Control technology and application of variable-diameter zoned pressure relief for surrounding rock in deep soft rock and large deformation roadway

WU Fengfeng; GU Haoyuan; YANG Peiju; LIU Changyou; WEI Mintao; JIANG Yufei; WANG Ping

doi:10.12438/cst.2024-0069

Abstract：Addressing significant deformation in the surrounding rock of deep soft rock road-ways subjected to repetitive repairs,this study focuses on the 21st transportation downhill of Quandian coal mine as the engineering context.We propose the variable-diameter par-tition roadway pressure relief technology.This approach utilizes theoretical analysis,numerical simulation,and practical engineering meth-ods.We established a theoretical model for pressure relief parameters,derived essential parameters for pressure relief,and outlined the dis-tribution pattern of elastic strain energy density.Additionally,we uncovered the principles governing energy dissipation in borehole un-loading,ultimately determining the optimal value for key pressure relief parameters.The study findings indicate the following:①The variable-diameter zoned pressure relief technology enlarges the energy reduction zone near the roadway while diminishing the energy elev-ation zone in the roof and floor.It redirects concentrated energy from the shoulder and floor corners deeper into the area,achieving precise pressure relief control within the roadway.②Increasing the length of shallow small-diameter boreholes(L1),the length of deep large-dia-meter boreholes(L2),and the radius of deep large-diameter boreholes(r)corresponds to increasing pre-peak,post-peak,and post-peak val-ues in the elastic strain energy density curves,demonstrating an overall positive correlation.③As the spacing(D)of deep large-diameter boreholes increases,the peak value of elastic strain energy density between holes shows the characteristics of firstly increasing,then de-creasing and then stabilizing,and the effect of unloading joint pressure between boreholes is negatively correlated with it,and based on the magnitude of the increase in the peak value of elastic strain energy,the key parameters affecting the effect of unloading are weighted as follows in the order of:L1,L2,r and D.④Based on the theoretical analysis and numerical simulation to determine the key parameters of the 21st transportation downhill roadway pressure relief technology reasonable value,roadway implementation of variable-diameter zoned pressure relief technology,the two ribs and the roof and floor deformation were reduced by 58.7%,23.7%,and 27.4%,respectively,the stability of the roadway has been effectively controlled,confirming the effectiveness of the variable-diameter zoned pressure relief technology.