预应力土钉支护结构变形与破坏的数值分析

研发的SnEpFem土钉有限元分析系统，具有以下新的特点：钉土接触单元采用了比Goodman单元更为合理的Desai单元；面层单元采用了弹性地基梁模型；对土体单元考虑了追踪破坏情况。用此系统分析了预应力施加位置及水平，对坡面水平位移、坡顶沉降及其范围、坑底隆起、张拉和塑性区的作用机制的研究表明：（1）预应力土钉布置在边坡中上部且施加较大的预应力对控制坡面水平位移、张拉区和塑性区比较有利；（2）预应力位置及大小对坡顶沉降值、沉降范围，坑底最大隆起值和隆起位置影响很小，基本可以忽略；（3）预应力施加位置及水平，对坡体内应力状态分布、拉张区、塑性区的影响较大。基于以上分析，总结了预应力土钉工作机理。对一工程实例进行了位移对比分析，证实了SnDpFem系统的可靠性。

Numerical analysis of deformation and failure in prestressed soil-nailed reinforcement structure

A soil nail FEM system, SnEpFem, developed by the authors, has the new features as follows: the interfacial soil-nail element adopts the better Desai element than the Goodman element; the mechanical behavior of the surface-layer element is described with an elastic foundation beam model; a pursuing failure mode is considered for the soil element. The SnEpFem system is used to analyze the influences of prestressed positions and magnitudes on the horizontal deflections, ground surface movements and scopes, uplifts at the pit bottom, and tension and plastic zones. It is found analytically that, (1) greater prestressed values applied at the upper-part and middle-part positions of slope is better for controlling the horizontal deflections, tension zone and plastic zone; (2) prestressed positions and magnitudes have a tiny influence on the ground surface movements and scopes, and the maximum uplift values and their locations; and (3) prestressed positions and magnitudes play a great impact on the stress distribution states and tension zones and plastic zones in the slope body. In terms of the above-mentioned analysis, the reinforcement mechanisms of soil nail are summarized. A case study is presented to illustrate the capability and merit of the SnEpFem system.