| With the continuous expansion of China's underground transportation network,the project situation of under-construction pipelines under tunnel drilling and blasting is still rare.In the process of tunnel blasting construction,the impact of blasting vibration on the pipeline is often encountered.If the blasting vibration cannot be controlled within the safe vibration range allowed by the pipeline,it may cause safety accidents such as explosion of the natural gas pipeline,burst of the water pipe and leakage of the oil pipeline..Based on the engineering background of Guiyang Rail Transit Metro Line 2,this paper uses the ABAQUS finite element software to establish the three-dimensional numerical value of the interaction between tunnel,rock and soil body and pipeline based on the investigation of buried pipeline types and geological conditions along the subway.The model focuses on analyzing the dynamic response characteristics of the tunnel near the buried pipeline and the surface measurement points above the tunnel during the blasting process to study the impact of the blasting construction on the safe operation of the buried pipeline.The main research contents and conclusions are as follows:(1)Briefly describe the generation mechanism,type,basic characteristics of propagation and propagation attenuation theory of blasting seismic waves.(2)A three-dimensional dynamic response model of the tunnel-rock-soil-pipe interaction under blasting is established on the ABAQUS finite element platform.The model comprehensively considers the calculation and application of equivalent blasting loads,and the setting of viscoelastic artificial boundaries,Tube-soil contact setting,selection of dynamic parameters of each material,etc.Based on this,through the numerical simulation,the vibration law of the particles at different positions of the pipeline is analyzed,and the results show that the peak vibration velocity intensity of the pipeline particle at the position directly above the explosion source is the largest in the vertical direction,and then gradually decreases to both sides;Taking the position of the pipeline particle directly above the explosion source as the starting point,the axial distance of the pipeline increases,and the peak vibration velocity of the pipeline particle in the axial direction generally increases first and then decreases.(3)Taking the rock layer-red clay layer model as an example,the pipes and thesoil mass points around the pipe are selected at the positions directly above the blast source,and the vibration velocity and displacement changes in different directions are studied and analyzed.The research shows that the trend of the vibration velocity and displacement curve of the pipeline and the soil around the pipe in different directions are basically the same.The peak vibration velocity of both of them appears at the vertical top position of the pipeline,and the peak vibration velocity of the pipeline is about the pipe.The peak vibration speed of the surrounding soil is 1.25 times;the difference between the displacement changes of the two is very small,and the separation of the pipeline and the soil layer is not obvious.(4)By changing the size of the rock layer and the diameter of the charge,numerical simulations are used to study the vibration response of the pipeline and the ground surface measurement points above it under blasting loads.Studies have shown that rock layer material directly affects the ratio of the vibration speed of the surface measurement point to the vibration speed of the pipeline.Under the red clay layer,the peak vibration velocity of the surface measurement point and the pipeline measurement point is nearly twice;the ratio of the peak vibration velocity between the surface measurement point and the pipeline under the asphalt and concrete layers is about 1.42 and 1.21 times respectively;the pipeline-surface measurement The point vibration speed will increase with the increase of the charging diameter. |
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