Digital Image Measurement Technology and Its Application in Tunnel Indoor Model Test

Abstract:

Based on the difference in basic principles of digital image technology， the application status， technical development， and basic principles of two-dimensional digital image measurement methods such as digital image correlation （DIC） and particle image velocimetry （PIV） in tunnel model test are summarized. Moreover， the principle of the three-dimensional measurement method and its application potential in tunnel model tests are analyzed. Furthermore， the application of digital image measurement technology in the tunnel model test is demonstrated through the tunneling simulation test of the shield tunnel in the loess stratum. The results show that DIC， digital photogrammetry for deformation measurement（DPDM）， and other non-contact measurement methods judge the displacement of each point by the correlation of points on the photo， and the use scenarios are more inclined to the deformation monitoring of civil structures such as indoor test roads， bridges， tunnels， foundations， dams， steel structures， and steel-concrete structures. PIV analysis can measure the size and direction of the fluid flow and is widely used in the study of fluid motion， such as slurry， debris flow， and fountains. Based on the indoor model test scheme of the shield tunnel in the loess stratum， it is found that the disturbance range of surrounding rock is about 1D on both sides of the central axis of shield tunneling and 1D above the shield when the shield tunneling is eight-ring segment distance in low water content loess stratum.

Key words:tunnel engineering;model test;non-contact measurement method;digital image correlation;shield tunneling;earth deformation