薄膜式压力传感器在隧道模型试验中的标定研究

Research on Calibration of Thin-film Pressure Sensor in Tunnel Model Test

随着缩尺模型试验在隧道工程研究中的不断应用,对岩土体力学测量硬件和技术提出了更高的要求。传统土压力盒尺寸较大,由于其对土体完整性影响较大,尤其对于模型尺寸较小的离心模型试验,已无法满足试验精度的要求。新型薄膜式土压力传感器具有厚度薄、形状多样、抗压强度高和灵敏度高等优点,正逐渐被引入岩土工程试验研究中,需通过试验标定其在岩土介质中的工作性能。通过薄膜式土压力传感器的标定试验,研究其漂移性、迟滞性、线性度和重复性等性能指标,为其在隧道模型试验测量领域的工程适宜性提供数据借鉴,试验对比同一传感器在不同岩土介质中的标定结果,分析标定介质对标定结果的影响。通过多组重复性的标定试验分析得出:薄膜式土压力传感器具有较好的线性度和重复性,但也存在较为明显的漂移性和迟滞性;标定介质的不同直接导致标定结果的不同,针对石英砂(散体)和模型相似材料(粉体)的对比,主要表现为传感器对荷载的响应程度的不同。

With the continuous application of scale model test in the research on the tunnel engineering,higher requirements on the geotechnical measurement hardware and technology are put forward.The traditional earth pressure cell has a large size,which has a great impact on the integrity of soil.Especially for the centrifugal model test with small model size,it can not meet the requirements of test accuracy.The new thin-film earth pressure sensor has advantages like thin thickness,diverse shapes,high compressive strength and high sensitivity.It is gradually introduced into the research on the geotechnical engineering test.Its working performance in geotechnical medium needs to be calibrated by test.Through the calibration test of thin-film earth pressure sensor,its performance indexes such as drift,hysteresis,linearity and repeatability are studied to provide data reference for its engineering suitability in the field of tunnel model test measurement.The calibration results of the same sensor in different geotechnical media are compared by the test,and the influence of calibration media on the calibration results is analyzed.Through the analysis on several groups of repeatability calibration tests,it is concluded that:the thin-film earth pressure sensor has good linearity and repeatability,but it also has obvious drift and hysteresis;different calibration media directly lead to different calibration results.The comparison between quartz sand(bulk)and similar model materials(powder)is mainly reflected in the different response degrees of the sensor to the load.