ABSTRACT:

The municipality of Amsterdam wish to reduce the level of car traffic within the City Centre. As a consequence the public transport is to be extended by a new North/South Metro line. This paper will focus on the design philosophy of the deep station boxes. The excavations depths for the stations will exceed 30m and will be constructed in difficult soft soil conditions. A further significant aspect is that the building pits are very near (3 to 5 m) to buildings of historical importance.

INTRODUCTION

The Amsterdam North/South metro line will connect several important public transport systems (train, tram, bus, and metro) with the north, centre and south districts of Amsterdam. The total length of the metro is 9 km, of which 4 km will be constructed underground. During the construction (early 70's) of the first metro line in Amsterdam it was necessary to demolish buildings in city centre. The client wishes to avoid any demolition during the construction of the new metro line. To minimise the effects of the construction to adjacent historical buildings a bored tunnel will be adopted for the underground sections in the city centre. The tunnel follows the street pattern as closely as possible, see Figure 1, and descends to a great depth. Consequently the metro stations are located at significant depths (over 30 meters below surface level). A building pit will be constructed for the stations, having braced diaphragm walls to a level of over 40m below street level. Much design effort was required and special test procedures were carried out to investigate the realistic effects of underground construction in the City.

GEOLOGY

The subsurface of Amsterdam is composed of sediments, up to depths varying between 800 to 1000 meters below ground level.

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