Fractures In Overlying Strata Research Articles

The Law of Fracture Evolution of Overlying Strata and Gas Emission in Goaf under the Influence of Mining

Mining is associated with poor safety due to pressure relief gas emission from the goaf during the production period. The aim of this study was to explore a case study of the Wangjialing coal mine 12322 working face in Shanxi, China, through physical simulation and field observation. The mine is characterized by overlying strata fracture in goaf during the process of working face mining. A mathematical model of gas source emission from the working face and gas migration and the finite element COMSOL software were used to simulate the law of gas migration in the region with overlying strata fissures under the influence of mining. The simulation results were used to explore the law of distribution of pressure relief gas in goaf. Rational parameters of the high-level directional long borehole for the pressure relief gas extraction in goaf were designed based on experimental results. The results showed that the development of the region with overlying strata fissures is affected by mining. In addition, the “trapezoid platform structure” is formed after fracture areas are connected. The maximum height of the stope caving zone was between 26.8 m and 28.1 m, and the maximum height of the fracture zone was approximately 110 m. The gas concentration exhibited a saddle-shaped distribution on the cut surface of the direction of the strike. Furthermore, the gas concentration showed an overall upward trend from the intake airflow roadway to the return airflow roadway and gradually decreased after reaching the maximum. In the vertical direction, gas concentration increased with the increase in the layer, and the position of the highest point of gas concentration gradually shifted to the direction of the intake airflow roadway. Construction parameters of the high directional long borehole were designed through simulation results. After steady extraction and stable extraction, the maximum gas concentration in the upper corner of the working face was 0.49%, and the maximum gas concentration in return airflow was 0.34%. The findings of this study provide information on the law of fracture evolution of overlying strata and gas migration in goaf under the influence of mining. These findings provide a basis for reducing gas overlimit in the working face or return airway corner, thus improving the safety production capacity of the coal mine.

Research on Evolution Rule of Inclination Fracture Field and Support Technology in Close Distance and Inclined Coal Seam Mining

This paper studies the evolution rule of inclination fracture field in close distance and inclined coal seams. It can fully understand the evolution rule and distribution characteristics of overlying strata in the coal cutting process. Taking the 21003 mining face of a mine in Guizhou as the engineering background, numerical simulation is used to simulate the evolution process of the overlying strata fracture field and deformation characteristics caused by the mining effect of the mining roadway during coal cutting. Finally, it is concluded that “triangular closed” structure at the bottom of mining face greater than upside during mining face, resulting in a large deformation of the roadway at the bottom of mining face; the composite support technology can effectively control the large deformation of surrounding rock roadway caused by the “triangular closed” structure.

Research on modelling of spatial dynamic structural mechanics and spatio-temporal evolution of coal mine stopes

Original scientific paper Major hazardous accidents in coal mines are basically attributable to a lack of understanding of or the failure to establish a complete spatial structural mechanical model of the stope during the course of exploitation, as well as of the spatial movement over time caused by the mining itself, mining at the wrong time, as well as improper roadway maintenance and advance of the work face. To efficiently study and analyze the mechanism behind major stope disasters, a method based on monitoring the stress and displacement of stopes was adopted to deduce the process whereby the overlying strata fracture, and a method of ascertaining stope stability based on qualitative identification of the dynamics was further proposed. The study found that the stability of stopes during the process of mining the face can be divided into two stages: (1) Unstable stage: i.e. the distance the work face has advanced Lx width of work face L0. These research results provide a basis for reasonable determination of a space-time relationship for the mining process.

Numerical Simulation and Analysis of the Height of Overlying Strata Fracture Belt Based on UDEC

Measuring the height of overlying strata fracture belt with the “Double-plugging device” after mining the 3 upper coal, obtained the height, inverted the mechanical parameters of overlying strata according to the height, then conducted the numerical simulation with UDEC, and getting the height of overlying strata fracture belt when mining 3 down coal, with the data of this study we could expect the height of overlaying strata crack belt under the similar conditions, We can improve the upper limit of coal mining with the data of this research, and ensure safety in coal mining under the water.