Development and performance evaluation of a soft-contact earth pressure transducer for geotechnical centrifuge modeling

The miniature earth pressure transducer is one of the key testing tools in geotechnical centrifuge modeling. Aiming at solving the classical problems such as arching effects, size effects and thickness-diameter ratio in the measurement of rigid transducers, and improving the frequency response rate and induction accuracy, a soft-contact pressure transducer ESP-Ⅱ is developed, and its innovations and design methods are introduced. Taking two internationally representative earth pressure transducers as reference, a series of centrifugal model tests are designed and carried out to evaluate its accuracy, frequency response and applicability. The main conclusions are as follows: (1) In the static centrifugal acceleration tests spinning up from 5g to 50g, the difference between the theoretical values and the test results of ESP-Ⅱ and the two reference transducers at each depth is small, and the average deviations are 5.16%, 6.70% and 4.85%, respectively. The coefficient R² of the three curves K₀ fitted along the depth is≥0.9893. (2) In the pulse load tests, the maximum response time of ESP-Ⅱ is about 7.8 ms, which is slightly better than that of the two reference transducers and has a satisfactory frequency response. (3) In the dynamic load tests of sine and seismic with different amplitudes, the incremental trend of earth pressure measured by the three transducers is basically consistent. The variation range of K₀ increases from 0.43~0.45 before the seismic to 0.51~0.56 after the seismic, which is consistent with the existing theory. (4) At the decelerating stage of the centrifuge, the good continuity and smoothness of the time history measured by the ESP-Ⅱ, which reflects the soft-contact design, is conducive to ensuring good contact and stable response between the soil and the transducer. The research results have preliminarily proved that the developed soft-contact transducer ESP-Ⅱ satisfies the requirements of static and dynamic centrifugal tests, with significant application value and immense potential.