Reliability evaluation of flexibly soft contact earth pressure cell testing based on centrifugal tests on tunnels

A series of centrifugal model tests are conducted by selecting the linear error, average amplitude error and response rate as the indice. Based on the tunnel model, a new flexibly soft contact earth pressure cell ESP-Ⅱ and two internationally representative traditional earth pressure sensors (PDA and EPL-D1) are compared and evaluated to verify the reliability of the newly developed earth pressure cell measurement. The main conclusions are as follows: (1) Under the static state, the linear errors of ESP-Ⅱ, PDA and EPL-D1 are 19.36%, 12.7% and 21.0%, respectively, and the average amplitude errors are 5.79%, 48.2% and 22.6%, indicating that the ESP-Ⅱ earth pressure cell has better static testing performance compared to the two international earth pressure cells. (2) Under the dynamic loads, the average response rates of ESP-Ⅱ, PDA and EPL-D1 earth pressure cells are 67.1, 51.5, and 65.8 Hz, respectively. The response rate of ESP-Ⅱ is slightly higher than that of the other two types of earth pressure cells, indicating a good response frequency. The earth pressures measured by ESP-Ⅱ and PDA under sequential seismic loads are different from those of EPL-D1, showing a consistent incremental pattern. However, there are certain differences in the numerical values, indicating that the soils have strong structural characteristics. (3) During the unloading process, the data measured by the three types of earth pressure cell show varying degrees of nonlinear changes. The time-history curves of earth pressures of PDA and EPL-D1 exhibit bending and jumping phenomena, while those of ESP-Ⅱ maintain good data continuity, indicating to some extent that the soft contact design can achieve good contact between the earth pressure cells and the soils.