SLOPE STABILITY STUDY OF LOWER TOPA TO VILLAGE BAN ROAD

Abstract

The objectives of this endeavor are to study the existing landslides on Lower Topa to village Ban road and evaluate the factors causing the landslides and suggest remedial measures to combat the problem. It is pertinent to mention that this study is envisaged to be an initiating process leading to progressive future studies and consistent long term efforts necessary to arrest the situation in totality. However, graduate students, research fellows and practicing geotechnical engineers will find this study as first hand information and a reference for undertaking any future work. Amongst the mountainous region of Pakistan, Murree is considered to be one of the worst slide-affected areas. The landslide hazard in Murree has been a cause of great concern affecting the safety of life and property. During last three decades, the extent and severity of the problem has aggravated due to indiscriminate land use and un-planned urbanization. Given this scenario it is obvious that landslide vulnerability studies of the area are of paramount importance. Landslides and related slope failure phenomenon occur in all parts of the world especially in mountainous area. A wealth of experience and knowledge has been accumulated over years in understanding, recognition and treatment of landslide hazards, however, due to diverse nature of this problem knowledge in this field is still fragmentary. The area requiring particular attention is the proper investigation and analysis for appropriate design and cost-effective remedial measures. This requires a clear understanding of the conditions and processes that cause landslide. In this study, extensive survey along the route revealed that stable areas occur where the grades are mild, vegetative growth is thick and surface / subsurface drainage measures are good. Contrarily, the slopes with less vegetative growth and improper surface / subsurface drainage and steep grades are found to be more susceptible to slope failure. The area is divided into different zones basing on stability potential i.e. meta stable, less stable and unstable zones. Two typical landslides were selected for detailed investigation and analysis. The results obtained can be applied all along the route on area exhibiting similar conditions. Field investigation plan was prepared to evaluate soil / rock strata and surface / subsurface drainage. Relevant field tests were performed to determine insitu strength properties of soil / rock. Detailed laboratory testing plan was prepared to determine the strength properties of soil and rock samples in simulated conditions. Computer software Geo Slope Office is used for the analysis of slopes basing on the material properties obtained from tests and survey conducted for each potential landslide, under simulated conditions. The slope analyses are performed for different scenarios, controlled by material input parameters. Finally, recommendations are made to overcome the problem of landsliding.