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汤兆光, 王永志, 孙锐, 王体强, 段雪锋, 王浩然. 土工离心试验微型孔压传感器标定方法与影响因素[J]. 岩土工程学报, 2020, 42(7): 1238-1246. DOI: 10.11779/CJGE202007007
引用本文: 汤兆光, 王永志, 孙锐, 王体强, 段雪锋, 王浩然. 土工离心试验微型孔压传感器标定方法与影响因素[J]. 岩土工程学报, 2020, 42(7): 1238-1246. DOI: 10.11779/CJGE202007007
TANG Zhao-guang, WANG Yong-zhi, SUN Rui, WANG Ti-qiang, DUAN Xue-feng, WANG Hao-ran. Calibration method and effect factors of miniature pore water pressure transducer for geotechnical centrifuge modelling[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(7): 1238-1246. DOI: 10.11779/CJGE202007007
Citation: TANG Zhao-guang, WANG Yong-zhi, SUN Rui, WANG Ti-qiang, DUAN Xue-feng, WANG Hao-ran. Calibration method and effect factors of miniature pore water pressure transducer for geotechnical centrifuge modelling[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(7): 1238-1246. DOI: 10.11779/CJGE202007007

土工离心试验微型孔压传感器标定方法与影响因素

Calibration method and effect factors of miniature pore water pressure transducer for geotechnical centrifuge modelling

  • 摘要: 准确量测孔隙水压力是土工离心模型试验的关键技术之一。针对近期国内外平行动力离心液化试验中孔压动力时程的普遍离散问题,自行开发了一套动力孔压响应标定装置,基于国际代表性的3种微型孔压传感器,开展了多组动力测试性能评价与影响因素对比试验。主要结论如下:①开发的标定装置具备长期承压密封、均匀荷载传递、任意输入等特点,可满足动力离心试验孔压传感器可靠性标定需求;②受传感器内腔与透水石气体可压缩作用,气体不适于直接作为压力媒介,用于动力响应测试;③充分饱和条件下,3种传感器最大响应频率均约200 Hz,满足常规土工离心地震液化试验需求;④《土工离心模型试验技术规程》真空–搅拌饱和法下,3种传感器出现不同程度的幅值衰减与响应滞后,表明不同传感器、饱和方法和标定装置,可成为导致土工离心液化试验中孔压动力时程与阈值条件离散的一个重要原因;⑤搅拌有助于提高传感器饱和速率,真空–搅拌、真空连续、常大气压条件下,3种孔压传感器达到动力可靠测试所需饱和时间,分别为9 h,16 h,4 d。提出的标定装置、方法与结论,对提高动力离心试验相关孔隙水压力测试技术与修订标准,具有重要指导与借鉴意义。

     

    Abstract: Accurate measurement of pore water pressure is one of key technologies in geotechnical centrifugal modelling. Aiming at noticeable scatter of dynamic pore pressure measuring results in the recently repeated dynamic centrifugal liquefaction tests at home and abroad, a novel device for calibrating the response of dynamic pore water pressure transducer is proposed. Moreover, three types of internationally widespread pore water pressure transducers are selected to perform a series of comparison tests over their dynamic performance evaluation and effect factors. The main conclusions are drawn: (1) The proposed calibration device has advantages of long-term high-pressure sealing, uniform load transferring and random loading generation, which can meet reliable calibration requirements of pore water pressure dynamics for dynamic centrifugal tests. (2) Due to the compressibility of air inside the inner chamber and porous stone of transducers, air is not suitable for direct usage as a pressure medium for dynamic calibration. (3) With full saturation of the porous stone, the maximum response frequencies of the three types of sensors are all about 200 Hz, basically meeting the requirements of dynamic centrifugal liquefaction tests. (4) Using the vacuum-stirring saturation method from China's code, the three types of transducers present phenomena of different amplitude attenuations and phase delays, which indicates that different transducers, saturation methods and calibration devices are likely the reasons for noticeable scatter of pore pressure time series and liquefaction thresholds in the repeated centrifuge tests. (5) With three saturating methods of vacuum-stirring, continuous-vacuum and atmospheric pressure, the periods requiring full saturation of the three-type transducers for reliable measurement are 9 h, 16 h and 4 d, respectively. The proposed calibration device, method and conclusions are of paramount importance to advance and standardize the measurement technology of pore water pressure for dynamic centrifugal modelling.

     

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