Numerical Simulation Of Deep Foundation Temporary Support Demolition Blasting Under Complicated Circumstance

With demolition blasting technology applied in urban construction, the safety of demolition blasting and its various damage effect have attracted the wide attention from the society, so studying the damage mechanism and control measures of blasting process and blasting seismic effect are conducted, which plays a very important role in engineering practice guide and safety of blasting construction engineering. Due to the many blast-holes, large volume of the work and complexity of detonating network in demolition blasting of shoring of trench, safety analysis and evaluation on the stability of bracing structure of foundation pit, the blasting seismic effect et. are necessary to ensure the safety and stability of foundation pit supporting structure and the building construction around.Basing on the practical project of demolition blasting in temporary supporting for deep foundation pit, studying safety problems of the underground wall during demolition blasting process and blasting vibration safety and selection of millisecond blasting delay intervals, and applying the theory such as explosion mechanics, seismic wave propagation and attenuation, the finite element theory, numerical simulation et., the above practical problem are studied and discussed. However, the main results and discovery contents are got as follows:1.The research on the explosion process and the failure process in rock during the blasting process, especially the stress variation of concrete and its effect are conducted.2.According to seismic wave theory, the formation, propagation and attenuation law of blasting seismic wave are analyzed and the features of demolition blasting seismic wave is comprehensively expounded3.Using ANSYS/LS-DYNA to establish the three-dimensional finite element model, blasting process of explosive in concrete is numerically simulated. Then, the failure process of concrete in the explosion is analyzed and difference damage effect of underground wall between pre-splitting blasting and millisecond blasting is compared. Last, the protection to supporting structure scheme is proposed;4.For the deep foundation pit support temporary in the characteristics of blasting demolition, the simulation object of blasting vibration model simplified. Study on propagation of blasting seismic wave and the influence of different charge, different millisecond delay interval and different initiation network of the deep foundation pit support blasting vibration characteristics analysis of blasting vibration wave propagation and superposition rule guiding and optimizing blasting design selection of reasonable blasting parameters of temporary, and can predict the blasting vibration of deep foundation pit temporary support blasting produced.