高分解度泥炭土-土水特征曲线研究

Study on Soil Water Characteristic Curve of Peaty Soil with High Degree of Decomposition

为了明确非饱和泥炭土的土水特征及其影响因素,以原状泥炭土和人工调配的5种不同有机质含量的重塑泥炭土为研究对象,采用滤纸法测试其基质吸力,绘制出相应的土水特征曲线,分析泥炭土原状样和重塑样土水特性的差别,以及不同有机质含量对于泥炭土土水特性的影响;选用Gardner模型、Van Genuchten模型和Fredlund&Xing模型对试验结果进行拟合,比较3种模型对泥炭土的适用性;最后分析比较高分解度泥炭土的土水特征曲线与其他土类的差异。试验结果表明:有机质含量相同时,原状土样的进气值和残余值小于重塑土样的进气值和残余值,说明原状土样的持水能力弱于重塑土样;有机质含量对泥炭土的土水特征曲线有很大影响,随着土中有机质含量的增加,土的持水能力变强,土样的进气值从155 kPa增长到1486 kPa,残余值从4796.7 kPa增长到35101.5 kPa;3种模型拟合优良度依次为Van Genuchten模型、Fredlund&Xing模型、Gardner模型;通过对比,发现高分解度泥炭土持水能力最强,其特征值大于膨润土。

In order to clarify the soil-water characteristics of unsaturated peat soil and the influencing factors,the remolded peat soil specimens with five different organic matter contents were prepared us‑ing undisturbed and artificially blended peat soil.The matric suction was measured using the filter pa‑per method and the corresponding soil-water characteristic curves were obtained.The soil-water char‑acteristic curves are used to analyze the difference of water characteristics between peat soil and re‑molded soil,and the effect of different organic matter contents on the soil-water characteristics of peat soil.The Gardner model,Van Genuchten model and Fredlund&Xing model are used to fit the test results.The applicability of the three models to peat soil was compared.Finally,the difference of the soil-water characteristic curves between peat soil with high degree of decomposition and other soils was compared.The test results show that when the organic matter content is the same,the air intake value and residual value of the undisturbed soil sample are smaller than those of the remolded soil sam‑ple,indicating that the water holding capacity of the undisturbed soil sample is weaker than that of the remolded soil sample;The organic matter has a great influence on the soil-water characteristic curve of the peat soil.With the increase of organic matter content in soil,the water holding capacity of soil becomes stronger.The intake value of the soil sample increased from 155 kPa to 1486 kPa,and the re‑sidual value increased from 4796.7 kPa to 35101.5 kPa.The fitting accuracy from high to low follows the order:Van Genuchten model,Fredlund&Xing model and Gardner model.By comparison,it is found that the peat soil with high degree of decomposition has the strongest water holding capacity and its characteristic value is larger than that of bentonite.