Advanced Support Structure

The aim is to create a full support structure prior to doing any of the major excavation. This can be done by using jacking, microtunnelling or pipe ramming methods to form an advance support structure. The illustrations  shows  a series of interlinking tubes installed by microtunnelling to form the support structures for an arch and rectangular  structure.. Frequently an arch structure is created but virtually any shape is possible. The interlinking steel tubes which form the support canopy are filled with reinforced concrete. Once the main excavation starts additional internal framing is installed as work proceeds to support and  complete the structure. This technique has been used for the construction of large underground structures such as metro stations.