Investigative measurements in the Voerde freeze shaft

As part of the 'New Shaft Construction Techniques' research project, the Gewerkschaft Walter company conducted a measurement program during the sinking of Voerde shaft from July 1982 to June 1985 comprising rock pressure measurements in the outer lining, extensometer readings and inclinometer readings in the foundation, inclination measurements in freeze boreholes after the freezing operation and asphalt thickness measurements. The rock pressure measurements in the outer lining found wall migration of only 2 cm in 98 days. Two years of extensometer readings came up with a buckling of 1.7mm. Inclinometers recorded no appreciable inclinations. The maximum displacement established by inclination measurement in freeze holes at depths of 200 to 500 m was 20 cm after the freezing operation. The asphalt joint could not be measured as cable damage made the metering equipment unusable. 12 refs., 2 figs., 3 tabs.