Performance of CAPS Method Considering its Interaction with Adjacent Structures – The Q7 Station of Tehran Metro Line 7

Abstract

In recent years, innovative underground construction techniques have been extensively utilized for many purposes in Iran. Using construction methods such as CAPS (concrete arc pre-supporting system) in the case of nearby special structures is regarded as a valuable technique. CAPS technique applied in this work is a supporting system implemented in urban areas, where the excavation-induced distribution of the soil settlement is considerably lower compared to other sequential excavation (SEM) methods. Our case study is Q7 station, which is an intersection station in Tehran metro line 7 located near Tohid Twin Tunnel and Gardoon Tower. Based on investigations carried out and presented in this paper, CAPS demonstrates an excellent performance and serviceability for structures located within congested urban areas. Q7 station was modeled using FLAC3D code. To ensure the accuracy of our model, monitoring data were compared with the numerical results. By performing sensitivity analysis on the shear parameters of the rehabilitated soil (c, φ) and the distance between beam elements (λ factor), we observed that increasing the shear parameters of the soil mass decreases the vertical displacement of the ground. The optimum value for the λ factor was estimated in this work based on the Rankin criteria for Gardoon Tower (a 20-story building) and Tohid Twin Tunnel.