Analysis And Treatment Technology Of Railway Subgrade Diseases In Expansive Soil Area

Expansive soil, as special clay, distributes widely at home and abroad. It mainly consists of kaolinite, montmorillonite and illite. This kind of soil has features of swelling by absorbing water while shrinking and cracking by losing water, which leads to the falling of soil strength that will bring great safety hazards and diseases to engineering if the soil swells and shrinks repeatedly. Therefore, for the railway construction and operation in expansive soil area, to prevent (remediate) diseases effectively is a very important technical work.The main diseases of railway subgrade bed in expansive soil area are subsidence, shoulder out and mud pumping. And subsidence and mud pumping are very conspicuous, which directly affects the stability of tracks, so it will be difficult to keep track geometry and traffic safety will be seriously threatened. By information collection, field surveys, field testing, laboratory tests and theoretical analysis, the engineering geological properties of expansive soils, the type of disease of subgrade bed, the basic conditions and mechanisms of diseases, the general principles of disease treatment and the existing treatment methods are discussed deeply, the improved technology of expansive soil improved by lime is promoted. Combined the engineering application of expansive soil improved by lime in segment from K1112 +225.3 to K1156 +250.0 of Hefei-Nanjing railway, the laboratory tests of lime improvement, the construction techniques and the subgrade conditions after operating are introduced. The technique of expansive soil improved by lime that is an effective prevention (regulation) method for the diseases of railway subgrade bed is verified.The engineering practice shows that the proposed scheme is advanced and practical, which solves the problem of key technology. It will bring significant economic and social benefits.