Experience from many facets of a cut-and-cover tunnel construction

摘要

A 340-meter long cut-and-cover tunnel was constructed in soft and sensitive postglacial clays and glacial sands with a high water table in a suburban area of Switzerland maintaining traffic with local detours only. The roof slab method with diaphragmwalls was used. The thickness of the diaphragm wall and the excavation sequence were adapted to the geotechnical conditions. Detailed site investigations with borehole tests (DMT), in-situ tests (CPTU) and pore pressure monitoring were carried out. Testpanels were constructed and monitored. The construction was followed by a detailed monitoring program, which included piezometers, inclinometers, settlements, and strut forces. Measurements were evaluated and corrective action taken, if necessary. Effects on neighbouring structures were limited even with the inter- and counteracting geotechnical and hydrogeological constraints.