灌渠水位变动影响下的潜水非稳定流计算

Calculation on Transient Phreatic Flow Subject to Varying Water Level of Irrigation Channel

【目的】解决渠道水位变化所形成的地下水非稳定渗流问题。【方法】将渠水位变化过程概化为瞬时上升连接线性时变两段,以其为第一类边界条件,建立渠水位边界控制下的一维潜水非稳定渗流模型;利用Laplace变换求模型解,在进行逆变换过程中引用变换的"积分性质",使求解过程相对简便,获得的解由常用函数组成且表达形式比较简单;讨论特定解及其对应的水文地质意义,依据解给出渠水与地下水之间水量交换强度的计算方法;结合实例,分析水位缓慢变化段对交换强度的影响规律。【结果】相对河流水位复杂多变的变化过程,灌渠水位变化有一定规律可循,往往是快速变化后再连接一相对缓慢的变化过程。【结论】渠道水位变化规律为先快后慢。

【Objective】Solve the problem of transient phreatic flow caused by the water level in the channel increases rapidly and then increases slowly or decreases,and the change of water level is generalized to the instantaneous ascending and linear time-varying.【Method】A one-dimensional transient phreatic flow model is established subjected to the bounded by channel.Using the Laplace transform,and paying attention to the'integral property'in Laplace transform,the paper gives a simple solution which is expressed by common functions.This paper expatiates the specific solution and its corresponding hydrogeological significance,deduces the calculation method for the exchange of water between the channel water and the groundwater,and illustrates the calculation process with an example.【Result】Relative to the complex and changeable process of river water level,the change of water level in irrigation canal can be followed by a certain law,which is often a relatively slow change process after rapid change.【Conclusion】The water level in the channel changing characteristics is first fast then slow.