Development and performance evaluation of separable high-frequency response miniature pore water pressure transducer

The pore water pressure is one of the key mechanical indexes in geotechnical model tests and in-situ engineering monitoring. Aiming at the characteristics of high frequency and instantaneous load of dynamic centrifugal model tests and the measuring requirements of dynamic pore water pressure, a novel separable high-frequency response miniature transducer DSP-II is developed. Moreover, the internationally recognized standard pore water pressure transducer PDCR-81 is selected to perform a series of static and dynamic calibration tests and centrifugal model tests to verify the accuracy, frequency response and stability performance of the DSP-II. The main conclusions are drawn: (1) The DSP-II has established key technology and design method in improving the frequency response, accuracy, life cycle, etc. (2) The dynamic calibration test results show that the response time of the DSP-II and the PDCR-81 is 4.93 and 4.97 ms, and the amplitude error is 0.483% and 0.575%, which indicates that the two transducers have basically the same dynamic performance and can meet the requirements of dynamic centrifugal tests with frequencies equal or less than 200 Hz. (3) From the static stepwise centrifugal loading and repeated tests after 39 days, the results of the two transducers with different buried depths are highly consistent with the theoretical values, the average amplitude error is 0.347% and 0.392%, and the repeatability index is 0.157% and 0.169%, which indicates that they have excellent long-term stability and consistency. (4) The results of the two transducers with different dynamic loads are nearly consistent in centrifugal model tests. The maximum time lag of peak value and the minimum correlation coefficient are 1.76 ms and 0.9908, which proves that the DSP-II reach the measurement performance of the PDCR-81. The research work and conclusions are essential for advancing pore water pressure measurement technology, and may provide important guidance and design method.