Instability mechanism and reinforcement effects of expansive soil channel slopes of Yangtze River to Huaihe River Diversion Project

The expansive soil is a kind of special soil that absorbs water, expands and softens, and shrinks and cracks after losing water. It is often called disastrous soil in engineering circles. Treatment of the expansive soil channel slopes is one of the main technical problems of the Yangtze River to Huaihe River Diversion Project. The instability mechanism and causes of the expansive soil channel slopes in typical section of the Yangtze River to Huaihe River Diversion Project are analyzed. The observation windows are set up to observe the fissures of the channel slopes. The technology of cement-modified soil replacement, reinforced anchor rod and GFRP-reinforced anchor rod to reinforce the channel slopes is used. The design scheme and special construction technology of cement-soil replacement and reinforcement of the channel slopes with anchor rod are introduced. The stress changes of the two anchor bolts during the water injection period and the water level stability period are monitored by using a stress meter, and an automatic monitoring system is used to monitor the deformation of the channel slopes after reinforcement. The monitoring results show that the maximum displacement of the slope strengthened by reinforced anchor rod is 1.03 mm, and the displacement of GFRP anchor rod is 1.96 mm. The stress of anchor rod increases gradually during the water injection period and tends to be stable during the water level stability period, and it decreases gradually during the precipitation period. The displacement of rock and soil in the deep layer of the channel bottom and slope is very small, which indicates that the reinforcement effects of the channel slopes are good and there is no obvious sliding surface.