Study On Rainfall Landslide Simulation Experiment And Meso Evolution Of Soil Failure Of Granite Residual Soils In Xiamen Area

China’s southeast coastal economic open zone are mainly distributed on the granite weathering crust and has a larger residual soil thickness which generally reachs20-35m in coastal area of Fujian and Guangdong. Fujian Province, located on the Southeast coast and in the subtropical monsoon climate zone, has80%area of the province for low mountains and hills. Granite residual soils are widely distributed owing to the humid climate, the frequently typhoon rainstorm, concentrated rainfall, strong seepage of rock and soil, and strong weathering and erosion of hills and mountains, and50%of which are distributed in hills and coastal plain of Southeast Fujian,and whose thickness reaches50-70m in Xiamen area. Therefore, granite residual soils are widespread in the southeastern provinces and most of mountains, hills and erosional peneplain in engineering, which become the important material of the foundation and geological environment of most engineering construction. Since the development strategy of the Economic Zone on the west side of the Straits are now being implemented in Fujian Province, which brings prosperous geotechnical engineering including marine reclamation land, highway, railway, seaport wharf, subway in Fuzhou and and Xiamen, the study on security, stability, mechanical properties of southeast coastal residual soils and geological disaster law initiated by rainfall is an important and urgent research topic for a new round of great-leap-forward development in Fujian Province.In this paper, bsed on the Fujian Province Natural Science Foundation Programs,"Research on the evolution mechanism of phase state in landslides, debris flow and other geological disasters of loose rocks and soils under the conditions of heavy rainfall condition", widespread granite residual soils are choosed as the representative sample, study and technical means, such as laboratory experiment, rainfall landslide simulation experiment, meso detection and analysis of rocks and soils, meso imaging-analysis of rocks and soils, and number processing etc, are used to the following work:1. Through consulting the domestic and foreign literature, the relationship nd mechanism between moisture content and mechanical property of rocks and soils are summarized and analysed, which provide the fundamental basis and reference for the planning of experimental study scheme.2. Granite residual soils in Xiamen area are choosed as the representative sample of5different moisture contents for direct shear test, the relationships between moisture content and internal cohesion, internal friction angle are analysed,and influence laws between moisture content and mechanical property of rocks and soils are revealed.3. Slope and rainfall intensity are choosed as controlled variables for16sets of rainfall landslide simulation experiments. Under the conditions of different rainfall intensities and slopes, results of each experiment are counted and analysed, soil instability and failure rules are discussed from the macroscopic level, meanwhile, the prototype experiment and survey results of soil instability and failure rules are summarized for proving the rationality of the results above.4. Image acquisition and analysis system for meso changing of rocks and soils are used for collecting images and photos of meso changing of rocks and soils,and data information and motion path of cluster of soils’meso motions are achieved by computer programming language. Through statistical analysis, meso evolution laws of soil instability and failure are discussed from the meso level, and relationships between macroscopic destructional forms and meso motion evolution of soils are revealed.