侧壁后注浆根式沉井竖向承载特性原位试验研究  

In-situ test on vertical compressive bearing characteristic of rooted caisson with grouting at caisson side

作　　者：龚维明[1,2] 杨超[1,3] 戴国亮[1,2] 殷永高 GONG Weiming;YANG Chao;DAI Guoliang;YIN Yonggao(School of Civil Engineering, Southeast University, Nanjing 210096, China;Key Laboratory of C ＆ PC Structures of the Ministry of Education, Southeast University, Nanjing 210096, China;School of Civil Engineering and Architecture, East China Jiaotong University, Nanchang 330013, China;Anhui Transportation Holding Group Co., Ltd, Hefei 230088, China)

机构地区：[1]东南大学土木工程学院,江苏南京210096 [2]东南大学混凝土及预应力混凝土结构教育部重点实验室,江苏南京210096 [3]华东交通大学土木建筑学院,江西南昌330013 [4]安徽省交通控股集团有限公司,安徽合肥230088

出　　处：《建筑结构学报》2018年第5期164-173,共10页Journal of Building Structures

基　　金：国家重点基础研究发展计划(973计划)(2013CB036304);国家自然科学基金(51478109);“十二五”交通运输重大专项(2011318494160)

摘　　要：为进一步完善根式沉井的设计方法并分析井侧注浆对根式沉井竖向承载性能的影响,以望东长江公路大桥为研究对象,对顶入根键前、顶入根键后和顶入根键并注浆后的沉井基础进行了竖向荷载现场试验。试验结果表明：根式沉井的井身轴力在根键布置区内呈阶梯式分布,沉井侧壁后注浆会使轴力的阶梯状分布变缓;扩大孔径并回填砂砾的施工工艺会使沉井周围土层的侧摩阻力无法充分发挥,顶入根键和沉井侧壁后注浆均可有效提高土层的侧摩阻力,注浆可消除回填砂砾对土层侧摩阻力发挥的不利影响;顶入根键和井侧后注浆均可大幅提高沉井的竖向极限承载力,提高幅度分别为126%和77%,沉井端阻力分担竖向极限承载力的比例由64.2%减小至42.1%。To improve the design method of rooted caisson and study the effect of grouting at caisson side on vertical bearing capacity of rooted caisson, the field vertical loading tests of caisson of Wangdong Yangtze River Highway Bridge were carried out. The rooted caisson and the rooted caisson with grouting at caisson side were also tested for comparative analysis. The results show that the axial force distribution of rooted caisson is stepped, which can be alleviated by grouting at caisson side. Due to the construction technology of expanding diameter of hole and backfilling pebbles, the shaft resistance of soil cannot develop completely. The shaft resistance of soil can be improved either by embedding roots in caisson or grouting at caisson side, which can reduce the harmful effect by the backfilling gravels technology. The vertical bearing capacity of caisson can be improved by 126% and 77% respectively by embedding roots in caisson and grouting at caisson side, and the ratio of end resistance to vertical bearing capacity of caisson can be decreased from 64.2% to 42.1%.

关 键 词：根式沉井 现场试验 竖向承载力 注浆 井侧摩阻力 

分 类 号：TU473.11[建筑科学—结构工程] TU473.16[建筑科学—土工工程]