路堤下“土工格室+碎石桩”双向增强复合地基桩土应力比及沉降计算  

Calculation for Stress Concentration Ratio and Settlement of Bidirectional Reinforced Composite Foundation Consisting of Geocell Mattress and Stone Column Under Embankment

作　　者：赵明华[1] 刘猛[1] 马缤辉[2] 龙军[1] 

机构地区：[1]湖南大学岩土工程研究所,湖南长沙410082 [2]湖南科技大学土木工程学院,湖南湘潭411201

出　　处：《中国公路学报》2016年第5期1-10,共10页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51478178;51308208)

摘　　要：为了充分考虑路堤、格室体、碎石桩以及桩间土体共同作用对路堤荷载下"土工格室+碎石桩"双向增强复合地基桩土应力比与沉降计算方法的影响,以单桩等效加固范围内的路堤与复合地基为分析对象,引入"土柱模型"与环形大挠度薄板分别考虑路堤土拱效应与土工格室的抗弯拉作用,同时基于分层总和法,结合胡克定律与双曲线模型,综合考虑桩体鼓胀与桩土界面滑移,建立了考虑路堤、格室体及碎石桩复合地基共同作用的三维模型,获得了该类复合地基的桩土应力比及沉降计算方法;并采用室内试验数据与某工程实例对该计算方法进行了验证,同时系统分析了格室体与碎石桩的变形特征。结果表明:土工格室可有效增加碎石桩鼓胀范围与鼓胀量,并使其最大鼓胀位置上移,充分发挥其承载能力,格室垫层可明显加大桩体上刺难度,降低土拱效应;在路堤荷载不变的情况下,碎石桩中性点以下部分的桩土相互作用对格室体刚度变化并不敏感;此外,格室垫层"柔性筏板效应"对荷载调节的贡献大于"拉膜效应"。Aiming at fully considering the influence of the coupling actions of all the components in the system consisting of embankment,BCF formed by geocell mattress and stone column and soil mass among columns on the methods for calculating the stress concentration ratio and settlement of bidirectional reinforced composite foundation consisting of geocell mattress and stone column under embankment load,taking the embankment within equivalent single pile strengthening area and composite foundation as research subject,a 3D model was established based on splitting summation method and the hook law which was introduced to evaluate lateral bulging of column and column-soil interface slip.The validity of the presented method was verified through the comparison with experiment data and data from an example of practical project. Meanwhile,the deformation characteristics of geocell and stone column weresystematically analyzed.The results show that geocell mattress can effectively increase the lateral bulging amount,enlarge the zone of bulging of the stone column,and raise the location of the largest bulging,which gives the full play to the bearing capacity of the stone column.Geocell reinforced cushion can significantly increase the penetration difficulties to big column and lower the soil arch effect.Under the constant embankment load,the coupling action of pile soil below the neutral point of stone column is not sensitive to the variation of the stiffness of the geocell mattress.Besides,flexible raft effect of geocell reinforced cushion has greater contribution to load regulation than membrane effect.

关 键 词：道路工程 路堤荷载 受力分析 碎石桩 土工格室 桩土应力比 沉降 

分 类 号：U416.03[交通运输工程—道路与铁道工程]