One-dimensional Dynamic Consolidation Analysis Of Saturated Soils

The single-side drainage consolidation test of saturated silty soil was carried out by using the consolidation instrument which can measure the pore pressure at the bottom.The test results show that the pore pressure in the soil sample does not reach the load value instantaneously,and there is obvious hysteresis phenomenon.This is not consistent with Terzaghi one-dimensional consolidation theory.Based on Biot dynamic consolidation theory,this paper analyzes the causes of the hysteresis phenomenon of pore water pressure,and then discusses the consolidation process of linear elastic foundation and nonlinear foundation respectively considering the dynamic effect.The main conclusions are as follows:(1)According to the results of single-side drainage tests on saturated clay or soft soil and on saturated silty soil in this paper,the pore pressure in saturated soil has obvious lag phenomenon.From the analysis of Biot’s one-dimensional dynamic consolidation theory,it can be seen that the consolidation equation considering the acceleration term can simulate this phenomenon.(2)The dynamic consolidation equation of one-dimensional linear elastic foundation is established and the corresponding solution scheme of finite volume method is given.Numerical analysis shows that the drainage conditions of the boundary have great influence on dynamic consolidation.The influence of dynamic effect on consolidation process is more significant in the case of double-sided drainage,and the pore pressure and vertical strain in the double-sided drainage foundation are not symmetric with respect to depth.When the external load is cyclic,the rise of pore pressure fluctuates at the initial stage of consolidation.With the increase of load period,the peak value of consolidation degree of pore water pressure becomes smaller,and the consolidation degree defined by pore water pressure appears negative value.This is because of the negative excess pore water pressure in shallow foundation due to unloading when the surface pressure becomes small.(3)One dimensional dynamic consolidation equation of nonlinear elastic foundation is derived and solved by finite volume method.Parameter analysis shows that the hysteresis phenomenon of pore water pressure will be strengthened by decreasing the compression coefficient,increasing the permeability index,decreasing the soil thickness or increasing the initial permeability coefficient at the initial stage of consolidation process.In the middle and late consolidation stage,namely the dissipation stage of pore water pressure,the dissipation process of pore water pressure will be accelerated with the decrease of compressibility coefficient and soil layer thickness,and the increase of permeability index,external load and initial permeability coefficient will accelerate the dissipation process of pore water pressure...