Abstract: The earth pressure cell sensitivity K in the actual working medium within reduced-scale model experiment is quite different from the sensitivity K0 obtained from the manufacturer’s oil calibration environment. To improve the measurement accuracy of the miniature earth pressure cell in model tests of underground structures, a serial of calibration tests for earth pressure cell were carried out by using the similar materials from grade V soil stratum as the working medium. The test results show that the optimal overburden thickness is 1-3cm for the similar material of grade V soil stratum. The correlation coefficients R2 for calibration test data are all greater than 0.99, and the load-strain curves of earth pressure cell with different overburden thicknesses are almost identical and linear. The unloading stress-strain curves, on the contrary, show hysteresis effect to a certain extent in the earth pressure cell calibration test. The sensitivity K obtained from the calibration test is slightly less than the K₀ provided by the manufacturer, which implies that the earth pressure cell should be re-calibrated before usage corresponding to the specific working environment. 

Key words: Earth Pressure Cell Sensitivity, Similar Material for Sols, Calibration Tests, Optimal Overburden Thickness