Numerical Test On The Reinforce Mechanism Of Soil Nailing

The soil-nailed support system has been applied widely at home and abroad, but it is short of research on mechanism of interactive action between support structure and rock and soil medium especially soft-weak medium and some understandings rest on the stage of qualitative descriptions. Current design theories base on engineering analogy. The systemic numerical tests on soil-nailed support are made utilizing the advantage of the FEM method on quantitative research in this dissertation, the reinforce mechanism in quantitative aspect is pointed out, and the reinforce effects of support parameter and soil property parameter are abstracted so as to provide scientific basis for optimization design. The main conclusions are remarked as follows:(a) The theory formula between the ultimate tensile force and interface cohesive intensity has been established. According to ultimate tensile force from in-site measure, the scientific interface cohesive intensity parameter has been achieved, then, the numerical analysis of the tension-draw test has been made. The reliability and precision of the interface element in theanalysis model has been validated and the failure mode of the soil nailing in the tension-draw test has been demarcated.(b) The reinforce mechanism combined reinforcing and anchoring, which displayed by single nail's stress-participating and stress-transferring, multi-nail's framework confining and the soil-arch's stress-proliferating, has been revealed in quantitative aspect.(c) Optimized lay-out of the soil nailing and critical parameters have been obtained by the sensitivity analysis of the length, density and stiffness in the sandy soil. In soft clay, it is proposed that the soil nailing associated with other support systems, such as piles and walls etc, should be used, for the drum-shape of the deformation at cut slope appears and the critical parameters aren't obvious.