This paper endeavors to reveal the squeezing failure mechanism of roof‐coal masses and its correlation with the movement of the roof strata. An integrated method incorporating field instruments and numerical modeling was conducted. The borehole camera detection revealed that the development degree and scope of cracks in the roof strata on the coal pillar side are significantly larger than that on the panel rib side, and the fracture line of the main roof occurred above the coal pillar. A rigorous modeling procedure verified the borehole camera detection results and also found that the vertical and horizontal displacement of the roof‐coal mass exhibited asynchronous development characteristics at various heights. Subsequently, a comprehensive control strategy was proposed to prevent the squeezing failure behavior of roof‐coal masses in DUOS gob‐side entry. This study provides a basis for understanding the squeezing failure behavior of roof‐coal masses, and the proposed control strategy can potentially be applied in other similar mining projects.
Support crushing and roof fall accidents frequently occur in the large mining height stope covered by the thin bedrock and large-thick alluvium (TBLA). A comprehensive method including field monitoring, numerical modelling, and theory analysis was performed to investigate the strata movement and its induced ground behaviors of a deep-buried stope under TBLA. The filed measurement results indicated that strong roof periodic weighting phenomenon occurred regularly at an interval of 18–23 m during panel 3301 retreating. During weighting period, dynamic characteristics of hydraulic supports are prominent and characterized by high safety valve opening rate and poor working conditions including tilt down operation and excessive end distance. Additionally, numerical modelling results revealed that the thickness of bedrock affects the movement behaviors of the roof strata and its generated spatial structure significantly. Based on the above results, an integrated control measure was proposed and successfully applied to the test site.
In engineering practice, properly characterizing the spatial distribution of soil liquefaction potential and induced surface settlement is essential for seismic hazard assessment and mitigation. However, geotechnical site investigations (e.g., cone penetration test (CPT)) usually provide limited and sparse data with high accuracy. Geophysical surveys provide abundant two-dimensional (2D) data, yet their accuracy is lower than that of geotechnical investigations. Moreover, correlating geotechnical and geophysical data can effectively reduce site investigation costs. This study proposes a data-driven adaptive fusion sampling strategy that automatically develops an assessment model of the spatial distribution of soil liquefaction potential from spatially sparse geotechnical data, performs monitoring of liquefaction-induced settlement, and integrates spatiotemporally unconstrained geophysical data to update the model systematically and quantitatively. The proposed strategy is illustrated using real data, and the results indicate that the proposed strategy overcomes the difficulty of generating high-resolution spatial distributions of liquefaction potential from sparse geotechnical data, enables more accurate judgment of settlement variations in local areas, and is an effective tool for site liquefaction hazard analysis.
In view of the supporting problems in the large-section weak- and thick-coal open-cutting roadway in the deep coal mines, this paper adopts numerical simulation, theoretical analysis, and field measurement to study the deformation and failure law of the surrounding rock and explore corresponding control measures. The results show that: 1) The surrounding rock of open-cutting roadways is divided into a fracture-through zone, a fracture development zone, and a micro-fracture zone. When the width of the roadway is 12 m, the maximum height of the fracture-through zone is 2.6 m, and the two-side fracture zone is 1.1 m, and the height of fracture-through zone of the top plate is 1.5 m. 2) Considering the actual geological production conditions, this paper proposes the control measures combining high-strength bolt support, large-diameter anchor cable support, and single column reinforcement, and expounds its control mechanism. In addition, on-site industrial test verifies the rationality of the supporting plan.
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