水平岩土层实体拦砂坝基底水压力研究

THEORETICAL STUDY ON UPLIFT PRESSURE OF CHECK DAM LAID ON HORIZONTAL SOIL

基于连续性方程、达西定律和伯努利表达式,在合理的假设条件下,本文推导了水平岩土层的实体拦砂坝基底处关键点的水压力解析式,通过与数值模拟(Autobank有限元程序)对比可知,本文解析式与数值分析结果误差非常小,其误差基本控制在1%以内,该解析方法是可靠稳定的。本文还进一步讨论了该方法的应用价值,依据得出的水头,可计算构筑物下游x处的水力坡降,判断构筑物下游土体的渗透变形类型,也可估算需要处理的范围以及对护坦长度的设计提供依据。依据相关文献结论,提出运用该解析式计算有坡度的沟床的拦砂坝基底扬压力偏于安全,并且提出了该解析式计算实体拦砂坝底部水压力是否需要考虑"地基的有效深度"对基底水压力的影响问题,此问题还需要进一步研究。

Based on the continuity equation and Darcy’s law and the Bernoulli expression,the paper deduces the analytical formula of the water pressure at the key point of the uplift pressure of a check dam laid on horizontal soil in reasonable hypothesis condition.Comparing the results with numerical simulation(Autobank finite element program),the error between the analytical calculation result and the numerical analysis result in this paper is very small,basically less than 1%,which shows the analytical method reliable and stable.The application value of this method is further discussed.Based on the obtained water head,the hydraulic gradient at the downstream x location of the structure can be calculated,the type of seepage deformation of the soil laid on downstream of the structure can be judged,and the range to be treated and the design of the length of the protective tank can be estimated.Referring to the conclusions of relevant literatures,it is proposed that it is safer to use this analytical formula to calculate the uplift pressure of the foundation base of a check dam built on a sloping channel bed.Further study is needed about whether the influence of"effective depth of foundation"to the water pressure of the foundation base needs to be considered in the calculation of uplift pressure of a check dam.