Role of Integrated Geophysical Studies in Defining the Rock Profile below Steep Hill Slope at the Base of an Endangered Multi-Storeyed Building in Himachal Pradesh

Failure of rock slopes in the Himalayan hills is a common feature. Such failures often pose site-investigation problems to geotechnical engineers for planning remedial measures to endangered civil engineering constructions. In such cases, integrated geophysical site investigations can be of much help.

However, geophysical measurements on hill slopes is both physically and technically a challenging job. The present case study deals with a geophysical methodology foi delineating hard lock profile on a hill-slope at the base of a partially exposed foundation of a four-storeyed government building in Rampur-Bushehar, H.P. The slope failure occurred due to heavy rains and flooding exposed the basement of a four-storeyed government building. The geophysical methods employed include gravity, seismic refraction and electrical resistivity (sounding and profiling) methods.

The two gravity profiles along the footpaths on the sloping ground at the base of the building has mapped the hard rock (phyllite locally) with other seismic and electrical resistivity results serving as constraints. This simple case study stresses the need for an integrated geophysical approach for addressing the site investigation problems related to civil engineering constructions/ remedial measures on hill slopes, especially in the Himalayan terrain.