基于连续排水边界条件的砂井地基固结解析解

For the limitations of the boundary condition under instantaneous constant load in traditional sand-drained consolidation theory, the three-dimensional consolidation equation of sand-drained ground was solved based on the continuous drainage boundary. And the analytical solution considering the effects of smear and well resistance was obtained. Then, the rationality of the solution was verified by degenerating and comparing the analytic solution with the existing research results. Finally, the excess pore water pressure and average consolidation degree of sand-drained ground under continuous drainage boundary conditions were analyzed according to the analytical solution. The results showed that the continuous drainage boundary condition realizes the whole process from impermeable to completely permeable by changing the value of interface parameterb, which compensates for the shortcoming of traditional boundary. In terms of the excess pore water pressure, the drainage capacity of ground surface is reduced with the decrease of the value ofb. Therefore, the excess pore water pressure exists at the top surface of the ground, and the smaller thebis, the greater the excess pore water pressure is. Meanwhile, the pore pressure increases with the enhancing distance from the sand-drained at the same plane. As for the consolidation degree, the average consolidation degree of the ground decreases with the decrease ofb. So, the consolidation rate of the ground may be overestimated under the complete drainage condition of the traditional consolidation theory. Moreover, the consolidation rate of the foundation would be significantly reduced with the decrease of the permeability coefficient in the smear area and the sand well. Therefore, the disturbance to the soil of the well wall should be reduced and the seepage capacity of the vertical drainage should be increased to weaken the smear effect and the well resistance. In addition, the rates of settlements and consolidation will be underestimated if the vertical seepage is ignored, although the radial seepage is dominant in sand-drain.