ABSTRACT:

Rock mass has many discontinuities and irregular initial stress conditions due to various geophysical and geological activities. Because the underground structure has many unreliable factors in design stage, it is required to predict discontinuities ahead of tunnel face during tunnel construction. By monitoring and analyzing 3-dimensional absolute displacement during tunnel excavation, it is possible to predict discontinuity zones ahead of tunnel face. This paper presents results of the analysis of 3-dimensional displacement obtained from 3-dimensional numerical simulations used for assessing the effect of discontinuity zones on monitoring data. The influence of fault zones, cavities, and in situ initial stress on the 3-dimensional tunnel movement is evaluated.

RÉSUMÉ:

A cause des activites geophysiques et geologiques, la masses d'une roche a beaucoup d'interruptions et de condition initiale de stress irreguliere. Parce que la structure sous terre a beaucoup de facteurs peu fiable a l'etage de conception, c'est requis de pr edire les interruptions avant la visage de tunnel pendent la construction d'un tunnel. Par contrôl et analyse du deplacement absolute 3-dimensional pendant la fouilles de tunnel, c'est possible de predire une zone de I'interruption avant la visage de tunnel. Cette these pr esente les resultats de I'analyse de deplacement 3-dimensionale obtnue par les simulations numericalles 3-dimensionale qui est utilis e pour evaluer I'effet des zones d'interruption du data contrôle, L'influence des zones de faute, la cavite, et en etat situ de stress par la movement de tunnel 3-dimensionale sont evalue.

ZUSAMMENFASSUNG:

Gesteinsmasse hat viele Unkontinuitat und unregelmassige Anfangsstresskondition wegen der geophysikalische und geologische Aktivitat. Weil die Untergrundstruktur viele unzuverlassige Faktore in der Phase des Design hat, ist es notwendig, die Unkontinuitat vor der Tunnelwand wahrend der Konstruktion der Tunnel zu vorhersagen. Mit der Beobachtung und Analyse der 3-dimensionale Absolutverschiebung wahrend der Tunnelgrabung, ist es möglich, die unkontinuierliche Zonen zu vorhersagen. Diese These prasentiert das Ergebnis der Analyse der 3-dimensionale Verschiebung, was von den 3-dimensionalen, numerischen Simulatione erhaltet war. Diese Simulatione war fuer die Einschatzung des Effekt der diskontinuierliche Zonen an der Datenbeobachtung verwendet. Und der Einfluss, was Defektzonen, Hohlraume, Anfangszustand der Stress auf die Bewegung der 3-dimensionalen Tunnel haben, war eingeschatzt.

INTRODUCTION

When fault zones or cavities exist ahead of a tunnel face and the tunnel is excavated without perceiving their existence, it will cause the stress concentration on the region between the face and the discontinuity zone. This is from the influence of the fault zone on the arching effect and may sometimes bring a collapse of underground structures. Recently, abandoned mines or naturally- made underground cavities caused a big problem during tunnel excavation in Korea. Because the underground structure has many unreliable factors in the design stage, the prediction of fault zones ahead of the tunnel face by monitoring displacements of the tunnel and the rapid change of the support systems are required for more economical and safer tunnel construction.

The conventional method in determining tunnel deformations has many drawbacks. It just shows the relative: displacement between two points and, shows only two dimensional displacement. By monitoring the 3-dimensional absolute displacement, the more useful information can be obtained without interrupting construction procedure. Recent studies show that, longitudinal displacement changes during excavation due to the rock property fluctuation, and show that if the longitudinal displacement and settlement measured in the field are considered together in displacement analysis

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