Tunneling in Difficult Ground

McCusker, T.G.

doi:10.1007/978-1-4613-0449-4_8

Cited by 1 publication

(1 citation statement)

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“…As a consequence of the time-dependency of ground behaviour, the overall advance rate not only represents the main outcome of the complex interaction between the ground, the TBM and the tunnel support, but also exercises a decisive influence over this interaction (Ramoni and Anagnostou 2010c). More specifically, as emphasized repeatedly in the literature, a rapid excavation rate (involving high net advance rates and short standstills) reduces the risk of the shield or back-up jamming (e.g., Herrenknecht and Rehm 2007;Kovári 1986a, b;Lombardi 1981;McCusker 1996;Robbins 1982). The frequency and duration of standstills can be reduced through appropriate operational measures and construction site organization.…”

Section: Introductionmentioning

confidence: 97%

The Effect of Consolidation on TBM Shield Loading in Water-Bearing Squeezing Ground

Ramoni

Anagnostou

2010

Rock Mech Rock Eng

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Jamming or overstressing of the shield due to ground pressure are potential problems for tunnel boring machine (TBM) tunnelling in squeezing ground. The risk of shield jamming depends essentially on the deformation rate of the ground in the vicinity of the working face. The time-dependency of the ground response to the excavation is associated with its rheological properties as well as with the transient consolidation process that takes place around the opening in the case of a low-permeability saturated ground. The present paper focuses on the second mechanism and investigates the interaction between the advancing shield, tunnel lining and consolidating ground by means of transient numerical analyses. For a given set of geotechnical conditions and a given TBM configuration, the load exerted by the ground upon the shield during TBM operation decreases with increasing gross advance rate. During a long break in operations, the ground pressure may increase significantly, thereby necessitating a higher thrust force to overcome shield skin friction and restart the TBM. It is interesting to note that a high advance rate reduces the risk of shield jamming not only during TBM advance, but is also favourable with respect to any subsequent long standstills. Keywords Tunnel boring machine Á Squeezing ground Á Shield jamming Á Advance rate Á Standstill Á Consolidation Á Numerical investigation Á Steady state method

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Section: Introductionmentioning

confidence: 97%