考虑真空度非稳态传递的真空排水抗滑桩边坡渗流分析

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

摘要

【目的】为解决边坡排水与加固措施分离引起的施工工序繁琐、成本高和排水效率低等问题，【方法】设计一种集真空负压排水与抗滑于一体的支护结构，即真空排水抗滑桩，建立了抽真空作用下真空排水抗滑桩边坡气体非稳态渗流模型。系统研究了真空排水抗滑桩引起的坡内真空度变化规律及其对定水头补给边界下地下水渗流的影响。得出了真空排水作用下坡内真空度的分布规律及边坡地下水渗流场的解析解。采用有限元模拟软件建立相应的有限元模型，对比理论值与模拟值的差异。【结果】结果表明，理论解析与有限元计算结果吻合较好，理论模型能较好描述真空排水抗滑桩抽真空作用下边坡地下水渗流特性。【结论】基于理论解的影响因素分析表明：真空度的影响范围随时间推移逐渐扩大，影响范围内的真空度与桩内真空度呈正相关。桩内真空度的增大与抽水量的增大均可提升真空抗滑桩的排水性能。真空排水抗滑桩对边坡边界水头差较小的边坡排水效果更明显。研究结果为今后真空排水抗滑桩在工程应用提供理论依据。

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.

关键词

真空排水抗滑桩 / 地下水渗流 / 非稳态气体渗流 / 解析解 / 数值模拟 / 边坡

Key words

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

基金资助

国家自然科学基金项目(51968061)

国家自然科学基金项目(52368050)

宁夏自然科学基金项目(2023AAC02024)

宁夏大学水利工程一流学科项目(NXYLXK2021A03)