不同上覆荷载作用下膨胀土特性研究

Study on Properties of Expansive Soil under Different Overburden Loads

以河南平顶山膨胀土为研究对象,通过室内土工试验,研究膨胀土颗粒粒径范围对自由膨胀率的影响;按照等质量原则将各粒径范围土混合后制取试样,研究了其在无上覆荷载、不同上覆荷载条件下的膨胀变形发展规律,以及试验后土体物性指标随上覆荷载变化规律等。结果表明:膨胀土粉碎过筛后颗粒粒径大小对自由膨胀率具有显著影响,最大相差可达2.3倍;无上覆荷载作用时,膨胀土膨胀率随浸水时间呈现明显的折线型增长规律,而在有上覆荷载作用时则转变为对数型曲线型增长模式。膨胀稳定后,土体含水率及其相对增量均呈现负对数型减小,而密实度则随上覆荷载的增加呈现正对数型逐渐增大。

Taking expansive soil of Pingdingshan city as the research object, the influence of the range of expansive soil particle size on the free expansion rate has been studied through indoor geotechnical tests. Samples are made after the soil with the range of expansive soil particle size have been mixed according to the principle of equal mass to study the development law of expansive deformation under the conditions of non-overlying load and various overlying loads and the variation law of soil physical property indexes with overlying load after test.The results show that the particle size of expansive soil after crushing and screening has a significant effect on the free expansion rate, and the maximum difference can reach 2.3 times. When there is no overlying load, the expansion rate of expansive soil shows an obvious broken line growth law with the immersion time, while under the action of overlying load, the expansion rate of expansive soil changes into a logarithmic curve growth pattern.The soil moisture content and its relative increment decrease in a negative logarithmic pattern, while the soil compactness increases in a positive logarithmic pattern with the increase of overlying load.