ABSTRACT:

In light of the coal roadway deformation in soft rock conditions under dynamic pressure influence, this research was made on the governance practices in No. 3101 working face, combined theories and computer numerical simulation, the floor heave and spalling mechanism under the influence of multiple mining activities were analyzed and a rational pillar size was calculated and bolt-cable coupling improvement support projects were designed on the basis of the original support plan. The study result shows that it was expansion-flexural composite of floor heave and rib spalling affected by coal pillar size. It can effectively control the volume expansion at the roadway bottom plastic zone and reduce the impact of the surrounding rock pressure of two sides on the floor by increasing coal pillar size to 25 m and using "add floor rock bolt and increase support density in two sides of roadway and enlarge anchor length" comprehensive reinforced support means.

1 INTRODUCTION

For a long time, the problem of soft rock roadway supporting is always one of the major technical hurdle which seriously influence the coal production safety in China coal mines (He & Sun 2004, Qian & Shi 2003). Influenced by soft rock and engineering stress disturbed, there were large-scale rib spalling and floor heave issues during mining in No. 3101 work face, and they are seriously restricting the safety production of coal mine (as shown in Fig. 1). In allusion to the problems mentioned above, the deformation mechanism of soft coal roadway was analyzed and an improved roadway support design scheme was proposed by combining the theories and computer numerical simulation.

2 ENGINEERING GENERAL SITUATION

The No. 3101 long-wall fully-mechanized working face with large mining height is the first mining face in Chahasu coal mine, its buried depth is 398.8 m and the thickness is 6.45 m. Structures in zonation are simple and dip angle of coal seam is 1~3°. The roof rock was composed of mudstones, sandy-mudstones and medium grain sandstones. Among them, the medium grain sandstone is the main roof and its thickness is about 12.55~24.85 m. The immediate floor of coal seam is carbon mudstone with a thickness of 0.85~1.8 m, the main floor is consisted of coarse-grained sandstones and its thickness is 5.35–14.18 m.

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