膨胀性土壤干缩裂隙对入渗产流影响

Influence of Swelling soil Shrinkage Cracks on Rainfall Infiltration Tests

膨胀性土壤具有吸水膨胀,失水干缩开裂的特性,其中土壤裂隙对降雨入渗和产流过程均会产生重要的影响。为探究膨胀性土壤干缩裂隙对入渗产流的影响规律,以青海湖流域常见的栗钙土为膨胀性土壤,针对土壤干缩过程,设置不同土壤初始含水量开展室内降雨入渗产流试验,研究在不同初始含水量下土壤干缩裂隙对土壤累计入渗量、径流强度和土壤含水量等的影响。结果表明:随着土壤初始含水量的降低,土壤干缩裂隙发育程度提高,土壤累计入渗量、初始入渗率、平均入渗率和稳定入渗率均增大;土壤表面裂隙率和裂隙线密度与累计入渗量相关程度较好,相关系数均大于0.85,表面裂隙面积率和线密度越大,裂隙对入渗的作用越显著;土壤干缩裂隙发育程度越高,土壤产流滞后时间越长,产流量越小,径流强度达到稳定的时间越长;土壤干缩裂隙有利于优先流形成,裂隙发育程度越高,土壤水分对深层土壤的补给能力越强。试验探究了膨胀性土壤干缩裂隙对入渗产流的影响,为膨胀性土壤降雨入渗产流规律提供了补充。

The properties of expansive soil include water expansion,dehydration shrinkage,and cracking,with soil fissure having a significant impact on rainfall infiltration and runoff generation.This paper uses chestnut soil,which is frequently found in the Qinghai Lake Basin,as expansive soil,and performs an indoor rainfall infiltration runoff generation experiment with varying initial soil moisture contents for the soil shrinkage process.The goal of the experiment is to investigate the influence of the law of desiccation cracks of expansive soil on infiltration runoff generation,the effects of soil fissure and shrinkage on runoff intensity,cumulative infiltration rate,and moisture content under various initial moisture content conditions.The findings indicate that when the initial water content of the soil declined,soil shrinkage and fissure development increases,and all of the infiltration rates—initial infiltration amount,cumulative infiltration amount,initial infiltration rate,average infiltration rate,and stable infiltration rate—increase as well.The accumulated infiltration amount,fissure linear density,and soil surface fissure rate all exhibit strong correlations with correlation coefficients above 0.85.The more surface fissure area rate and linear density there are,the greater the impact of the fissure on infiltration.The longer the lag time between soil runoff generation and runoff generation from other sources,the smaller the runoff generation,and the longer it takes for the runoff intensity to stabilize,all are related to the degree of soil shrinkage and fissure development.Soil shrinkage and fissure are advantageous for the development of preferred flow.The capacity of the soil to supply water to deep soil increases with the degree of fissure formation.In order to complement the rainfall infiltration runoff generation law of expansive soil,the experiment investigates the influence of expansive soil shrinkage and fissure on infiltration runoff generation.