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Bolt Supporting of Large-Span Soft Rockway in Shaqu Colliery

Abstract The instability of trapezoidal I-steel support is analysed for the compound roof of main coal seam in Shaqu Colliery, and the mechanism of bolt supporting is studied. A scheme of bolt supporting has been given and put into practice,remarkable technical and economic benefits have been got.

Key words :large-span,compound roof, bolt supporting, mechanism

1.Introduction

In shaqu colliery a large coal mine mining rare coking coal in China, most roadways are laid out in main coal seam .The soft compound roof of coal seam is composed of mudstone and coal seam ,which contains aboundant beddings and joints. The strength of the roof is so low that its uniaxial-saturated compressive strength is only 10.7 Mpa.RQD value of coal seam and is zero ,and that of mudstone is lower than 10%. There is clay minerals in mudstone, main compositions are interbedded strata of illite and montmorillonite which will swell when soaked by water, The span of preperation roadways and gateways is wider than 4m, and that of some main roadways is over 5m. In shaqu colliery , preperation roadways and gateways were supported by trapezoidal I-steel support, the beams of which were bent and damaged, and the roadways were destroyed seriously within a short period just after excavated. Roof controlling of Large-Span Soft Rockways in the coal seam became the key to the production and construction of shaqu colliery.

2.supporting status and instability analysis of trapezoidal I-steel supports