Zou Junpeng, Li Gang, Li Zibo, Zhang Yabing, Liu Hang, Wang Yiming
Collage of Mining, Liaoning Technical University, Fuxin, 123000, China.
School of Safety Engineering, Heilongjiang University of Science and Technology, Harbin, 150022, China.
Sci Rep. 2024 Jul 4;14(1):15364. doi: 10.1038/s41598-024-65024-1.
With the gradual shift of coal mining to the western coal mining region of China, floor heave in weakly cemented mudstone roadways has become an issue affecting the safety and efficiency of coal mine production. Additionally, different mining rates can lead to fluctuating support stresses on the roof and floor of weakly cemented mudstone roadways. Therefore, obtaining a comprehensive understanding of the mechanical properties of weakly cemented mudstone at different loading rates is conducive to improving the issue of floor heave in such roadways and provides a theoretical basis for further study. In this context, a series of uniaxial mechanical tests with concurrent acoustic emission monitoring were conducted on specimens of weakly cemented mudstone under various loading rates (0.005, 0.01, 0.05, and 0.1 mm/s). The stress‒strain and acoustic emission response curves were obtained to effectively characterize the strength, deformation, damage, macroscale instability, and crack propagation characteristics of the mudstone under the influence of loading rate effects. The research results support the following findings: (1) With increasing loading rate, the peak strength and elastic modulus of weakly cemented mudstone significantly increase, while the peak axial strain and peak radial deformation significantly decrease. (2) With increasing loading rate, the stress required to trigger the expansion of weakly cemented mudstone gradually increases, and a significant power-law relationship arises between the strain of the mudstone at the start of expansion and the loading rate. (3) With increasing loading rate, the acoustic emission ringing count of weakly cemented mudstone increases: The failure of weakly cemented mudstone changes from small-range progressive failure to sudden failure, and the failure mode transitions from shear failure to tensile‒shear composite failure. (4) The studied mudstone damage variables increase with increasing loading rate, following an approximate exponential function. The conclusions obtained in this work can provide a theoretical basis for the evolution mechanism and control of floor heave in deep roadway mining.
随着我国煤炭开采逐渐向西部矿区转移，弱胶结泥岩巷道底鼓已成为影响煤矿安全生产与效率的问题。此外，不同开采速率会导致弱胶结泥岩巷道顶底板的支承压力波动。因此，全面了解不同加载速率下弱胶结泥岩的力学特性，有利于改善此类巷道的底鼓问题，并为进一步研究提供理论依据。在此背景下，对弱胶结泥岩试样在不同加载速率（0.005、0.01、0.05和0.1 mm/s）下进行了一系列同步声发射监测的单轴力学试验。获得了应力-应变和声发射响应曲线，以有效表征加载速率影响下泥岩的强度、变形、损伤、宏观失稳及裂纹扩展特性。研究结果支持以下发现：（1）随着加载速率的增加，弱胶结泥岩的峰值强度和弹性模量显著增大，而峰值轴向应变和峰值径向变形显著减小。（2）随着加载速率的增加，引发弱胶结泥岩膨胀所需的应力逐渐增大，且泥岩开始膨胀时的应变与加载速率之间呈现出显著的幂律关系。（3）随着加载速率的增加，弱胶结泥岩的声发射振铃计数增加：弱胶结泥岩的破坏由小范围渐进破坏转变为突然破坏，破坏模式从剪切破坏转变为拉剪复合破坏。（4）所研究的泥岩损伤变量随加载速率的增加而增大，呈近似指数函数关系。本研究所得结论可为深部巷道开采底鼓的演化机理及控制提供理论依据。
