PSI - Issue 32

V. Epin et al. / Procedia Structural Integrity 32 (2021) 64–70 V. Epin/ Structural Integrity Procedia 00 (2021) 000–000

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Fig. 3. Layout of the sensors of the hydrostatic leveling system of headframe columns.

Fifteen sensors are located at 4.7 m from the ground surface. Each circuit has an expansion tank, which includes an electric pump for mixing the liquid during maintenance. 4. Analysis of measurement results Fig. 4a and Fig. 4b show graphs of the evolution of uneven settlements accumulated during the measurement period from December 2019 to March 2021. Settlement measurements are performed at intervals of 20 minutes. In each measurement, ten sensor surveys are performed with an interval of 3s. Based on these surveys, the average value is calculated, which is the result of the measurement. This choice of measurement parameters eliminates high frequency fluctuations in the sensor readings associated with random errors. During the observations, the hydro-leveling system registered the "settling" and "lifting" of all the columns of the structure relative to the columns resting on the concrete head of the mine shaft (sensors 3, 7 and 8). This result can be interpreted as lifting the height of the mine shaft relative to the other supporting elements of the structure. For clarity, the image of the surface corresponding to the change in the vertical displacements field relative to the start of measurements, is shown in Fig. 5. This measurement data may be used to model the stress-strain state of the headframe structure. -8 -6 -4 -2 0 Date ΔU, mm 2019-12 2020-03 2020-06 2020-09 2020-12 2021-03 1-3 2-3 4-3 5-3 6-3 a -8 -6 -4 -2 0 Date ΔU, mm 2019-12 2020-03 2020-06 2020-09 2020-12 2021-03 15-7 14-7 13-7 11-7 10-7 9-7 b Fig. 4. The evolution of uneven settlements for loop 1 (a) and loop 2 (b) from December 2019 to March 2021.