Pinglin tunnel, which is 12.9 km in length, is under construction in Taiwan. Three tunnels, including two separated main tunnels with 12m in diameter and one pilot tunnel with 5m in diameter, are parallel in direction and were constructed simultaneously. Large deformation of main tunnels and the pilot tunnel were observed during the excavation of main tunnels. A detail study based on the monitoring results has been performed to gain more understanding on the behavior and stability of the rock mass surrounding the tunnels.


Le tunnel de Pinglin, qui a l2.9kms de long, est maintenant en cours de construction a Taiwan. Les trois tunnels, dont deux tunnels principaux de 12m de diamètre et un tunnel pilote de 5m de diamètre, sont parallèles et construits simultanement. L'excavation des tunnels principaux a provoque d'importantes deformations de ceux-ci et des ruptures du soutènement primaire du tunnel pilote. Une etude detaillee prenant en compte les resultats d'instrumentation et la reaction du système de soutènement a ete realisee en vue d'obtenir une comprehension valable du comportement et de la stabilite du massif rocheux autour des tunnels.


Der Bau des 12,90 km langen Pinglin Tunnels in Taiwan hat begonnen. Drei Tunnel, die beiden Haupttunnel mit einem Durchmesser von 12 m und ein Pilotstollen mit einem Durchmesser von 5 m, verlaufen parallel und werden gleichzeitig aufgefahren. Grosse Deformationen in den Hauptstollen sowie Beschadgungen des primaren Ausbaus im Pilotstollen wurden durch den Vortrieb der Hauptstollen herbeigefuehrt. Aufgrund von Messergebnissen sowie dem Verhalten des Tunnelausbaus wurde eine detaillierte Studie erstellt, um zu einem guten Verstandnis zu gelangen ueber das verhalten des Gesteins und der umliegenden Gebirgsmasse.


The rugged Central Mountain Range runs through Taiwan roughly in the north-south direction, which makes the land transportation difficult between Taipei city on the west and Ilan country on the east. The Taipei-Han expressway project is aimed to shortening the travel time between the two places. The expressway, totaling 31km in length and two lanes in each direction, starts at Nankang in Taipei city and ends at Toucheng in Han county, passing through Shihting and Pinglin on the way (see Fig. 1). Due to the craggy topographical condition of the mountainous terrain, five tunnels account for 20km in length will be constructed. The longest tunnel is the Pinglin tunnel with 12m in diameter and 12.9km in length. There are two parallel main tubes, west bound and east bound, to be constructed for the Pinglin tunnel (see Fig.2). To minimize uncertain geological risk and to ensure progress rate for the main tunnels construction, a pilot tunnel, 5m in diameter and located between the main tubes, has been implemented in advance in order to perform detailed geological investigation and to treat weak zones, if necessary. Fig. 2 illustrates the layout of the two main tunnels and the pilot tunnel. The distance between two main tunnels are in general 60m apart except at the portal being reduced to 42m. The pilot tunnel locates in the middle location between these two main tunnels, and the elevation of the pilot tunnel is lightly lower than the main tunnel. The purpose of this paper is to utilize the monitoring instruments installed in the first eight hundred meters tunnel excavation from the eastern portal, which was completed by drilling and blasting (D&B) construction method in april 1996, in order to gain more understanding on the behavior of rock mass during excavation.

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