Mechanical Behaviour and Failure Analysis of Glass Fibre-Reinforced Plastic Panels for a Directional Tunnel: An Underground Water Storage Device

Abstract

Water management is a prominent aspect because worldwide groundwater declination is faster than expected. Multiple studies have developed numerous innovative techniques for enhancing secured water storage. One among them is the directional tunnel method, a water storage device placed at a declined angle below the ground level. Previous researchers have manufactured directional tunnel using composite glass fibre-reinforced plastic material. However, GRP’s mechanical properties and behaviour remain unexplored. The current study investigates the detailed work of employing bidirectional glass fibre mats in the fabrication of GRP panels for a directional tunnel. Two types, namely two-layered GRP panels and three-layered GRP panels, have been tested for determining the mechanical properties. An earlier study recommended that the directional tunnel’s installation at 30° declination underground was feasible with respect to sandy soil conditions as reported by Raghavendra Kumar and Gupta (in: IOP Conference Series: Materials Science and Engineering, 2021). The present study explores the tunnel’s stability at the same declination concerning GRP material through PLAXIS 3D simulations. Various parameters such as maximum displacement, total stresses, and total strains helped in understanding the structure’s stability. The generated results represent that soil mass deformation in the directional tunnel made of three-layered GRP panels has a 66.75% decrement against the conventional tunnelling method. Moreover, the failure pattern in the tunnel has been studied. Finally, the directional tunnel structure’s strengthening has been employed based on the identified failure points.