低频扰动下不同预静载水平煤样动态响应特征
Dynamic characteristics of coal specimens with varying static preloading levels under low-frequency disturbance load
文晓泽 1冯国瑞 1郭军 1于露杨 1钱瑞鹏 2张洁 1张鹏飞 1冯文明1
作者信息
- 1. 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
- 2. State Key Laboratory of Hydroelectric and Engineering,Tsinghua University,Beijing 100084,China
- 折叠
摘要
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.
Abstract
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.
关键词
低频扰动/动态响应/煤样/静态预应力水平Key words
low-frequency disturbance/dynamic response/coal specimens/static preloading level引用本文复制引用
基金项目
National Natural Science Foundation of China(51925402)
National Natural Science Foundation of China(52334005)
National Natural Science Foundation of China(52304094)
Shanxi Science and Technology Major Project,China(20201102004)
出版年
2024
NETL
NSTL
万方数据