积AE计数的率相关性则相反(幂函数的指数项b'减小)。率相关性参数(b,b')均能不同程度提前于循环残余应变预示加速破坏阶段的来临。(2)循环累积AE计数加速增长点在循环残余应变发展趋势的一、二阶段过渡点左右,该点在上限应力为19,23,27 MPa试验中大致对应2.382%,3.464%,4.297%的累积残余应变。(3)每循环内低频信号占比随循环速率增大而减小,高频信号占比随速率减小而增大,中频信号占比仅随应力等级提升而增长。(4)快、慢循环分别起到了硬化、软化作用,软化作用使后一循环中有更小起裂应力和更强塑性变形能力(硬化作用则反之),这种机制与慢速循环中更多小尺度裂纹萌生扩展,以及慢速卸载过程中内应力的充分释放有关。研究成果对压气蓄能盐穴注采气频率调节方式和损伤演化分析有一定参考意义。In order to investigate the impact of variations in gas injection and extraction rates on the fatigue mechanical properties and fine-scale mechanism of the surrounding rock in compressed air energy storage salt caverns(CAES).Four groups of variable cyclic rate fatigue tests on salt rock were conducted using acoustic emission monitoring(loading and unloading rates are consistent),with varying upper limit stress and stress routes.The correlations of residual strain,cyclic acoustic emission cumulative ring counts(AE counts)and peak frequency with cyclic rate were analyzed.The results showed that:(1)Cyclic residual strain and cumulative AE counts have an obvious rate correlation(obvious power law relationship with the cyclic rate,ε_(ri)=mv_(i)^(-b)+ε_(l),N_(AE-i)=m'v_(i)^(-b')),and a positive correlation has been observed between stress level and stress factor(coefficient terms of power functions m,m').The rate dependence of creep plasticity is positively correlated with stress level(power function exponential term b),while the rate dependence of cyclic cumulative AE counts is opposite(power function exponential term b'decreases).The rate correlation parameters(b,b')are all able to predict the onset of the accelerated damage stage differently in advance of the cyclic residual strain.(2)Accelerated rise of cyclic cumulative AE counts occurs at the transition point between phases I and II of the cyclic residual strain development trend.This corresponds to 2.382%,3.464%and 4.297%cumulative residual strains in tests of 19,23,27 MPa upper limit stress,respectively.(3)The proportion of low-frequency signals reduces with increasing cyclic rate,while highfrequency signals rise with lowering cyclic rate.Mid-frequency signals only increase with increasing stress level.(4)Fast and slow cycling operate as hardening and softening,respectively,with the softening effect resulting in lower fracture initiation stresses and stronger plastic deformability(and vice versa for hardening)in the latter cycle.This mechanism can be linked t

关 键 词：岩石力学 压气蓄能 盐岩 疲劳试验 声发射 

分 类 号：TU45[建筑科学—岩土工程]