台阶式加筋土挡墙结构行为演变及设计方法研究

The tiered geogrids reinforced soil retaining walls are used extensively in the high fill engineering because of the well established technical advantage. The bigger vertical settlement and horizontal deformation of the reinforced soil retaining wall will bring more difficulties to control the deformation of reinforcement and the soil. The typical design and calculation theories on the tiered reinforced soil retaining wall nowadays are mainly following conventional experience, without realizing that the force and deformation characteristics of the wall have already changed, and these are possible interactions between the upper and the lower tiers. Based on the theoretical derivation, model tests, numerical simulation and analyses of typical engineering observation data, the interaction models between the upper and the lower tiers will be built, and the offset distance on the influence of the internal-external stability, deformation and the failure model will be revealed.The critical offset distance considering the interaction between the upper and the lower tiers will be decided in this project. By determining the variation of soil strength and its influence on the reinforcement stress in the tiered reinforced soil retaining wall, the characteristic mechanism and the model from working stress state to limit state of tiered geogrids reinforced soil retaining wall will be decided. And the project will bring to the method of determining the foundation soil bearing capacity and the controlling demand of reinforced soil filling of the tiered reinforced soil retaining wall. The reasonable design method of the tiered geogrids reinforced soil retaining wall will be established. The result will lay a theoretical foundation for the engineering application.

台阶式土工格栅加筋土挡墙以其良好的技术优势广泛应用于高填方工程。这种加筋土高挡墙产生的较大竖向沉降和水平变形会使筋材与土体之间的变形协调困难。但目前关于台阶式加筋土挡墙的设计计算只是常规经验的直接推广，对结构受力、变形演化机理和上下级墙体间相互作用的认识还不完善。本项目将通过理论推导、模型试验、数值模拟，并结合典型工程观测资料的计算分析，建立上下级墙体间的相互作用模型，揭示墙间平台宽度对上下级墙内外部稳定性、变形及破坏模式的影响规律，确定上级墙体荷载对下级墙影响的临界平台宽度。明确台阶式加筋土挡墙土体强度变化规律及其对拉筋应力的影响，构建台阶式土工格栅加筋土挡墙从工作应力状态向极限状态过渡的特征机制和模式，从墙体稳定性控制和筋土协调角度提出台阶式加筋土挡墙地基承载力的确定方法与墙体填料填筑质量控制要求，提出台阶式土工格栅加筋土挡墙合理的设计方法，为结构的工程应用奠定理论基础，推广前景广阔。

土工格栅加筋土挡墙以节约占地、抗震性好、结构稳定、外形美观等优良的工程特性广泛应用于土木工程、交通运输工程和水利工程等领域。台阶式土工格栅加筋土挡墙以其良好的技术优势广泛应用于高填方工程。但是加筋土高挡墙产生的较大竖向沉降和水平变形会使筋材与土体之间的变形协调困难。项目组通过四年的工作，对台阶式土工格栅加筋土挡墙的结构行为与演化过程、上下墙相互作用模型及结构性能、结构从工作应力状态向极限状态过渡的特征机制和模式以及台阶式加筋土挡墙设计技术方法进行了系统研究并取得了系列研究成果。通过建立台阶式加筋土挡墙上下级墙体间的相互作用模型，确定了墙间平台宽度对上下级墙内外部稳定性、变形及破坏模式的影响规律，基于筋材用量及结构稳定等多方面提出了台阶式加筋土挡墙的临界平台宽度。通过数值分析，明确了台阶式加筋土挡墙土体强度变化规律及其对拉筋应力的影响，建立了台阶式土工格栅加筋土挡墙从工作应力状态向极限状态过渡的特征机制和模式，提出了台阶式土工格栅加筋土挡墙合理的设计方法，通过工程应用，系统研究了台阶式加筋土挡墙施工期及使用期的结构特征及变形规律。研究成果对结构的应用推广具有重要的理论价值和现实意义，推广前景广阔。截止到2017年12月，已发表SCI收录论文4篇，发表EI收录论文11篇，培养硕士研究生8人。