Study On Mechanical Mechanism And Model Test Of Urban Viaduct Demolition Blasting

Urban traffic increased with the rapid development of economy in our country, sopart of viaducts built in early stage are difficult to meet the needs of the traffic and needto be upgraded by demolition. Surroundings around urban viaducts are often extremelycomplex, so demolition blasting must follow the predetermined blasting scheme. Theharmful effect of blasting on surroundings and the environment must be strictlycontrolled. However, the research related to demolition blasting for urban viaduct is stillscanty.Theoretical analysis, numerical simulation, experimental research and engineeringapplication are combined in this paper to study the mechanics mechanism and modeltest of demolition blasting for urban viaduct. The following main conclusions can bedrawn from the quantitative analysis:(1) According to the characteristics of piers and the deformation of reinforcing barsafter blasting, the different shape for reinforcing bars under different constraintconditions is described. Furthermore, initial bending instability model of exposedreinforcing bars in demolition projects is used to calculate the height of incision on pier,the precision of calculation is effectively improved.(2) Continuous collapse mechanics models are established according to thecontinuous beam bridge, continuous girder bridge and continuous bridge. Meanwhile,numerical analysis is made by using the finite element software to provide a basis forthe selection of key parameters in the design of blasting.(3) Putting forward the main content of model test for demolition blasting of urbanviaduct through the analysis of the significance, basic principle and design principle ofmodel test for urban viaduct.(4) Getting the parameters of specific explosive consumption with differentstrength of concrete and reinforcement according to the study of model test on singlepier with different strength and stiffness.(5) Finding the best delay time is about250ms through the analysis of the collapseprocess, blasting vibration and collapse vibration according to the single span model testfor the urban viaduct.(6) Achievements of this research have applied to demolition blasting of ultra-longurban viaduct and acquired good effect.