水运工程堆载预压处理地基动力测试应用研究

Dynamic Testing Application of Foundation Treated by Preloading in the Water Transport Engineering

地基经过真空堆载预压处理后,其地基承载性状及动力参数特性都产生不同改变,这种变化会对动力基础设计产生较大影响。基于此,结合实际水运工程项目对真空堆载预压处理后旋喷桩复合地基及钻孔灌注桩基础分别进行地基动力测试,通过测试获得地基及桩基模型基础的抗压、抗剪及抗扭的刚度参数、竖向及水平转向的第一振型以及扭转向的阻尼比及参振总质量。依据各项实测数据计算出旋喷桩复合地基及钻孔灌注桩基础底面与静应力有关的振动换算系数,推算出两种不同类型基础的地基抗压、抗剪、抗扭刚度,扭转向阻尼比以及地基竖向和水平回转向第一振型的提高系数。各项实际参数测试计算结果显示,当把两种不同类型地基现场实际获得的地基动力参数用于动力机器基础振动和隔振设计时,应分别根据动力机器基础的实际使用工况换算成设计采用的地基动力参数,以免对基础设计造成偏差。

After the foundation is treated by vacuum stacking pre-pressure,the bearing characteristics,dynamic parameters and characteristics of the foundation are abnormal,which has a great impact on the design of dynamic foundation.Combined with the actual water transport engineering project on the vacuum stack pre-pressure treatment of the rotary jet grouting pile composite foundation and bored pile foundation,dynamic tests were conducted to obtain the stiffness parameters of compression,shear and torsion,the first vibration mode of vertical and horizontal steering,the damping ratio of torsional steering and the total vibration mass of the foundation and pile.Based on the measured data,the vibration conversion coefficients related to the static stress on the bottom surface of rotary jet grouting pile composite foundation and bored pile foundation were calculated,and the foundation compression,shear,torsional stiffness,torsional steering damping ratio and the improvement coefficient of the first vibration mode of vertical and horizontal return steering of the foundation were also calculated.The test and calculation results of various actual parameters show that when the foundation dynamic parameters actually obtained on the site of two different types of foundations are used for the vibration and vibration isolation design of power machine foundation,parameters should be converted into the foundation dynamic parameters adopted in the design according to the actual service conditions of power machine foundation,so as to avoid deviation to the foundation design.