Ground Responses to Tunneling in Soft Soil Using the URUP Method

The ultrarapid underpass (URUP) tunneling method, in which a shield machine is launched and received at the ground surface level, has been developed for tunneling in congested areas. This paper reports monitoring results of a full-scale test conducted for the first URUP tunneling project in China. In the investigation, special attention was paid to tunneling phases in which the shield machine was buried super-shallowly or partially above the ground surface. The paper focuses on the tunneling-induced soil movements and on the grouting process. Measurement results indicated that surface settlements can be represented by the commonly used Gaussian function regardless of the cover depth, and that the load-factor approach provides a fair prediction of the volume loss. A contracting transverse soil-displacement field was identified as the dominating pattern, although an expanding displacement field was observed at several locations. Pressure measurements were used to identify a time-dependent response of the grouting process.