Research On Vibration Rules Induced By Collapseinduced Ground Vibration And Its Influence On Surrounding Environment

With the rapid development of our society and economy and the advancement of urbanization,a large number of buildings and infrastructures are facing the problem of blasting demolition.In the process of demolition of these structures,the falling structure will impact the ground and cause collapse-induced ground vibration.As the frequency of collapse-induced ground vibration(CIGV)is close to the natural frequency of the surrounding field and structures,the vibration has a great safety hazard to the surrounding structures.Moreover,under the background of increasingly complex surrounding environment,there have been cases of damage to adjacent buildings and infrastructures caused by the CIGV.Therefore,much attention should be paid to the impact of CIGV on the surrounding environment.At present,the research on this issue is still limited,and there are no mature standards to guide engineering practice.Therefore,the study of this problem has both important theoretical significance and engineering application value.In this dissertation,a comprehensive research method including field mesurement,model test,theoretical analysis and numerical simulation are employed to systematically study the impact of CIGV of falling objects on the surrounding environment(soil,surface and underground structures).Two vibration isolation techniques,namely,the trenches and water sac,are considered,and their vibration reduction performance are analyzed.The specific research contents are as follows:(1)The characteristics of the vibration source of CIGV are investigated,and the mechanism of the vibration is analyzed.Based on the test of afull-scale model of a single-span viaduct,the characteristics of CIGV are analyzed,and the applicability and accuracy of the numerical method are verified through the numerical simulation.(2)The propagation of CIGV is studied.The vibration response of a surface in elastic semi-infinite space under collapse contact load is derived theoretically.The dynamic compaction test and the corresponding numerical simulation are carried out to analyze the response characteristics of ground vibration and the vibration attenuation along the distance.Besides,the influence of vibration isolation trench on vibration propagation is studied.(3)The influence of CIGV on surface structures is studied.Model test of a frame structure under the impact of collapse is carried out and its numerical model is established.After validation of the model,the dynamic response characteristics of frame structures with shallow foundation and pile foundation are further studied,and the reduction effect of vibration isolation trench on surface structure is analyzed.(4)The influence of CIGV on underground structure is studied.Model test of a buried pipeline under the impact of dynamic compaction is carried out and the corresponding numerical model is established.Based on the verified model,the dynamic response characteristics of typical underground structures(rectangular subway station and circular tunnel)are further studied,and the reduction effect of vibration isolation trenches on underground structure is analyzed.(5)Based on the comprehensive summarization of the existing vibration evaluation methods and standards at home and abroad,together with the analysis results of a large amount of working conditions considered in this paper,the research mainly discusses and suggests the potential methods for vibration safety evaluation of underground structure.(6)A new type of water sac is proposed in this study,which can be used to reduce vibration and prevent the dust caused by CIGV.The vibration reduction effect of the device is verified by numerical model,and the effect of key parameters is further discussed.