Development and performance evaluation of a novel 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 error problems such as arching effect, size effect and thickness-diameter ratio in the measurement of rigid transducer, improving the frequency response rate and induction accuracy, a novel soft-contact transducer ESP-II was developed, and its innovations and design methods were introduced. Taking two internationally representative earth pressure transducers as reference, a series of centrifuge model tests were designed and carried out to evaluate its accuracy, frequency response and applicability. The main conclusions are as follows: 1) In the static centrifugal acceleration test 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%, the coefficient R2 of the three curves K0 which fitting along the depth is ≥ 0.9893. 2) In the pulse load test, the maximum response time of ESP-II is about 7.8ms, which is slightly better than 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) In the deceleration 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 ensure good contact and stable response between the soil and the transducer. The research results have preliminarily proved that the developed soft-contact transducer satisfies the requirements of static and dynamic centrifugal test, ESP-II has significant application value and immense potential.