| Soft clay foundations are characterized by high water content,low strength and high compressibility,so some measures need to be taken to strengthen soft clay foundations to improve their bearing capacity and stability.Composite foundations are an effective method of reinforcing soft clay foundations,and the study of their consolidation and deformation laws and influencing factors is of great significance to the design and construction of composite foundations.In this paper,on the basis of the existing soft clay foundation consolidation treatment,a multiple composite foundation with vertical drain-impervious pile is studied,and a calculation model with "well-soil-pile" as the unit is established based on the traditional sand well foundation consolidation theoretical model.The effects of initial pore pressure nonuniformity,well resistance effect,temperature and load variation with time on the overall foundation consolidation were analyzed.The main work and research results are as follows:(1)In order to solve the problem of consolidation of multi-composite foundations with vertical drains-impervious piles under non-uniform initial pore pressure,an analytical solution for consolidation of multi-composite foundations based on the assumption of equal strain is derived based on the axisymmetric model,and the consolidation properties of multi-composite foundations are analyzed by plotting the consolidation curves of relevant influencing parameters.The study shows that the foundation consolidates faster as the initial pore pressure at the bottom of the soil layer becomes smaller.Consolidation is slowest when the initial pore pressure is distributed in a positive triangle,faster when it is distributed in a trapezoid than in a rectangle,and fastest when it is distributed in an inverted triangle.Compared to a single pile type foundation,a multiple composite foundation can significantly accelerate consolidation.(2)The influence of the change in well resistance with time and the combined soil radialvertical seepage on the multifaceted composite foundation is considered to derive the solution for consolidation under this influence and to verify the correctness of the solution.The study shows that the presence of well resistance slows down the consolidation rate of the composite foundation,with increasing well resistance factor,the foundation consolidation rate becomes slower,and the change of well resistance mainly affects the later consolidation of the foundation.When the thickness of the foundation is different,the change in the vertical permeability coefficient of the soil has a different effect on the consolidation rate of the foundation.The magnitude of the vertical shaft permeability coefficient also has an important influence on the consolidation characteristics of multifaceted composite foundations.(3)Considering the influence of temperature effect on the consolidation of the multicomposite foundation,a consolidation calculation model is established and the analytical solution for the consolidation of the vertical drain-impervious pile multi-composite foundation under this influence factor is derived.The solution is validated by degradation analysis,and parameter sensitivity analysis is carried out to investigate the consolidation characteristics of the multi-composite foundation using the derived consolidation solution.The results show that the consolidation rate of the multi-composite foundation will be significantly accelerated with the increase of temperature,but the development of soil consolidation will be slowed down with time,and the influence of temperature on soil consolidation will also be gradually weakened,resulting in the growth rate of consolidation with the increase of temperature will also be gradually reduced.(4)The effect of load variation with time on the multi-composite foundation is considered,and the boundary conditions and initial conditions are determined according to the basic assumptions to derive the analytical solution for the consolidation of the vertical drainimpervious pile multi-composite foundation under variable load.The relevant calculation program is prepared for this consolidation solution,and the effect of each parameter on the consolidation rate of the multi-composite foundation is analyzed by plotting the consolidation curve.The study shows that the shorter the loading time of the upper part of the foundation,the faster the consolidation rate of the composite foundation.The consolidation rate of the composite foundations increases with the increase of the replacement rate and compression modulus of the undrained piles. |
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