Construction monitoring activities in the Yucca Mountain ESF Starter Tunnel

An underground test facility known as the Exploratory Studies Facility (ESF) is planned as part of the characterization of a site for a potential high-level nuclear waste repository at Yucca Mountain, NV. The first part of the ESF that will be constructed is the North Ramp Starter Tunnel (NRST), which will provide a facility for launching the tunnel-boring machine to be used in the construction of the ESF. Geotechnical monitoring activities are planned for the NRST to provide for the collection of data to confirm design concepts and to enhance safety during construction. This paper describes the activities to be conducted and their objectives. The construction monitoring activities are part of a study defined in the In Situ Design Verification Study Plan. The objectives of this study are to (1) monitor and observe the long-term behavior of openings in a range of ground conditions in the repository host rock, and (2) to observe and evaluate the construction of the ESF with respect to implications for repository construction and performance. Initiating geotechnical monitoring activities in the NRST will allow geotechnical data required to confirm adequate design, construction and long term performance to be collected from the very beginning of underground construction.more » In addition, the planned monitoring is consistent with standard practice for assuring quality and safety during similar rock excavation for civil construction. The geotechnical monitoring activities addressed by this experiment plan are grouped into three tasks: (1) evaluation of mining methods, (2) monitoring of ground support systems and (3) monitoring drift stability. A general description of each of the tasks is presented below.« less