Analysis of Engineering Properties of Typical Coal-measure Soils in Western Fujian

To reveal the engineering characteristics of typical coal-measure soils in western Fujian, a typical coal-measure soils distributed along the Longyan East Ring Expressway was taken as an example, a large number of laboratory tests were carried out to analyze the basic engineering properties, disintegration resistance and dry/wet/freeze properties of coal-measure soils. The change law of soil strength index under melting cycle, etc. The results show that the coal-measure soil in western Fujian has the characteristics of high plastic index, high dry density and high compressibility. The mineral composition is muscovite, quartz and kaolinite, which belongs to medium compressibility soil and low liquid limit silty clay. During the compaction process, coal-measure soil has obvious particle breakage phenomenon. Coal-measure soil has low cohesion between particles, and is easier to disintegrate when exposed to water. Coal-measure soil with the same compaction degree, the higher the moisture content, the easier it is to be compressed. The cohesion force and the internal friction angle both increased with the increase of the compaction degree and decreased with the increase of the water content. The effect of compaction and moisture content on the cohesion of coal-measure soil is greater than that of the internal friction angle. After 4 dry-wetting cycles or 5 freeze-thaw cycles, the compressive strength and shear strength tend to be stable, and the soil samples basically have no cracks. The void ratio of coal-measure soil samples decreased continuously with the increase of cycle times, water content and compaction degree; cohesion increased with the increase of cycle times, while the internal friction angle showed an opposite trend.