高铁荷载下横观各向同性CFG桩桩土复合路基减振特性研究  

Vibration mitigation characteristics of CFG pile-supported transversely isotropic subgrade under high-speed train loading

作　　者：毕俊伟 高广运[1,4] 耿建龙 BI Junwei;GAO Guangyun;GENG Jianlong(College of Civil Engineering,Tongji University,Shanghai 200092,China;School of Civil Engineering&Transportation,South China University of Technology,Guangzhou 510641,China;Guangzhou Design Institute Group Co.,Ltd.,Guangzhou 510620,China;Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Shanghai 200092,China)

机构地区：[1]同济大学土木工程学院,上海200092 [2]华南理工大学土木与交通学院,广州510641 [3]广州市设计院集团有限公司,广州510620 [4]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《振动与冲击》2023年第4期116-125,共10页Journal of Vibration and Shock

基　　金：国家自然科学基金(51978510,42277130)。

摘　　要：基于2.5D有限元法基本原理,推导横观各向同性地基2.5D有限元控制方程,利用等代桩墙对水泥粉煤灰碎石(cement fly-ash gravel, CFG)桩桩土复合路基进行简化,建立高铁荷载下横观各向同性CFG桩桩土复合路基2.5D有限元分析模型。考虑不同车速,分析横观各向同性地基土体刚度比n对高铁荷载下地面振动的影响,研究CFG桩桩土复合路基的减振机理,探讨桩径、桩间距、面积置换率m对其减振特性的影响。结果表明:高铁荷载下地面振动随横观各向同性地基土体刚度比n的提高而减小;CFG桩能更多地将高铁运行引起的动荷载沿深度方向传导至复合路基深处,从而显著减小地面振动,且减振效果随与轨道中心距离逐渐增强;CFG桩桩土复合路基的减振效果随桩径增大或桩间距减小而增强,当桩径大于等于0.5 m或桩间距小于等于4倍桩径时,进一步增大桩径或缩短桩间距难以显著提高减振效果;振动衰减系数FVR随CFG桩桩土复合路基面积置换率m的增大而减小,当面积置换率m≥0.06时,继续增大面积置换率m对减振效果的影响较小。Deducing the 2.5D finite element method governing equations for the transversely isotropic ground, and simplifying the cement fly-ash gravel(CFG) pile-supported subgrade by the equivalent pile walls, a 2.5D finite element method model for CFG pile-supported transversely isotropic subgrade under high-speed train loading was established. Considering different train speeds, the effects of the stiffness ratio n of transversely isotropic ground on vibrations were analyzed. The vibration reduction mechanism of CFG pile composite subgrade was studied. Meanwhile, the influences of pile diameter, spacing, and area replacement ratio m on the vibration mitigation performance were discussed in detail. Results show that the ground vibrations induced by high-speed trains decrease with stiffness ratio n. Most of the dynamic load was undertaken by CFG pile composite subgrade, and transmitted along the depth into composite subgrade, which results in evidently reduction of ground vibrations. And the vibration mitigation effect enhances with the increasing diameter or the decreasing spacing. However, when the pile diameter or spacing exceeds one certain limit, further increasing diameter or shortening pile spacing cannot significantly improve the effect of vibration reduction. Additionally, with the increasing area replacement ratio m, the factor of vibration reduction FVRdecreases gradually. When the area replacement ratio m is equal to or greater than 0.06, further increasing area replacement ratio m has little effect on vibration mitigation performance.

关 键 词：高速铁路 地面振动 横观各向同性地基 水泥粉煤灰碎石(CFG)桩桩土复合路基 减振特性 2.5D有限元法 

分 类 号：TU435[建筑科学—岩土工程]