A study of landslide hazards in North Eastern India

The paper discusses the landslide occurred during the period of heavy rainfall and after an earthquake shock on 7(th) September, 1987 on the north side of a hillock endangering the oil wells. To analyse the problem geotechnical investigations were carried out at field and laboratory. Stability analysis (back analysis) for slopes was carried out using the Bishop's equation. It was found from the stability analysis that the upper part of the hill-slope sections considered was unstable. Therefore, remedial measures were necessary to protect the wells. Remedial measures were suggested as surface pacca drains on the top and the side of the hillock to remove the run off quickly. The dimensions and spacing of the drains were calculated based on rainfall data. Crated masonry and RCC retaining walls on timber/steel pile groups were also suggested at suitable places: The measures so provided were proved to be effective.