基于BBM非饱和土本构模型的高填路堤沉降特性  

Settlement Characteristics of High-filled Embankment Based on Unsaturated Soil Constitutive Model

作　　者：关振长[1] 毛顺飞 张淑宝 徐惠明 GUAN Zhen-chang;MAO Shun-fei;ZHANG Shu-bao;XU Hui-ming(School of Civil Engineering,Fuzhou University,Fuzhou Fujian 350116,China;Zhangzhou Xiamen・Chengdu Expressway Extension Engineering Co.,Ltd.,Zhangzhou Fujian 363000,China)

机构地区：[1]福州大学土木工程学院,福建福州350116 [2]漳州厦蓉高速扩建工程有限公司,福建漳州363000

出　　处：《公路交通科技》2020年第11期31-38,共8页Journal of Highway and Transportation Research and Development

基　　金：国家自然科学基金项目(51678155);福建省交通运输科技发展项目(201531)。

摘　　要：基质吸力是非饱和土的重要特性,对边坡稳定性、填筑路基沉降等具有较大影响。常规本构模型未考虑非饱和土中基质吸力的影响,用以分析高填路堤沉降特性时,其计算结果不够准确。为研究非饱和土中基质吸力对路堤工程的影响,采用BBM(Barcelona Basic Model)本构模型,以临界状态线和状态边界面来描绘非饱和土的应力空间,以平均净应力、偏应力、基质吸力3种应力变量来划分弹性空间与塑性空间;在FLAC3D数值平台上通过FISH语言对传统MCC(Modified Cam-Clay Model)模型进行修正后,得以实现非饱和土的BBM模型。以厦蓉高速公路漳州段高填路堤工程为背景,分别采用BBM和MCC两种本构模型对陡坡高填路堤的分层沉降特性展开数值模拟。模拟结果表明,高填路堤的分层沉降量沿填土高度呈现中间大、两头小的分布形态;路堤中部既承受了较大的上覆荷载,下伏也有较厚的可压缩层,因此最大分层沉降发生在路堤中部;由于BBM本构模型充分考虑了非饱和土基质吸力的影响,其计算沉降量略小于MCC本构模型,其沉降计算量与分布规律更符合工程实际。以上研究成果可为高填路堤的沉降计算及工程设计提供借鉴与参考。Matrix suction is the key characteristic of unsaturated soil,which has great influence on geotechnical slope stability and filled subgrade settlement,etc.The regular constitutive models often neglect the influence of matrix suction in unsaturated soil,when used to analyze the settlement characteristics of high-filled embankment,the calculation results are not accurate enough.To study the influence of matrix suction in unsaturated soil on embankment engineering,the Barcelona Basic Model(BBM)constitutive model is used to describe the stress space of unsaturated soil with critical state line and state boundary surface,the elastic space and plastic space are divided by 3 stress variables(average net stress,partial stress and matrix suction).On the FLAC3D numerical platform,the traditional Modified Cam-Clay(MCC)Model is modified by FISH language to realize the BBM model of unsaturated soil.On the background of the high-filled embankment project in Xiamen-Chengdu expressway,the numerical simulation on the stratified settlement characteristics of the high-fill embankment with steep slope is conducted by using both BBM constitutive model and MCC constitutive model.The simulation result shows that(1)the stratified settlement of the high-filled embankment is featured as a spindle shape;(2)the middle of the embankment not only bears a large overlying load,but also has a thick compressible layer underneath,so the largest stratified settlement occurs in the middle of the embankment;(3)because the BBM constitutive model fully considers the influence of unsaturated soil matrix suction,the settlement calculated by it is slightly smaller than that calculated by the MCC constitutive model,and the calculated settlement and the distribution rule are more in line with engineering reality.The research result could provide a technical reference for the settlement calculation and the engineering design of high-filled embankment.

关 键 词：道路工程 非饱和土本构模型 数值模拟 基质吸力 高填路堤 沉降特性 

分 类 号：U416.1[交通运输工程—道路与铁道工程]