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With the development of economy and society, various types of infrastructures have produced many high and steep slopes in Loess Plateau areas. In order to provide references for the restoration of loess steep slopes and soil erosion control, based on the results of field insitu plot observation and artificial simulated rainfall tests, the erosion control effects and mechanisms of the new organic material crosslinked polystyrene (CLPs) is the plant joint slope protection technology on the loess steep slopes were analyzed. The results show that a) the runoff depth of the loess slope treated with CLPs is larger than that of the bare slope under the same rainfall condition, and the sand production was comparable with that of the bare slope under the same rainfall conditions, there is basically no erosion-control effect of treating loess slopes only with CLPs; b) The CLPs-grass and shrub slopes and CLPs-turf slopes using CLPs-vegetation co-remediation technology, the runoff depth and soil erosion modulus were much smaller than that of traditional grass-shrub slopes and fish-scale pits planted shrub slopes, and the annual average soil erosion modulus is only 0.9%-3.2% of that of traditional grass-shrub slopes and fish-scale pits planted shrub slopes, this means that the erosion control effect of CLPs and plants on loess slopes is remarkable; e) Compared with the CLPs protection slopes without vegetation cover, the CLPs-grass and shrub joint restoration slopes with 100% vegetation coverage show a significant decrease in runoff flow rate, Reynolds number, Rroude number, shear force, and power, and a significant increase in slope resistance coefficient and roughness coefficient, which is the hydrodynamic mechanism of the CLPs-grass and shrub joint slope restoration technology for erosion control; d) Using CLPs-vegetation slope protection technology, an effective soil reinforcement system, erosion control system and water retention system can be formed on the loess steep slopes. [ABSTRACT FROM AUTHOR]

The original geological environment of the Loess Plateau is extremely weak. In recent years, the intensity of human engineering activities (such as building cities on flattened mountains, governing valleys, and retain plateau) are beyond geological land ecological carrying capacity. It leads to frequent geo-disasters. Firstly, the high and steep slopes of loess tableland located in the typical ecological restoration area (in Yan'an City, northern Shaanxi) was selected as demonstration area of disaster prevention and control. The new materials of loess curing agent combined with turf transplant technique was plan to adopt to modify and remediate the loess slope. Several physical simulation contrast experiments was carried out under different rainfall intensity conditions (60, 120, 150,180 mm/h). The dynamic evolution process of loess tableland slope erosion was revealed. Then it was refined that the response relation between underground physical and mechanical parameters and surface deformation and rainfall intensity. Based on the perspective of water controlling, the experimental results show that the application of improved loess and new technology can successfully decreased erosion degree of slope runoff. On the other hand, hypotonic materials slow down surface water vertical infiltration then transformed into groundwater and prevent soil and water loss, collapsibility failure and large range loess collapse deformation. [ABSTRACT FROM AUTHOR]

To further realize the correlation between rainfall and the starting mechanism of the slope debris flow in the source area of Yindongzi gully, a typical model was selected after a detailed fieldwork and engineering investigation. The rainfall intensity and gradient were set as control variables using 20 large artificial rainfall physical model tests under four gradients and five rainfall intensity conditions to research the instability mechanism and failure patterns of the slope debris flow. The experimental results revealed the starting and failure model of the source of the loose slope and the response relationship of the surface deformation and the underground physical mechanical parameters. Then, a traditional I-D (rainfall intensity-duration) early warning model was established. Next, reliable warning parameters (i. e. gradient and moisture content) were extracted and the exponential model and means of the mathematical regression analysis were used to determine the IGD and IGM multi-parameter forecast model, while the traditional model was effectively modified for dependability and practical utility. [ABSTRACT FROM AUTHOR]