Study On Constitutive Model Of Reinforced Earth Construction

Based on analyzing comprehensively the status quo of the study on reinforced soil structure, a study on the constitutive model of this structure, especially on the soil-reinforcement interface damage model, is conducted. And the study is a important problem in the field.A shear mechanical characteristic in the soil-reinforcement interface is made a clear by the direct shear test and pull out test of reinforced earth structure. The whole shear process is divided into four stages: elastic shear, elastic-plastic shear, strain softening and residual friction. The breakage type of reinforced earth structure can be divided into four kinds: reinforcement snap breakage, reinforcement pull-out breakage Ⅰ , reinforcement pull-out breakage Ⅱ, and limit breakage.And the mechanical characteristic in the soil-reinforcement interface is described by introducing the theory of damage soil mechanics. It is supposed that any state of soil-reinforcement interface consists of undamage state and full damage state, The former is defined as a state without any shear action in soil-reinforcement interface, and is simulated by a elastic-plastic constitutive model according as the principles of geotechnical plastic mechanics. The later is simulated by a ideal-plastic constitutive model and is defined as a state when the shear process of soil-reinforcement interface is in a residual shear stage with a big displacement. The former is transformed gradually to the later in the shear process of soil-reinforcement interface. So, the soil-reinforcement interface damage model isconstructed by the damage evolvement variable—plastic shear strain, whichcombines the interface constitutive model of the undamage state with the one of the full damage state, and the approachs of acquiring the parameters included in the model are listed. A separative reinforced soil structure model is constructed by combining the soil-reinforcement interface damage model with E- K model of soil and the reinforcement elastic~ ideal plastic model.Acquiring the parameters included in this model is a key problem after it isconstructed, and the change of each parameter affects greatly the stress-displacement of soil structure. So, on the one hand, sensitivity analysis of E-K model parameters is conducted by the SIGMA/W module in the GEO-SLOPE program, this analysis makes a clear for each parameter's sensitivity to the stress-displacement of soil structure, and these parameters which have high sensitivity to them must be paid more attention to during being acquired. On the other hand, based on the theory of artificial neural network, the BP neural network model of soil shear strength indexes is constructed, this model can map comprehensively the non-linear relationship among physical property indexes. The prediction results of the model close to the ones of the experiments, and have high precision, which provides a new way to acquire these parameters.of shear strength indexes in E-K model.