Related Experiment Video
Updated: Aug 6, 2026

A Uniaxial Compression Experiment with CO2-Bearing Coal Using a Visualized and Constant-Volume Gas-Solid Coupling Test System
Published on: June 12, 2019
Strata behavior and advanced control technologies in longwall top coal caving of extra-thick coal seams under hard
Yu Guo1, Zewei Li2, Tukhtaev Bobirjon Isomitdinovich3
1School of Intelligent Construction and Management, Jiangsu University of Architectural Technology, Xuzhou, 221116, People's Republic of China.
Abstract:
The extraction of extra-thick coal seams under hard, massive roofs using Longwall Top Coal Caving (LTCC) can induce dynamic hazards, including large-area roof suspension, intense advanced abutment pressures, and extreme roadway deformation. Taking the 8401 working face of the Tongfa Dongzhouyao Coal Mine as the engineering background, this study systematically investigates the dynamic evolution of overlying strata and proposes a comprehensive stability control strategy. Two-dimensional non-linear numerical simulations using RS2(Phase 2) were conducted to evaluate the spatiotemporal evolution of roof subsidence under different mining-to-caving ratios. The 2D numerical results provide theoretical insights indicating that a 3 + 7 extraction pattern (3 m cutting, 7 m caving) helps balance void space and bulking effects, facilitating progressive energy release and preventing the sudden delayed caving observed in extreme ratios (e.g., 1 + 9 pattern). Furthermore, the numerical models validate that directional hydraulic fracturing effectively pre-weakens the hard sandstone roof, creating a fracture-induced damage zone that forces predictable, controlled caving. To manage the intense mining-induced stresses in the entry, a "horseshoe-shaped" closed combined support system-integrating deep-hole cable bolts and reinforced concrete floor paving-was developed. Field monitoring confirmed the system's efficacy: macroscopic deformation was remarkably suppressed, with roof-to-floor and rib-to-rib convergences stabilized at 290 mm and 210 mm, respectively. Crucially, the support system maintained a residual bearing capacity of approximately 14 MPa in the shallow coal rib, mitigating excessive stress transfer to the deep strata and eliminating the risk of dynamic impact disasters. These findings provide a robust theoretical basis and practical engineering reference for disaster prevention in similar complex geological environments.
Related Concept Videos
Quarrying of Stone
One common method involves using a diamond belt saw to cut large blocks from the quarry face. These blocks can be about 50 feet long and 12 feet high. After the initial vertical cut, drilling is performed at the base of the block.
Masonry Cavity Walls
Maintaining a clean cavity during construction is...
Reinforced Brick Masonry
To fortify brick walls...
Placing Concrete
While placing concrete, care is taken to ensure that the concrete is laid in uniform layers, and hand shoveling and moving concrete using poker vibrators is avoided. Also,...
Mass Concreting
To reduce the risk of such cracking, the concrete mix may incorporate low-heat cement and pozzolans to reduce the temperature rise. Pre-cooled angular aggregates and water-reducing admixtures...
Cardiopulmonary Resuscitation V: Advanced Airway Management Techniques
