Failure evaluation method for a slope monitoring system

Abstract

Recently safety of Korean railway lines has been threatened by typhoon and heavy rainfall due to global warming and representative rainfall induced risks are landslides, slope failure, debris flow, fallen rocks etc. Risks of slope failures are evaluated by deformation of ground surface and underground movements. But many bore holes and sensors must be equipped in the ground for detecting of deformation of ground movements. Furthermore, it is not easy to confirm slope failure immediately and needs much time for post-processing of various data. Only one or very specific sections could be monitored for limited area due to budget. A multipurpose sensor is developed for overcoming these problems by use of data from inclinometer installed on the ground surface. Motions at a point of ground surface could be simply divided into rotation and linear movements and they might be representative sensor signals. In this study, failure types, slip surface, failed mass and failure direction could be recognized by use of these characteristics; sensor data and an algorithm to detect these movements are suggested. Failure shapes such as circular and planar failure are estimated by combination of simplified ground movements. For determination of a two-dimensional (2D) slip surface, 3D coordinates of a main slope profile and all sensor locations should be defined. Then specific equation to estimate slip surface is selected. After selection of starting and ending point of slip surface, the tangent value of a slip surface could be calculated from each sensor. 2D slip surface is calculated by combination of sensor location, the equation, tangent values and each ending point. 3D failed soil mass is also estimated from various 2D slip surfaces. By use of centre of mass, we could get movement direction of failed soil mass. An examination of this algorithm has been executed in a railway slope. Consequently, it is possible to estimate slip surface and failed soil mass using data from ground surface.