Study On Seismic Isolated Experiment Of Support And Hanger In Utility Tunnel Based On Rubber Bearing

The utility tunnels play an increasingly important role as a "lifeline" project in urban construction,operation and development.The construction of China’s utility tunnels is developing rapidly,and the volume of investment and construction scale is the highest in the world.Corridor support hanger is the only support structure for all kinds of important pipelines and the first line of defence for pipelines against the effects of disasters.At present,the design method of common load-bearing support hangers in the corridor is relatively mature,but the seismic design and research of the pipe corridor support hanger are relatively scarce.In this paper,the research is carried out for the seismic problem of pipe corridor support hanger.Firstly,based on the finite element numerical analysis method,the mechanical response of the seismic isolation system of the pipe corridor support hanger under the seismic action was explored;Secondly,two kinds of vibration isolation and damping bearings were developed,and the experimental research on the performance parameters and vibration isolation performance of vibration isolation bearings was carried out,and the parameters of the bearings were optimized;Finally,a shaking table model test was conducted on the seismic isolation effect of the footprint power pipe corridor support hanger system.The main research contents and conclusions of this paper are as follows.(1)The finite element numerical simulation analysis of the seismic action and vibration isolation performance of the underground pipe corridor support hanger was carried out.Based on ABAQUS finite element analysis software,an overall three-dimensional analysis model of the soil-tube corridor support hanger system was established.The results of seismic wave loading and analysis show that: 1)the smaller the horizontal stiffness of the seismic isolation support,the better the seismic isolation effect,provided that the vertical stiffness is sufficient;2)as the damping of the isolation support increases gradually from none to one,the acceleration response of the cable decreases first and then increases,and there is an optimal value of damping matching the system parameters,which makes the best seismic isolation effect;3)as the input seismic wave amplitude increases,the acceleration response of the cable equipped with the isolation support decreases first and then increases,and the system with specific parameters has the best seismic isolation effect for a certain value of seismic waves.(2)Two types of vibration isolation and damping bearings were developed,and the performance parameters of the isolation bearings were tested and the preliminary experimental study of the vibration isolation performance of the bearings was conducted.The results show that: 1)the rubber damper made by vulcanization process has better integrity and greater displacement travel and horizontal stiffness than the rubber damper made by bonding process;2)the lead-core rubber damper has better energy dissipation capacity and greater displacement travel than the rubber damper,but the horizontal stiffness increases and the stiffness degrades faster in the initial shear phase;3)under transient shock load,compared with the condition without vibration isolation bearing,the acceleration of the mass block above the vibration isolated rubber bearing is reduced by 93.9%,and the acceleration of the mass block above the vibration isolated spring bearing is reduced by 97.9%,and the corresponding displacements are reduced by 87.3% and 94.9%,respectively.The two types of vibration isolation bearings have very good seismic isolation effect.(3)The shaking table model test of the pipe gallery support hanger structure was carried out,and the acceleration,displacement and strain responses of three cable support hanger systems(no vibration isolation bearing,rubber bearing and lead-core rubber bearing)under the earthquake action were compared and analyzed.The results show that: 1)under white noise,the seismic isolation effect of the two vibration isolation bearings can reach about 60% in the direction of the cable,and the seismic isolation effect in the direction perpendicular to the cable is between 40% and 50%,and the vibration isolation bearings have good damping effect under environmental vibration;2)when loaded with 8 degrees of small and medium earthquakes,the seismic isolation effect of the two vibration isolation bearings rises with the rise of the seismic wave amplitude,and when loaded to 8 degrees of large earthquakes,the seismic isolation effect of both types of isolation bearings decreases to a certain extent;3)The seismic isolation effect of seismic isolation lead-core rubber bearing is better than that of seismic isolation rubber bearing,and the difference of seismic isolation effect is more obvious with the enhancement of seismic excitation;4)The seismic isolation effect of seismic isolation bearing in the direction of downward cable is better than that in the direction of vertical cable.