采用激光粒度仪对膨胀土、黄土和红土进行了颗粒分析试验,研究了取样质量和超声波分散时间对试验结果的影响,发现遮光率与取样质量呈现很好的线性正相关,给出了特殊土在激光粒度仪法试验中适宜的遮光率范围(15%~25%)、取样质量(膨胀土取0.1~0.2 g,黄土取0.4~0.8 g,红土取0.2~0.4 g)和超声波分散时间(膨胀土取6 min,黄土和红土取2 min);激光粒度仪法试验结果的离散性,对于黄土和膨胀土较小,但对红土相对较大,红土平行试验中粒组含量极差的最大值为10.1%;与密度计法相比,激光粒度仪法测得的胶粒(0,0.002]mm含量偏小,而黏粒(0.002,0.005]mm或更大粒组的含量则偏大,可能是因为两者试验原理的不同而导致的;2种方法对红土的测试结果差异较大,与红土的特殊性质有一定关系。研究成果为激光粒度仪在特殊土颗粒分析试验中的应用提供了借鉴。

A laser particle size analyzer was employed to test the grain size of expansive soil, loess, and laterite to examine how sample mass and ultrasonic dispersion time affect the test results. A strong linear positive correlation was observed between shading rate and sample mass. Optimal conditions were determined for the laser particle size analyzer tests: shading rate between 15% and 25%, sample mass of 0.1-0.2 g for expansive soil, 0.4-0.8 g for loess, and 0.2-0.4 g for laterite, with ultrasonic dispersion times of 6 minutes for expansive soil and 2 minutes for loess and laterite. The test results are less discrete for loess and expansive soil but more discretized for laterite. In parallel tests, the maximum range in fraction content for laterite reached 10.1%. Compared to the densimeter method, the laser particle size analyzer reported lower contents of colloidal particles (smaller than 0.002 mm) and higher contents of clay particles (0.005-0.002 mm) or larger fractions. These discrepancies are likely due to the different principles underlying the two methods. The substantial differences in test results for laterite may be attributed to its unique properties. This study provides valuable insights for utilizing laser particle size analyzers in the grain-size analysis of special soils.