振杆密实法加固粉土地基效果试验  

Vibratory Probe Compaction Effect on Silty Foundation Treatment

作　　者：程远 韩杰[2] 朱合华[3] 刘松玉[4] CHENG Yuan;HAN Jie;ZHU He-hua;LIU Song-yu(School of Civil Engineering,Zhengzhou University,Zhengzhou 450001. Henan,China;Department of Civil,Environmental and Architectural Engineering,University of Kansas,Lawrence KS66044 ,Kansas,USA;School of Civil Engineering,Tongji University,Shanghai 200092,China;School of Transportation,Southeast University,Nanjing 210096 ,Jiangsu,China)

机构地区：[1]郑州大学土木工程学院,河南郑州450001 [2]堪萨斯大学土木环境与建筑工程系,堪萨斯劳伦斯ks66044 [3]同济大学土木工程学院,上海200092 [4]东南大学交通学院,江苏南京210096

出　　处：《中国公路学报》2019年第3期63-70,共8页China Journal of Highway and Transport

基　　金：中国博士后科学基金项目(2016M601649);江苏省自然科学基金项目(BK20150279);苏州市姑苏区科技创新创业领军人才项目(姑苏人才办[2015]17号);江苏省省级高层次创新创业博士计划项目(苏人才办[2014]27号)

摘　　要：为了评价振杆密实法加固粉土地基的效果,对宿(迁)新(沂)高速公路粉土地基采用十字形振杆密实技术进行处理,通过加固前后室内试验和原位测试分析了侧向土压力系数和超固结比等参数的变化;研究了路堤填筑期工作性状,分别基于CPTu原位测试和室内试验得到的压缩模量计算加固后上覆荷载下沉降,并与采用双曲线法基于现场实测资料的预测沉降和瑞典振动翼加固沉降进行对比,以证明基于CPTu测试的沉降计算方法的可靠性;比较加固前后相同上覆荷载下地基计算沉降量以分析地基加固前后路堤荷载作用下控制变形能力的差异;比较了加固前后场地土类别的变化。结果表明:试验场地土层加固后静止侧压力系数提高了40%,超固结比提高到1.8～2.3,出现超固结效应;十字形振杆控制粉土地基沉降效果优于瑞典振动翼,基于CPTu测试确定土压缩模量的方法能较好地预测地基沉降,在相同高度填土荷载下,加固后地基沉降比加固前减少约25%;加固后场地指数提高,特征周期减小,场地土类由软弱土提高为中软土,场地类别由Ⅳ类提高为Ⅲ类,在不影响建筑物基础抗震要求的情况下,可大幅降低建设投资。Crisscross section vibratory probe compaction was used to reinforce a silty foundation at Suqian-Xinyi Expressway in order to investigate the compaction effect. Field and laboratory tests were conducted to analyze variation of the lateral earth pressure coefficient and the over-consolidation ratio before and after reinforcement. The properties of an embankment during filling was studied, and settlement under overburden load after reinforcement was calculated based on the compressive modulus obtained by piezocone penetration test(CPTu) and laboratory tests. These results were compared with settlement predicted by applying the hyperbolic method to measured data as well as that of Swedish vibro-wing compaction, which verified the reliability of settlement calculation based on CPTu. The calculated settlement of the foundation under the same overburden load before and after reinforcement was compared to analyze the difference in deformation control ability under embankment load. The change of site classification before and after reinforcement was also discussed. The results show that the lateral earth pressure coefficient is increased by 40%, and the over-consolidation ratio is increased to 1.8-2.3 after reinforcement;the over-consolidation effect appears in the soil layer. Therefore, the effect of crisscross section vibratory probe compaction on the settlement of a silty foundation under embankment load is better than that of Swedish vibro-wing compaction. Determining the soil compression modulus based on CPTu can also better predict foundation settlement. The foundation settlement after reinforcement is approximately 25% less than that before reinforcement under the same overburden load. After reinforcement, the site index improves, and characteristic period reduces;soil type improves from soft soil to medium soft soil;and site classification improves. Therefore, construction investment can be greatly reduced without affecting the seismic requirement of the foundation.

关 键 词：道路工程 粉土地基 振杆密实法 应力条件 地基沉降 场地类别 

分 类 号：U416.1[交通运输工程—道路与铁道工程]