降雨入渗路基湿度场演变规律

摘要

为研究受地下水位高度差异的影响降雨入渗路基湿度场的分布与变化状态,基于饱和-非饱和土渗流理论,构建了5种具备不同初始地下水位的路基数值试验模型. 通过分析两种降雨强度情况下的试验结果,总结了湿度场变化的主要规律,并阐述其根本机理. 结果表明:降雨雨强越大,地下水受到扰动抬升越显著,路基层位越低,其湿度和扰动区扩距受地下水影响越显著;随着初始水位降低,路堤湿度极差的增幅呈二次曲线增大并至稳定值,扰动区水平扩距呈二次曲线减小并至稳定值;工况一定,则对应存在一个平衡水位线,当初始水位在其之下时,对路基湿度演变影响甚微,反之,随着初始水位的增高,路基湿度增幅呈对数递增. 处于平衡水位之上时,初始地下水位高度对降雨入渗路基引发湿度场的分布与变化状态影响显著.%To study different influences of original water tables on the roadbed moisture field infiltrated by rainfall, five scale-down laboratory roadbed physical models with different original water tables were tested base on saturated-unsaturated soil seepage theory. The roadbed moisture field change rules were examined and its mechanism was explained through analyzing infiltration test results of two different rainfall intensities. The results show that the water tables rise significantly with the increase of rainfall strength, and the influences of original levels on moisture fields get more significant along with the increase of roadbed depths. With decrease of original levels the amplifications of roadbed moisture range increase quadratically to a steady value and the extended distances of moisture disturbed zone decrease quadratically to a steady value. A balanced original water table should exist according to a given field situation. The influences of groundwater on moisture fields are very slight while the original levels are deeper than the balanced one, otherwise, with increase of original levels the amplifications of roadbed moisture increase logarithmically and the influence is very significantly when the water table is higher than the balanced one.