Abstract: Gravel soil landslide has a unique internal seepage system, since the soil contains a large number of gravels constituting a matrix structure. Depending on the diversity of gravel soil structures, the network of flow channels can be different and correspondently the landslide pattern is also different. Hence, it is difficult to make the targeted mitigation plans for slope failures. In this study, the case of Yanshanjiaoluo landslide, which is located in Anxi County of Fujian Province, is investigated. The relationship between the seepage system of the gravel soil with multivairiate-structure and the material composition of the landslide is obtained based on the comprehensive geotechnical investigation including geophysical prospecting, drilling, water level monitoring as well as SketchUp modeling analysis. Comparative analysis is performed to evaluate the deformation and rainfall sensibilities of two sorts of seepage system. The results indicate that the coarse gravel soil area is characterized by concentrated seepage, while the false porphyritic gravel soil area is characterized by pipe network seepage. The former is more sensitive to the rainfall than the latter. However, influenced by the overall strength of the seepage channel and seepage stability, the latter is more sensitive to the deformation of landslide than the former. Based on the above analysis, a combined measure of anti-slide pile and blind drainage ditch is employed to improve the stability of the landslide. The field observation confirms the effectiveness of the mitigating measures.

Key words: gravel soil landslide, multivairiate -structure, seepage system, SketchUp, blind drainage ditch