Song Cheng, Cao Guangming, Bai Jinwen, Wang Shanyong, Feng Guorui, Shi Xudong, Wang Kai, Zhu Chun
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.
Materials (Basel). 2023 Mar 28;16(7):2690. doi: 10.3390/ma16072690.
The fracturing behaviors of serial coal pillars is significant for understanding their failure mechanism. To reveal this, the bearing stress, acoustic emission, electrical resistivity, local strain, force chain distribution, and cracks evolution of serial coal pillars under uniaxial compression were evaluated by experiment and numerical simulation. The results show that four bearing stages are observed during the fracturing process (i.e., nonlinear growth, linear growth, yielding growth, and weakening stages). The acoustic emission features, electrical resistivity responses, strain develops, force chain distributions, cracks evolutions, and local displacement are highly consistent to illustrate the fracturing behaviors. System fracturing of serial coal pillar specimens is appeared along with the collapse of lower uniaxial compressive strength coal pillar specimen. The limit bearing capacity of serial coal pillar specimens is almost equal to the strength of lower uniaxial compressive strength coal pillar specimen. The unbalanced deformation characteristics of serial coal pillar specimens are presented due to the strength differences. The evolution of the key deformation element is the rooted reason for the overall fracturing mechanism of serial coal pillar specimens. For serial coal pillar specimens with different strengths, the critical condition of system fracturing is that the sum of secant modulus of upper and bottom coal pillars is zero, which is expected to predict the system fracturing of serial pillars in the underground coal mining.
连续煤柱的破裂行为对于理解其破坏机制具有重要意义。为揭示这一点，通过实验和数值模拟对连续煤柱在单轴压缩下的承载应力、声发射、电阻率、局部应变、力链分布及裂纹扩展进行了评估。结果表明，在破裂过程中观察到四个承载阶段（即非线性增长、线性增长、屈服增长和弱化阶段）。声发射特征、电阻率响应、应变发展、力链分布、裂纹扩展及局部位移高度一致，以说明破裂行为。随着单轴抗压强度较低的煤柱试件的破坏，连续煤柱试件出现系统破坏。连续煤柱试件的极限承载能力几乎等于单轴抗压强度较低的煤柱试件的强度。由于强度差异，连续煤柱试件呈现出不平衡变形特征。关键变形要素的演化是连续煤柱试件整体破坏机制的根本原因。对于不同强度的连续煤柱试件，系统破坏的临界条件是上部和下部煤柱割线模量之和为零，这有望预测地下煤矿开采中连续煤柱的系统破坏。
