Numerical Research Of Foundation Vibration Effect Under Consolidation With Dynamic Compaction

Part of compaction energy spread around in the form of wave. When the wave is strong enough it can cause the destruction of precision instruments and adjacent pipes, accelerate old buildings’ aging, even affect residents’ life.This paper summarizes previous theoretical research results. And establish the finite element model using a gas foundation reinforcement project in Turkmenistan as the prototype. Then study vibration effect and vibration reduction measures with LS-DYNA software. Contents mainly include: dynamic compaction wave characteristics and the attenuation law of vibration wave, the relationship between vibration intensity and hammer’s weight, vibration reduction effect between damping groove position and depth, the influence of different construction order to ground vibration, the influence of double or three hammer to ground vibration.After systematic literature and numerical research, according to numerical results of 2000 k Nm dynamic compaction, the paper comes to conclusions though sorting and analyzing data:1)The field vibration intensity exponentially decrease with the distance, the formula of fitting curve of ground vertical vibration velocity and distance:1.794y629.82x-=In the type, y is vertical vibration velocity(cm/s);x is the distance(m).2)Keeping the compaction energy constant, when the hammer is 18 ~ 20 m high from the ground, the vibration on the ground is strongest. In the actual construction, it is best to keep the distance between hammer and ground away from the scope. When the vibration mitigation ditch is 25 to 30 m form tamping points, the effect is best. And the deeper ditch is the better the effect will gain.3)In the construction of dynamic compaction, the reinforcement from the far field first can reduce the ground vibration intensity. According to the importance of the surrounding buildings, choose the region farthest from the most important building to be reinforced first. When a foundation is improved with several hammers, vibration wave superpose in the field, strengthen regional and weaken region distribute complexly. And the maximum vibration intensity is lager, the control of the compaction vibration wave become more difficult.