Research On Function Mechanism And Analysis Of Force On The Facing Of Soil-Nailing Wall Supporting Structure

Soil nailing wall is widely used in deep excavation and slope stability, a lot of research work has been done at Home and abroad,but the calculation method of soil nailing supporting technology is not perfect, little research work on function mechanism and analysis of force on the facing has been done.Facing only used as structural treatment in reference documents and design code, the design and construction depend on empirical method, it bring adverse effect on the stability of soil nail wall. In view of this, the study work is as follows:(1) The formation, the development and the current research present situation of soil nailing supporting structure are discussed. The Function Mechanism of soil nailing supporting structure is comprehensively described. In additional, the problems in the current research are analyzed.(2) According to the characteristics of soil nailing supporting structure, based on the analysis of the theoretical solution of pullout test of soil nail and soil arching effect, the function mechanism of soil nail is discussed, and function mechanism of the facing is concluded.Calculation formulas of limit bearing capacity of bending and punching are given with reference to reinforced concrete slab.(3) Based on the assumption of elastic foundation beam, Synergistic effect model of the facing and soil nail and soil is set up. The formula to calculate the internal forces of facing was worked out by use of finite difference method and boundary conditions, Based on the theory, and using advanced programming language Matlab, the computation procedure is developed. The calculation method is applied to engineering practice. The calculation results indicate the moment of the facing is non-uniform curve in accordance with the practical situation, which embody binding effects of head of the soil nail. The results also indicate the method is a useful technique for design and analysis of internal forces of the facing. Based on mechanics parameters of soil and pullout test of soil nail, the internal force of facing is very easily calculated by means of the procedure, which provided valuable reference for design and construction of the facing.(4) By applying finite element analysis software known as ADINA, the 3D and 2D finite element models are established. Based on the analysis and the comparison of the simulation result, this paper makes some research on the mechanism of the facing of the soil-nailing. The results show that:in the supporting structure system, the supporting facing can effectively reduce the horizontal displacement of the excavation, balance the soil stress disturbed by the soil excavation. The facing can fully display the potential utility of each soil nail, and adjust their axial force, but plays little role in limiting the vertical displacement of the soil near the excavation. The result of numerical calculation is accord with theoretical solution of moment of the facing, it indicates the correctness and rationality of the calculation method in the paper.