【作者】 鲁绪文；

【导师】 娄炎；

【作者基本信息】 南京水利科学研究院 ， 岩土工程， 2007， 博士

【摘要】 复合地基技术在软土分布地区得到了广泛的应用，对于深厚软土地区，建筑物的沉降问题一直未得到较好的解决，尤其高等级公路在软土地区的大量兴建，路基的工后沉降变形往往需要数年，甚至更长时间，工后变形产生的桥台与桥头路面段的沉降差而引起的“桥头跳车”现象一直是困扰岩土工程界头痛的技术难题，如何有效地解决深厚软基上建筑物的沉降，无论在经济上，还是在技术上都是需要面对和亟待解决的问题，基于沉降控制理论的长短桩复合地基技术正是为解决这一问题的尝试。依托杭州湾跨海大桥南岸连接线试验段项目，本文首次将刚柔性长短桩复合地基技术应用于柔性荷载(路堤)下的深厚软基处理中。主要研究工作如下：1、利用杭州湾跨海大桥南岸高速公路连接线工程的试验段项目为依托，对深厚软土地基上的长短桩复合地基技术进行了现场试验，全面系统地分析和总结了现场试验路段试验结果，对长短桩复合地基沉降特性、孔压消敖特性、深层水平位移特性、桩土应力比等作了深入细致地分析，得到了许多有应用价值的结论。2、控制沉降本身就意味着改变土层中的附加应力，应用弹性力学Mindlin解和Boussinesq解求解长短桩复合地基的附加应力，再利用分层总和法计算长短桩复合地基的沉降。3、在荷载传递法、剪切位移法等单桩分析法的基础上，运用群桩分析理论和Mylonakis与Gazetas的研究，采用等效土桩的方法，考虑长短桩复合地基中桩土之间的相互作用，对复合地基的沉降进行了理论分析。4、建立起相应的实体模型，通过数值模拟，研究了深厚软基中长短桩复合地基的受力与变形特性的诸多影响因素(如桩长、桩间距、桩端持力层等)，从数值试验角度研究了长短桩复合地基技术在不同条件下对深厚软基的控制沉降作用。5、根据试验研究及理论分析成果，对深厚软土地基中的长短桩复合地基技术设计理论进行了研究，提出了具体的设计与应用步骤。此外，还从优化角度对长短桩复合地基的设计进行了分析。更多还原

【Abstract】 Composite foundation technique has been widely applied in soft-soil area, where theproblem of building settlement sinkage has not been solved well, especially the high-gradehighway whose post-construction settlement needs a few years to be over. So thephenomenon of bridgehead vehicle jump appears, which is a long-term technique problem ingeotechnical engineering. This paper has discussed composite foundation with long-shortpiles technology which is based on the theory of settlement control. Composite foundationwith long-short piles technology is just a attempt to deal with the problem of bridgeheadvehicle jump and the main research work is as follows:1、Rely on the experimental segment of expressway of the south shore connecting line ofHangzhou Bay Spanning Bridge, field experiment of composite foundation withlong-short-pile technology has been done and the test result has been systematicallysummarized and analyzed in which settlement characteristic, pore water pressure dissipatingcharacteristic, deep horizontal displacement characteristic and stress ratio of pile to soil havebeen thoroughly studied and some applicable conclusions also have been obtained.2、Settlement control means to change additional stress of the gound. In the test, theadditional stress of composite foundation with long-short piles has been calculated by MindlinSolutions and Boussinesq Solutions in elastic mechanics and then the settlement of the pileshas been calculated by layer wise summation method.3、Basing on the single-pile analytical approach such as load-transfer method and sheardisplacement method, on the application of group piles analysis theory and the studies ofMylonakis and Gazetas, adopting equivalent soil-pile method, considering pile-soilinteraction of composite foundation with long-short piles, the settlement of the compositefoundation has been theoretically analyzed.4、Building up corresponding body model and through numerical simulation, variousinfluential factors such as pile length, pile interval, pile end bearing layer which mayinfluence the stress and deformation behaviors of the composite foundation in the soft soilhave been studied. What’s more, how the composite foundation with long-short pilestechnology controls the settlement of deep and soft soil foundation in different conditions hasalso been studied from the prospective of numerical experiment. technology controls the settlement of deep and soft soil foundation in different conditions hasalso been studied from the prospective of numerical experiment.5、According to the result of theoretical analysis and experimental study, the theory ofthe design of composite foundation with long-short piles in the deep and thick soft soilfoundation has been studied and the detail procedures of design and application have alsobeen put forward. What’s more, how to design composite foundation with long-short piles inview of optimization has also been analyzed.更多还原