Research on large deformation mechanism and repair support technology of high stress soft rock roadway

In the context of the destruction and continuous deformation of the surrounding rock of the high stress soft rock roadway, how to scientifically and reasonably repair and support the roadway that has undergone large deformation, and how to achieve effective control of the surrounding rock of the roadway. In order to solve the above problems, taking the No.4 crosscut transport roadway of Baijiao Coal Mine +300 level as an example, this paper comprehensively analyzes the deformation and destruction characteristics of the roadway surrounding rock based on the roadway surrounding rock observation boreholes, the surrounding rock mechanical condition and the support technology. It is pointed out that the prominent tectonic stress, weak lithology of the roadway surrounding rock, concentrated layout of the roadway, low strength of the roadway surrounding rock support, mismatch of support materials and substandard construction quality are the causes of the continuous deformation of the roadway. It is pointed out that for the broken surrounding rock of the roadway that has been separated and destructed, when only anchor bolts and cables are used to reinforce the support, the existence of discontinuous deformation in the surrounding rock will lead to insufficient overall stability of the surrounding rock structure of the roadway. Unable to effectively resist the continuous extrusion of stress, the roadway is prone to continuous deformation. Therefore, grouting reinforcement is required to fill the cracks caused by discontinuous deformation in the surrounding rock, and then anchor bolts and cables are used to further support the roadway. On this basis, a roadway repair support program of 'high-pressure grouting + high-strength and high-prestressed bolt and cable combined support + shotcreting' is proposed. Firstly, the surrounding rock cracks and discontinuous structural surface are reinforced in time by grouting reinforcement. Then the surrounding rock are supported by prestressed strong anchor bolts and cables support to form a bearing structure in the surrounding rock. The surface of the surrounding rock is sealed by surface shotcreting to stop the weathering of the surrounding rock and improve the stability of the surface surrounding rock. Numerical simulation and field test results show that after adopting 'high-pressure grouting + high-strength and high-prestressed bolt and cable combined support + shotcreting', the maximum displacement of the top and bottom plates is 109 mm, and the maximum displacement of the two sides is 212 mm. This method can effectively control the deformation of the roadway surrounding rock.