Mechanical performance of fiber-reinforced polymer tank under road pavements for stormwater storage

Due to increasing precipitation intensity, rising sea level, and land development, urban flooding has become a major issue in many places around the world. This research aims to develop underground storage tanks (USTs) using fiber-reinforced polymer (FRP) materials for stormwater detention, storage, and reuse. The USTs are intended to be placed underneath highway or street pavements. FRP as one of the emerging structural materials possesses several advantages including high strength-to-weight ratio and corrosion resistance. The mechanical performance of USTs has rarely been visited in the literature, the majority of which focuses on leakage issues and associated environmental problems. This paper presents detailed analyses of the mechanical performance of FRP USTs, including a laboratory test on a small-scale FRP UST and a verified finite element (FE) analysis on full-scale FRP USTs. The influences of various factors on the mechanical performance of the USTs were examined, including wall thickness, water storage, interfacial roughness between FRP and soil, and tank sizes. Both results from experiments and FE studies agree satisfactorily and reveal that (i) underground FRP UST developed tensile axial strains at the top surface at the mid-span of the tank and the side surface at the mid-height; (ii) compressive axial strains developed in most of the cap region; and (iii) large compressive circumference strains developed in the FRP UST in most locations. Insights gained from the laboratory test and the FE analysis are expected to provide a general guidance on the design of FRP USTs under road pavements for urban flooding mitigation and stormwater harvesting.