The Formation Mechanism And Numerical Simulation Of Slope Disintegration In Granite Region Of Fujian Province

Slope disintegration is one of the most serious type of water and soil loss inFijian Province, its hazard has been a serious threat to ecological security, foodsecurity, flood control safety and human resident security for the mountainous andhilly regions in Fujian Province, resulting in receiving great social attention. Thepaper, taking one typical slope disintegration in Yangkeng Village, Longmen Town,An’xi of Fujian Province as the research object, drawing on previous research resultsand methods, through on-site investigation and research, laboratory test analysis andnumerical software simulation,studies the formation and development mechanism ofslope disintegration in the granite region of Fujian Province to provide scientificbasis for predicting and controlling slope disintegration.The major research workinvolves the following aspects:1. The characteristics of geological structure,topography,lithology,hydrogeologyand engineering geological are summarized about the formation of slopedisintegration in granite region of Fujian Province. According to the regionalgeological survey, the slope disintegration occurs in the granite which forms in theMesozoic Era magmatic activity usually. Loose and deep of granite weathering crustis the material basis of slope disintegration.2. The physical and mechanical property of granite weathering sand is studied.The granule analysis test analysises the size of sand particle and the scope of thequality of percentage content.Triaxial shear test studies the stress-strain relations andeffective stress path of sand. The property of sand changes from the strain softeningto strain hardening as a result of the increasing relative density of sand.It is possiblethat the unconsolidated sand of slope disintegration occurs flowslide when theunconsolidated sand is in saturation state.3. The development feature of slope disintegration is studied under theinteraction of water erosion and gravitational erosion.The process of water erosion israinfall to sputtering to sheet erosion to rill erosion to gully erosion to slope disintegration.The gravitational erosion includes mainly exfoliation and collapse.During the process, water erosion and gravitational erosion alternate the role of eachother and promote mutually.4. The micromechanics of slope disintegration formation is analysised. Theweathering swelling force and triggered a significant increase in joint are the mainreasons that the slope disintegration occurs mainly in the granite weatheringcrust.The results of disintegration test show that the disintegration strength of clasticlayer is the strongest，laterite is the weakest, sand layer is middle.When the soil watercontent is lower, the soil is drier, the micro joints and the dry cracks are more,and theeffect of disintegration is more obvious.According to the triaxial shear test, themechanism,mechanical condition and the range of flowslide is studied.5. FLAC3D numerical simulation software is used to analysis the stability ofslope before and after the formation of slope disintegration in the natural state, thestability of slope disintegration in the different rainfall intensity state,the influence ofthermal stress for the stability of slope disintegration.Finally, the main works in this paper and some useful conclusions are summedup, and some advices for the further research are suggested.