The subgrade below the under-construction Kunming–Shanghai high-speed railway faces serious stability problems induced by considerable swelling and shrinkage volume change of expansive soil along with variation of moisture content. To prevent the occurrence of potential damage, reasons for the frequent occurrence of drainage ditch breakage and platform damage along the railway corridor in expansive soil areas were analyzed. A novel integral ancillary facility and semi-rigid waterproof functional layer were developed. Large-scale field dynamic tests were carried out to investigate the fatigue performance of the waterproof functional layer and the influences of different service environments (relatively dry condition and immersion condition) on the dynamic response of the subgrade. Results show that the fatigue property and waterproofing capability of the waterproof functional layer can fulfill the standard requirements for the high-speed railway subgrade. There was an enlargement phenomenon of the dynamic stress and vibration velocity when the service environment of subgrade changed from a relatively dry condition to an immersion condition. The vibration velocity seemed to increase along the depth of the graded broken stone surface layer and decrease linearly with further depth increase from the bottom surface of the waterproof functional layer.
Field study on swelling-shrinkage response of an expansive soil foundation under high-speed railway embankment loads
