基于墙趾真实约束条件的模块式加筋土挡墙数值模拟
Numerical modeling of reinforced soil segmental retaining walls under real toe restraint conditions
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摘要: 墙趾约束条件对硬质墙面加筋土挡墙性状影响显著。基于混凝土模块与级配碎石土直剪试验剪应力和剪切位移关系曲线,建立一非线性双曲线界面模型,并通过FLAC有限差分程序分析刚性地基上3.6 m高聚丙烯土工格栅加筋土挡墙在工作应力下的墙趾界面剪切特性、墙面和墙趾位移以及墙趾和筋材承担的荷载,得出在挡墙填筑过程中墙趾界面剪应力-剪切位移曲线呈上凹型;墙趾界面上的正应力、界面剪切刚度及墙趾和筋材承担的荷载随挡墙填筑高度而增大,在挡墙填筑至3.6 m时,其界面正应力是墙面模块自重应力的1.7倍,墙趾承担约87%的作用在墙背上的总水平荷载;在挡墙填筑初期由于界面剪切刚度较小,墙面和墙趾位移增大显著。较挡墙模型试验及以往数值模拟采用的墙趾恒定约束刚度,论文采用的双曲线界面模型可更好地反映挡墙墙趾与地基土真实剪切性状。Abstract: The toe restraint has a significant effect on the behaviour of hard facing reinforced soil retaining walls (RSWs). A non-linear hyperbolic interface model is established based on shear stress-displacement curves from modular block-grading gravel interface shear tests. A 3.6 m-high polypropylene geogrid reinforced soil wall on rigid foundation is simulated under working stress conditions using FLAC incoperated with the interface model. The shear properties of the toe interface, the horizontal displacements of the wall facing and toe block as well as the loads carried by the toe and reinforcements are then analyzed. The results show that the shear stress-dispalcement curve of the toe interface exhibits concave during wall construction. The interface normal stress, interface shear stiffness and loads carried by the toe and reinforcements increase with the wall height during construction. When the wall is constructed up to 3.6 m in height, the interface normal stress is 1.7 times the self-weight of wall facing blocks and approximately 87% of the total loads are carried by the toe. The displacments of the wall facing and toe block increase apparently during the initial stage of wall construction due to less shear stiffness of the toe interface. Compared to the constant toe restraint stiffness used in the former laboratory tests and numerical modeling of RSWs, the hyperbolic interface model can better reflect shear properties of the toe and foundation soils.