Dynamic Analysis Of Recycled Concrete Circular Tunnel Structure

With the 40 years of reform and opening up in China,a large number of underground tunnel structures have been produced in China’s mining areas.In recent years,due to the earthquake prone period of China’s continental plate,the stability of underground tunnel structure under the earthquake has become more and more important.Different from the underground structure such as subway tunnel,because the service life of underground tunnel structure is generally short,which makes the tunnel structure use the original concrete as the lining material,resulting in a great waste of resources.This paper aims to improve the utilization rate of materials,reduce environmental pollution and ensure the seismic resistance of the tunnel structure.For the dynamic response characteristics of recycled concrete as the lining of the tunnel structure In this paper,based on the shaking table similar model test and dynamic finite element numerical calculation,aiming at the dynamic characteristics and change rules of recycled concrete circular tunnel structure,the method of combining test and numerical calculation is adopted,and the factors affecting the dynamic characteristics of recycled concrete tunnel structure are studied as follows:(1)Based on the similar model vibration test of surrounding rock of roadway.Based on the engineering practice and similarity theory,according to the geometric similarity ratio of 1:50,the similar model of surrounding rock of roadway is made,and the dynamic test is carried out on the ANCO vibration table.The test results show that: the peak value of the acceleration time history curve of the response output of recycled concrete tunnel lining structure has amplification phenomenon compared with the peak value of the input seismic wave acceleration;the peak strain response of the tunnel structure using recycled concrete as lining material is similar to that using ordinary concrete as lining.It shows that the dynamic response characteristics of the tunnel under the two lining materials are similar,and the dynamic performance of the tunnel lining is relatively similar.(2)The numerical model of surrounding rock structure of roadway is established by MIDAS.The dynamic response of tunnel structure under earthquake is calculated and analyzed.The velocity,displacement and stress data of the monitoring points of the tunnel structure under different working conditions are calculated and compared.The results show that: under the earthquake,the velocity response value of the tunnel with recycled concrete lining is slightly higher than that of the tunnel with ordinary concrete lining;the displacement change trend of each monitoring point in the horizontal direction of the tunnel structure is the same,and thedifference between the values is small;the stress concentration phenomenon appears in the upper and lower sides of the tunnel structure,which is mainly the compressive stress,and the compressive stress is pulled down with the earthquake action At the same time,the shear stress of the upper and lower sides of the tunnel structure is easy to cause the damage of the tunnel structure.(3)Through the comparative analysis of shaking table similar model test and numerical calculation,it is found that: the change trend of seismic dynamic characteristics of tunnel lining with recycled concrete material is basically similar to that with ordinary concrete lining,but the dynamic response value of recycled concrete tunnel structure is slightly higher than that of ordinary concrete tunnel structure,which shows the seismic performance of recycled concrete material It can meet the seismic requirements of tunnel structure,but some seismic measures should be taken to reduce the dynamic response of recycled concrete tunnel structure.