Study On Mechanical Behavior Of Smooth Blasting Construction Of Wall Rock In Sandy Dolomite Tunnel

The dolomite formations crossed by tunnels in the Yuxi section of the Central Yunnan Water Diversion Project have the characteristics of strong sanding.The special geological phenomenon of dolomite sanding has led to a significant decrease in the quality and strength of rock mass.Geological problems such as tunnel blasting and difficulty in controlling over-excavation are more prominent.This paper relies on the tunnel of the Yuxi section of the Yunnan Central Yunnan Water Diversion Project,using data research,theoretical analysis,numerical simulation and other means to study the construction mechanical behavior of sandy dolomite under blasting,and the main research work and results are as follows:(1)LS-DYNA software was used to study the crack propagation law of sandy dolomite under single-hole blasting.Numerical experiments were used to analyze the influence of rock mechanics parameters on the radius of blasting crushing circles and fracture circles,and the sensitivity and significance of rock mass parameters were analyzed.(2)LS-DYNA software was used to study the influence of smooth blasting design parameters on crack propagation of blasting,and a reasonable range of values for the design parameters of smooth blasting,such as radial non-coupling coefficient K,peripheral hole spacing E,and minimum resistance line distance W,which were suitable for sandy dolomite land.(3)Combined with the numerical simulation results and the blasting test at the project site,a set of smooth blasting design suitable for the tunnel of the sandy dolomite formation was optimized,and the over-excavation of the tunnel was effectively controlled.(4)Based on the optimized smooth blasting design,the numerical simulation of full-section smooth blasting of sandy dolomite tunnels was carried out,and the dynamic response and over-excavation of tunnel blasting excavation under the optimized blasting design were studied.The effects of dolomite sanding degree on the dynamic response and ultra-under-excavation of tunnel blasting were analyzed.