Study On Strata Pressure Characteristics Of The Interbedded Rocks And The Anchor Scheme In Soft Coal

According to statistics, the vast majority roadways of mining areas possess soft sides and interbedded roof structure, for this kind of roadway, traditional supporting way can not achieve a good effect. The soft sides of many roadways will be destroyed under the influence of mining, but as the anchors of the roof,destruction of the two sides will inevitably lead to the increased deformation of the roof strata, and even lead to the failure of the support system.This paper takes TongZhou Group An-Da Coal 2# Coal return airway as the background, studied the deformation characteristics of interbedded roof roadway for soft coal seams and the mechanism of the deformation interaction that between the two soft sides and the interbedded roof, by field observations,theoretical analysis and numerical simulation methods. And gave a integral anchor program for air-return way of TongZhou Group An-Da Coal 2# Coal.(1) Through the peep site and core analysis, the structure of TongZhou Group AnDa Coal Industry 2# Coal return airway is characterized: the structureof roof is coarse sandstones interbedded with mudstone, and the two sides are coal with low strength, the base plate is limestone that has high strength and without floor heave.(2) Assuming that when the ends of the span are fractured, the roof rock change from clamped to simply supported, it shows that after the two sides are destroyed(assuming that both ends of the roof structure are simply supported)the maximum deflection of the roof is four times of the two sides before they are destroyed(assuming that both ends of the roof structure are clamped) by mechanical discussion, so it’s essential to support at the corner of the roof.(3) With the two sides’ damage extent increasing, the failure process of the interbedded roof is mainly reflected in the following stages: the shale crossed off—— the cross off degree of the shale increasing —— overburden deformation expanded —— separation of the first grit floor appeared above the shale ——separation appeared in the direct top of the each overlying strata —— with the overburden collapsed and damaged gradually, tapered region is formed.(4) When the roof is not damaged, destroyed of the two sides mainly refers to the bulged center destroy of the two sides, when the direct top shale damaged,in corner of the roadway the roof strata is damaged by sliding along the bedding plane of the roadway sides, when the second sandstone floor damaged, the extent of damage on two sides and upper corner shale increases, then with the extent of the damage on interbedded roof increasing, the extend of damage on two sides and upper corner shale is not obvious, because of the relief of the roofdamage, the damage area decreases. In summary, due to the relief of the roof deformed, the extent of damage of the two sides slowed down.(5) For the structure of this surrounding rock, the support mainly focus on:①The support of the two sides is strengthened. ②The support of the roadways’ upper corner is strengthened. ③Anchorage structure forms a whole reinforced arch. Overall frame-anchor support scheme is put forward for the surrounding rock structure of 2# coal return airway, and the support parameters are designed,it shows that this scheme maintains the stability of the surrounding rock better,and has a good effect, by the comparison between the deformation properties of surrounding rock and the actual results.