Experimental study on secondary bolting and grouting reinforcement of large section chamber in deep three-soft coal seam

In order to solve the key problem of support technology of large section roadways or chambers in deep three-soft coal seam, the dynamic superimposed coupled support technology of initial bolting and shotcreting and secondary bolting and grouting was proposed, based on the geological conditions and deformation and broken characteristics of panel pump house chamber in Zhaozhuang mine. The detailed technical parameters were given in the surrounding rock control technology. The results show that the positive and effective structure of bolting and grouting in full section and multilayer combined voussoir beams were formed by secondary bolting and grouting. The rock bolts and pre-stressed anchors were turned into all-lengthy anchorage. Bearing together of support structure and surrounding rock was achieved,and integrity and bearing capacity of support structure was improved. The stability of surrounding rock and support structure was ensured for a long time. Practical application shows that the secondary bolting and grouting reinforcement can effectively control the deformation of chamber, and satisfactory reinforcement and technical-economic effects can be achieved. It also provides some references for other large section roadways or chambers support design and construct in deep three-soft coal seam.