Damage Evolution And Dynamic Response Of Anchorage Caverns With Cracks Under Explosion

The dynamic response and damage distribution of anchored caverns under explosive loading are complex.Especially when there are cracks in the surrounding rock of the tunnel,the dynamic response and damage distribution of the anchored cavern are more complicated because of the many factors affecting the failure.In order to provide a reference for the design of Anchorage caverns with cracks under explosive load,the damage distribution and dynamic response of the Anchorage caverns with different cracks are simulated by using numerical analysis method based on the model test results.The main research contents and conclusions are as follows:(1)By comparing the results of numerical analysis and model experiment,it is found that the time history curve of compressive stress at the same position in numerical analysis and model experiment is similar,and the damage distribution of numerical analysis is the same as that of crack area in experimental results,which proves that the data in numerical analysis are reliable;the damage distribution of caverns with different bolt spacing and length is compared,it is found that the maximum tensile damage area is mainly concentrated in the anchorage area and the boundary of the anchorage area.By comparing the damage area,the optimum anchor spacing and length are 4 cm and 24 cm,respectively.(2)By studying the influence of the length,inclination and position of the single crack on the damage distribution and dynamic response of the Anchorage cavern,it is found that with the increase of the crack length,the area of the Anchorage area and the maximum damage area of the boundary of the arch roof increases first and then decreases.When the crack length is 1/3 of the cavity span,the damage is the most serious,the peak displacement and peak particle velocity of the arch first decrease and then increase,and the dynamic response of the crack length of 1/2 of the span of the cavern is the smallest.With the increase of fracture dip angle,the area of Anchorage area and maximum damage area of arch roof decreases first and then increases.When the angle of fracture angle is 45o,the damage is minimum,and the peak displacement and peak particle velocity of arch top decrease first and then increase.When the angle of fracture is 45 o,the dynamic response is minimum;The damage,displacement and vibration velocity increase when the crack is near the top of the cavern or offset the top of the cavern.(3)The influence of the spacing of parallel double cracks,the angle of cross double cracks and the distribution of group cracks on the damage distribution and dynamic response of anchoring cavern is studied.The results show that the damage area of the Anchorage area and the boundary of the arch roof decreases obviously with the increase of the crack.The peak displacement of the arch top increases with the increase of the distance between the parallel double cracks,and decreases first and then increases with the increase of the angle between the cross double cracks,and the peak displacement is the smallest when the angle is 90 o.The peak particle velocity increases at first and then decreases with the increase of the distance between parallel and double cracks,and then decreases with the increase of the angle between the cross double cracks,and the peak particle velocity is the smallest when the angle is 90 o.The peak displacement and particle velocity of the arch roof with groups of parallel cracks are larger than those of the chambers with double cracks.The peak displacement and velocity of particles of the arch roof with groups of cross cracks are the smallest of all the simulated cases.