超载预压施工过程软土固结变形特征研究  

STUDY ON THE CHARACTERISTICS OF SOFT SOIL CONSOLIDATION DEFORMATION DURING OVERLOAD PRELOADING CONSTRUCTION PROCESS

作　　者：贺建清[1,3] 王湘春 胡惠华 陈谦 林滢 张鹏 HE Jianqing;WANG Xiangchun;HU Huihua;CHEN Qian;LIN Ying;ZHANG Peng(Hunan Provincial Key Laboratory of Geotechnical Engineering for Stability Control and Health Monitoring,Chinese Academy of Sciences,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Provincial Communications Planning,Survey&Design Institute Co.,Ltd.,Changsha 410200,China;Central South Highway Construction and Maintenance Technology Key Laboratory of Hunan Province,Changsha 410200,China)

机构地区：[1]湖南科技大学岩土工程稳定控制与健康监测省重点实验室,湘潭411201 [2]湖南省交通规划勘察设计院有限公司,长沙410200 [3]中南公路建设及养护技术湖南省重点实验室,长沙410200

出　　处：《工程地质学报》2024年第6期2277-2285,共9页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:52078211);交通运输部企业技术创新项目(资助号:2015315798060);湖南省自然科学基金项目(资助号:2017JJ30252);湖南省自然资源厅科技计划项目(资助号:湘自资科20230143DZ)。

摘　　要：超载预压法作为一种有效的软土地基处理方法,常被广泛应用于对工后沉降有严格要求的软基处理工程。为研究软土在超载预压、卸荷回弹、再加载(运营)各个阶段的次固结变形特征,尤其是超载卸除后土体的回弹、次固结变形特征,模拟超载预压处理软土地基施工过程现场土体受压工况,重塑洞庭湖安乡软土进行一维固结蠕变试验。研究结果表明,超载预压阶段,软土的压缩曲线主、次固结分界明显,次固结阶段的压缩曲线近似直线。随着预压荷载增大,次固结系数呈逐渐减小。卸荷回弹阶段,回弹峰值及达到回弹峰值所需时间与预压卸荷增量比呈线性递增关系,并提出了相应的计算公式。卸除超载可延缓但不能阻止土体次固结变形,次固结系数受预压荷载影响明显,随着预压荷载增加,呈现出逐渐增大的趋势。再加载阶段,主、次固结阶段曲线连接线逐渐平缓,次固结系数随着施加荷载增加呈逐渐减小的趋势。经超载预压处理软土的次固结系数明显降低,超载预压法能有效控制工后沉降。As an effective method for treating soft soil foundations,the overload preloading method is widely utilized in projects with stringent requirements for post-construction settlement.To investigate the sub-consolidation deformation characteristics of soft soil during various stages of overload preloading,including unloading rebound and reloading operations—especially the rebound and sub-consolidation deformation features post-surcharge removal—simulations of in-situ soil compression conditions during the construction process of overload preloading treatment for soft soil foundations were conducted.Additionally,one-dimensional consolidation creep tests were performed on the soft soil of Anxiang,Dongting Lake.The results indicate that during the overload preloading stage,the compression curve of soft soil exhibits an evident boundary between primary and secondary consolidation,and the curve in the secondary consolidation stage is nearly straight.With the increase of preload,the secondary consolidation coefficient gradually decreases.In the unloading rebound stage,the rebound peak and the time required to reach it linearly increase with the preload unloading increment ratio,and a corresponding calculation formula is proposed.The removal of overload can delay,but not prevent,the secondary consolidation deformation of soil.The secondary consolidation coefficient is notably influenced by the precompression load,showing a gradual increase with the precompression load.During the reloading stage,the curve connection lines in the primary and secondary consolidation stages gradually flatten out,and the secondary consolidation coefficient decreases with the increase of the applied load.The secondary consolidation coefficient of soft soil treated by overload preloading is significantly reduced,demonstrating that the overload preloading method can effectively control settlement after construction.

关 键 词：超载预压 一维固结蠕变试验 洞庭湖 安乡软土 次固结系数 回弹 工后沉降 

分 类 号：P642.133[天文地球—工程地质学]