EROSION MODEL TEST OF LOESS SLOPE WITH FRAMEWORK PROTECTION

The high slopes in the western loess area are mostly protected by skeleton structures. During its service,the structure is prone to erosion and damage of slope soil,resulting in partial loss of protective effectiveness. Moreover,it can even induce collapse disasters in severe cases. This paper carries out a series of artificial simulated rainfall erosion model tests. The slope erosion process,sediment content,runoff,and cumulative erosion amount of bare slope,and skeleton slope are compared and analyzed. The protective effect of the skeleton structure is discussed,and the slope erosion law of the key parts of the skeleton is clarified. The mechanism of erosion and damage to skeleton protection slope induced by heavy rainfall is revealed. The results show the follows. The skeleton structure has a certain protective effect,but the soil at the edge of the sash is easy to be eroded and damaged. With the increase in rainfall time,the sediment content,runoff,and cumulative erosion of bare slope and skeleton slope gradually increase. Compared with the bare slope,the sediment content of the skeleton slope at erosion for 60 min is decreased by 25%(slope ratio 1 ︰ 1.5),21.4%(slope ratio 1 ︰ 1.75),and the runoff is decreased by 33.6%(slope ratio 1 ︰ 1.5),31.4%(slope ratio 1 ︰ 1.75),the cumulative erosion amount is decreased by 43.6%(slope ratio 1 ︰ 1.5),40.0%(slope ratio 1 ︰ 1.75). The key parts of the skeleton structure,especially the soil at the sharp corners,are strongly eroded by rainwater. The erosion evolution process can be summarized as from splash erosion to sheet erosion, to rill erosion, to cutting ditch erosion(primary erosion),or from splash erosion to sheet erosion, and to gully erosion(erosion again). The skeleton structure can limit the migration of soil particles,weaken the runoff erosion,and play the role of interception,water retention,and diversion. However,there would also be a relatively obvious edge confluence phenomenon at the key parts of the skeleton. It is easy to cause erosion and damage to the soil below the vertical support of the skeleton,making the skeleton partially suspended. The research results can provide a reference for the optimal design and site construction of arched skeleton slope protection for embankment slopes in loess areas.