H.R. Pasand Masoumi - Mashhad subway project, Line ۳, Mashhad, Iran
A. Abdollahipour - School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran
Kh. Baghernia - Deputy manager, Ahwaz subway project, Iran

Determination of the optimum soil conditioning parameters in the earth pressure balance-tunnel boring machines (EPB-TBMs) plays an important role in reaching an optimum thrust force and advance speed. Silty-clay (CL-ML) in line ۱ of the Ahwaz metro project is used in order to find the conditioning parameters of slumps with different water contents and foam agents. The results obtained are a quantitative comparison between the parameters with different soil conditioning and water contents. Hence, the test results can be used to determine the most economical and technical conditioning parameters for a special condition of soil. The optimum quantity of foam expansion ratio (FER), foam injection ratio (FIR), percent ratio between the surfactant agent and the water volume (Cf), and cost for foam in this soil (based on the soil conditioning production cost) are ۱۰, ۱۵۷%, ۲.۰۷, ۲۴۸ units, respectively. Soil conditioning with the optimum parameters obtained are tested in a TBM in two stages during excavation of ۱۴۰ rings. This results in a lower soil conditioning cost and almost ۴۰% higher advance speed.

EPB tunneling machine, Soil conditioning, Slump test, Foam expansion ratio, Foam injection ratio