Semi-analytical solution of pore pressure response around excavations to groundwater level fluctuation

The behavior of excavations subjected to water fluctuation is a new subject in engineering practices, with the pore pressure response around them being the focus. By dividing the seepage area around the excavations into several zones and assuming the total stress constant, the consolidation equation is decoupled, and then a semi-analytical solution of pore pressure response around a plate-supported excavation to water level fluctuation is deduced in conjunction with the Laplace and Fourier transformations. Based on the above solution, a parametric study is carried out to examine the effects of comprehensive coefficient θ (related to consolidation coefficient, seabed thickness and period) and compressibility of pore fluid on the pore pressure response. The results indicate that the amplitude of the relative pore pressure attenuates along the shortest seepage path, while the phase lag increases accordingly. The larger the θ, the smaller the amplitude of relative pore pressure and the larger the phase lag; furthermore, the maximum amplitude equals the value of the relative pore pressure in steady condition. In addition, the larger the compressibility of pore fluid, the smaller the amplitude of excess pore pressure and the larger the phase lag. The larger the embedded depth of retaining wall, the larger the amplitude of pore pressure in active side and the smaller the amplitude of pore pressure in passive side.