Diversion Tunnel Blast Vibration Effect Analysis During Powerstation Expansion Project

Blast construction is always used in the excavation of tunnel in many hydroelectric engineerings.It is unavoidable to appear the questions that the effects on the tunnel itself and neighboring constructions by blast vibration. Especially we will meet the question of blast vibration on the existent tunnel by blast excavation of hydroelectric diversion tunnel under construction of many tunnels or two following tunnels. When the intensity of blast vibration exceed the criterion value,it will damage even destroy the concrete construction and rocks.So it is very essential to understand the effect and characteristic of blast vibration dynamic load on concrete lining and rock. The suggestions for safety criterion of blasting vibration should be proposed ,and the regulation can be offered for practical design of blasting construction.In the factual engineering, safe control criterion is often in virtue of measure the spot's blast vibration velocity and regression analyze attenuation equation of blast vibration so that forecast possible coming into being vibration intensity.In this article, author has done some research on dynamic response on cirque tunnel concrete and different direction attenuation equation under blast vibration dynamic load by making use of general FEM analysis software-ANSYS-LS/DYNA.This thesis, author has summarized the theory of passes and attenuation equation of stress wave;deduced process and solution of vibration equation; calculated the velocity of concrete lining and rock under blast vibration dynamic load; explained concrete different part's blast vibration velocity and distributing changes by theory of Stress reflecting; emphasized attenuation equation of radial velocity on axis top of tunnel; at last analyzed the effect by the blast vibration frequency.By means of calculation and anslysis ,some conclusions are reached as follows:(1) Ihe effect is smaller that is made by water pressure on vibration caused by blast dynamic load inside and outside of existent tunnel.(2) Low frequency stress wave does more damage.(3) As far as blast vibration dynamic load is concerned,the time is longer and the damage on concrete and rock is bigger.(4) Blast vibration velocity has magnify effect in the vertical direction,the vibration value of vertical direction is bigger than horizontal direction at the same distance to blast place.(5) Radial velocity is bigger on axis top of tunnel at the distance of 3 times of radius to free face.(6) As blast vibration velocity of existent tunnel, it is bigger that is closer to blast spot, it is bigger in Interior side of concrete lining because of free face.(7) In the factual engineering blast vibration velocity's attenuation is decided by medium damp,but it has magnify effect in some area because of free face and corner.