水库水位非均匀下降情况下库岸浸润线求解

以往计算库区边坡浸润线大都是基于库水的均匀下降。当库水位较高时,随着泄水时间的增加,泄水口水压将不断减小,下泄流量和库水变幅速度都会非均匀变化,此时再以库水均匀下降来计算得到的浸润线必然会存在误差。为此,首先建立库水位下降高度和时间的函数关系,再根据布西涅斯克非稳定渗流微分方程和一定假设条件,应用拉普拉斯正变换和逆变换,得到了考虑库水非均匀下降条件下的坡体内浸润线的简化计算公式。通过算例分析了下降时间和初始速度对浸润线的影响,结果表明下降时间对浸润线的影响比较显著。

Solution of reservoir bank phreatic line during reservoir water uneven drawdown

Previous solution of phreatic line in the reservoir bank is derived based on even drawdown of water level. However, the water pressure at the discharge opening will keep decreasing with the discharge time, so the discharge flow and water level fluctuation would change in an uneven way. Under this condition, errors are inevitable in the previous solution based on even drawdown process. First, the functional relation between drawdown height and time is established, and then the Boussinnesq differential equation for unsteady seepage flow and some assumptions are applied to analyze the phreatic line in the bank of reservoir during drawdown by using the Laplace positive and inverse transform, so a simplified formula that considers uneven drawdown is proposed. With a example, we analyze the influence of drawdown duration and initial velocity on the phreatic line, and the drawdown duration is proved to be an important influential factor. Key words：uneven drawdown; unsteady seepage; phreatic line; bank of reservoir