Dome Roof Fall Geohazards of Full-Seam Chamber with Ultra-Large Section in Coal Mine

Abstract

Featured Application: In this study, the mechanism of roof fall of full-seam ultra-large section chamber was uncovered and the corresponding control technology was put forward and successfully applied. The study provide a successful case of roof fall control in a special condition, and has a guiding and reference significance for ultra-large section chamber control during extra-thick coal seam mining, which is beneficial to ensure the production efficiency of coal mine. Abstract:The roof fall hazard is more likely to take place within chamber with ultra-large section, which would not only damage mechanical equipment, but also cause casualties. In this paper, the strap joint chamber of the Tashan coal mine is studied, and finite and discrete element method (FDEM) is used to establish the numerical model of the roof fall of the chamber dome. The simulation results show that the chamber dome mainly undergoes shear failure and forms a large number of cracks. With further development and penetration of cracks, a distinct roof separation is found in the chamber dome. When the crack develops to the dome surface of the chamber, under the effect of the mine pressure, the coal body is separated from the surface of the chamber and the roof fall hazard occurs. Based on the mechanism of roof fall hazard of the chamber dome, it is concluded that improving the shear strength of the surrounding rock and reducing the crack penetration are the main ways to control the roof fall. Therefore, the high-strength anchor bolt and cable support is adopted to fill the cracks and improve the shear strength of the surrounding rock. The result showed that the roof separation of the chamber dome in the field is confined to 0.012 m. The surrounding rock is well controlled and no roof fall occurs.

Numerical simulation on fracturing behaviour of hard roofs at different levels during extra-thick coal seam mining

“…For the tensile properties, the bilinear constitutive model has been most commonly used [26]. As shown in the first phase boundary in figure 3, the cohesive constitutive model of the cohesive unit was determined by defining the rock stiffness, ultimate strength and critical breaking energy release rate.…”

Full-Stress Anchoring Technology and Application of Bolts in the Coal Roadway

“…As an active support method of the coal roadway, bolt support is widely used in the coal roadway because of its high support strength and low cost [9,10]. In recent years, the carrying capacity of single bolts has been strengthened [11,12].…”

Control for the large section roadway under small abandoned mines in the same coal seam by secondary support

“…The maximum deformation of roadway measured on site is not exceed 25 mm; Zhang et al 12 used UDEC polygonal methods to analyze the failure characteristics of the large section roadway and proposed a new scheme involving key area strengthening and high strength yielding bolts. The deformation of large section roadway is controlled at about 550 mm; Gao et al 13 analyzed the characteristics of the roof crack development of the large section roadway by the discrete element software. On this basis, the roadway roof control method based on the crack control is proposed, and the anchor cable support parameters are optimized.…”