Abstract：Through uniaxial compression test, we obtain the elastic modulus and Poisson’s ratio of the drill core of the borehole strainmeters in Jiangsu province. We calculate the theoretical coupling coefficient and the measured coupling coefficient of the borehole strainmeters using surface strain theory, and discuss their correlation. On this basis, we introduce the observation accuracy, study the relationship between the observation accuracy of the instrument, the coupling coefficient and the data quality, and determine the threshold of the difference of the coupling coefficient. The results show that: 1) The observation accuracy of the borehole strainmeter is positively correlated with the theoretical coupling coefficient and the measured coupling coefficient. The better the consistency between the theoretical coupling coefficient and the measured coupling coefficient, the higher the observation accuracy of the borehole strainmeters and the better the data quality. 2) The threshold of difference between the theoretical coupling coefficient and the measured coupling coefficient of the surface strain at each station in Jiangsu province is 0.1. When the difference is less than 0.1, the observation data quality is higher. When the difference is between 0.1 and 0.2, the downhole coupling has a certain, but not significant, effect on the observation accuracy. When the difference exceeds 0.2, downhole coupling problems occur, resulting in low instrument observation accuracy and poor data observation quality.
HE Bin,LI Feng,TIAN Tao et al. Study on the Borehole Coupling Coefficients and the Threshold of Their Difference Base on Core Mechanical Tests[J]. jgg, 2023, 43(9): 931-935.
