Improved Technology Of High-speed Railway Roadbed Filler

On the basis of the situation of lacking high quality subgrade filling for theplanning high-speed railway from Beijing to Shanghai, representative cohesive soil wasselected. According to its basic physical and mechanical properties, we developed akind of soil stabilizer sieved from varied test formulations in a series of indoorexperiments by using unconfined compression strength as the main index. Then,experiments of unconfined compression strength, flexure strength, water stability,wetting and drying, freezing and thawing were carried out on the stabilizer-improvedsoil for studying its strength and endurance performances and analyzing theimprovement effect of the stabilizer. Those experiments were also contrasted with theuntreated and the cement-improved soil.The final adopted stabilizer is a kind of cement-based powdery blend mainlyincluding cement, lime, sulfate and aluminate in the appropriate proportion. When it isput into the soil, a lot of hydrates of calcium silicate gel, aluminate colloid and calciumcrystal are created in the alkaline environment. As time goes on, they increasegradually, interweave together and finally a kind of spatial net-shaped structure isformed in the improved soil. At the same time, the free water is absorbed and changedinto crystal or bound water. So the purpose of strength increasing, compactnessenhancing, volume microswelling and endurance improving can be achieved.The results of the strength and endurance experiments show that the strength ofthe untreated soil is very low and its water stability is so bad that it will soften fastwhen immersing into water. The strength of the cement-improved soil is a litter higher,but it does not grow very rapidly, it has the property of drying shrinkage, and itsendurance is not good enough as the whole. Contrasting with the cement-improvedsoil, the unconfined compression and flexure strength of the stabilizer-improved soilincrease greatly, the property of microswelling counteracts the shrinkage causing bycement, the water stability and the ability of wetting-and-drying resisting become alittle better, and the ability of freezing-and-thawing resisting improves obviously.The strength and endurance of the soft clay improved by using the stabilizerdeveloped in this thesis can be increased greatly, and its technical economic indicatorsare satisfied on the whole. The stabilizer-improved soil is a kind of high qualitysubgrade filling for high-speed railway and super highway. Therefore, the stabilizer hasa wide application prospect.