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Zhang H.,CAS Chengdu Institute of Mountain Hazards and Environment | Zhang H.,CAS Institute of Remote Sensing | Zhang H.,University of Chinese Academy of Sciences | Wang X.,CAS Institute of Remote Sensing | And 5 more authors.
Remote Sensing | Year: 2015

The 2008 Wenchuan earthquake destroyed large areas of vegetation in the Baisha River and Longxi River basins, in Dujiangyan County, China. There were several debris flow events in these mountainous river basins after 2008. Currently, these damaged vegetation areas are in various stages of recovery. This recovery vegetation improves the resistance of slopes to both surficial erosion and mass wasting. We introduce a probabilistic approach to determining the relationships between damaged vegetation and slope materials' stability, and model the sediment and flow (hydrological) connectivity index to detect the hydrological changes in a given river basin, using the multi-temporal (1994-2014) remote-sensing images to monitor the vegetation recovery processes. Our results demonstrated that the earthquake-damaged vegetation areas have coupling relationships with topographic environment and slope material properties, and can be used to assess the slope material stability. Further, our analysis results showed that the areas with horizontal distance to river streams < 500 m are areas that actively contribute sediment to the stream channel network, and are main material sources for debris flow processes in one given mountainous basin. © 2015 by the authors.

Zhou Y.-T.,Technical Center for Geological Hazard Prevention and Control | Zhou Y.-T.,Chinese Academy of Geological Sciences
Yantu Lixue/Rock and Soil Mechanics | Year: 2016

The collapse of unstable rock is actually the problem of fracture and extension in dominant fissure of unstable rocks. Based on fracture mechanics model of dominant fissure, this paper puts forward a fracture stability determination method for unstable rocks, and establishing stability coefficient by the index of union stress intensity factor. By this method tip stress distribution forms of dominant fissure and its calculation expression are deduced. Fracture mechanism model of tip in dominant fissure for unstable rocks is proposed; and then for this calculation method union stress intensity factor in tips of dominant fissure is deduced. Fracture stability calculation results of unstable rocks in Shouli Mountain, Wanzhou Area, Chongqing show that the calculation results fit well with the field situation, so as to show that the fracture stability calculation method proposed is more security, objective and practical than the existing "specification method". © 2016, Science Press. All right reserved.

Zhang Y.,Technical Center for Geological Hazard Prevention and Control | Zhang Y.,Chinese Academy of Geological Sciences | Shi S.-W.,Technical Center for Geological Hazard Prevention and Control | Shi S.-W.,Chinese Academy of Geological Sciences | And 2 more authors.
Geological Bulletin of China | Year: 2013

With the large landslide disasters in Three Gorges Reservoir area as the study object, this paper has summarized and analyzed totally 72 control engineering projects used for tackling the disasters. The characteristics of prevention technology for large landslide disasters in the area are summed up. Through the analysis of the basic types and characteristics of the control engineering projects for the large landslide disasters in the Three Gorges Reservoir area, an evaluation index system for the control engineering measures against the large landslide disasters has been established, and the effects of the control project against the landslide disasters are classified in accordance with the evaluation index and standard.

Shi S.-W.,Technical Center for Geological Hazard Prevention and Control | Shi S.-W.,Chinese Academy of Geological Sciences | Liang J.,Technical Center for Geological Hazard Prevention and Control | Liang J.,Chinese Academy of Geological Sciences | And 6 more authors.
Geological Bulletin of China | Year: 2013

Aimed at solving the problem of gravel soil landslide slip along the bedrock surface, the authors studied the formation of the soil arching effect and the load-bearing mechanism under the condition of parallel arrangement of three rows of micro combined anti-slide pile reinforcement and according to the model test and finite element analysis. The result reveals the optimum distance-to-diameter ratio. As the result shows, in a certain load, the soil arching effect is first formed at the first row of micro-piles, and then with the increase of distance-to-diameter ratio, the soil arching effect is gradually formed at the second and third row; furthermore, load sharing ratio in the front row is significantly greater than that of the rear one. Soil arching effect is inconspicuous or non -existent when the distance-to-diameter ratio is less than 3 or greater than 11. The most ideal distance-to-diameter ratio is 7 and 8.

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