Dynamic characteristics of coal specimens with varying static preloading levels under low-frequency disturbance load  

低频扰动下不同预静载水平煤样动态响应特征

作　　者：WEN Xiao-ze FENG Guo-rui GUO Jun YU Lu-yang QIAN Rui-peng ZHANG Jie ZHANG Peng-fei FENG Wen-ming 文晓泽;冯国瑞;郭军;于露杨;钱瑞鹏;张洁;张鹏飞;冯文明(College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention,Taiyuan University of Technology,Taiyuan 030024,China;State Key Laboratory of Hydroelectric and Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]College of Mining Engineering,Taiyuan University of Technology,Taiyuan 030024,China [2]Key Laboratory of Shanxi Province for Mine Rock Strata Control and Disaster Prevention,Taiyuan University of Technology,Taiyuan 030024,China [3]State Key Laboratory of Hydroelectric and Engineering,Tsinghua University,Beijing 100084,China

出　　处：《Journal of Central South University》2024年第8期2644-2657,共14页中南大学学报（英文版）

基　　金：Projects(51925402,52334005,52304094)supported by the National Natural Science Foundation of China;Project(20201102004)supported by the Shanxi Science and Technology Major Project,China。

摘　　要：The mechanical properties of residual coal pillars under the influence of upward mining disturbances significantly affect the safety of residual mining activities on working faces.This study conducted low-frequency disturbance dynamic uniaxial compression tests on coal specimens using a self-developed dynamic-static load coupling electro-hydraulic servo system,and studied the strength evolutions,surface deformations,acoustic emission(AE)characteristic parameters,and the failure modes of coal specimens with different static preloading levels were studied.The disturbance damage is positively correlated with the coal specimen static preload level.Specifically,the cumulative AE count rates of the initial accelerated damage stage for the coal specimens with static preloading level of 60%and 70%of the uniaxial compressive strength(UCS)were 2.66 and 3.19 times that of the 50%UCS specimens,respectively.Macroscopically,this behaviour manifested as a decrease in the compressive strength,and the mean strengths of the disturbance-damaged coal specimens with 60%and 70%of UCS static preloading decreased by 8.53%and 9.32%,respectively,compared to those of the specimens under pure static loading.The crack sources,such as the primary fissures,strongly control the dynamic response of the coal specimen.The difference between the dynamic responses of the coal specimens and that of dense rocks is significant.开采扰动影响下残采区遗留煤柱的力学特性对遗煤资源复采的安全性有重要影响。为了明晰低频扰动(5 Hz,正弦波)下不同预静载水平煤样的动态响应特征,基于自主研发的动静载耦合电液伺服试验机,开展了低频扰动荷载作用下不同预静载水平煤样的动态单轴压缩试验;同时采用数字图像相关技术及声发射设备对煤样破裂过程进行监测。结果表明,低频扰动损伤与煤样的预静载水平成正比,预静载水平为60%单轴抗压强度(UCS)和70%UCS组煤样的累计声发射(AE)计数率是50%UCS组的2.66和3.19倍;宏观上表现为扰动损伤煤样强度的劣化,预静载水平为60%UCS和70%UCS的扰动损伤煤样强度相较纯静态加载分别降低了8.53%和9.32%。此外,低频扰动荷下煤样的不可逆应变较小,但是强度劣化较大,与致密硬岩的动态响应差异显著。内部随机分布的原生裂隙等裂纹源对煤样扰动损伤和动态力学响应特征有明显的控制作用。

关 键 词：low-frequency disturbance dynamic response coal specimens static preloading level 

分 类 号：TD315[矿业工程—矿井建设]