Accuracy analysis of photogrammetric triaxial model considering the influence of refraction
TANG Yihuai¹, HUANG Shaoran¹, MU Chunmei^1,2
1. College of Civil and Architectural Engineering, Guilin University of Technology, Guilin 541004, China;
2. Guangxi Key Laboratory in Geotechnical Mechanics and Engineering, Guilin 541004, China
Abstract: The photogrammetric method was used in geotechnical triaxial test to obtain the dimensional deformation field of soil samples, but the refraction caused by the light passing through the pressure chamber and water would affect the accuracy of the test. How to eliminating the influence of refraction and improving the accuracy of triaxial soil deformation measurement is the key of the research. The authors used the hard cylinder with marked points as the research model, then established a refraction correction model to correct the refraction error through the three-axis simulation experiment of photogrammetry to obtain the axial and radial values of the triaxial model in air, water injection pressure chamber and after refraction correction. Besides, they defined the measured value of the vernier caliper of the triaxial model in the air as the “reference value”, compared the measured value of the model size obtained after the water injection pressure chamber and refraction correction with the “reference value”, and analyzed the influence of refraction on the imaging of the triaxial model. As shown in the results: Photogrammetry has high measurement accuracy in air. The refraction error can be effectively reduced through the refraction correction model. After refraction correction, the radial average error is 0.63% and the axial average error is 0.23%, which was reduced by 26.29% and 3.09% respectively compared with the radial average error and axial average error before refraction correction. The influence of refraction on the axial and radial directions of the triaxial model is inconsistent, the influence of refraction on the axial direction is not as significant as that on the radial direction, and the influence of refraction on each direction of the triaxial model is different.
Keywords: photogrammetry;refraction correction;triaxial soil sample;precision analysis
2022, 48(12):146-153  收稿日期: 2021-10-28;收到修改稿日期: 2022-01-25
基金项目: 国家自然科学基金项目(41867039)；广西自然科学基金项目(2020GXNSFAA297247)；广西岩土力学与工程重点实验室项目(2015-A-01-03)
作者简介: 唐怡怀(1997-),男,江西赣州市人,硕士研究生,专业方向为岩土工程及工程地质
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