Application of GPR in the Engineering Project: A Case Study from Satluj River Valley, Himachal Pradesh

Abstract

The Ground Penetration Radar (GPR) is an extensively used geophysical technique for investigating shallow subsurface structures. We present the results of a GPR survey at the two construction sites of a hydropower project (Tunnel and Adit) in the Satluj River valley, Himachal Pradesh. The GPR survey has been carried at the construction site -1 with an objective to determine the overburden thickness as well as to map subsurface structural features like anomaly zone inside the subsurface strata. Similarly, GPR has been carried out at Site II on the vertical wall and floor of an adit with an objective to map the number of joint sets and shear bands and their continuity inside the rock strata that could make the structure unstable. Results revealed the presence of disturbed strata that are ready to detach at site no 1. Also, the depth of alteration zones at the major discontinuities has been assessed in GPR profile. Similarly, GPR profile of site-2 confers the presence of three joint sets with a shear zone.The radar survey therefore allows the localisation of possible weak zones and a precise mapping of the overburden thickness, joint sets and shear bands etc. Thus, it can be effectively used in mapping the geological structural features and hidden anomalies in rugged terrain of Himalaya.