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; ; Adachi, Tetsuya; Sato, Toshinori;
PNC TN7410 95-049, 47 Pages, 1995/10
Excavation of a shaft or a horizontal drift in a rock mass probably affects the rock mass around the underground openings. It is necessary in the design, construction and safety assessment of underground facilities to consider the properties and extent of the EDZ (Excavation Disturbed Zone; the zone where rock properties and rock conditions have been changed due to excavation). In-situ experiment on excavation disturbance has been carried out in the Tono mine and the controlling factors of properties and extent of the EDZ due to blasting has been studied. In order to evaluate dependence of the change of properties and extent of the EDZ on excavation method, Machine Excavation Effects Experiment has been carried out. In FY 1992, a horizontal drift for measurements was excavated. A horizontal drift parallel to the measuring drift is scheduled to be excavated by a machine in FY 1995. The investigations and numerical analysis before excavation of the test drift were carried out in FY 1993 and FY 1994. The objectives of the investigations and numerical analysis carried out in FY 1993 and 1994 are as follows: (1)to measure and evaluate the rock properties and the rock conditions around the test drift before excavation, and (2)to predict the displacements and stress change during excavation of the test drift. The investigations and numerical analysis in FY 1994 consist of the following items: (1)core logging and borehole wall observation, (2)installation of extensometers, and (3)numerical analysis with the Finite Element Method. This report describes the details of the investigations and numerical analysis carried out in FY 1994.
Sato, Toshinori; ; ; Yoshioka, Naoya
PNC TN7410 92-051, 56 Pages, 1992/12
Excavation of a shaft or a drift in rock mass influences the rock mass around a shaft or a drift mechanically and hydraulically. In Chubu Works, we excavated a shaft having a diameter of 6 m and a depth of 150 m at the Tono Mine, and studied the excavation effects. We call this study Shaft Excavation Effects Project (SEE Project). Measurements with extensometers were carried out at four sections during the shaft excavation to understand the behavior of rock mass around the shaft. The displacement was locally occurred and it's amount depends on geology and presence of a fault and fractures. Numerical analysis was performed to understand the observed phenomena and the excavation effects. It was suggested that the deformation of rock mass around the shaft was within elastic limit and the numerical simulations could describe time-dependent behavior of the measured displacement.