Research Into The Parameter Optimization Of Smooth Blasting And Application In Xinlin Tunnel

Smooth blasting is a blasting technology which is wildly applied in engineering.This technology can make the excavation face smooth,reduce the damage degree of surrounding rock and improve the stability of surrounding rock.So Smooth blasting technology is a blasting technology which is secure,economical and scientific.In this paper,we analyze the correlative parameters of smooth blasting by theoretical analysis and numerical simulation.Rock blasting is a high-speed vibration problem.In order to solve the problem more accurately,we select finite element software ANSYS/ LS-DYNA.Based on the comparison and analysis of the different algorithm,the ALE algorithm and the flow coupling method are used to simulate and analyze rock blasting.On account ofthe characteristics of rock blasting,the constitutive models of rock,explosive,air and water are selected reasonably,and the material parameters were determined.The rock damage factor was selected as the analysis variable to describe the degree of rock damage.In rock blasting,the hole effect only works within a certain range around the blasting hole.The stress concentration phenomenon and free surface effect of rock blasting are explained theoretically.The influences of the distance between empty hole and blasting and empty hole diameter on the stress distribution of rock mass are analyzed through numerical simulation.There are three main aspects of the uncoupled charging: the uncoupled charging method,the uncoupled medium and the uncoupled charging coefficient.In this paper,the theoretical and numerical simulation analysis of two uncoupled media,air and water,is carried out and compared with the coupling charge.The numerical simulation is performed on the two loading methods of axial uncoupled charging and radial uncoupled charging.We can know the differences between the two loading methods of the pressure distribution on the pore wall and damage area of the rock mass by numerical simulation results.The burden is an important parameter in smooth blasting.Based on the theory of wave propagation,we analyze the reflection on the free surface and the superposition in the rock mass of the explosive stress wave.The relationship between burdensand the damage distribution in the rock mass is analyzed by establishing modelswith different burdens,and the reasonable smooth burden is acquired.On the basis of theoretical analysis and numerical simulation,the parameters such as the hole spacing,the uncoupling charging coefficientand the burden are proposed.The application of the parameters to engineering practice has achieved good blasting effect.