中文摘要：

土壤的颗粒组成是土壤最基本的物理性质，是计算与测定土壤其他特征参数的基础。细粒土壤的颗粒组成多利用密度计法来测定，试验耗时较长。对研究区335个土样利用密度计法测定其颗粒组成的结果发现：密度计的读数时刻t和该时刻对应的悬浮液中最大颗粒粒径d之间存在显著的非线性负相关（Spearman相关系数为-0．999），两者关系曲线的拟合公式（5）为：t=43．956d^-2.068（R^2=0．997）。利用公式求得dpc=2μm（粉粒与黏粒界限值）所对应的时间tpc=10．5h；而对土样中各粒度组分质量分数的分析发现，砂粒和粉粒质量分数（Wa，Wp）之间存在显著线性负相关（Pearson相关系数为-0．972），两者关系曲线的拟合公式（6）为：Wp=86．6-0．929ws（R^2=0．945）。利用上述结果，对密度计法的测定时间进行了压缩，利用式（5）的计算结果将试验时间缩短至10．5h（简捷法），而利用武（6）则缩短至0．5h（公式法），与常规法所需24h相比，筒捷法与公式法的工作效率分别是常规法的2．3倍与48倍。公式（5），（6）同时也存在条件限制及自身不足，使用时应谨慎。希望能将筒捷法推广至其他试验条件或其他土壤采集区，而公式法则能为研究区以后的土壤颗粒分析与第四系地层成因研究提供参考。

英文摘要：

Particle-size distribution, one of the basic physical properties of soil, can be used to calculate other characteristic parameters of the soil. Though time consuming , the densimeter method is the common way to determine particle-size distribution of fine grain soils. The analysis of 335 soil samples from the study area by using this method yieds the following results. （ Ⅰ ） the reading time t for densimeter had remarkable nonlinear negative correlation with maximum particle-size d（equivalent diameter） in soil suspending liquid with coefficient of Spearman correlation of -0. 999. The fitted formula（a） for t and d was. t=43. 956d^-2.068 （coefficient of determination R^2 =0. 997）. Using the formula （a）, we got the time tsc = 10.5 h which corresponds to the critical diameter dsc=2 μm between silt and clay component; （ Ⅱ ）Analysing the relationship between sand and silt content, the result indicated that the percentage of sand and silt content （ws,wp） had obvious linear negative correlation（coefficient of Pearson correlation is -0. 972）. The fitted formula（b） for ws and wp was.wp=86.6-0. 929w,（R^2 =0. 945）. Based on the above results, testing time of densimeter method can be shortened to 10.5h （shortcut method, SM） applying formula （a） and to 0.5h （formula method, FM ） applying formula （b）. Compared to the conventional method （CM, consuming 24h）, SM and FM have their working efficiency rasied as much as 2.3 times and 48 times respectively. At the same time, formula （a） and （b） have their own limitations and insufficiency, so their application must be discreet. It is expected that SM can be used in other similar experimental conditions and for soil sampling in other areas and FM can provide some references for future research on soil lithology analysis and origin of Quaternary sediments.