覆土厚度对裸岩石砾地土壤颗粒迁移过程的影响

Experimental Study on Influence of Overburden Thickness on Soil Particle Transport Process in Bare Rock Gravel Land

为了明确裸岩石砾地土地整治工程中人为构建耕作层的合理覆土厚度,通过室内土柱模拟试验,研究了覆土厚度对裸岩石砾地土壤颗粒迁移过程的影响。根据裸岩石砾地土地整治工程特点,试验共设计4个覆土厚度,分别为5,10,15,20cm,土柱底部装填5cm厚直径为10mm的玻璃珠,试验从土柱下端出水开始记时,共接取渗漏液6h。结果表明:(1)较厚的土层具有较好的保水蓄水能力和较强的土体稳定性,4个土层厚度的水分渗漏量均随着土层厚度增加而减小,水分渗漏速率表现为先增大后减小,最终趋于稳定的趋势;(2)土壤颗粒迁出量与土层厚度呈负相关关系,土壤颗粒累积迁出量与土层厚度的拟合关系式为:y=3.19e-0.11x(R2=0.96);(3)水分渗漏前期往往伴随着大量土壤颗粒的迁出,且土层越薄,水分渗漏量和土壤颗粒迁出量越大,随着渗漏过程的进行土壤颗粒迁出量逐渐减小;(4)迁出颗粒中粉粒含量最高,黏粒次之,砂粒含量最低,且不同粒径土壤颗粒随时间的迁出特征也不同。研究结果为裸岩石砾地土地整治提供了科学依据。

In order to clarify the reasonable soil thickness of man-made tillage layer in the bare rock and gravel land remediation project,a simulation experiment of indoor soil column was conducted.The effect of soil thickness on particle migration process in bare rock and gravel soil was studied.According to the characteristics of bare rock and gravel soil reclamation project,the soil layers thickness treatments included 5 cm,10 cm,15 cm and 20 cm respectively.The bottom of the column was filled with the 5 cm thick glass beads with a diameter of 10 mm.From the start of water seepage from the bottom of the soil column,the collecting test of leakage fluid was taken for 6 h.The results showed that：（1）The thicker soil had greater water retaining capacity and stronger stability.The water leakage in the four soil layers decreased with the increasing soil thickness.The water leakage rate increased at first and then reduced,ultimately,tended to be stable.（2）The migration quantity was negatively correlated with the soil thickness,showing an exponential function of y=3.19 e-0.11 x（R2=0.96）.（3）The water leakage was often accompanied by the migration of the soil particles in the earlier stage,and the thinner the soil thickness was,the greater amount of water leakage and soil particles were.As the leakage process progressed,the quantity of soil particles migration was gradually decreased.（4）The content of silt was the highest in the migration particles,followed by the clay,and the sand content was the lowest.The migration characteristics of different soil particles varied withtime.These findings provide scientific basis for the development and consolidation of bare rock gravel land.