Control Technology of Soft Rock Floor in Mining Roadway with Coal Pillar Protection: A case study

Abstract

This study considered the mining roadway with coal pillar protection in the fully mechanized caving face of the Dananhu No.1 Coal Mine, China. Theoretical analysis, numerical simulation, and field tests were conducted, and the stress environment, deformation, and failure characteristics of the mining roadway in the fully mechanized caving face were analyzed. The results revealed that the intrinsic cause for the large asymmetrical floor deformation in the mining roadway is the asymmetrical phenomenon of the surrounding rock's stress environment, caused by mining. This also results in the non-uniform distribution of the mining roadway floor's plastic zone. The degree of asymmetrical floor heave is internally related to the thickness of the caving coal. When the thickness of the caving coal was in the range of 5.9 m, the deformation of the asymmetrical floor heave, caused by the plastic failure in the floor, became more obvious as certain parameters increased. As the rotation angle of the principal stress direction increased, the maximum plastic failure depth position of the floor gradually moved toward the middle of the roadway. This caused a different distribution for the maximum deformation position. The control of the floor heave deformation was poor, and it was not feasible to use high-strength support under the existing engineering conditions. Hence, the control should mainly be applied to the floor heave deformation. When the thickness of the caving coal was more than 5.9 m, the main roof strata was prone to instability and being cut along the edge of the coal pillar; the rock stress environment surrounding the roadway tended to revert back to the initial geostress state. The proposed floor heave control strategy achieved good results, and as the deformation of the floor heave decreased, the workload of the floor heave was also greatly reduced.Energies 2019, 12, 3009 2 of 21 and law governing the asymmetric floor heave of the mining roadway in a fully mechanized caving face, we propose a targeted response plan to ensure the normal operation and safety of the roadway.The floor heave control of mining roadways has always been an important issue in the field of mine pressure and rock mechanics. In recent years, many studies have been conducted to clarify the deformation mechanism of the roadway floor heave, and countermeasures have been proposed to control it. To date, different types of roadway floor heave management methods have been proposed. Hou et al. [8][9][10] reported that the main factor influencing the floor heave of the mining roadway is the front abutment pressure of the coal face. The floor heave of the mining roadway is mainly caused by the post-peak deformation of the floor's broken strata. The deformation of the roof and two sides of the roadway also exert a significant influence on the floor heave. Reinforcing the two sides of the roadway and the corners can achieve better control over the floor heave of the mining roadway. He et al. [11][12][13] proposed a new method to effectively control the ...

Combined support technology for main roadway passing through goaf: A case study

“…For example, when b = 2.6 m, a maximum bending moment of 175 kN m is observed (still located at both ends), and the bending moment at the center is 89 kN m. The reduction factors are 9.43 and 9.27, respectively, indicating that the double‐row reinforced concrete pillars can effectively support the goaf roof, increase the constraint points of the roof, and reduce the roof span to further improve the roof stress state. Accordingly, it is possible to prevent roof separation instability, and even roof falls 69,70 . However, with an increase in b (2.6 m → 3.1 m → 3.6 m → 4.1 m), the bending moments at the center and action positions of the pillars significantly increase.…”

“…Accordingly, it is possible to prevent roof separation instability, and even roof falls. 69,70 However, with an increase in b (2 .6 m → 3.1 m → 3.6 m → 4.1 m), the bending moments at the center and action positions of the pillars significantly increase. Thus, the pillars can be arranged on both sides of the main roadway (b = 2.75 m) in view of the field engineering experience.…”

Research on Key Technologies of Floor Heave Control in Soft Rock Roadway

“…In terms of control of the floor heave, Jia et al [15] believed that the lateral side-cutting pressure relief of the roadway can be used to control the deformation. Xie and Chang [16] proposed the use of grouting anchors and concrete backfill to control the bottom roadway of deep roadways.…”

Failure Mechanism and Control Technology of Thick and Soft Coal Fully Mechanized Caving Roadway under Double Gobs in Close Coal Seams

“…e instability mechanisms of these two structures are not the same, but they will cause the working resistance of the working face bracket to be too large. Research on coal roadways under close coal seams includes roof span, prestressed load-bearing structure of the anchor cable, and roof tensile and shear failure [14][15][16][17]. e study of the stability of the surrounding rocks for coal seams under close coal seams includes the compression bearing capacity of the coal and rock mass, the relative proportions of the coal and rock mass, and the coal and rock roadway tensile shear failure structure [18][19][20][21].…”