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Simple and reliable displacement measurements, as a means for the continuous observation of the behavior of underground works during every construction phase,' provide an indispensable help for a safe and economical execution. The displacement measurements enable to: - immediately verify the adequateness of the selected construction method and of the safety measures adopted - determine, at an early stage, possible instabilities which cannot be detected visually - draw conclusions about the overall rock quality with help of a stress analysis based upon an estimated or measured primary state of stress. Particularly useful information is obtained from the measurements of the displacements resulting from the excavation. The present paper deals with the problem of the practical execution of convergence measurements and also describes a recently developed precision instrument, the ISETH-DISTOMETER, which is particularly adequate for use in underground works. Due to its simple operation, solid construction, reduced possibility of errors and adaptability to the difficult underground working conditions, this instrument has been successfully used in many instances.
Authors:Kovári, Kalman and Amstad, Christian and Grob, Hans
Index Terms:tunneling; measurements; Displacement measurements; rock; TunnelingGroup
Further Information:Date published: 1974