刚性面加筋土挡墙工作性状与设计方法探讨

“重力式”加筋土挡墙和“全高刚性面”加筋土挡墙是墙面为具有抗弯刚性的新型挡土结构, 可统称为“刚性墙面加筋土挡墙”。与普通面板式加筋土挡墙的主要不同在于其墙面厚、刚度大, 对墙后填土侧向变形的约束较大, 并要求刚性墙面承担墙后土压力的作用。但目前我国对其工作性状、设计方法缺少系统、深入的研究, 相关规范也没有涉及, 明显落后于实践。针对墙顶有堆载的路堤式挡墙, 采用数值分析方法, 考虑“先筑刚性墙、后填加筋土”和“先填加筋土、后筑刚性墙”2种不同施工顺序, 从筋材与填土的应力、应变和挡墙变形等方面, 分析了刚性墙面加筋土挡墙的工作性状。结果表明:刚性墙面的水平变形沿墙高为直线分布, 墙顶处最大;“先填加筋土、后筑刚性墙面”的施工顺序能更好地发挥筋材的作用, 减小墙后土压力, 控制墙体的变形。综合数值分析结果和现有文献资料, 提出了刚性墙面加筋土挡墙筋材拉力的确定方法, 并建议借鉴日本《RRR-B工法设计·施工规范》的“双楔法”计算墙后土压力。

Working Behaviour and Design Method of Geosynthetic-reinforced Soil Retaining Wall with Rigid Facing

Geosynthetic-reinforced soil retaining wall (GRS RW) with a gravity wall(GW)facing and GRS RW with a full-height rigid (FHR) facing are new retaining wall structures, which are collectively known as GRS RW-RWF (rigid wall facing). The differences of GRS RW-RWF with normal GRS RW with a thin concrete slab lie in that the rigid wall facing has larger thickness and higher rigidity, which can restrain the deformation of backfill soil and bear soil pressure. At present, the working behaviour and design method of GRS RW-RWF are not covered in specifications and systematic in-depth researches are in lack. In this paper, we take embankment retaining wall which is commonly employed in roadbed engineering of railway and highway as a research object, and analyzed the working behaviour of GRS RW-RWF is analyzed from aspects including the stress and strain of reinforced material and filling soil as well as the deformation of rigid retaining wall in the presence of two different construction sequences (construction sequence A: pouring rigid retaining wall before filling geosynthetic-reinforced soil, and construction sequence B: filling geosynthetic-reinforced soil before pouring rigid retaining wall). Results show that the lateral deformation of GRS RW-RWF is linearly distributed along the height of retaining wall, and the maximum value of lateral deformation occurs on the top of the rigid retaining wall. Construction sequence B is superior to construction sequence A because it better develops the function of reinforced material, reduces the soil pressure acting on rigid retaining wall and controls the deformation of rigid retaining wall. Moreover, the method of determining the reinforcement tension in GRS RW-RWF is presented, and the two-part wedge method recommended by Japanese Code of Design and Construction for RRR-B Construction System can be used to calculate soil pressure acting on rigid retaining wall.