Current bases for roof fall prediction at WIPP and a preliminary prediction for SPDV Room 2.

摘要

This document presents the current bases for roof fall prediction at the Waste Isolation Pilot Plant (WIPP) and a preliminary prediction of the date of a roof fall in SPDV Test Room 2. The ability to correctly assess the stability of the excavations at the WIPP is necessary to protect the safety of site workers, the environment, and the integrity of in situ experiments that use transuranic mixed waste. Roof fall is the extreme case of instability. Although roof falls have been allowed to occur unused, barricaded rooms so that the pre-collapse behavior of this room could be studied. This document presents a discussion of some deformation mechanisms that can be expected around excavations in bedded salt at the WIPP. The geomechanical instrument data and fracture maps from the Site and Preliminary Design Validation (SPDV) room area have been analyzed to determine the deformation history of the rooms and to identify precursors to the SPDV Room 1 roof fall. The deformation history of the excavations as recorded by the instruments was then correlated with these proposed deformation mechanisms, providing a basis for prediction of roof falls in other locations. Finally, the means used at the WIPP to identify and monitor unstable ground are discussed. Throughout this document, ''Room 1 '' and ''Room 2'' refer to SPDV Rooms 1 and 2 unless otherwise stated.