Use of vertical reinforcement to reduce ground movement due to tunnelling

Abstract

This paper examines centrifuge results of tunnel excavation adjacent to vertical reinforcement in small-scale sand beds. The tunnel walls were represented by pressurised rubber liner. Results of 6 tests conducted at 50g using large diameter centrifuge at IITBombay are reported. Depth of the tunnel and spacing between the tunnel axis and reinforcement are the variables investigated. To simulate tunnel excavation, hydraulic pressure on walls of the rubber liner was decreased in steps whilst the centrifuge was in-flight. The magnitude and extent of settlement trough with increase in ground loss was captured using potentiometers and pore pressure transducers placed in vicinity of the tunnel axis. From the limited test observations, vertical rods of not more than 14-times the particle size is shown to affect the width of settlement trough. © 2009 IOS Press.