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含有与大气不相连通的封闭气泡且饱和度接近100%的土体称为近饱和土体。通过室内土柱一维积水入渗模型试验,研究了入渗稳定时土壤类型、干密度和初始含水率对近饱和土体中封闭气泡的含量以及气相逸出率的影响,分析了3种影响因素对封闭气泡体积的影响趋势和影响机理。试验结果表明:土样孔隙中封闭气泡的体积随土样干密度的增大而减小;当土样初始含水率超过某一临界含水率时,土样孔隙中封闭气泡的逸出随初始含水率的增加显著减少;由于黏性土达到渗流稳定需要的时间较砂性土长,因而砂性土的气相逸出率要明显小于黏性土的气相逸出率。通过试验揭示了实际土体入渗中的一些物理现象,为更好地理解土壤入渗过程和建立数值模拟模型提供了试验数据。
Soil containing closed air bubbles that are not connected to the atmosphere and with nearly 100% saturation is called a nearly saturated soil. Through the one-dimensional water infiltration model experiment of indoor soil column, the effect of soil type, dry density and initial moisture content on the closed bubble content and gas-phase escape rate in near saturated soil was studied. Influencing factors on the closed bubble volume trend and influence mechanism. The results show that the volume of closed bubbles decreases with the increase of dry density of soil samples. When the initial moisture content of soil samples exceeds a certain critical moisture content, the escape of closed bubbles in soil samples with initial water content The rate of increase is significantly reduced. Because the time required to reach the seepage stability of cohesive soil is longer than that of sandy soil, the gas phase escape rate of sandy soil is obviously smaller than that of cohesive soil. Experiments revealed some physical phenomena in actual soil infiltration, which provided experimental data for better understanding soil infiltration process and establishing numerical simulation model.