不透水边界条件下双层堤基上盖重的渗流计算方法

Seepage computation methods for landside seepage berms on two-stratum dike foundations with impervious boundaries

盖重是堤防工程中最常用也是非常有效的管涌除险措施,对背水侧堤基透水层端部为已知水头边界的情况,已有许多研究成果给出了盖重渗流计算的方法。但是,实际工程中也会碰到背水侧堤基透水层端部为不透水边界的情况,对这种情况下的盖重渗流计算方法尚未见到有研究成果发表。为此,本文针对不透水边界条件下的有限远和无限远双层堤基,推导了弱透水和透水盖重的渗流计算公式,盖重的渗透性可以是任意的,盖重首末端可以取不同的安全系数,同时对影响盖重宽度和厚度的参数进行了讨论,对安全系数的取值以及盖重材料的选用提出了建议。

The constructions of seepage berms are the most common measures against sand boils in dike projects. Under the condition of deterministic water head at downstream boundary of pervious foundation, seepage computation methods had been suggested by several researches. However, downstream boundary condition in the pervious foundation maybe impervious in practical engineering, and there has not been studies for such cases before. This paper works out formulae for seepage computations of seepage berms with low-permeability and high-permeability on finite and infinite two-stratum dike foundations with impervious downstream boundary. In these formulae, the permeability of berm embankment can be arbitrary and the safety factor for seepage control at the two ends of the berms can be different. In addition, parameters affecting berm thickness and length are discussed. The paper also gives some suggestions on the selections of berm soils and acceptable safety factors for seepage control, which can be referred in future dike design.