基于双温度补偿的瞬接续采型空心包体地应力测试技术研究

Development of CSIRO cell with the compromised application of instantaneous data-logging,no-power data-connection and twin temperature compensation techniques

为满足地应力精确测量和长期监测的技术发展要求,基于空心包体应变计地应力测量技术,通过对采集电路稳定性、完全温度补偿技术数字化及复杂环境下装备适应性进行研究,开发出具有瞬时采集、断电续采功能的前端数字化采集系统。基于温度自补偿技术及双温度补偿设计实现完全温度补偿技术在前端数字化型空心包体应变计地应力测量中的应用。室内标定试验和现场测试数据显示,双温度补偿技术对原温度补偿算法数据的修正量达到15%。采用围压率定法和真三维地应力试验台进行模拟现场条件的室内测试,结果显示数据真实反映空间应力变化。在3组现场地应力测量中,应变数据真实反映解除过程的岩芯缺陷、构造扰动、温度变化影响及解除应力演化过程,双温度影响修正应变值分别为64,86με。在温度强扰动条件下,通过双温度补偿算法修正,数据稳定性仍然达到了30 min内数据波动幅度小于5με的标准。双温度补偿算法的瞬接续采型前端数字化空心包体应变计地应力测量技术在室内试验和现场测试中均表现了良好的测试精度和采集系统稳定性。

The stability of electric circuit,the digital techniques for the improvement of complete temperature compensation method and the application of in-situ equipment under complex environment were investigated with the technique of CSIRO cell in order to meet the demand of accurate measurement and long-term monitoring of in-situ stresses. The development of the collection system with the function of instantaneous data-logging and data-connection in power cut-off condition were discussed in this paper as well. The compromised techniques of temperature self-compensation transducers and a double circuit set for temperature compensation（twin temperature compensation） are involved in the realization of complete temperature compensation in the front-end digital CSIRO cell. The test results of lab and in-situ measurement show that the twin temperature compensation technique can improve the precision of measurement to 15%（compared with the results from the original temperature compensation method）. Three groups of in-situ tests were also carried out with the new digital hollow cell,and the recorded curves of strain gauges correctly indicate the defects of rock core,the tectonic disturbance,the intense influence of temperature and the process of stress release. The modified values from the twin temperature compensation calculation of the last two in-situ measurement are 64 με and 86 με respectively and the stability of the data can still meet the standard of 5 με in 30 minutes under the intense disturbance of temperature. The new type of digital CSIRO cell shows good accuracy and stability both in laboratory experiments and in-situ tests.