Analysis of gob gas venthole production performances for strata gas control in longwall mining

Comparative analysis of permeability model construction and risk fields evaluation by roof cutting along the gob in a coal mine

The productivity of coal mines is seriously threatened by the combined disasters of gas and coal spontaneous combustion, which have become a common disaster mode. It is unclear how the gas and coal spontaneously combusted in the roof cutting along gob working face. The goal of this study is to identify the distinctive features of combined disasters in gob from two different types of roof cutting along working faces. In these two different types of roof cutting along gob working faces, the paper constructs the permeability model of the gob. The findings demonstrate that the data from the field experiment and the simulation results agree, which validates the simulation's reliability. In contrast to single sided roof cutting along gob working faces, double sided roof cutting along gob working faces clearly has a thinner oxidation zone. Moreover, the oxidation zone of the double side roof cutting along gob working faces is closer to the working face, which is located in the shallow area of the gob 50 m behind the working face. The gas explosion area and the coal spontaneous combustion area are divided by the double side roof cutting along gob working face, which reduces the risk of compound disasters. Important theoretical direction for the prevention and control of gob disasters in the roof cutting along gob working face is provided by the simulation results.

Height identification of water-permeable fractured zone based on synchronous movement in overlying strata

Height identification of water-permeable fractured zone (WPFZ) is one of the decisive influence factors for mining safety, especially in some specific conditions, such as mining under aquifer. In order to demonstrate the formation process of the WPFZ, the scaling model experiment is carried out. Through the analysis of movement and breaking in overlying strata, the WPFZ height is significantly affected by mining range, movement characteristics of key strata and its follow-up strata. Based on the research findings, a new theoretical method, " overlying strata synchronous movement method " (OSSM) is established to predict the WPFZ height. Taking 3301 mining face of Zhujiamao Coal Mine in China as the engineering background, the WPFZ height is estimated by OSSM. Additionally, the field detection is carried out by the downhole segmented water injection method combined with borehole camera method. By comparing the results of different methods, the accuracy of OSSM is verified and the WPFZ height is determined finally. What´s more, various methods for determining WPFZ height are evaluated.