Three-dimensional Numerical Analysis Of The Soil Nailing Support's Working Behavior

At present the soil-nailed support system obtained a more widespread application in the deep hole excavated for building foundation project. Scholars on soil-nailed support already done a lot of research, and gained some achievements, but generally speaking, the operating performance fundamental research for the soil-nailed support has far behind the practice.FLAC^3D is a three-dimensional explicit finite-difference program for engineering mechanics computation. FLAC^3D can simulates the behavior of three-dimensional structures built of soil, rock or other materials that undergo plastic flow when their yield limits are reached. There are eleven built-in models in FLAC^3D. The material can yield and flow, and the grid can deform (in large-strain mode) and move with the material that is represented. The explicit, Lagrangian calculation scheme and the mixed-discretization zoning technique used in FLAC^3D ensure that plastic collapse and flow are modeled very accurately.Research in this dissertation is expected to reveal the further behaviors of soil nailing, including stability, deflection, strength, combined with the project example:(a) Firstly, based on a lot of documents and data, mechanism and performance and the background theory of soil nailing are discussed and analyzed in detail.(b) In numerical analysis, the computation model establishment appropriate or not, measured data is whether reliable effective directly is relating the analogue result is accurate or not. In the beginning of the analysis, the methods of how to select each parameter, for example, such as pseudo-cohesion AC, bonding intensity intension is discussed.(c) Simulating the process of excavate and support, calculating the horizontal deflection, vertical deflection, nail tension forces of each stage excavation. The maximum horizontal deflections occur on the top surface. The maximum vertical deflections occur on the slope surface where was close to the top surface.(d) The nail tension forces increase is similar. The nail tension force occur in the middle depth of the cut slope is bigger, on the top and in the bottom is smaller. After the staged excavation, the nail tension force is max which was installed in the previous stage, and then tend to steady after the completion of the staged excavation and retaining. It is suggested that the next excavation step should not be started until certain strength of the grout slurry has reached and adhered to the surrounding soil firmly after the installation ofnails.