Micromorphology of landslide soil——Case study on the Jibazi landslide in Yunyang in the Three Gorges Region, China

Introduction The studies on landslides in the Three Gorges Region were conducted, e.g., those on affecting factors and forming mechanism of landslide (YIN Kunlong et al. 1998, DENG Qinglu et al. 2000, CHEN Yongbo et al. 2003, XU Qiang et al. 2003), on ris…

Micromorphology of landslide soil

Landslide is one of natural catastrophes affecting national economy and people’s livelihood. There are many reports on the forming mechanism and control of landslide, but the studies on micromorphology of landslide soil are few. There are many potential landslides in the Three Gorges Region in China. In this paper, the micromorphologic features of the Jibazi landslide soil in Yunyang in the Three Gorges Region of the Yangtze River were studied using routine methods, that is, soil micromorphology, X-ray diffractometer and scanning electron microscope. The main conclusions are as follow: (1) The basic micromorphologic characteristics of the landslide soil are that the fine soil particles are commonly cohesive matrix, finer and lower content of skeleton grains, the microstructures are mainly types of phenocrystal gelatinization, densely chap and fissure structure. As a result, these micromorphologic features affect the discharging of soil water, favor the movement of landslide body and provide an internal basis of materials for the formation of landslide. (2) The concept on the forming material of landslide was proposed, and types of optical beamed clay aggregates, Fe-Mn isolates and glassy material were found in landslide-belt soil, which were remarkably different from the natural soil formation, and had some scientific significance in analyzing the forming mechanism of landslide and distinguishing the landslide-belt soil. (3) Some special micromorphologic and sub-micromorphologic characteristics, such as fingerprint microstructure, clay beamed bedding microstructure, oppressive microstructure, moulage microstructure and extending hole microstructure, could bring useful micromorphologic evidences for the observation and forecasting of landslide. The results mentioned above will bring helpful micromorphologic evidences for distinguishing slide soil, analyzing the formation mechanism of landslide, and monitoring and forecasting the occurrence of landslide.