auch als Buch erhältlich

On the role of constitutive behaviour in the response of squeezing ground to tunnelling
  • Autoren: Weijie Dong

  • On the role of constitutive behaviour in the response of squeezing ground to tunnelling

Rock Pressure, Tunnel, Tunnelling, Gotthard, Gibraltar Tunnel

Squeezing conditions in tunnelling are characterized by the occurrence of large deformations of the opening or high rock pressure that may overstress the lining. Squeezing is associated with poor quality rock. Tunnelling in squeezing ground involves great uncertainties. It is therefore very important to gain a better understanding of the underlying mechanisms.

Triaxial testing is the main source of information in order to understand the mechanical features of squeezing ground. Despite the complexity of the squeezing mechanism and the behaviour observed under relatively simple loading conditions, most of previous research work and engineering design practice considers the ground as a linearly elastic, perfectly plastic material obeying the Mohr-Coulomb yield criterion. While the MC model is capable of predicting the final strength and post-failure volumetric behaviour of the squeezing rock, it cannot map some potentially important pre-failure features or the occasionally observed contractant plastic deformation.  In addition, the MC model usually leads to an overestimation of the strength under undrained conditions, which is unsafe for tunnel design.

The present thesis mainly addresses the influence of constitutive modelling on predictions about the response of squeezing ground to tunnelling in order to provide some general guidelines for basic engineering analysis. This objective is achieved by investigating the behaviour of squeezing rocks theoretically and experimentally, using samples from several tunnel projects, including the Gotthard base tunnel and the planned Gibraltar strait tunnel.

For further information see extract.


Name Dateityp Zugriff
Inhaltsverzeichnis / Table of Contents PDF-Dokument
Leseprobe / Extract PDF-Dokument

eBook Anbieter

Preis je nach Anbieter, erhältlich u.a. bei: (Lüthy, Balmer, Stocker) zum Anbieter zum Anbieter
Google Play zum Anbieter
Amazon Kindle zum Anbieter
Ciando zum Anbieter

Ähnliche Artikel

Florence Mezger
On the variability of squeezing behaviour in tunnelling

Tunnelling, Squeezing, Schistosity, Heterogeneity, Analytical Solution, Numerical Modelling, Segmental Lining

The magnitude of squeezing deformations in tunnelling often varies over short distances, even if there is no obvious change in the construction method, in the depth of cover, in the lithology or rock structure. As long as the reasons for the variability are not known, the tunnelling-induced convergences cannot be predicted with sufficient reliability. Reliable predictions, however, are important for determining the temporary support or the excavation diameter. Otherwise, large-scale tunnel repairs may be necessary, which can cause delay and additional costs due to remedial actions as well as due to the enforced interruption of other operations in progress at the same time.

Roberto Schuerch
On the delayed failure of geotechnical structures in low permeability ground

Tunnelling, Tunnel Jacking, Ground Stability, MC Model, MCC Model

This thesis investigates the problem of time-dependent stability of geotechnical structures (such as trenches or tunnels) in medium- to low-permeability water-bearing grounds, typically clayey or silty soils. The peculiarity of these soils is that they respond to excavation with a delay. The time-dependency can be traced back to the swelling process triggered by the dissipation of the excavation-induced negative excess pore pressures. Unstable conditionsmay necessitate improvement or reinforcement of the ground or the application of a support (e.g. by compressed air or pressurized bentonite slurry in the case of tunnel face). As such measures may present economical and operational disadvantages, the question of whether and for how long the excavation can remain stable without support is of great practical relevance. The stand-up time (time lapsing between end of the excavation and the occurrence of failure), and thus the feasibility of refraining from ground reinforcement, improvement or support, depends essentially on soil strength and permeability.
Sara Zingg
Static effects and aspects of feasibility and design of drainages in tunnelling

Advance Drainage, Drainage Boreholes, Tunnel, Face Stability, Limit Equilibrium, Fault Zone, Drainage Capacity, Equivalent Hydraulic Conductivity, Borehole Casing, Lead-Time, Groundwater Drawdown, Settlement, Inflow, Grouting Body, Displacement, Characteristic Line

This PhD thesis investigates the effectiveness of drainage measures with respect to two particularly important problems associated with tunnelling through water-bearing, weak ground: the stability of the tunnel face and the stability and deformation of grouting bodies. Water is an adverse factor with respect to the stability and deformation of underground structures due to the pore water pressure and the seepage forces associated with seepage flow towards the tunnel. Drainage boreholes reduce the pore water pressure and the seepage forces in the vicinity of the cavity. Furthermore, loss of pore water pressure increases the effective stresses and thus the shearing resistance of the ground ("consolidation"), which is favourable in terms the deformation occurring during and after tunnelling.
Rechtsklick um diese Infobox zu fixieren
Klicken Sie ausserhalb um diese Infobox auszublenden