Study On Vibration Comfort Of Underground Space Structure Under Vehicle Load

In order to alleviate the contradiction and improve the utilization rate of urban land,an intensive scheme of joint construction of municipal roads and civil commercial buildings is proposed.The joint construction of underground space structure of municipal roads is a new type of structure.When the car is driving directly above the top plate of underground space structure,the structural vibration generated by factors such as road roughness and vehicle’s own dynamic characteristics is directly transmitted to the underground space structure without attenuation of soil layer,which will reduce the human comfort of underground space structure,and under long-term operation conditions,due to the continuous increase of road roughness,The more intense the vibration generated by the car,the vibration response of the underground space structure will continue to increase,and the human comfort of the underground space structure will gradually become worse.In order to ensure the vibration comfort of underground space structures during normal use,it is necessary to study the vibration comfort of underground space structures under vehicle loads.The main research contents,technical means and results of this thesis are as follows:This thesis summarizes the existing national codes and standards on environmental vibration caused by traffic load,comprehensively considers the existing environmental vibration evaluation standards of different countries,mainly introduces the common vibration evaluation indexes and lists their calculation formulas.With reference to China’s（GB10070-88）standard of vibration in urban area environment,the proposed vibration limit value of underground space structure in the core area of Wanbo central business district is given by using the new weighting curve.Based on the similarity theory,four kinds of floating plate roads and frame supporting structures with different number and spacing of steel springs are designed and manufactured,and hammering experiments are carried out.The vibration reduction performance of floating plate on the combined structure is studied from the aspects of typical acceleration time history and spectrum,impedance,transmission loss and insertion loss.The vibration reduction effect of four kinds of steel spring floating plates is better with the increase of frequency in the range of 20～80Hz;The insertion loss of Z vibration level of 4 spring,6spring,8 spring and 10 spring floating plate is 9.99 dB,18.17 dB,9.99 dB and 13.17 dB respectively.Taking the minivan and the bus with large axle load on the municipal road as the vehicle load,the multi rigid body vehicle model and the finite element model of the underground space structure are established.According to the displacement power spectral density formula of the national pavement spectrum GB/T 7031-2005,the class A,B,C and D pavement unevenness is simulated by the trigonometric series method,and the vibration response of the underground space structure under the vehicle model with the same wheelbase and axle load as the field measured minivan is calculated,Combined with the field test data of the underground space structure of Wanbo center,the correctness of the finite element model of the vehicle underground space structure is verified.Under the road design speed and the action of 3T vehicles,the Z vibration level of the negative layer of the underground space structure can meet the standard limit requirements under four road conditions.According to the established finite element model of vehicle underground space structure,select the 14 T vehicle model with large axle load of municipal road,set the pavement conditions of A,B,C and D and the vehicle speeds of 10km/h,20km/h,30km/h and 40km/h,and analyze the vibration response of underground space structure.The vibration response of underground space structure exceeds the limit.According to the above,steel spring floating plate road is used for vibration reduction,and the vibration response of underground space after vibration reduction is calculated.Under the design speed of 14 T vehicle and under the working conditions of four pavement grades,the Z vibration level of the negative layer of underground space structure still meets the specification requirements,and the vibration comfort is maintained within the comfort range of human body;Under the action of vehicle load,the floating slab road amplifies the vibration of the negative first floor of underground structure space at its fundamental frequency,with a maximum amplification of 19.65 dB and a maximum reduction of 34.49 dB.