预制桩施工的振动影响分析

Analysis of vibration caused by prefabricated pile’s dynamic driving

动力打桩过程中,地面质点的振动可能引起地面建筑物和构筑物的损坏。通过对电厂工程的试桩施工的全程监测,建立了桩尖入土深度与地面质点振动关系曲线,揭示了桩尖土的特性是控制地面振动的主要因素。地面的振动与波的特征有关,因而近场和远场有不同的衰减规律,即近场振动衰减快,远场衰减慢。动力打桩过程中,由于土层的振源在桩尖处,且由浅到深,通过远场在被保护对象附近设置减振沟是一项有效的减振措施。

The vibration caused by the pile＇s dynamic driving may result in damage to the structure near the site. A vibration monitoring has been completed in a power plant project where prefabricated piles are driven dynamically. Based on the monitoring data, the relationship between the depth of the pile＇s tip in the soil and the peak velocity of vibration on the ground has been established; and the property of the soil at the pile＇s tip is thought to be the main factor for the vibration. In addition, the vibration on the ground is related to the character of elastic waves, thus the decay laws are different at vicinity and there far from the pile. Moreover, the damping ditch near the object to be protected is more effective to reduce the magnitude of vibration on account of the epicentre being in the deep soil.