路堤下刚性桩复合地基沉降变形控制理论

With the more accurate and scientific technologic requests for soft foundation treatment under embankment by using rigid pile composite foundation at present stage, the measurement technique of distributed fiber to measure strain and stress will be developed and applied in field prototype tests and model experiments of rigid pile composite foundation under embankment, in order to study the stress and deformation; By using the physical model with big ratio, the operating characteristics of rigid pile composite foundation under embankment will be simulated in all conditions with multi-program, and the stress distribution and it's transference, the deformation distribution and it's development will be obtained. Based on the large number of measured data in field and physical model experiments and the plenty of data got in the field experiments done by our group, the temporal distribution of stress and deformation and their influencing factors will be studied for rigid pile composite foundation under embankment, and its basic mechanism will be revealed. Combined with mechanical analysis, its mechanical model will be built by using numerical analysis, and the calculation method and theory which can describe its stress and deformation characteristics and laws exactly will be proposed, which can be verified and perfected by the experiments results. On the basis, the deformation calculating theory and post-construction settlement control theory of rigid pile composite foundation under embankment will be constructed, which will provide the theoretical support and accurate calculation methods for the reinforcement technology design, construction management, and effect evaluation on the post- construction settlement of rigid pile composite foundation.

针对刚性桩复合地基加固公路软土地基精细化、科学化发展的技术要求，开发完善分布式光纤测量技术并应用于路堤作用下刚性桩复合地基原型和模型试验，系统研究其受力和变形特性；利用大比尺物理模型，模拟多方案全工况路堤下刚性桩复合地基工作特性，得到刚性桩复合地基受力分布及传递规律与变形分布和发展规律；基于丰富原型试验和模型试验测试资料并结合前期大量原型试验监测成果，研究路堤作用下刚性桩复合地基受力和变形的时空分布规律及其主要影响因素，揭示其基本工作机理。结合力学分析，采用数值解析法构建路堤下刚性桩复合地基受力模型，提出能够更准确描述其受力、变形特性和规律的数值模型和计算方法，并利用物理模型试验及原型试验实测成果验证完善。在此基础上，构建路堤作用下刚性桩复合地基沉降变形计算理论与工后沉降控制理论，为路堤作用下刚性桩复合地基加固技术设计、施工管理和工后沉降控制效果评价提供理论支撑和精细化计算分析方法。

通过设计多组室内离心模型试验和现场试验，开展路堤下刚性桩复合地基受力特性新型量测技术研究，主要包括利用分布式光纤传感技术测量刚性桩复合地基受力特性等新型原位量测技术的研发和工程实践应用；结合现场原型试验测量结果，开展室内离心模型试验研究，分析路堤下刚性桩复合地基的表面沉降及其沿深度的分层沉降等，揭示刚性桩复合地基受力和变形的时空分布规律及其主要影响因素，以及离心模型试验中有关变形测试分析方法及桩模拟技术研究；以实际工程中刚性桩复合地基加固试验段为原型，建立了与离心模型试验相对应的三维有限元数值模型，对比了多种单桩有限元数值建模方法，基于轴对称接触模型结果分析研究了刚性桩复合地基荷载分配、传递和沉降变形等规律，探讨了复合地基中桩土应力测试方法及应力分布规律；基于土拱效应理论分析，推演建立了刚性桩复合地基沉降计算模型，计算分析了刚性桩复合地基土拱效应和沉降变形规律，综合离心机模型试验及有限元数值模拟结果，对比分析了各关键设计参数变化对路堤下刚性桩复合地基土拱效应及沉降变形产生的影响；开展刚性桩复合地基的加筋垫层、桩顶承台、桩布置的设计方法，及沉降、承载力、整体稳定的实用设计分析研究，建立刚性桩复合地基工后沉降函数，分析确定了刚性桩复合地基最终设计方案和备选方案等设计方案，讨论了刚性桩复合地基实用设计有限元建模方法，能够为路堤下刚性桩复合地基设计提供理论支撑，具有显著的理论价值和实践意义。