ANALYSIS OF POTENTIAL CAVE-IN FROM FAULT ZONES IN HARD-ROCK SUBSEA TUNNELS

NILSEN B

B. Nilsen, ANALYSIS OF POTENTIAL CAVE-IN FROM FAULT ZONES IN HARD-ROCK SUBSEA TUNNELS, Rock mechanics and rock engineering, 27(2), 1994, pp. 63-75

9

INGLESE

Article

Geosciences, Interdisciplinary","Engineering, Civil

Rock mechanics and rock engineering → ACNP

0723-2632

27

2

1994

63 - 75

ISI

0723-2632(1994)27:2<63:AOPCFF>2.0.ZU;2-I

As a part of a research program on the rock engineering aspects of har d rock subsea tunnelling, analyses of potential cave-in from fault zon es have been carried out at the Norwegian Institute of Technology. Thi s is a topic of great importance for the planning of future subsea tun nels, and particularly for the selection of the minimum rock cover of such projects. The paper is divided into three main parts: a) review o f cases of instability in Norwegian subsea tunnels, b) evaluation of t heoretical maximum sliding, and c) discussion of cases of cave-in in t unnels under land. In theory, a cave-in during subsea tunnelling may p ropagate far higher than the normal minimum rock cover. Taking into co nsideration the comprehensive geo-investigations that are always carri ed out for subsea tunnel projects today, it would, however, be unreali stic to base the dimensioning of rock cover for future projects on wor st-case scenarios. Consequently, the main result of this study is to e mphasize the importance of comprehensive geo-investigations, detailed tunnel mapping, a high degree of readiness during tunnelling and a tho rough quality control.