Use of TBM excavated materials as rock filling material in an abandoned quarry pit designed for water storage

Abstract

Material from tunnel excavations (muck) for Istanbul's metro rail transport system must be rapidly removed from the construction site and stored in a suitable area. This time restriction necessitates categorization of the excavation materials according to technical specifications and usability. The excavated material (muck) could be used as aggregate in concrete, filling and paving material in road construction, and as a soil replacement for covering or foresting stony/rocky areas, etc. This study examines the use of the tunnel boring machine (TBM) excavation material (muck) as rock filling in water storages, and as rock embankments in abandoned quarry pits designed for water storage. The study was designed in two phases. In the post excavation phase, physical and mechanical properties of materials [sandstone, shale, and diabase] excavated from the Kadıköy–Kartal metro tunnels were tested under laboratory conditions for their suitability as rock and crushed stone (aggregate) material. In the pre-excavation phase, a total of 227 samples representing eight different rock types were analyzed in this geotechnical study of the tunnel route. This phase contains core-drilling data during the tunnel opening survey.Analyses indicate that the various TBM excavation materials from the Kadıköy–Kartal metro tunnel are suitable for use as filling material in abandoned quarry pits for water storage in a forested hillslope. The establishment of a storing area based on water inflow from precipitation and infiltration of water from naturally-sloping forested land could provide the needed water and perhaps generate revenue.