Instrumentation and monitoring of mahawewa landslide off walapane in central hills of Sri Lanka

Abstract

As instability of the slope area at Mahawewa, Walapane has been identified as a major threat to the people since 1986, National Building Research Organization has started a project of monitoring and stabilization of the slope, cooperating with the Japan International Cooperation Agency in 2010. Main involvement of this study was to do the instrumentation and monitoring, mainly based on analysis of un-stabilization parameters of the area which measured using five instruments. That is horizontal movement at sub surface using Inclinometer, fluctuation of ground water level using piezometers, characteristics of slip surfaces using strain gauges, movement of the surface using extensometers and rainfall using rain gauges. In addition to above drill log data of the site, visual information of cracks generated and springs available were also used. Finally, according to the results of analysis the unfavourable ground water level in slope area has been identified as the most critical factor of the landslide. According to that conclusion a suitable mitigation options for Mahawewa landslide were proposed.