Discrete Element Modeling Of Composite Soil-nailing Wall In Soft Soil

Composite soil-nailed wall is of highly security, highly economy, wide range ofapplications and other features. Thus it has been widely used in Foundation pit support.However, because of the complexity of composite soil-nailing wall, there is a little theoreticalstudy which leads to we are not clear about its working mechanism. This article tries tounderstand its inner working mechanism based on the discerte element method.The main work of this article can be summarized as follows：(1) A2-dimensional pure cement mixing pile simulation model which consider the purecement piles deformation characteristics, is established by the software of PFC2D. Basedon this model, this article analysis of the pile stiffness, pile diameter and constructionprogress. The results showed that: increased the pile stffness and diameter can be moreeffective in controlling the level of displacement; slow progress of work will increase thedisplacement.(2) A2-dimensional soil-nailing walls simulation model which consider the soil-nailing wallsdeformation characteristics, is established by the software of PFC2D. Based on thismodel, this article analysis of the pile stiffness, pile diameter and construction progress.The results showed that: increased the surface stiffness can be more effective incontrolling the level of displacement; slow progress of work will increase thedisplacement; dip angle of soil nail should be controled between10°to15°; the longestnail should be set at upper of foundation.(3) A2-dimensional composite soil-nailing wall simulation model which consider thecomposite soil-nailing wall deformation characteristics, is established by the software ofPFC2D. Based on this model, this article analysis of the pile stiffness, pile diameter andconstruction progress. The results showed that: increased the nail stiffness can be moreeffective in controlling the level of displacement; slow progress of work will increase thedisplacement; increased the pile stiffness restrict displacement is not obvious.(4) Comparing with other two kinds supporting structure, composite soil-nailing wall is moreeffective in controlling the level of displacement. At the same time, this article found thesoil sensitive area of excavation and put forward some suggests by the analysis of the mesoscopic mechanism.