Drip Sealing Grouting of Tunnels in Crystalline Rock: Conceptualisation and Technical Strategies
Doktorsavhandling, 2012

A conceptual model of the groundwater hydraulic conditions around the tunnel contour in ancient brittle crystalline rocks has been developed and verified. The general aim has been to reach an understanding of the groundwater conditions in and close to the tunnel roof where dripping takes place and to propose technical and practical strategies for waterproofing. Dripping is accompanied by ice growth and icicle formation in cold regions, creating additional problems such as shotcrete fall-outs, icicle fall-outs, damage to vehicles, damage to trains, etc. The methodology for the development of the conceptual model is based mainly on transmissivity determinations from short-duration hydraulic tests and analyses of the connectivity of the fracture structure by means of semi-variogram analysis. The determination of the dimensionality of the flow in the fractures has also been found to be essential in order to describe the conductive system. This conceptual model describes the fracture systems as a combination of transmissive patches (2D-flow fractures) connected by less pervious channels (1D-flow fractures). It provides an understanding of the heterogeneity and connectivity of the fracture network and thus the groundwater conditions, not only in the roof but also around the tunnel contour. The pre-excavation grouting design process used in the tunnelling projects followed a structured approach and the evaluation showed that the grouting design reduced the inflow and fulfilled the environmental demands. However, dripping remained, making its characterisation very important when proposing a possible solution for its control. It is proposed that the remaining dripping comes from a channelised system that has been left unsealed and which would be extremely difficult to intersect with future boreholes, as well as from some ungrouted fractures with inconvenient orientations. Geomembrane lining and post-excavation grouting are possible solutions, although particular attention needs to be given to the location. With the proper grouting technique and knowledge of the fracture system and hydrogeology, it is possible to propose technical strategies for waterproofing a tunnel roof.

icicle formation

drip sealing

unsaturated flow

rock fracture

dripping.

channels

crystalline rock

design

Grouting

ice growth

evaluation

VG-salen, Sven Hultins gata 6, Chalmers University of Technology
Opponent: Prof. Bo Olofsson, Land and Water Resources Engineering, Royal Institute of Technology, Sweden

Författare

Christian Butron

Chalmers, Bygg- och miljöteknik, Geologi och geoteknik

Characterisation of the hydraulic properties of fractured rock from grouting data

Toyama, Japan-IAH 2008 Toyoma: Integrating Groundwater Science and Human Well-Being,; (2008)

Paper i proceeding

How impermeable can a tunnel get? A case study with drip mapping as a method

11th IAEG Congress 2010: Geologically active,; (2010)p. 2711 - 2719

Paper i proceeding

Silica sol for rock grouting: Laboratory testing of strength, fracture behaviour and hydraulic conductivity

Tunnelling and Underground Space Technology,; Vol. 24(2009)p. 603-607

Artikel i vetenskaplig tidskrift

Assessment of the transmissivity field in fractured rock: A case study in the tass tunnel

Nordic Symposium of Rock Grouting,; (2009)

Paper i proceeding

Drip sealing of tunnels in hard rock: A new concept for the design and evaluation of permeation grouting

Tunnelling and Underground Space Technology,; Vol. 25(2010)p. 114-121

Artikel i vetenskaplig tidskrift

Styrkeområden

Building Futures

Produktion

Ämneskategorier

Annan geovetenskap och miljövetenskap

Annan samhällsbyggnadsteknik

ISBN

978-91-7385-656-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3337

VG-salen, Sven Hultins gata 6, Chalmers University of Technology

Opponent: Prof. Bo Olofsson, Land and Water Resources Engineering, Royal Institute of Technology, Sweden