Weakly cemented rocks are characterized by low strength, loose structure, and easy disintegration. High-intensity mining activities can damage and rupture such rock bodies and induce damage, such as flaking and roofing on roadways. To reveal the mining intensity influence on the weakly cemented rocks’ deformation and damage, a numerical particle flow model of weakly cemented sandstone was established based on particle flow theory. Uniaxial compression simulation tests were conducted at four loading rates of 0.01, 0.1, 0.5, and 1 mm/min to study the weakly cemented sandstone’s stress–strain relationship, damage rupture, acoustic emission, and energy evolution. The results show that, with an increased loading rate, the uniaxial compressive strength of weakly cemented sandstone increases exponentially, and the rupture mode transforms from brittle damage to ductile damage; the greater the loading rate, the greater the degree of damage and crushing range of the rock. Further, with an increased loading rate, the peak hysteresis of rock acoustic emission events decreases, and the number of events increases; the energy accumulated in the rock increases, thus intensifying the degree of rock damage. Therefore, the possibility of engineering disasters should be considered when conducting high-speed underground mining activities.

In weakly cemented rocks, the mesoscopic parameters have a great influence on the macroscopic mechanical properties. One example of a typical weakly cemented rock is the Cretaceous coarse sandstone in the Hongqinghe Coal Mine. In this study, rock samples were subjected to physical and mechanical experiments, from which a sample model was constructed based on particle flow theory. Uniaxial compression numerical simulation experiments and analyses were conducted, and sensitivity analyses of various microscopic parameters in relation to the macroscopic mechanical properties of the rock were performed via a control variable method. A response mechanism between the macroscopic and mesoscopic parameters was then inferred. On the microscopic scale, the rock is porous with a loose structure and extremely low average uniaxial compressive strength, indicating looseness and weakness. The mesoscopic parameters were then divided into three grades based on their degrees of influence from high to low on the peak strength, peak strain, and elastic modulus. Laboratory experiments revealed that the fracture form of weakly cemented coarse sandstone is typically due to single-section shear failure, whereas through simulation, cracks are caused mainly by tension failure. These two failure modes were inferred to be consistent with each other.

This study examines frequent disasters, including large-scale deformation and collapse, caused by underground mining in weakly cemented strata in Western China. The weakly cemented rock’s unique characteristics, including low strength and easy disintegration, demonstrate a different damage pattern than that traditionally seen in the central and eastern regions. Using Fast Lagrangian Analysis of Continua-Particle Flow Code (FLAC2D-PFC2D) coupling, we model the strata, focusing on the 3-1 coal seam roadway at Hongqinghe mine. This study investigates the damage–rupture–destabilization progression in the peripheral rock under varying levels of moisture content. Our findings indicate that a water content of ω = 5.5% is the threshold for roadway damage, and moisture content 5.5% abruptly increases cracks and shifts the rock’s force chain, causing significant deformation and affecting the ceiling the most. Moreover, higher levels of moisture content weaken the anchor solid’s performance, with two primary failure modes: anchor interface slippage (comprising five stages: elasticity, elasticity–shear hardening, elasticity–shear hardening–decohesion, shear hardening–decohesion, and decohesion) and shear damage. These insights are vital for improving numerical simulations of underground mining, obtaining a more accurate understanding of mineral pressure disasters in weakly cemented strata mining regions in Western China, and developing a solid foundation for the better control of such strata.

Weakly cemented rocks have a loose structure, poor mechanical properties, and soften and disintegrate upon contact with water. Mining operations cause damage and ruptures to rocks under cyclic loading and unloading, leading to serious disasters. This study investigated the effects of cyclic loading and unloading on the mechanical properties of weakly cemented sandstone (WCS) with various water contents (0–7.72%). A numerical model based on the particle flow theory simulated the behavior of WCS particles. The stress–strain relationships, damage and rupture patterns, energy evolution, and damage properties of WCS were examined using loading–unloading simulations. Water negatively affected the strength and elastic modulus of WCS. High water contents (>2.31%) increased the rupture probability and affected the rupture modes. Ruptures mainly occurred via the main fissure and caused cleavage damage; however, instances of tensile damage and shear slippage increased with an increasing water content. The elastic, dissipation, and total energies gradually increased with increasing cyclic loading and unloading. The damage factors of WCS with different water contents gradually increased with the growth rate. The mechanical properties of the sandstone were deteriorated by water, which increased the peak value of the damage factor from 0.77 for 0% moisture to 0.81 for 7.72% moisture.