反演含碎石碳酸盐岩红土水力特性

Inversion of Hydraulic Properties of Carbonate-Derived Laterite Containing Gravel

为探究喀斯特地区碎石夹层对碳酸盐岩红土水力特性的影响因素,通过室内模拟土柱入渗试验,采用垂直入渗水头法研究3种碎石体积含量(0,40%,80%)和3种碎石埋藏深度(0,5,15 cm)分别与累积入渗量、湿润锋、入渗特性和土壤水分特征曲线之间的关系,并采用3种模型分析了含碎石土壤对传统土壤入渗模型的适用性,将实测入渗数据结合改进的Green-Ampt模型反演Brooks-Corey模型参数。结果表明:在相同碎石埋藏深度下,累积入渗量、湿润锋、初始入渗率、平均入渗率和稳定入渗率均随碎石含量增加而减小;当碎石含量为40%时,埋藏深度是15 cm的土壤稳定入渗率最大(12.71 mm/h),是埋藏深度为0 cm的1.33倍。Horton模型对含碎石夹层土壤入渗规律的适用性要优于Kostiakov模型和Philip模型。反演参数a、n和h_(d)在同一碎石埋藏深度(0,5 cm)下,随碎石含量增加而增大,而K_(s)随碎石含量增加而减小。通过土壤水分特征曲线可知,对照组土壤持水性最低;含碎石夹层土壤持水性随碎石含量增加而减弱,但碎石埋藏深度为15 cm时,含碎石夹层土壤持水性随碎石含量增加而增强;当碎石含量为40%时,不同碎石埋藏深度下土壤持水能力大小为埋藏深度0 cm>埋藏深度5 cm>埋藏深度15 cm。研究结果可为西南喀斯特地区水资源利用提供数据参考。

In order to explore the influence of the gravel interbed on the carbonate-derived laterite hydraulic properties,indoor soil column infiltration and vertical infiltration experiments were conducted to examine the relationship of 3 different gravel volume contents(0,40%and 80%)and 3 different gravel burial depths(0,5 and 15 cm)between the cumulative infiltration,wetting front,infiltration characteristics,and soil water characteristic curves.The applicability of the traditional soil infiltration model was analyzed by three models.These Brooks-Corey model parameters were inverted by the measured infiltration data and the modified Green-Ampt model.The results showed that the cumulative infiltration,wetting front,initial infiltration rate,average infiltration rate,and steady infiltration rate obviously decline,along with the increase of the gravel content at the same gravel burial depth.When the gravel content was 40%,the largest soil steady infiltration rate(12.71 mm/h)was found in gravel burial depth of 15 cm,which was 1.33 times higher than that of 0 cm.The Horton equation's validation of the infiltration characteristics were superior to those expressed by the Kostiakov model and Philip formula.At the same gravel burial depth(0 and 5 cm),the inverted parameters a,n,and h_(d) increased with the increase of gravel content,while K_(s) decreased.The soil water retention of control group was the lowest,and the soil water retention of the gravel interbed decreased with the increase of the gravel content.However,when the gravel burial depth was 15 cm,the soil water retention of the gravel interbed increased with the increase of the gravel content.As the gravel content arrived at 40%,the relationship of soil water retention in different gravel burial depths was 0 cm>5 cm>15 cm.These results can provide data reference for the taking advantage of water resource in the southwest karst regions.