DOI: 10.5176/2251-3361_GEOS12.07
Authors: Ibrahim Ocak
Abstract: Increasing demand on infrastructures increases attention to shallow soft ground tunneling methods in urbanized areas. Especially in metro tunnel excavations, it is important to control surface settlements observed before and after excavation, which may cause damage to surface structures. Solving this problem, Earth pressure balance machine (EPBM) has been widely used. This paper focuses on transverse surface settlement measurements, interaction of twin tunnel transverse surface settlement and relationship between shield parameters and transverse surface settlement for parallel tunnels using EPBM shields in clay and sand soils. Tunnels are excavated by using two EPBM with a 6.5 m diameter as twin tubes with 14 m distance from center to center. The EPBM in the one tube was followed about 100 m behind the other tube. Segmental lining with 1.4 m of length and 0.3 m of thick was employed as final support.
The results of this study show that: (1) most important parameters for the maximum surface settlements are the face pressure and backfill parameters; (2) volume loss value of second tunnel is 48.6{6e6090cdd558c53a8bc18225ef4499fead9160abd3419ad4f137e902b483c465} bigger than first tunnel; (3) a good construction quality is very effective issue for controlling the face stability and minimizing surface settlement.
Keywords: Twin tunnel excavation, surface settlement, EPBM, interaction of settlements.
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