三轴土样摄影测量中误差与精度分析  

Error and precision analysis in triaxial soil samples in photogrammetry

作　　者：黄子恒 吴静 蔡娇 李刘悦 牟春梅[1,2] HUANG Ziheng;WU Jing;CAI Jiao;LI Liuyue;MU Chunmei(College of Civil and Architectural Engineering,Guilin University of Technology,Guilin 541004,China;Guangxi Key Laboratory in Geomechanics and Geotechnical Engineering,Guilin 541004,China)

机构地区：[1]桂林理工大学土木与建筑工程学院,广西桂林541004 [2]广西岩土力学与工程重点实验室,广西桂林541004

出　　处：《中国测试》2024年第11期98-106,共9页China Measurement & Test

基　　金：国家自然科学基金(41867039);广西自然科学基金(2020GXNSFAA297247)。

摘　　要：为能够在不扰动三轴土样的前提下实现体积变化的直接测量,并有效地避免传统三轴试验中因端部“藏水区”造成的测量误差。三轴摄影测量技术将传统三轴试验与数字测量技术相结合,通过追踪测量光线传播途径,修正折射误差得出准确的RAD编码点坐标数据,将数据导入Matlab中进行识别与计算从而实现模型重构,最终测得土样体变结果。选用与三轴土样尺寸相似的刚性圆柱体模拟土样,表面粘贴RAD编码点,在不同的密闭介质(空气、水)和不同目标围压作用下进行一系列测试。通过数据比对,详细分析三轴摄影测量技术的误差因素及其影响。借助拟合分析发现折射率对测量精度影响最大,并针对折射率影响建立校正模型进行误差修正。结果表明:修正后三轴摄影测量轴向平均相对误差和径向平均相对误差分别为0.056%和0.17%,能够满足土样体积测量的精度要求。In order to enable the direct measurement of volume change without disturbing the triaxial soil sample,and effectively avoid the measurement error caused by the'reservoir area'at the end of traditional triaxial test.The triaxial photogrammetry technology combines the traditional triaxial test with the digital measurement technology.By tracing the propagation path of the measured light and correcting for refraction errors,to derive the accurate RAD coded point coordinate data.The data were imported into Matlab for identification and calculation so as to achieve model reconstruction,and finally the soil sample change measurement results were obtained.A rigid cylinder similar in size to the triaxial soil sample is used to simulate the triaxial soil sample.RAD coding points are affixed to the surface and a series of tests are carried out under different sealed media(air,water)and confining pressures.Through data comparison,the error factors and their effects of three-axis photogrammetric technology are analyzed in detail.With the help of fitting analysis,it was found that the refractive index has the greatest impact on the measurement accuracy,and a correction model was established to correct the error.The results show that the average relative errors in axial direction and radial direction are 0.056%and 0.17%respectively,which can meet the accuracy requirements of soil sample volume measurement.

关 键 词：摄影测量 三轴试验 光线追踪 误差分析 

分 类 号：TB9[一般工业技术—计量学] TU411[机械工程—测试计量技术及仪器]