Analytical Study On Non-homogeneous Subgrade With Continuous Variation Of Shear Modulus Versus Depth

The non-homogeneity of soil's shear modulus varying versus depth of the subgrade has great influence on its deforming. The multilayer subgrade model was accepted to study the problems in the past because of the non-homogeneity of soils. In nature the soil's rigidity varies continuously because it was formed in a long natural geologic history. The subgrade model which could show this characteristic of soils is more appropriate in study. Gibson studied a subgrade model whose soil's shear modulus varies linearly versus depth( G = nz), and then this subgrade was called "Gibson subgrade". If the shear modulus is not zero in the surface of subgrade (G = G(0) + nz ), it was called "generalized Gibson subgrade". Because of the complexity of mathematic, the study of this kind of non-homogeneous subgrade whose soil's shear modulus varying continuously versus depth is much not sufficient until to now. In this paper, the static problems of generalized Gibson sugbrade the steady-state dynamic problems of Gibson subgrade and a new non-homogeneous subgrade model were studied in analytic method.The author studied the axisymmetrical problems of generalized Gibson subgrade on rock. Analytical solutions of stresses and displacements were obtained. Selected numerical results of three kind of loads for vertical displacements were presented to portray the influence of the degree of non-homogeneity depth of rock located of the non-homogeneous subgrade. Results shows that the great difference exists between generalized Gibson subgrade and Gibson subgrade.Based on the general solutions of generalized Gibson subgrade, the solutions of double layers generalized Gibson subgrade were obtained firstly. Influence of the degree of non-homogeneity depth of second layer and different rigidity of the two layers on the responses of the non-homogeneous subgrade were studied.A new non-homogeneous subgrade model whose soil's shear modulus decays versus depth( G = ηG /(η + z)) was brought forward to study influence of dry crust on the vertical subsidiary stress of the soft clay. The variations of the thickness of dry curst the non-homogeneity of dry curst soil and the Poisson's ratio of soft clay were...