Evolution and application of airflow permeability characteristics of gob in roof cutting and pressure releasing mining method

Abstract

Cutting roof and release pressure technology has changed the pressure transmission mode of the roof and the caving characteristics of roof rock, which in turn has changed the permeability evolution of the gob. To obtain the permeability characteristics of the gob for the roof cutting and pressure releasing mining method, a mathematical model for the gob voidage and permeability was established by analyzing the overlying strata movement law and the lateral stress variation in the gob. The airflow migration law of haulage roadway 12 201 in Halagou coal mine was studied using Fluent software and an established mathematical model. The main conclusions obtained are as follows: The overburden pressure and lateral stress in the gob gradually increase with the advancement of the working face; along the direction of the retaining roadway, there are two roadway windflows entering the critical zones (the 22-100 m and 390-398 m sections). The inflow at these two sections accounted for 59% of the total air inflow, of which the most critical is the 28-53 m section, which accounts for 43% of the total air inflow in the two severe air leakage sections. The findings of this work provide a theoretical basis for the implementation of antileakage technology in the gob under the roof cutting and pressure releasing mining method and help reduce the risk of spontaneous combustion in the gob. K E Y W O R D Scaving characteristics of roof rock, cutting roof and release pressure, gob, voidage and permeability model 2074 |

Distribution and Prevention of CO in a Goaf of a Working Face with Y-Type Ventilation

“…The specific distribution distance is shown in Figure 16 . 43 The study found that the goaf under the roof cutting and pressure releasing Y-type ventilation mode has a significantly larger range of influence than the traditional longwall mining oxidation heating zone, which greatly increases the possibility of coal spontaneous combustion. Combined with the research in this paper, it can be analyzed that the CO slow rising area is in the scattered tropical zone of the goaf spontaneous combustion zone.…”

“…Chen determined the specific length of the three spontaneous combustion zones in the goaf under the traditional longwall mining mode and the roof cutting and pressure releasing mining mode based on the O 2 concentration through field measurement. The specific distribution distance is shown in Figure . The study found that the goaf under the roof cutting and pressure releasing Y-type ventilation mode has a significantly larger range of influence than the traditional longwall mining oxidation heating zone, which greatly increases the possibility of coal spontaneous combustion.…”

Targeted inertization with flue gas injection in fully mechanized caving gob for residual coal spontaneous combustion prevention with CFD modeling

“…The void characteristics of fractured coal rocks are the key parameters affecting the volume and path of air leakage. 10,[47][48][49][50] Therefore, there is a relationship between the void fraction and the bulking factor of fractured coal rocks in a gob:…”

“…Air leakage in a gob supplies oxygen to the residual coal while taking away the heat generated by oxidation. The void characteristics of fractured coal rocks are the key parameters affecting the volume and path of air leakage 10,47‐50 . Therefore, there is a relationship between the void fraction and the bulking factor of fractured coal rocks in a gob: where K p is the bulking factor of the fractured coal rocks.…”

Study on the optimal position of the roof low roadway based on the response surface methodology

“…Zhang et al 23 conducted FLUENT numerical simulation of the dust distribution on the footway in the goaf. Chen et al 24 used FLUENT software to study the law of air movement in the return air roadway. Zhou et al 25 used FLUENT software to study the distribution of various gases in the goaf.…”