Research On Mechanical Characteristics Of Bolt And Grouting In Deep Fractured Metamorphic Soft Rock And Stability Control Of Roadway

The research on deep roadway support theory and technology is relatively mature,but most of them are based on sedimentary rock coal mine roadways dominated by mudstone and sandstone.For metal mine roadways with soft and broken igneous rock and metamorphic rock strata as the medium There are relatively few studies on stability support issues.Therefore,further research on the stability of the surrounding rock of metal mine roadways in complex stratum is very important for the safe mining of deep metal mines.In this paper,a series of researches are carried out on the deep fractured metamorphic soft rock of Xinhui Gold Mine.The main research results are as follows:(1)The influence law of bolt density,gravel gradation and water-cement ratio on the mechanical parameters of anchor-grouting body is obtained through the indoor model test.Based on the analysis of the compression test data,it is found that the peak stress and elastic / secant modulus of the bolt-grouting specimen increase first and then decrease with the increase of the density of the bolt,while the peak strain of the bolted specimen is basically unchanged.With the increase of water cement ratio,the mechanical parameters showed a monotonic decreasing phenomenon.With the increase of n in the gravel Talbot gradation,the peak stress and elastic / secant modulus increase first and then decrease,while the peak stress decreases first and then increases.The results of shear test show that the variation trends of cohesion and internal friction angle of anchor-grouting specimens are basically consistent with the peak stress.(2)Based on the voidage measurement and calculation results of the anchorgrouting specimen,it is revealed that the strength deformation parameters of the anchorgrouting body show a monotonic decreasing function with the voidage.From the typical failure diagram of the test process,it can be seen that the bolt-grouting specimen basically presents vertical splitting failure,and the crushing degree is basically positively correlated with the strength of the peak stress.The statistical analysis of the fragment mass after the test proves that the fragment mass after the failure of the specimen has obvious fractal characteristics,and the fractal dimension and the peak strength show a monotonic decreasing function relationship.(3)The influence of bolt parameters and confining pressure on the internal stress distribution of anchor body is analyzed by Flac3 D software.The simulation results show that the compressive stress concentration appears at the upper end and lower tail of the bolt,and the stress diffusion and superposition are carried out around the two ends as the center.The stress is mainly transmitted along the axial direction of the bolt,and the stress decays with the bolt away in the horizontal direction.The internal stress of bolt-grouting increases linearly with the increase of bolt preload;With the increase of bolt length,the change of internal stress of anchor-grouting body shows an increasingly obvious trend from top to bottom,and the anchorage range is becoming wider and wider.With the increase of bolt density,the stress superposition area in the bolt is increasing.Increasing confining pressure can increase the ability of anchor to resist external load,but it can narrow the anchorage range of anchor.(4)Based on specific projects,the deformation and failure reasons of-1070 horizontal roadway in Xinhui Gold Mine are analyzed,and the corresponding supporting countermeasures are given.Combining the physical test and numerical simulation results with the engineering practice,the support scheme of the roadway was redesigned by using the soft rock control principles and measures,and the support effect was evaluated and analyzed by using the numerical simulation software and the construction monitoring results.The final support results show that the full-face support technology of ‘ bolt-mesh-shotcrete primary support + secondary bolt-grouting combined support + key parts strengthening support ' can effectively control the deformation and instability of the broken metamorphic soft rock roadway in metal mines.This paper has 50 figures,25 tables,91 references...