Seepage analysis of vacuum drainage anti-slide pile slopes considering unsteady transfer of vacuum degree

Abstract

[Objective] To solve the problems of cumbersome construction process, high cost and low drainage efficiency caused by the separation of slope drainage and reinforcement measures, [Methods]the vacuum drainage anti-slide pile(VDAP) which is a kind of support measure integrating vacuum drainage and anti-slide is designed. The model of gas unsteady seepage on slopes of the VDAP under evacuation is established. The change rule of vacuum degree in the slope caused by the VDAP and its influence on groundwater seepage under a fixed-head recharge boundary are investigated. The distribution rule of the vacuum degree in the slope under the action of vacuum drainage and the analytical solution of the groundwater seepage field in the slope are obtained. The finite element simulation software is used to establish the corresponding finite element model, and the differences between the theoretical and simulated values are compared. [Results] The results show that the theoretical analysis and the finite element calculation are in well agreement with each other, so the theoretical model can better describe the seepage characteristics of groundwater on the slope under the action of the VDAP. [Conclusion] The analysis of the influencing factors based on the theoretical solution showed that the influence range of the vacuum degree gradually expands with time, and the vacuum degree within the influence range is positively correlated with the vacuum degree in the VDAP. The increase of vacuum and pumping volume in the pile can improve the drainage performance of the VDAP. The drainage effect of the VDAP is more obvious for slopes with smaller head differences at the slope boundaries. The result of the study provide a theoretical basis for the future application of the VDAP in engineering.

Keywords

vacuum drainage anti-slide pile / groundwater seepage / unsteady gas seepage / analytical solution / numerical modeling / slope