Research On Dynamic Response And Cracking Under The Laws Of Blasting Seismic Wave

The bedrock under Qingdao City belongs to granite, which is buried depth and hashigh level. Qingdao subway tunnel excavation that is ongoing now has used the drilland blast construction method on the multi-line. Blasting technology has brought higheconomic efficiency and at the same time, construction blasting impacts on thesurrounding buildings are also increasingly prominent. After the blast occurred itgenerates shock waves, stress waves and seismic waves, with the propagation distanceincreasing, the shock and stress wave energy gradually decay, only blasting seismicwave propagates near the ground, causing the ground to vibrate. When it spreads tobuildings on the ground, it will make the buildings have different degrees damage, thedamage resulting of the masonry structure is the most obvious. Qingdao subway tunnelM3line crossed more than90buildings and they are majority residential buildings.Therefore, building security issue on the blasting vibration is increasingly becomingurgent to solve. In this text, it will study the dynamic response of blasting vibration andthe cracking laws of buildings along with Qingdao subway, we will use the software tosimulate, combine with the field date and housing vibration harm instance. To analyzestructure the different dynamic response at different vibration intensity and summarizethe general cracking laws of the house. The main contents are as follows:(1)To summarize the generation, types, characteristics and laws of energypropagation and attenuation of seismic waves in the rock mass. And to analyze thecharacteristics and effects of blasting seismic wave three elements (amplitude,frequency, duration) on the structure. And analyze the blasting seismic wave on theeffects of structure, and the damage characteristics of the structure and type analysis ofdynamic response of the structure, and use single degree of freedom and multi degree offreedom system to solve the vibration equation respectively.(2)To compare with the response spectrum method and time history analysismethod. In this text, it will choose the dynamic process analysis method, with the aid oflarge-scale finite element analysis software ANSYS, using RVE equivalent units tobuild masonry walls in accordance with multi-degree of freedom system structuremodel. Choosing appropriate blasting seismic wave, using Fourier spectrum transformto determine the vibration wave frequency range. To simulate the piece of masonry wallstructures in seismic waves under different intensity, and analyze the time-history variation of acceleration, stress and displacement of structures, and the crack underdifferent velocity. According to the simulation results summary law of cracking, anddetermine the structure cracking when the corresponding velocity represent value.(3)To analyze the vibration dates and investigate the seismic damage of buildingsalong the subway tunnel in Qingdao. It will study the situation and the distribution ofcrack, to sum up the general rules of vibration crack. Combined with houses securityusing principle and blasting safety regulations, to give a recommendation of Qingdaosubway tunnel blasting vibration velocity values within a certain range of vibrationfrequency.