Discussion on stability analysis and support technology of surrounding rock of gob-side entry retaining

Abstract

In order to further analyze the stability and control mechanism of surrounding rock in the gob-side entry retaining, the slip instability coefficient and compression failure coefficient are proposed by the mechanical analysis of the established filling body mechanics model, and when both and are less than 1, the roadside filling body can keep stable. The mechanical model of main roof is analyzed by the static equilibrium method, and the formula for calculating the maximum roof subsidence is deduced. Based on the data of haulage gateway of No. 21201 coal face of Juncheng Coal Mine, using the formula to calculate the amount of roof subsidence at the junction point of filling body and the roof, and proposes two methods to reduce roadway floor heave by increasing the roadside filling width and transferring the surrounding rock stress to the gob. Finally, the corresponding surrounding rock control technology is proposed according to the surrounding rock deformation characteristics during roadway excavation, roadway retention and roadway reuse, and then carries out field monitoring and evaluation. The results show that after adopting the corresponding supporting technology, the surrounding rock of the gob-side entry retaining has been effectively controlled from the excavation to the reuse period with the coal face advancing, the roof-to-floor convergence of roadway solid coal side is less than 220 mm, the roof-to-floor convergence of filling body side is less than 280 mm, and the convergence on the both sides of the roadway is about 190 mm. At the same time, the calculated roof subsidence with the junction point of filling body and the roof is similar to the field monitoring results, which achieves the expected control effect, and the research contents provides a certain reference for the support technology of the gob-side entry retaining.

Method for Determining Spontaneous Combustion Risk in Roof Cutting Gob-Side Entry Retaining U + L Ventilation Goaf for Mining Safety

“…The setting of model porosity in fluid simulation is crucial to achieving accurate simulation results in a goaf, and this setting mainly depends on the correct description of the rock fragmentation coefficient. Generally, the compaction distribution of the RCGSER goaf still follows the "O" circle rule [32]; however, the rock fragmentation coefficient differs considerably near the entranceway [33,34].…”

Determination of Reasonable Width of Filling Body for Gob-Side Entry Retaining in Mining Face with Large Cutting Height

“…However, when the strength of the filling body material is low and the stiffness is small, the bearing capacity of the filling body is limited, and the load of the overburden is mainly borne by coal; then, the filling body has little influence on the lateral fracture law of the basic roof. When the filling materials on the strength and stiffness are bigger and have a certain width, overburden load is shared by the mass media and the roadway beside filling body and roof coal and the pack on the structure of the two supporting functions; key block B in the coal side fracture location will change with the change of the support resistance; when the immediate roof can be large enough to be transferred to the main roof, the support resistance on the key block B may even occur at the gob-side secondary fracture [27,28]. In the case of different support resistances, the fracture positions of the main roof are mainly divided into the following three categories [29], as shown in Figure 3.…”

Determination of Reasonable Width of Filling Body for Gob-Side Entry Retaining in Mining Face With Large Cutting Height

“…However, when the strength of the filling body material is low and the stiffness is small, the bearing capacity of the filling body is limited, and the load of the overburden is mainly borne by coal, then the filling body has little influence on the lateral fracture law of the basic roof. When the filling materials on the strength and stiffness is bigger and has a certain width, overburden load shared by the mass media and the roadway beside filling body and roof coal and the pack on the structure of the two supporting function, key block B in coal side fracture location will change with the change of the support resistance on, when the immediate roof can be large enough transfer to main roof, the support resistance on the key block B may even occur at gob side secondary fracture (Feng et al, 2015;Zheng et al 2019). In the case of different support resistances, the fracture positions of the main roof are mainly divided into the following three categories (Zhang, 2019b), as shown in Figure 3.…”