Tunnels and excavations

Abstract

Most tunnels are formed by tubes at the place where there are large traffic intersections of waterways and/or roads. Tubes are constructed at the deepest location and basin structures consisting of a floor and walls are constructed on each side. In these the road is returned to the normal level, which is either at or above ground level. Reinforced concrete is used as the building material. After completion, the road is beneath the groundwater level over practically the entire length of the works. The construction of the tube and the basin ensure that no groundwater is withdrawn from the surroundings. This is in contrast to the end phase, during the implementation of which the groundwater conditions in the tunnel surroundings are indeed affected. The cheapest building method is practically always obtained by carrying out the work in an open excavation. It is generally advisable for the civil engineer to be aware that although he may know the geological composition of his building land, he is not always in a position to complete specific projects on the basis of his own knowledge and experience. The assistance of a geologist having specific civil engineering knowledge is frequently very important so that he can help to assess a project and the steps required for its implementation.