| The subway plays an important role in modern transportation,undertaking the transportation tasks is getting heavier and heavier.With the rapid development of transportation industry in our country,the underground tunnel through the urban will be more and more,a large part of the tunnel adopted blasting method to conduct the field opration,but this method will cause certain vibration effect for the safety of adjacent buildings.Therefore,the research under the action of blasting seismic wave about adjacent buildings vibration response rules,and controlling the damage and loss of property of buildings caused by blasting operation,which has an important scientific significance to guarantee building safety.In this paper,a section of Dalian metro no.1 line was the research object,using ANSYS/LS-DYNA to establish the model of tunnel blasting excavation;The author used Matlab to programme back analysis in order to gain reasonable input time parameter of time history curve of triangle blasting load,and then the selection of time parameters of the classic triangle blasting load was improved to reduce the error of simulation results.The specific research contents are as follows:(1)In the process of tunnel blasting excavation,blasting vibration cavity effect has been produced in the excavated area.Many literatures have proved the "blasting safety regulations "GB6722-2014 Sadov’s formula,it has a high precision in the analysis of the regression prediction of flat ground,but tunnel cavity effect leading to the surface blasting seismic wave attenuation regularity of the rear of tunnel face does not conform to the calculation results of the existing Sadov’s formula.For the tunnel cavity effect,this paper usedπ theorem,and improved Sadov’s formula,and then the improved formula and Sadov’s formula was used to conduct regression analysis for the same group of tunnel blasting monitoring data,the improved formula indeed reduced the error caused by the cavity effect.(2)Currently for the study of numerical simulation of tunnel blasting,numerical simulation is only aimed at the blasting instant,the factor of geostatic stress in rock mass is seldom considered.In this paper,the finite element model of blasting peration is set up by using the "implicit and explicit" solution sequence of ANSYS/LS-DYNA,adding geostatic stress for rock mass,making the blasting simulation more intact,in the hope of improving the reliability and credibility of the simulation results.(3)When using the classical triangular blasting load time history curve to add the blasting load,there are a lot of randomness in the selection of time parameters.This paper was based on the neural network technique of the particle swarm optimization algorithm conducting back analysis in order to select the time parameters of the time history curve of the triangle blasting load,it made the selection of time parameters has evidence,and the simulation accuracy was increased.(4)According to "blasting safety regulations"(GB6722-2014)article 13.2.2 the control criterion can only ensure the overall safety of the building,and it can not ensure the safety of the internal structure of the building.This paper is based on numerical simulation,according to"blasting safety procedures"(GB6722-2014)article13.2.3 control criterion and the "code for seismic design of buildings"(50011-2010 GB),aricle5.4.2、5.5.1 control criterion,the safety checking calculation of the structural and non structural members of adjacent buildings is carried out,and combined with the calculation results safety rating scale is provided. |
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