Shaft coal pocket is an important segment of the coal mine transportation system,mainly responsible for the storage and transportation of underground coal, and once deformation and instability occur, its stability directly affects the production of the entire mine. In the process of coal loading and unloading, the inner wall of the shaft coal pocket is prone to fatigue damage under the repeated action of dynamic pressure (flow and impact of
bulk coal) and static pressure (full bunker and empty bunker).It is extremely difficult to monitor the micro crack on the inner wall under frequent loading and unloading conditions. So the micro cracks will evolution into large cracks. Then the large deformation collapse instability. Therefore, conducting research on the deformation and failure mechanism and stability control of the inner wall of shaft coal pocket has important theoretical and practical significance for the safety production of mines.
The thesis adopts research methods such as theoretical analysis, numerical simulation,physical similarity simulation, and industrial experiments to analyze the damage and failure characteristics and influencing factors of the shaft coal pocket, reveal the loading, deformation, and failure mechanisms of the inner wall of the shaft coal pocket, and propose stability control measures. The main achievements are as follows:
(1) The main factors affecting the stability of the inner wall of shaft coal pocket are determined as follows: the strength and material characteristics of the inner shaft wall, the internal bearing structure of the bulk storage materials in the shaft coal pocket, the properties of surrounding rock, and the operating state of the shaft coal pocket. The failure types of the shaft coal pocket are divided into five categories: shear failure, tensile failure, combined tensile and shear failure, impact failure, and long-term wear failure.
(2) The deformation trend of the inner shaft wall and the loose bearing structure inside the shaft coal pocket are given. A mechanical model of the inner wall structure of the shaft
coal pocket of the well has been established. Based on relevant theories such as thick walled cylinders buried in infinite elastic bodies, expressions for the stress and displacement of the shaft wall and surrounding rock under different working conditions have been given. It hasd been revealed that there exists a "three-dimensional conical shell" load-bearing structure for the dispersed particles in the shaft coal pocket The formation and instability of this structure are the fundamental reasons for the unloading overpressure on the shaft wall. Different arch positions have an impact on the stress and strain distribution of the shaft wall. The higher the arch position, the lower the corresponding stress on the shaft wall. As the arch position increases, the corresponding strain on the inner wall of shaft coal pocket also gradually decreases. The flow patterns of loose particles in the shaft coal pocket are divided into "three zones" in the longitudinal direction (natural flow zone below the structure, compaction zone above the structure, and overall flow zone at the top), and "two circles" in the horizontal direction (smooth flow zone at the center and slow flow circle on the side of the shaft wall).
(3) Revealed the deformation and failure mechanism of the inner wall of shaft coal pocket. During the process of loading and unloading coal (gangue) in bulk storage, the deformation of the shaft wall increases with the increase of cyclic loading times, while the strength of the wall decreases, followed by damage crack development failure instability. The deformation of the shaft wall shows a trend of first increasing, then stabilizing, and then decreasing, which determines the criteria for determining the instability of the inner wall of shaft coal pocket. The inner wall of the shaft coal pocket undergoes four stages: elastic deformation, plastic deformation, failure, and instability of the load-bearing structure inside the bunker. When the shaft wall is mainly subjected to internal granular loading, shear failure mainly occurs; When mainly affected by weak rock layers on the outside, tensile failure mainly occurs; When the two act together, it is a tensile shear composite failure.
(4) The approach and method for controlling the stability of the inner wall of shaft coal pocket are provided. A collaborative control technology for the design, construction, and operation of the stability of the inner wall of shaft coal pocket has been proposed, guiding on-site engineering practice and achieving satisfied application effect.
谷歌
火狐
