Research on collabration control method of bolt/cable-surrounding rock deformation in coal roadway with weakly cemented soft rock

In order to solve support problem of weak cemented soft rock, mudstone physical components are tested, and failure characteristic is analyzed. Then, based on analysis of failure characteristics of surrounding rock, its instability mechanism is revealed. Therefirce, cooperative control mechanism of bolt-cable- surrounding rock deformation under high pretension is proposed, and its design method is given and used in roadway support. Conclusions are as follows:① high content of clay minerals and developed micro-cracks cause weakly cemented soft rock with low strength, low cohesion, poor cementation, and fragile swelling. It produces shear slip failure under low confining pressure. And the most effective way to improve its resistance to deformation and fracture is improving its equivalent cohesion and surrounding rock stress level.②Under the combined action of weak cemented mudstone characteristics, high level stress and low bolt(cable) pre-tightening force，it is prone to overall sinking, with serious internal fractures, and a maximum fracture range of 4.0 m, especially the fracture and dilatancy of the coal-rock interface, which makes part of the bolt- cable failure and aggravates the roof fracture and sink; ③the role of bolt support is reflected in increasing the equivalent cohesive force of the rock formation within the reinforcement range of the bolt, while the anchor cable support emphasizes providing strong support stress to the rock formation within the support range. The higher the working resistance, the better the support effect;④the elongation of bolt or cable and roof deformation should be adaptive after it is supported, and bolt or cable elongation is in allowed range of elongation deformation. At the same time, the most supporting effectiveness of bolt or cable should be made. Field application shows that, weak cementation of soft rock roadways roof control effect is better, to meet the design expectations, and this method can provide reference for the weakly consolidated soft rock supporting.