超临界CO_(2)浸泡作用下煤岩力学特性应变率效应实验研究  

Experimental study of loading strain rate effect on mechanical properties of supercritical CO_(2) soaked coal rock

作　　者：吴韬 梁卫国[1,2] 于永军 武鹏飞[1,2] WU Tao;LIANG Weiguo;YU Yongjun;WU Pengfei(College of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Key Laboratory of In-situ Property-improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)

机构地区：[1]太原理工大学矿业工程学院,山西太原030024 [2]太原理工大学原位改性采矿教育部重点实验室,山西太原030024

出　　处：《岩石力学与工程学报》2023年第11期2727-2738,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家区域创新发展联合基金重点项目(U22A20167)。

摘　　要：为研究超临界CO_(2)浸泡对煤岩单轴压缩力学特性应变率效应的影响,进行未浸泡及超临界CO_(2)浸泡煤岩在准静态应变率加载(10^(-5),10^(-4),10^(-3),10^(-2) s^(-1))下的单轴压缩实验,并利用声发射监测系统记录加载过程中的能量信号,从应变率效应和Sc CO_(2)浸泡弱化机制角度对煤岩单轴抗压强度、弹性模量、破坏形态、能量演化和AE特征参数进行了研究。结果表明:(1)随着应变率增加,未浸泡和超临界CO_(2)浸泡煤岩的抗压强度和弹性模量均表现为先增加后降低趋势。在10^(-5)和10^(-2 )s^(-1)应变率条件下,超临界CO_(2)浸泡煤岩的力学特性劣化作用更为明显;煤岩单轴抗压强度分别降低28.66%,34.98%,相应弹性模量分别降低35.50%,27.68%;(2)未浸泡超临界CO_(2)煤岩的破坏形态主要为X状共轭剪切破坏,而超临界CO_(2)浸泡煤岩试件的破坏形式由斜面剪切破坏转变为竖向劈裂拉伸破坏;(3)应变率效应及Sc CO_(2)浸泡弱化作用对煤岩的力学性质的影响,同时也影响着煤岩可储存弹性应变能的大小,从煤岩破坏时表征能量释放的声发射信号强弱可以获证。该研究有助于揭示超临界CO_(2)浸泡煤岩在准静态加载条件下力学特性变化规律,以及分析理解煤岩储层压裂过程中煤体变形和裂缝扩展条件特征。In order to study the effects of loading strain rate and supercritical CO_(2 )on the mechanical properties of coal rock,uniaxial compression experiments of un-soaked and supercritical CO_(2) soaked coal rock are carried out under different quasi-static strain rate(10^(-5),10^(-4),10^(-3),10^(-2) s^(-1)) loading.The energy signals during the loading process are recorded by acoustic emission monitoring system.The uniaxial compressive strength,elastic modulus,failure mode,energy evolution and AE characteristic parameters of the tested coal rock are studied from the perspective of strain rate effect and Sc CO_(2) soaking weakened mechanism.The results show that:(1) With the increase of the loading strain rate,the compressive strength and elastic modulus of the un-soaked and supercritical CO_(2)-soaked coal rock increase at first and decrease later.Under the loading strain rates of 10~(-5) and 10^(-2) s^(-1),the deterioration of mechanical properties of coal soaked in supercritical CO_(2) is more obvious.The uniaxial compressive strength of coal rock is reduced by 28.66%and 34.98%,and the corresponding elastic modulus is reduced by 35.50%and 27.68%,respectively.(2) The failure mode of un-soaked supercritical CO_(2) coal rock is mainly in the style of the X-shaped conjugated shear failure,while the failure mode of the supercritical CO_(2) soaked coal rock changes from inclined shear failure to vertical splitting tensile failure with the loading rate increase.(3) Both the loading strain rate and Sc CO_(2) have effects on the mechanical properties of coal and rock.They also affect the elastic strain energy stored in the tested coal rock.It can be proved from the measured acoustic emission signal which characterizes the energy release during the failure process of the coal rock.This study is not only meaningful for revealing the variation law of mechanical properties of the supercritical CO_(2)-soaked coal rock under different loading rates,but also helpful for understanding the coal rock deformation and fracture characte

关 键 词：岩石力学 准静态应变率 超临界CO_(2)浸泡 煤体单轴力学特性 能量演化 声发射 

分 类 号：TU45[建筑科学—岩土工程]