岸边软土区双向增强复合地基工作性状及按沉降差控制智能优化设计方法

Expressway, high-speed railway and other transportation infrastructure facilities are continually involved as one of key areas of construction in National Twelfth Five-Year Plan. Extensive soft shore ground (with inclined stiff underlying stratum) will come across when the construction travels through soft soil region such as rivers, lakes, marshes, valleys and swales, a quick and effective treatment technique and the corresponding calculation method of design for this situation are not available by now. Hence, this project devotes into a new treatment technique of two-directional reinforced composite foundation to tackle the problem that applies binding material piles as vertical support and high-strength reinforced cushion as horizontal reinforcement. A series of laboratory tests and in situ tests as well as numerical stimulation experiments will be designed and conducted based on test optimization technique to investigate the mechanical and deformed characteristics of soft shore ground and two-directional reinforced composite foundation used in shore region of soft soil. It is expected to reveal the loads transferring mechanic, failure modes and improvement mechanism of this two-directional reinforced composite foundation of binding material piles supported incorporating horizontal reinforced cushion. Combining with theoretical analysis, the analytical computation models of bearing capacity, settlement and stability, for this two-directional reinforced composite foundation located in shore region of soft soil with inclined stiff underlying stratum, will be established respectively. A optimal differnential-settlement-based optimal design methodology of the two-directional reinforced composite foundation will be developed. The achievements of this work can not only enrich and develop the theory of composite foundation, but also provide reliable treatment technique and calculation method of design for cases in similar complicated soft ground.

国家十二五规划仍将高速公路、高速铁路等交通基础设施作为重点建设领域之一，在工程建设中必将因穿越江河、湖泊、沼泽、山谷、洼地等软土区而遇到大量的岸边（下卧有倾斜硬土层）软土地基，但目前对其尚缺乏快速有效的处治技术及相应设计计算方法。对此，本课题提出采用新型的高强水平加筋层-粘结材料桩双向增强复合地基技术进行处治，并基于试验优化技术设计并完成一系列室内外物理模型试验和数值模拟实验，深入研究岸边软土地基以及岸边软土区双向增强复合地基的受力变形特性，揭示出高强水平加筋垫层-粘结材料桩双向增强复合地基的荷载传递机理、破坏模式和加固原理，同时结合理论分析，建立出岸边软土区下卧有倾斜硬层时双向增强复合地基的承载力、沉降和稳定性分析计算模型，并提出按沉降差控制智能优化设计计算方法。研究成果不仅可丰富和发展复合地基理论，而且可为类似复杂软土地基提供可靠的处治技术和设计计算方法。

国家十三五规划仍将高速公路、高速铁路等交通基础设施作为重点建设领域之一。在公路、铁路等工程建设中，经常要穿越江河、湖泊、沼泽、山谷、洼地等软土区,不可避免地要遇到大量的岸边（下卧有倾斜硬层）软土地基。但目前对岸边软土地基尚缺乏快速有效的处治技术及相应的设计计算方法。本课题设计并完成了岸边软土区、深厚软土区刚性带帽桩复合地基室内模型试验，研究了不同地质条件下带帽桩复合地基在极限荷载下的破坏模式、桩身轴力分布、桩侧摩阻力变化情况、桩顶的荷载-位移曲线及其承载力。基于数值试验优化方法提出了岸边软土地基沉降图式确定法和岸边软土区散体材料桩复合地基沉降计算式。提出了顶部加箍碎石桩复合地基承载力和沉降计算方法。基于模型试验和数值模拟分析，研究了带帽刚性桩复合地基的荷载传递规律，并分别基于极限平衡原理和极限分析原理导得了大桩帽刚性短桩带桩帽刚性桩复合地基承载力计算公式，同时提出了考虑高路堤土拱效应层状地基中带帽刚性长桩复合地基桩土应力比和桩土差异沉降计算方法。提出了路堤荷载下成层土刚性桩复合地基加固区沉降计算方法。提出了分析地基荷载-位移关系的滑块位移法，并进而建立了大桩帽刚性短桩荷载-位移关系的分析模型和计算方法。发明了一种处治下卧有倾斜硬层岸边软土路基的锚拉式桩承加筋土挡墙路堤，并提出了相应的实用设计计算方法。引入均匀设计方法布置数值模拟试验方案，通过计算结果回归得到代理沉降计算模型，建立了按沉降控制岸边软土区复合地基改进粒子群智能优化设计方法。本课题的成果不仅解决了岸边软土区的地基和散体材料桩复合地基的沉降计算问题，而且为处治岸边软土地基提供了实用的处治技术和相应的设计计算方法，同时提出了一种按沉降控制岸边软土区复合地基智能优化设计方法。