Abstract
When tunnelling through fault zones with large overburden depth, large displacements are frequently observed. Whether this causes
problems very much depends on the approach used. Challenges are the prediction of the expected displacements prior to excavation in
order not to violate the clearance profile, as well as choosing support characteristics compatible with the strains. Shotcrete linings can
sustain a strain of approximately 0.5% to 1% without failure. Strain above this value inevitably leads to failure of the lining and a loss
of resistance, causing additional displacements. A criterion for a critical overburden depth for closed linings has been developed. As
an improvement to open slots, yielding elements have been developed, allowing large strains and controlled development of support
resistance. The development of the displacements, as well as the rheological behaviour of the supports must be considered. Using stan-
dard grouted bolts, a potential that the “fresh” grout is sheared due to the initially large strain rates exists. Special bolt designs allow
for a higher strain tolerance. Quality monitoring and up-to-date data evaluation is of crucial importance, allowing the prediction of
changes in the ground conditions ahead of the face. With the help of empirical relations, the development of the displacements for dif-
ferent advance rates and supports can be predicted
problems very much depends on the approach used. Challenges are the prediction of the expected displacements prior to excavation in
order not to violate the clearance profile, as well as choosing support characteristics compatible with the strains. Shotcrete linings can
sustain a strain of approximately 0.5% to 1% without failure. Strain above this value inevitably leads to failure of the lining and a loss
of resistance, causing additional displacements. A criterion for a critical overburden depth for closed linings has been developed. As
an improvement to open slots, yielding elements have been developed, allowing large strains and controlled development of support
resistance. The development of the displacements, as well as the rheological behaviour of the supports must be considered. Using stan-
dard grouted bolts, a potential that the “fresh” grout is sheared due to the initially large strain rates exists. Special bolt designs allow
for a higher strain tolerance. Quality monitoring and up-to-date data evaluation is of crucial importance, allowing the prediction of
changes in the ground conditions ahead of the face. With the help of empirical relations, the development of the displacements for dif-
ferent advance rates and supports can be predicted
Translated title of the contribution | Tunnelling in Fault zones - Problems and Solutions |
---|---|
Original language | Czech |
Pages (from-to) | 49-56 |
Number of pages | 8 |
Journal | Tunel |
Volume | 25 |
Issue number | 3 |
Publication status | Published - 2016 |
ASJC Scopus subject areas
- Engineering(all)
Fields of Expertise
- Sustainable Systems
Treatment code (Nähere Zuordnung)
- Application
Cooperations
- NAWI Graz