Failure of multistorey parking site in hilly region and its forensic geotechnical investigation

A multi-storey car parking was proposed on a sloping ground in the hilly region of an Indian state, which started showing distress during the initial stages of the construction. The RCC wall, which was integrated with the framed structure and constructed for the purpose of supporting the excavated earth material at the construction site, initially deformed and then finally failed after the heavy rainfall in the region. Forensic Geotechnical investigation (FGE) was carried out in the light of IS:1904, IS:6403, IS:3764 and IS:14,243 (Part2) as well as with the help of numerical analysis using FEM based tool PLAXIS 2D. The outcome of the FGE revealed shortcomings pertaining to (i) improper geotechnical subsurface investigations up to the desired depth as well as estimation of Safe Bearing Capacity (SBC), (ii) site development activity carried out without taking appropriate measures for slope protection works and (iii) insufficient drainage facilities, (iv) loading the frame structure without connecting columns with tie beams. Finally, recommendations and suggestions on various ground improvement techniques, such as slope protection measures using soil-nailing or constructing a retaining wall to protect the nearby properties; retrofitting of constructed foundation using micro-piles, providing proper drainage facilities, etc., are made to protect the site before the resumption of the work.