基于力学-经验模型的交通荷载作用下软基长期沉降计算  

Long-term settlement calculation of soft soil foundation under traffic load based on mechanical-empirical model

作　　者：徐林荣[1,2] 陈昀灏 商拥辉[1,3] 冯多 丁奎 XU Lin-rong;CHEN Yun-hao;SHANG Yong-hui;FENG Duo;DING Kui(School of Civil Engineering,Central South University,Changsha 410075,Hunan,China;NationalEngineering Laboratory for Construction Technology of High Speed Railway,Central South University,Changsha 410075,Hunan,China;School of Civil Engineering and Architecture,Huanghuai University,Zhumadian 463000,Henan,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学高速铁路建造技术国家工程实验室,湖南长沙410075 [3]黄淮学院建筑工程学院,河南驻马店463000

出　　处：《长安大学学报（自然科学版）》2021年第5期1-10,共10页Journal of Chang’an University(Natural Science Edition)

基　　金：国家自然科学基金项目(51778634);浙江省交通运输厅交通建设科研计划项目(2019001)。

摘　　要：为合理表征交通荷载循环作用下各因素对软土累积塑性应变的影响,并对运营期内车辆荷载引起的软土地基沉降进行有效预测,在总结归纳上海地区典型饱和软黏土动三轴试验基础上,充分衡量动、静偏应力耦合效应的影响,给出耦合应力水平的定义,利用耦合指数χ反映动、静偏应力的各自影响程度,以此对循环荷载影响下软土的强度弱化模型进行指数化修正;引入软化指数极限值,提出修正耦合应力水平的概念,建立起综合反映动、静偏应力耦合作用、固结围压、土体结构性、强度弱化及循环加载次数因素影响的软土累积塑性应变模型,并以此模型为基础进行交通荷载诱发的软土地基长期沉降计算,结合申嘉湖(上海—嘉兴—湖州)高速公路沉降实测数据对计算结果进行检验。研究结果表明:通过对强度弱化模型及累积塑性应变模型进行参数分析可知,耦合应力水平对模型的描述在等向、偏压固结状态下具有统一的适用性;申嘉湖高速公路长期沉降计算表明地基浅表层塑性变形最为显著;在运营初期理论计算曲线与实测曲线略有差异,在运营1年后两者差异逐渐减弱,后期保持较强的一致性;随着运营年限逐渐增大,沉降逐渐趋于稳定,预估通车550 d后软土地基累积沉降量达128 mm,与实测数据的相对误差仅为1.68%,说明该模型合理可靠。To reasonably characterize the influence of various factors on the cumulative plastic strain of soft soil under the cyclic action of traffic load, and effectively predict the settlement of soft soil foundation caused by vehicle load during the operation period, based on summarizing the typical dynamic triaxial test of saturated soft clay in Shanghai, and on the basis of fully measure the effect of dynamic and static deviatoric stress coupling effect, the definition of coupling stress level was given, the parameter χ that reflect the dynamic and static deviatoric stress the degree of their influence, in order to strength weakening of soft clay under the influence of cyclic loading model to correct the indexation. By introducing the limit value of softening index, the concept of modified coupling stress level was proposed, and the cumulative plastic strain model of soft soil was established, which comprehensively reflected the influence of coupling effect of static and static deviator stress, consolidation confining pressure, soil structure, strength weakening and cyclic loading times. Based on this model, the long-term settlement of soft soil foundation induced by traffic load was calculated, and the calculated results were tested with the measured data of Shenjiahu(Shanghai-Jiaxing-Huzhou) Expressway settlement. The results show that the description of the coupling stress level has uniform applicability in the isotropic and biased consolidation state, through the parameter analysis of the strength weakening model and the cumulative plastic strain model. The calculation results of long-term settlement of Shenjiahu Expressway show that the plastic deformation of shallow surface layer is the most significant. There is a slight difference between the theoretical calculation curve and the measured fitting curve in the initial operation period, and the difference between them gradually weaken after one year of operation, and maintain a strong consistency in the later period.With the increasing of operation years, the

关 键 词：道路工程 软土地基 交通荷载 累积塑性应变 动、静偏应力 强度弱化 长期沉降计算 

分 类 号：U416[交通运输工程—道路与铁道工程]