Vibration Reduction Effect Analysis And Influencing Factors Of Damping Layer In Shenzhen Subway Tunnel

The problem of rail transit vibration has now caused strong social reactions and has become an urgent problem to be resolved in the current rail transportation industry.In response to the problem of environmental vibration caused by subway train loading,studying on the vibration reduction method based on tunnel structure,summarized the domestic and international research status such as vibration source generation,vibration propagation,and vibration isolation measures etc.Combined with the actuality of the southern extension of Shenzhen Metro Line 5,physical experiments and numerical experiments were used to investigate the method of vibration reduction from the perspective of the tunnel structure,analyze the structure of the damping layer structure and the vibration reduction effect of different damping materials under different surrounding rock conditions.The main research content is as follows:Single-point excitation method was used to study the vibration transmission characteristics of different damping materials,and the dynamic response of damping materials was analyzed.The test results show that the asphalt material has the largest vibration attenuation rate while the foam concrete vibration attenuation rate is the smallest.According to the principle of load-structure method,a finite element model of tunnel-enclosing rock was established to analyze the vibration response of the tunnel structure containing asphalt,rubber,and foam concrete damping layers.The results show that all three materials can reduce the acceleration and amplitude of Z vibration level.Among them,the foam concrete has the best vibration reduction effect.The rubber layer can be used to protect the vibration absorber at a specific position.Numerical experiments were used to analyze the effect of vibration reduction layer on vibration reduction of three kinds of vibration reduction materials in different locations and different surrounding rock conditions in the lining structure.The results show that the vibration damping effect of the material with larger stiffness is pre-set in the shield segment,while the damping effect is better between the primary lining and the second lining for the less rigid damping material.Different formation parameters cause the position of the vibration amplification area in the orbit to shift.There are differences in the damping performance of damping materials under different surrounding rock conditions.When the surrounding rock conditions are poor,the damping material with less stiffness is better.