The invalidation mechanism of bolt-mesh support in soft coal roadway

Abstract

The bolting is easy to go out of force in soft coal roadway. Based on the field measured data, the reason of bolt pre-stressed hysteresis descending in soft coal roadway was analyzed in detail by theoretical analysis and field measurement. Closely encircling the changing law of anchorage force during the bolt bearing course, the reason of the low initial anchorage force in soft coal roadway, the effect of surrounding rock deformation on bolt anchorage force and the circulating hysteresis descending of anchorage force as well as the impact of the structure stability on bearing structure of the bolt-mesh support were analyzed. The analyzed results show there exists a great amount of bolt pre-stress hysteresis descending in soft coal roadway because of remarkable difference between bolt and soft coal deformable capability. Thus, many comprehensive measures should be taken to effectively control the initial loose deformation of non-anchorage rocks between two bolts, to achieve higher initial anchorage force and to prevent anchorage force losing during bolt bearing course. At the same time along with increasing the bolting strength, the structure compensating measures should be taken to ensure the structure stability of the bolt-mesh support and to realize the high-strength stable bolting.