Experimental study on slope morphological characteristics and stability analysis of GCHP engineering in the loess plateau

Abstract

Construction gully slope to terrace (STT) is one of soil and water conservation measure in Gully Consolidation and Highland Protection (GCHP) Project. If the design is unreasonable, not only can’t play its due role, but even more severe soil erosion will occur. In order to quantify the relationship between drainage system of STT and soil erosion, this paper took Fengbao gully head in Dongzhi Plateau as a prototype, and analyzed the hydraulic erosion process of gully head with and without drainage system. Based on the actual precipitation in the area where the prototype is located, three groups of slopes (scenario 1 is an untreated slope, scenario 2 is only STT treatment, and scenario 3 is a STT with a relatively complete drainage system). A series of scouring experiments (flow rates of 0.43, 0.32, 0.86, 1.62, 1.24 and 0.32 m3/h) were carried out on the physical model. The results show that secondary geological disasters such as landslides and diarrhea are more likely to occur on the STT without drainage system than on the untreated slope. Having a relatively perfect drainage system can reduce the sediment concentration to a great extent. The sediment concentration produced by each scouring experiment in scenario 1 is 270.27%, 1018.63%, 479.21%, 250.38%, 556.78% and 151.18% higher than that in scenario 3, respectively. The sediment concentration produced by each scouring experiment in scenario 2 is 486.03%, 1625.21%, 536.96%, 959.29%, 158.94% and 316.67% higher than that in scenario 3, respectively. The sediment concentration fluctuated continuously with time, with multiple peaks and valleys. It is considered that the first few years of construction, if the slope surface after leveling is still exposed, the drainage pipe is suspended to drain and collect water, and the pipeline mouth is directly washed away, which may cause more serious erosion. This study can provide a scientific basis for soil and water conservation and ecological environment construction in the Loess Plateau and the health management of the GCHP Project.