Ground Impact Load Characterisation And Simulation Analysis Of Building Demolition Collapses

Along with urbanisation and industrial upgrading activities,a large number of buildings(structures)are actively demolished.During building demolition,the touchdown effect caused by the impact of collapsing bodies touching the ground may lead to cracking or damage to the surrounding infrastructure,which is the most prominent harmful effect of building demolition.While blasting and demolition play an important role in supporting urban regeneration and local economic and social development,their safety is also a growing concern,so research into the impact of building demolition collapses on the ground is imminent.In order to clarify the load characteristics of building collapse impact and its ground vibration characteristics,this paper summarizes the calculation model of ground impact load and finds out the calculation method applicable to building collapse impact load;carries out the model test and numerical simulation of high-rise building impact on homogeneous strata to analyze the distribution characteristics and propagation law of soil pressure and acceleration of deep soil body;carries out the model test and numerical simulation of high-rise building demolition impact on top hard and bottom soft strata to analyze the distribution characteristics and propagation law of soil pressure and acceleration of deep soil body under the effect of ground vibration.The model tests and numerical simulations of the impact of demolition of high-rise buildings on hard and soft strata were carried out to analyse the distribution characteristics and propagation laws of soil pressure and acceleration in the deep soil of hard and soft strata under the action of ground contact vibration;the dynamic response of soil under the action of ground contact impact of building collapse was studied in conjunction with actual projects.The main conclusions are as follows.(1)Through the comparative analysis of impact load models and the combination of engineering calculations and LS-DYNA numerical simulations,four applicable impact load calculation models for building collapse touchdown have been compiled.Model tests and numerical simulations of collapse body touchdown impact on homogeneous strata were carried out to reveal the distribution characteristics and propagation laws of deep soil pressure and acceleration of touchdown impact effects,and these touchdown effects were verified by LS-DYNA numerical simulations,and the results were relatively consistent.(3)Model tests and numerical simulations were carried out for the impact of collapsing body touchdown on hard and soft layers,and the distribution characteristics and propagation laws of soil pressure and acceleration in hard and soft layers were derived and verified by numerical simulations,and the results were consistent.In order to compare the model tests of collapse touchdown impact on homogeneous soil layer,the impact effect of homogeneous soil layer under touchdown impact is compared and the phenomenon that the earth pressure amplitude of soft soil layer will become smaller after overlying hard soil layer is derived from the dispersion effect of impact ground pressure in hard soil layer.(4)The results of field tests carried out on actual building demolition projects reflect that the simultaneous and continuous touchdown impact of multiple collapsed bodies from aerial disintegration of buildings increases the extent and magnitude of earth pressure propagation in deep soils.