Optimization Design Study Of Blasthole Layout For Full Section Smooth Blasting Of Rock Tunnel

The optimal design of blast-hole layout for full section smooth blasting of rock tunnel is investigated by using theoretical analysis and numerical simulation method.Based on the synthetic consideration of a large number of blasting parameters of rock tunnel,the quality evaluation model of smooth blasting,cost evaluation model of blasthole layout,safe evaluation model of surrounding rock mass and comprehensive evaluation model of blast-hole layout for smooth blasting of rock tunnel are established by using catastrophe theory.Based on this comprehensive evaluation model,the relation between smooth blasting parameters and quality evaluation index of smooth blasting is connected by back propagation(BP)neural network.Based on the design theory and empirical method of tunnel blasting,the algorithm of automatic blasthole layout for full section tunnel is proposed,including layout algorithm of spiral cutting,wedge cutting,relief holes,peripheral holes and breast holes.The algorithm of automatic blasthole layout for full section tunnel is also applied and verified in the tunnels with semi-circular arch,circular,elliptic and rectangular section.For the numerical research of vibration and damage of surrounding rock in tunnel blasting,numerical results of different forms of blasting load and different damping conditions are analysed and compared with the field test data,on the basis of an in-situ underground blasting in rock cavern and its four-dimensional Lattice Spring Model(4D-LSM),and the optimal blasting loading form and damping model in 4D-LSM are proposed to analyse underground blasting problems in viscoelastic medium.Based on the above,numerical model of tunnel blasting vibrations in surrounding rock and numerical model of rock damage of peripheral-hole blasting are established to investigate the vibrations and damage of surrounding rock under different blasthole layout designs.At last,based on the blasthole layout schemes designed by blasthole layout code for tunnel blasting,BP neural network and 4D-LSM numerical models,blasthole layout schemes are evaluated and optimally selected by the comprehensive evaluation model.