Consolidation behaviors of multi-reinforcement composite ground considering time- and depth-dependent clogging effects of prefabricated vertical drains

Taking the composite ground improved by prefabricated vertical drains (PVDs) and cement mixing piles as the research object, an analytical model for the consolidation of multi-reinforcement composite foundation is established by considering the clogging effects of PVDs based on an assumption that their permeability coefficient decays simultaneously as an exponential function of time and a linear function of depth. Moreover, the following factors are also considered: the smearing effects of PVDs, the disturbance effects of cement mixing piles, and the radial and vertical seepages within the soil. The analytical solutions for the analytical model are subsequently deduced. After then, the solutions are degenerated to the cases with only the time- or depth-dependent well resistance. The correctness of the solutions is verified by comparing the predicted results with the measured data. Finally, the consolidation behaviors of the multi-reinforcement composite foundation are investigated through a series of the parametrical analysis. The results show the consolidation rate slows down when considering the time- and depth-dependent well resistance of PVDs by comparing that of the constant well resistance. Moreover, the reduction in the consolidation rate can be regarded as the sum of the influences of each single factor. The smaller the values of \theta _1 and the larger the values of \theta _2 and \theta _3 , the slower the consolidation rate. When \theta _3 increases to a certain extent, the radial consolidation ceases, and the consolidation process will be completed only by the vertical flow at the later stage of consolidation.