Study on the Mechanism and Control of Rock Burst of Coal Pillar under Complex Conditions

Abstract

In order to explore the mechanism of coal pillar rock burst in the overlying coal body area, taking W1123 working face of Kuangou Coal Mine as the engineering background, the full mining stage of W1123 is simulated by FLAC3D. It is found that the high stress concentration area has appeared on both sides of the coal pillar when W1123 does not start mining. With the advance of the working face, the high stress concentration area forms X-shaped overlap. There is an obvious difference in the stress state between the coal pillar under the solid coal and the coal pillar under the gob in W1123. The concrete manifestation is that the vertical stress of the coal pillar below the solid coal is greater than the vertical stress of the coal pillar below the gob. The position of the obvious increase of the stress of the coal pillar in the lower part of the solid coal is ahead of the advancing position of the working face, and the position of the obvious increase of the stress of the lower coal pillar in the gob lags behind the advancing position of the working face. At the same time, in order to accurately reflect the true stress environment of coal pillars, the author conducted a physical similarity simulation experiment in the laboratory to study the local mining process of the W1123 working face, and it is found that under the condition of extremely thick and hard roof, the roof will be formed in the gob, the mechanical model of roof hinged structurer is constructed and analyzed, and the results show that the horizontal thrust of roof structure increases with the increase of rotation angle. With the development of mining activities, the self-stable state of the high stress balance in the coal pillar is easily broken by the impact energy formed by the sudden collapse of the key strata. Therefore, the rock burst of coal pillar in the overlying coal body area is the result of both static load and dynamic load. In view of the actual situation of the Kuangou Coal Mine, the treatment measures of rock burst are put forward from the point of view of the coal body and rock mass.

Mechanism of Support Optimization and Confined Blasting of Thick and Hard Rock with a Wedge-Structure Immediate Roof: A Case Study

“…The construction scheme can be described as follows: (1) after the installation of the KHYD75 rock drilling machine (Jining Zhuoli Mining Equipment Co. Ltd.), blasting drilling was conducted to the predesignated position [20], (2) next is installing the explosives into the drilling holes, connection and debug of the explosive leads, the hole-sealing device, and the high-pressure pump-opening the pressure test device, injecting of water before starting the monitoring instrument, increasing the water pressure slowly, and 9 Geofluids stopping the pumping when the pressure reaches 2 MPa as shown in Figure 10, and (3) finalizing the placement of safety device and monitoring system and initiating and completing the blasting were done (Figure 11) [21,22].…”

Mining-induced deformation for a haulage drift of the hanging wall at Jinshandian iron mine in China

“…A deformation model needs to be developed with relationships linking rock mass data, distance to undercut front, mining depth, relative position of the mining activity and the type of researched roadway, geotechnical indexing, support pattern, etc. (Fernandez et al, 2012;Jones et al, 2019;Lai et al, 2020). In the Malmberget mine, blast-instrument vectors were established in a spherical coordinate system to represent the spatial geometric relationship between mining blast and monitoring instrument.…”

Research on Structural Evolution and Microseismic Response Characteristics of Overlying Strata during Repeated Mining of Steeply Inclined and Extra Thick Coal Seams

“…The fracture structure of the overlying strata induced by deep mining in SIETCS was significantly different from the fracture induced by shallow mining. The risk of dynamic disasters was increased [7,8], and the difficulty of prevention and control was markedly increased, which directly affects the safe mining of the working face and the stable and effective supply of energy. Therefore, it is urgent to further improve the techniques for prediction and prevention of dynamic disasters in mines.…”