水泥注浆改性土体对地面振动衰减作用的原位试验研究

In-situ tests for attenuation effect of cement grouting modified soil body on ground vibration

提高地基动力刚度是减小高科技设施环境振动的有效措施。而水泥注浆是提高地基动力刚度的行之有效的工程技术之一。基于原位振动扫频试验,以5~100 Hz、步长为0.5 Hz的简谐激励作为动力荷载,通过测量和对比注浆区域和非注浆区的地面振动响应,研究了水泥注浆改性卵石土对地面振动的衰减作用。试验结果表明,水泥注浆改性卵石土能够降低29.5%的竖直向地面振动速度总有效值和30.8%的东西向地面振动速度总有效值,而对南北向地面振动速度总有效值几乎没有影响。此外,在整个分析频率范围内,水泥注浆改性卵石土的振动衰减作用是不连续的,表现为有些频率地面振动的速度有效值得以衰减而有些频率地面振动的速度有效值得以放大,但是总体而言衰减作用大于放大作用。

Improving dynamic stiffness of foundation is an effective measure to reduce environmental vibration of high-tech facilities.Cement grouting is one of effective engineering techniques to improve dynamic stiffness of foundation.Here,based on in-situ vibration frequency sweep tests under dynamic load of harmonic excitation with 5-100 Hz and 0.5 Hz as step length,the attenuation effect of cement grouting modified pebble soil on ground vibration was studied by measuring and comparing ground vibration responses of grouting area and non-grouting area.The test results showed that cement grouting modified pebble soil can reduce 29.5%of the total effective value of vertical ground vibration velocity and 30.8%of the total effective value of ground vibration velocity in east-west direction,but have little effect on the total effective value of ground vibration velocity in north-south direction;within the whole analysis frequency range,the vibration attenuation of cement grouting modified pebble soil is discontinuous,effective values of ground vibration velocities with some frequencies are reduced,while those with some other frequencies are amplified,but totally,attenuation effect is larger than amplification one.