Study On The Security Allowed Vibration Velocity Of Underground Pipeline Under Blasting

Blasting method is widely used in the process of subway construction and pit projects as one of the main means.The instantaneous seismic wave must disturb the soil,which influence the embedded pipelines even lead the embedded pipelines are destroyed at the serious moment.But the relevant specification are lack of the standards about embedded pipeline included safety regulation for blasting.Hence,it is significance to study the dynamic response of pipelines and the critical vibration velocity under blasting load.In this paper the single-hole blast experiment was carried out to study the propagation attenuation regular of seismic wave.Except for,3D-model of numerical simulation included tunel,pipeline and soil also was used to analysis the characteristic of the change,taking the deepth of pipiline,distance,material and diameter into consideration.The main researched achievement are as follows:1.The date of single-hole blast experiment show that vertical vibration gives priority to the seismic wave,As the blast center distance increase,however,all the vibrating velocity of particle ware decrease.The FFT frequence of vibration was between of 100HZ to 200HZ,but the FFT frequence do not change with the change of blast center distance.The method of analysis of regression was used to dispose the date,getting the equation of the surface particle vibration velocity.2.Using the numerical software of ANSYS/LS-DYNA to creat the 3D-model of numerical simulation,and the conclusion showed that the result of the numerical simulation is bigger twenty percent than the result of experiment date,which proved the reliability of the numerical simulation.3.The field test about dynamic response of pipelines was done,caming to a conclusion that the stress of the meet blast>back the blast>TOP>socle.The model of pipeline failure was axial damage under blasting.The main principal stress direction and horizontal direction at 90° Angle that the destruction of pipeline was decided by axial stress under blasting.4.The responsed result of pipeline showed that the order of vibration velocity was the sureface of the meet blast>back the blast>left side closed to explosive source>right side closed to explosive source.The deeper,the vibration velocity of pipeline was greater,the vibration velocity pipeline which buried deeper was larger than the pipeline buried superficial.The smaller the net distance,the vibration velocity of pipeline was greater.The fewer crack the medium the vibration velocity of pipeline was greater,the vibration velocity pipeline.The vibration strength of pipelines has realation with the material of pipelines,and the steel<cast iron<Pvc<concert.When the diameter of pipelines was less than a certain value,vibration velocity of pipeline was increase with diameter increasing obviously,while the diameter of pipelines was more than the value,the vibration velocity increased not obviously.5.The limit stress of different material were calculated and the biggest single dose that pipeline could bear among steel cast iron.PVC concrete were 75 kg,65kg,30 kg,25 kg.And the vibration velocity was 23 cm/s,19 cm/s,15 cm/s,14 cm/s.