Evaluation of Accuracy of Photogrammetry-Based Deformation Measurement Method

Triaxial test has been widely used to evaluate unsaturated soil behaviors. Volume change measurement on unsaturated soils during triaxial testing remains a challenge. Recently, a photogrammetry-based method has been developed for unsaturated soil deformation measurement during triaxial testing. Preliminary study indicated that the photogrammetry-based method is a simple, cost- and time-effective option for monitoring soil deformation during triaxial testing. However, there are still concerns regarding the accuracy, reliability, and repeatability of the photogrammetry-based method for soil deformation measurement during triaxial testing. In this study, to evaluate the point measurement accuracy, validation tests were performed on an aluminum cylinder under different chamber pressure and confining medium (i.e. air, water, and silicone oil which are commonly used as the confining medium for triaxial tests) conditions. A sensitivity analysis was also carried out to evaluate the impact of the system parameters (i.e. refractive indices of air and confining fluid, cell wall thickness) on the volume measurement accuracy of the photogrammetry-based method. Beside these, a triaxial test on a saturated sand specimen was carried out to evaluate the volume change measurement accuracy of the photogrammetry-based method. Effects of target number and mesh pattern on soil volume change measurement accuracy were also evaluated. In addition, the repeatability of the photogrammetry-based method was validated through a series of triaxial tests on unsaturated soils. Some suggestions are also presented to improve the accuracy of the photogrammetry-based method. Results from this study indicate that the photogrammetry-based method is an accurate and reliable option for soil deformation measurement during triaxial testing.

• 
• Supplemental Notes:
  • This paper was sponsored by TRB committee AFP60 Standing Committee on Engineering Behavior of Unsaturated Soils. Alternate title: Evaluation of Accuracy of Photogrammetry-Based Deformation Measurement Method
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Li, Lin
  • Zhang, Xiong
• Conference:
  • Transportation Research Board 95th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2016-1-10 to 2016-1-14
• Date: 2016

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 26p
• Monograph Title: TRB 95th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Accuracy; Cost effectiveness; Deformation; Measurement; Photogrammetry; Reliability; Triaxial shear tests; Unsaturated soils; Volume changes
• Uncontrolled Terms: Repeatability
• Subject Areas: Geotechnology; Highways;

Filing Info

• Accession Number: 01594136
• Record Type: Publication
• Report/Paper Numbers: 16-6798
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Mar 21 2016 4:41PM