考虑固结的桩-吹填欠固结土相互作用机理及应用研究

The mechanism of soil-pile interaction is often investigated on normally consolidated soils. There is a lack of study on the responses of underconsolidated dredged sediments. The success of land reclamation is usually evaluated based on a preliminary study, where it requires a leveled construction site with access to water, electricity and transportation. However, the influence of long-term consolidation settlement during the service life of adjacent infrastructure, such as buildings and roads, has not been paid enough attention. The interaction between displacement piles and underconsolidated dredged sediments should be studied by taking into account the consolidation behavior of the surrounding soil, for providing a sound theoretical framework that is of practical significance. Finite element analyses will be conducted first to model the consolidation process of underconsolidated dredged sediments, where the initial geostatic stress field could be calculated for subsequent pile installation. The pile driving process will also be simulated, which could provide calculations of the initial stress field for the analysis of soil-pile interaction. The complex response of soil-pile interaction can be modeled numerically by taking into account the whole consolidation response of the surrounding soil. In addition, centrifuge tests will be carried out to model the initial geostatic stress field in underconsolidated dredged sediments. Reduced-scale model piles will be fabricated and pushed into the soil to model the installation process for further analysis of soil-pile interaction by considering consolidation effects. The outcome of this research could improve the understanding of the interaction between displacement piles and underconsolidated dredged sediments, and provide guidance for land reclamation projects in reality.

桩土共同作用研究大多基于原状正常固结土，而针对吹填欠固结土很少；吹填造陆研究以地基处理满足三通一平的前期研究为主，而关于吹填欠固结土对建筑运营影响的后期研究很少；开展考虑固结的桩-吹填欠固结土相互作用研究具有重要理论和工程价值。首先进行精细化数值分析研究：建立考虑固结的吹填欠固结土地基有限元模拟方法，作为桩基施工的初始应力场；建立考虑桩基压入吹填欠固结土地基的有限元模拟方法，作为桩土相互作用分析的初始应力场；建立考虑固结的桩-吹填欠固结土相互作用有限元模拟方法，探讨吹填欠固结土对建筑长期运营影响的规律。其次开展离心试验研究：吹填欠固结土地基场地形成的离心试验；桩基压入吹填欠固结土地基的离心试验；考虑固结的桩-吹填欠固结土相互作用的离心试验。最后探讨吹填欠固结土对桩基工作性状影响规律，建立桩-吹填欠固结土相互作用理论分析方法。成果将丰富桩土共同作用理论，对吹填造地桩基实践有指导作用。

地基处理满足三通一平的前期研究为主，而关于吹填欠固结土对建筑运营影响的后期研究很少，开展考虑固结的桩-吹填欠固结土相互作用研究具有重要理论和工程价值。鉴于此，本项目构建了吹填欠固结土地基中压入桩基全过程的数值分析模型以及考虑固结的桩-吹填欠固结土地基数值分析模型，分析了桩-吹填欠固结土地基工作机理；采用土工试验、离心模型试验和单元体试验等试验手段，研究了吹填欠固结土体固结特性、桩-吹填欠固结土体相互作用规律，验证了所建立桩-吹填欠固结土共同作用精细化数值模型的合理性；在数值模拟和试验研究成果基础上，利用解析手段研究了吹填土欠固结特性对运营阶段桩基受荷变形的影响规律，建立了考虑固结的桩-吹填欠固结土地基理论分析方法。研究成果极大地丰富了桩土共同作用理论，对吹填造地桩基实践有重要指导作用。依托本项目，共发表科技论文12篇，其中SCI收录10篇，EI收录2篇。授权国家发明专利1项，美国发明专利1项。在项目支持下，共毕业2名博士生、4名硕士生，另外，本基金项目还为10余名本科生的毕业设计或论文提供了素材和经费支持。项目负责人参与的科技成果及应用获2019年广西科学技术进步奖一等奖和2022年广西技术发明奖一等奖。