安哥拉本哥拉市膨胀性粉质粘土浸水试验研究

Field Water Immersion Test on Expansive Silty Clay in Benguela,Angola

本哥拉GRASA地区山前冲洪积成因的膨胀性粉质粘土因其含水率很小,难于取得原状土样,通过自由膨胀率、界限含水率等室内试验指标评价为非膨胀性土。但是现场浸水载荷试验结果表明:室内试验结果具有很大的局限性且存在误判的可能;本哥拉粉质粘土常年处于干燥低含水率状态,具有很大的膨胀潜势,浸水饱和后的膨胀量和膨胀力均很强烈;载荷板的变形过程揭示了土体遇水明显膨胀又容易发生地基破坏的性质,承载力在接近或达到饱和后,其强度又迅速大幅降低,粉质粘土具有明显遇水膨胀和增湿软化强烈的水敏特性。本哥拉粉质粘土的室内试验和现场试验具有显著的差异性,现场浸水载荷试验对于正确判定该类膨胀土的工程性质具有不可替代的作用。

The alluvial or diluvial silty clay around Benguela GRASA in Angola has the properties of swelling. Because of the very low water content, it is too dry to fetch the undisturbed sample, but the laboratory index from disturbed samples such as free swell and atterberg limits may distort the real facts. So it is necessary and helpful to adopt field water immersion test for ascertaining the swelling properties. The results of the field test indicated that the laboratory results have limitations and mistakes to determine the swelling properties; the silty clay has a high potential of swelling because of low water content; while increasing the water content, the soil has high swelling deformation and expansive {orce~ the de{orrnation curve of the plate shows subsoil heave is sensitive with small fluctuation of moisture content~ but, the strength would fall fast if the water content increase more, the Benguela silty clay has obvious sensitivity to water with the phenomena swelling and weakness during water content increasing.