Compressibility of Compacted Weathered Basalt Soil

在佐贺县东北部的宇和场地区，分布着玄武岩风化的产物--温泉土。根据日本标准土壤分类法，将以埃洛石和埃洛石为主要成分的温泉土归类为粘土。该土的一般特点是土粒比重大，粘粒含量小，含水量高，干密度小，约为lg/cm^3。以及由于浸水而引起的沉降行为。在最佳含水量以下击实的土样，浸水后其压缩特性发生变化，出现膨胀或沉降;在最佳含水量以上击实的土样，饱和度大于85%时，浸水后其压缩特性保持不变，不发生沉降。

Onjaku Soil, the weathering product of basalt, is distributed in Uwaba area, north eastern part of Saga Prefecture. Onjaku soil which consist mainly of halloysite and chlorite as clay mineral is classified as clay soil according to Japanese Standard Soil Classification. The general features of this soil are great specific gravity of soil particles, high water content for small clay fraction percentage, and small dried density of around lg/cm^3.The present paper investigates the compressibility of compacted Onjaku soil. and its settlement behavior due to water immersion. The characteristics of soil compressibility, due to water immersion, changed for soil samples compacted below optimum water content, and expansion or settlement occurred, while the soil compressibilty remained unchanged and no settlement occurred for soil samples compacted above optimum water content, with saturation degree greater than around 85%.