Soil Interaction Parameter And Reinforced Embankment Slope Design Method

Three issues must be resolved when reinforced soil slope designed which were: suitable reinforcement chosen, the design value of interface parameters between reinforcements and soils, and the construction damage. Furthermore, the various uncertain factors in engineering were not considered in Limit Equilibrium Method which was the traditional design method using fixed safety factory. Therefore, the tension characters of reinforcements were combined with the allowable engineering deformation to research the selection of reinforcement in this paper, the variation of influence factors and the influence degree of the construction damage were investigated by direct shear test and pullout test, and abundant tests achievement of the interface parameters were summarized, large numbers of statistical analysis were carried out through regarding the loads, the resistance, the geometry of the slopes as Random Variables, based on them, the Limit State Approach was developed which was a new method that depended on Statistics Theory and Reliability Concept for reinforced soil slope design. The main conclusions are as follows:1. After statistical analysis mechanical characters of current reinforcements, and combining with allowable engineering deformation, it is brought forward that the simplified rules for geosynthetics selection of reinforced soil structure forms.2. The inpect degree of the construction damage was obtained in direct shear tests by using the geogrid with or without ribs; moreover, the bilinear model can be used to simulate the curve of pullout force verse displacement.3. The interface parameters between reinforcements and soils can be classified two forms of interface strength parameters and apparent coefficient of friction. Considering the impact of interface adherence, the interface strength parameters are more reasonable than the apparent coefficient of friction in design. At the same time, the achievements of direct shear test and pull out test during recent years are classified and summarized, then, the design value range of interface parameters are recommend.4. Based on comprehensive tidying the last studies and plenty of statistical analysis, the statistics parameters and probability distribution models of live loads (vehicle load and uniform live load), gravity and shear strength of backfills, tensile strength of reinforcement, interface parameters between reinforcements and soils, geometric parameters of slope were determined.5. The internal and external stability limit state equations of reinforced soil slope are established based on the experience of traditional method whose computing model is circular failure surface;6. The self-programming which is based on the object reliability index of reinforced soil slope and MATLAB platform is adopt to optimize calculate the load partial factors and resistance partial factors which are used in all kinds of limit state design formulae about two load combinations (dead load combining with uniform live load and dead load combining with vehicle load).