High Pressure Customised Shear Box: Politecnico di Torino

Built in 1957, the Beauregard Dam in the Aosta Valley in Italy, has a potential capacity of 70 million cubic metres of water. Currently, the maximum allowable capacity is 6.8 million cubic metres of water, the applied restriction being due to concerns in the early 1970's of infiltrations of water in the mountain sides reducing the overall stability of the slope adjacent to one of the dam abutments. This caused the regional administration to order the reduction of the size of the artificial lake to the minimum necessary to operate the hydroelectric power plant and the problem has been taxing engineers ever since.

Shear strength of rocks are usually investigated by means of unconfined and triaxial compression tests, which were deemed unrepresentative in the case of the Beauregard Dam. To fully understand the mechanical behaviour of the dam slopes, it was imperative to determine the shear strength and deformability characteristics, including creep behaviour of the material under the desired effective in-situ state of stress. Such test conditions could not be completely reproduced using traditional devices.

The Solution

Together Politecnico di Torino (PoliTo) and GDS Instruments (GDS), both with extensive knowledge and experience in shear testing devices, teamed up to design and develop a new direct shear apparatus that had the following design brief: To read the complete case study, download the PDF file.

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