auch als Buch erhältlich

On the delayed failure of geotechnical structures in low permeability ground
  • Autoren: 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 conditions may 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.

The goal of the thesis is to develop a computational method that allows the estimation of the stand-up time, and thus improve construction safety and economy. The main objectives towards this goal are:

  • analysis of the mechanism of delayed failure by means of fully coupled hydraulic-mechanical continuum-mechanical simulations, investigation into the role of the constitutive behaviour of the ground (particularly that of plastic dilation), and
  • development of a practical method of dealing with the numerical problem of mesh-sensitivity which occurs due to the localization of deformations when assuming non-associated plasticflow in any geotechnical structure at failure;
  • planning and performing experiments and validation of the computational method and assumptions; systematic investigation of the stand-up time of the tunnel face and working-out of design charts.

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

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

Rock Pressure, Tunnel, Tunnelling, Gotthard, Gibraltar Tunnel

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.
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