Research on stability mechanism of roadway roof under dynamic loading induced by blasting excavation
LIU Xiao
Abstract：Addressing the stability issues of the immediate roof in roadways caused by subsidence and vibration during blasting ex-cavation,this study takes the high-level drainage roadway of Panel 3203 in Wangpo Coal Mine as the engineering background.Based on the calculation formula for blasting dynamic load attenuation,the stress characteristics of the roof under blasting loads and their interrelationship with blasting parameters were analyzed.A stability criterion based on the tensile strength of the rock was es-tablished,and the quantitative relationship between blasting parameters(charge length,borehole diameter,borehole length)and roof tensile stress was determined.Combining this with the specific engineering conditions of the 3203 high-level drainage roadway,an optimal combination of blasting parameters was proposed.The research results indicate that after blasting,the peak compressive stress acting on the roadway roof exhibits an exponential decrease with increasing borehole length and charge diameter,and an expo-nential increase with decreasing charge length.Furthermore,it shows significant sensitivity to all these blasting parameters;using tensile strength as the stability criterion for the roof,a tensile stress expression was derived.This expression reveals the phenomenon of transition between tensile stress and compressive stress along the cross-section of the roof under blasting dynamic loads.The max-imum tensile stress is distributed in the middle of the roadway immediate roof,while the tensile-compressive transition points(inflec-tion points)are located near the ribs(sidewalls)of the roadway;the quantitative relationship between the distribution of roof tensile stress and blasting parameters(borehole length,charge diameter,charge length)was analyzed.The optimal blasting parameters for maintaining the stability of the immediate roof in the 3203 high-level drainage roadway were determined as:charge length of 1.8 m,borehole diameter of ϕ42 mm,and borehole length of 2.4 m.Combined with a specific engineering case,the tensile-compressive transition points were found within the ranges of 0.6-0.8 m and 2.6-2.8 m from the centerline.Engineering practive verification con-firmed that the immediate roof did not experience tensile failure during the blasting excavation process,resulting in effective road-way formation.
Keywords：blasting excavationblasting dynamic loadtensile-compressive zonesroadway roofstability criterionblasting para-meters
Publication Date：2025-09-30
Online Publishing Date：2025-09-12(First online date of this platform, not the publication date of the document)
Pages：11( 178-188 )