Performance of two EPBMs in twin metro tunnel construction in soft ground

摘要

The prediction of machine utilization and determination of machine performance play animportant role in scheduling and planning of tunnel excavations, and the database createdserves a major role in further applications.In this study, the construction methods of twin metro tunnels between Kirazl? 1 stationand Mahmutbey station in Istanbul are summarized. The strata in the study area comprise(from surface) fill, stiff clay, dense sand, very dense sand, and hard clay. The tunnels, 2.5 kmin length, were excavated with two different earth pressure balance machines (EPBMs). Theexcavation diameters of the Herrenknecht EPBM and Lovat 1 EPBM were 6.50 m and 6.564m respectively. The performances of the machines are analysed and compared in order toaccumulate data for further applications in similar ground conditions in Istanbul.The distance between twin tunnels is 14 m from centre to centre, and the EPBM in theone tube was almost about 100 m behind the other. Segmental lining 1.4 m in length and 30cm thickness was used as final support.For the Herrenknecht EPBM and Lovat 1 EPBM, the best daily advance rates were 26.6m and 29.4 m respectively, the best weekly advance were 102.2 m and 92.4 m, and the bestmonthly advance rates 417.2 m and 410.2 m respectively. Standby times due to maintenancewere 17.3% and 17.4% respectively.