工程科学与技术 (Jan 2025)
Stability Evaluation and Location Optimization of Waterproof Sealing Wall in Liaison Lane
Abstract
Objective The waterproof sealing wall in the connecting roadway is affected by two mining operations, and its stability is related to the safety of adjacent mining working faces.Methods Firstly, theoretical analysis was performed to calculate and analyze the maximum safe water head height the waterproof sealing wall can withstand without being affected by mining activities. In addition, the structural weak plane between the waterproof sealing wall and the coal rock column, which is prone to instability, was identified. By generalizing the physical model of waterproof sealing walls, the water pressure resistance of these walls was calculated in terms of compression resistance, shear resistance, and impermeability. Secondly, numerical simulation was used to analyze the stress state, displacement, and contact surface sliding of the waterproof sealing wall under one or two mining operations at different water head heights (6.0 m, 9.0 m, 12.0 m, and 15.0 m). Using numerical models, the stress state, deformation, and plastic failure zone distribution of the sealed wall were simulated and studied as the working face approached and passed the wall’s location. By assigning different water head heights to the goaf, the damage and stability of the sealed wall under mining and water pressure conditions were evaluated. Based on an analysis of structural weak planes, a self-developed stress and displacement monitoring system for the waterproof sealing wall in the underground goaf was employed. This system was used to strategically arrange and monitor measuring points on the sealing wall. The stress or displacement monitoring device was placed in direct contact with the waterproof sealing wall to record the stress and displacement of the wall. The data acquisition device included a memory unit and a collector. The memory was connected to the stress or displacement monitoring device to store the data, whereas the collector was electrically connected to the memory to retrieve the monitoring data. An analysis device was connected to the acquisition device to process the data and evaluate the stress or deformation state of the waterproof sealing wall. The maximum safe water head height of the waterproof sealing wall under mining and water pressure conditions was determined. In addition, a borehole stress meter was used to measure the distribution pattern of lateral stress in coal pillars, revealing the distribution law of lateral support pressure in mining face 3-1. This data was used to optimize the placement of the waterproof sealing wall.Results and Discussions Without considering the impact of mining, the maximum safe water head height of the waterproof sealing wall is 12.4 m. Structural weak surfaces, such as the top and bottom corners of the wall and the contact surface with the coal pillar, are prone to damage. Recent stress and displacement monitoring of the sealed wall indicated it is generally in a stable state. However, weak structural surfaces are commonly observed at the contact surface between the sealing wall and the coal pillar, as well as at the bottom corner of the sealing roof. Therefore, these areas require enhanced monitoring or observation. Through theoretical analysis, numerical simulation, and consideration of mining and water pressure, the maximum water head height for the sealed wall was determined to be 9.0 m.Conclusions A warning water level was set at 80% of this value, making the warning water head level for the 31313～31315 connecting roadway 7.2 m. Monitoring results confirm that the sealing wall is currently in a stable state. The peak area of lateral pressure on the working face lies between 10.5 and 12.5 m. To avoid peak support pressure, it is recommended that waterproof sealing walls be positioned more than 15～20 m away from the goaf side. These findings provide a theoretical basis and practical reference for the stability evaluation and placement optimization of similar waterproof sealing walls in mining operations.
