薄膜压力传感器在土工试验中的适用性初探

薄膜压力传感器因其厚度小、柔软、测压单元面积小等特点,可准确测量土体应力及土颗粒间作用力,因而在土工试验中有着广阔的应用前景。初步探究了薄膜压力传感器在静力和动力土工试验中的适用性。首先,提供了结合3D打印技术,将薄膜压力传感器安装于土体内部设定位置上测量相应土体应力及颗粒间作用力的方法。其次,提出了测量静力时直接建立初始DO值与施加压强值间函数关系的标定方法,并建议选用拟合优度判定系数(R~2)判定测压单元表现的优劣。最后,结合模型桩试验,验证了在动力试验中通过薄膜压力传感器、利用初始DO值可大体了解土体应力在动力荷载下的变化趋势。

Feasibility of applying tactile pressure sensors in geotechnical tests

Due to their small thickness, high flexibility and tiny sensing element, the tactile pressure sensors can be used to measure the soil stresses and contact forces between soil particles. Hence, the tactile pressure sensors have a vast application prospect in laboratory geotechnical tests. This study aims to examine the feasibility of applying the tactile pressure sensors in static and dynamic tests. First, an installation approach for the tactile pressure sensors, which relies on 3D printed sensor holders, is proposed to place the sensors in the designed locations. Second, a modified calibration method is proposed for the static tests. In this calibration method, the “equilibration” step is abandoned. A relationship between the original digital output and the applied pressure is used in the calibration. In addition, it is suggested that only the measurements from the sensors with higher values of R² are used in the analysis. Finally, for the dynamic tests, the results of the model pile tests validate the feasibility of tactile pressure sensors and suggest that the change in the digital output might imply the trend of the soils stresses.