Abstract: 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.

Key words: prestress, soil nail, FEM, horizontal deflection, ground surface movement, tension zone and plastic zone