Research On Hydraulic Gradient Model Based On One-dimensional Consolidation Of Soft Clay

Research on consolidation theory of saturated soft clay has developed well.Some solutions were got corresponding to complicated engineering conditions, while the variation law of hydraulic gradient still remains to be learned. Hydraulic gradient which is closely related to soil properties changes regularly in consolidation process.And soil subsidence rate is positively related to it when the coefficient of permeability is almost constant. To build hydraulic gradient model and analyze the variation rule could contribute to consolidation mechanism.Firstly, analytic solutions of hydraulic gradient are acquired based on Terzaghi's one-dimensional consolidation and nonlinear consolidation theory as well as changeable curves with time. It shows that hydraulic gradient always increases firstly and reduces afterward with time in both S-shaped curves. Torrents of hydraulic gradient data is available from illustrative examples, fitted into Logistic function. And parameters are defined by dimensional method. Logistic model of hydraulic gradient is already established instead of complex formula to accurately describe consolidation process.Then, saturated soft clay consolidation of elastic, Duncan-Chang and Modified Cam-clay constitutive models is simulated with FEM software ABAQUS. The result shows changeable curves of hydraulic gradient fit well with Logistic function, and the validity of Logistic model is verified whatever the constitutive model is elastic or asto-plastic.Next, the extreme point and two inflection points of hydraulic gradient could be easily calculated in Logistic model. The variation of hydraulic gradient is divided into four periods which means different velocity and acceleration .Finally, the Logistic model of hydraulic gradient is simplified to a function of time factor tv, linking variation of hydraulic gradient with degree of soil consolidation.While degree of soil consolidation of each period is available, it could conduce to elaborate study of effect and application of hydraulic gradient on consolidation process.