Stability Analysis of Weak Surrounding Rock at the Intersection with Large Section and Optimization of Its Support Scheme in the Deep Phosphate Mine
Through the analysis of the deformation problem of the roof at 3# intersection of the 1080 air intake inclined roadway in Mofang Mine of Wengfu Phosphate Mine,it is founded that the main reason for the roof deformation is that the surrounding rock is located in a relatively fragmented dolomite zone,with poor stability and significant influence from groundwater.At the same time,the support structure was not targeted,and the support and surrounding rock were not coupled in terms of stiffness,strength,and deformation.To prevent subsequent mining from affecting the deformation of the area,the original support scheme was optimized and a combined support method of anchor rod,steel mesh,steel arch,prestressed anchor cable was adopted to support the broken roof.Simulated and analyzed the support scheme before and after optimization using FLAC3D,and conducted 210 d underground monitoring on the optimized scheme.The results show that the optimized support scheme reduces the settlement displacement of the surrounding rock roof by 95.35％compared to the original scheme,and the maximum value monitored is about 2.00 mm.After optimizing the support scheme,the two-sided displacement decreases by 94.29％compared to the original scheme,which is less than 3.00 mm.The optimized support scheme can effectively control the deformation of surrounding rock,indicating that adding prestressed anchor cables on the basis of the original support scheme has a significant improvement effect on the stability of fragmented roadway surrounding rock.
IntersectionFragmented surrounding rockOptimization of support schemeLarge sectionDeformation monitoring
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