Field study of treatment for expansive soil/rock channel slope with soilbags

A full-scale field test in the South-to-North Water Transfer Project (SNWTP) in China was conducted on a 60 m long expansive soil/rock channel slope reinforced with soilbags. The field test involved the construction of the soilbags, the rising and falling of the channel water level as well as the natural and artificial rainfalls. During the testing period, in-situ monitoring of water contents, earth pressures and lateral displacements was conducted. It was found that: 1) the water content of the expansive soil/rock slope changed slightly with the rainfalls and other environmental factors after the reinforcement with soilbags; 2) the earth pressure measured under the soilbags layer was close to its overburden pressure with no swelling pressure of the expansive soil contained in the bags; and 3) the lateral displacement of the expansive soil/rock channel slope mainly occurred before the construction of the soilbags layer and tended to be stable after the completion of the soilbags layer. The monitored results suggested the effectiveness of soilbags to prevent moisture migration, mitigate the swelling potential and enhance the slope stability.