Vol14 No.8: 1655-1665
【Title】Measurement on soil deformation caused by expanded-base pile in transparent soil using particle image velocimetry (PIV)
【Author】QI Chang-guang1*; ZHENG Jin-hui1; ZUO Dian-jun2; CHEN Geng3
【Addresses】1 Faculty of Architectural, Civil Engineering and Environment, Ningbo University, Ningbo 315211, China; 2 Tianjin Research Institute for Water Transport Engineering, M.O.T., Tianjin 300456, China; 3 Geotechnical Research Institute, Hohai University, Nanjing 210098, China
【Citation】Qi CG, Zheng JH, Zuo DJ, et al. (2017) Measurement on soil deformation caused by expanded-base pile in transparent soil using particle image velocimetry (PIV). Journal of Mountain Science 14(8). DOI: 10.1007/s11629-016-4025-0
【Abstract】A new small-scale geotechnical physical model in 1-g and unconfined condition, combining the transparent soil, close-range photogrammetry and particle image velocimetry (PIV), was employed, which provides a non-intrusively internal deformation measurement approach to monitor the internal deformation of soil caused by expanded-base pile jacking with casing. The transparent soil was made of fused quartz and its refractive index matched blended oil, adding reflective particles (glass beads). Close-range photogrammetry was employed to record the images of the process of casing jacking and extraction in transparent soil, allowing the use of Matlab-based Geo-PIV to figure out the displacement field converted from image space to object space. Analysis of test results indicates that the maximum displacement caused by casing jacking for expanded-conical-base pile is decreased by 29% compared with that for expanded-flat-base pile. The main movement happens at the early stage of casing extraction. The maximum displacement caused by casing extraction for the conical base is about 43% of that for the flat base, while the affected zone caused by casing extraction for the conical base accountsfor about 1/3 of that for the flat base. The contraction for horizontal displacements tends to decrease with the depth increasing. By contrast, the contraction under pile base decreases with the increasing of displacement. The displacements generated by jacking a conventional pile having a diameter equal to the casing diameter of the expanded-base pile were comparable to the net displacement taking place due to expanded-base pile installation for the conical base pile.
【Keywords】Geotechnical physical model; Expanded-base pile; Transparent soil; Particle image velocimetry (PIV); Close-range photogrammetry