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Internal Sand Deformation around a Tunnel Boring Machine
This paper presents an experimental investigation of internal sand deformation around a scaled tunnel boring machine using transparent soil. Soil deformation and its control is always a critical issue, particularly in urban environments, for protecting adjacent properties and services during tunnel construction. Visualization of an internal soil deformation will improve our understanding of the influence of tunneling as most deformation measurement available are limited to ground surface settlement due to the opacity of natural soils. A new kind of transparent soil is used in this study, which is made of fused silica and a calcium bromide solution. An optical setup is developed to consist of a laser, a camera, and a computer. The laser is used to illuminate the targeted section around the scaled shield machine. A series of laser speckle images are captured during shield driving. The digital image correlation method is used to calculate the relative displacement between two consecutive images. Two model tests are performed with an overburden cover varying from once to twice the tunnel diameter. The results show that soil deformation changes with tunnel depth increases. The influence zone is changing from a rectangle over a reversed trapezoid shape in the shallower tunnel to a bell over a trapezoid shape restrained within soil mass in the deeper case. The longitudinal deformation extends to ground surface in the shallow cover case, whereas the influence zone is confined within the soil mass in the deep cover case.
Internal Sand Deformation around a Tunnel Boring Machine
This paper presents an experimental investigation of internal sand deformation around a scaled tunnel boring machine using transparent soil. Soil deformation and its control is always a critical issue, particularly in urban environments, for protecting adjacent properties and services during tunnel construction. Visualization of an internal soil deformation will improve our understanding of the influence of tunneling as most deformation measurement available are limited to ground surface settlement due to the opacity of natural soils. A new kind of transparent soil is used in this study, which is made of fused silica and a calcium bromide solution. An optical setup is developed to consist of a laser, a camera, and a computer. The laser is used to illuminate the targeted section around the scaled shield machine. A series of laser speckle images are captured during shield driving. The digital image correlation method is used to calculate the relative displacement between two consecutive images. Two model tests are performed with an overburden cover varying from once to twice the tunnel diameter. The results show that soil deformation changes with tunnel depth increases. The influence zone is changing from a rectangle over a reversed trapezoid shape in the shallower tunnel to a bell over a trapezoid shape restrained within soil mass in the deeper case. The longitudinal deformation extends to ground surface in the shallow cover case, whereas the influence zone is confined within the soil mass in the deep cover case.
Internal Sand Deformation around a Tunnel Boring Machine
Liu, Jinyuan (author) / Sun, Jizhu (author)
Geo-Hubei 2014 International Conference on Sustainable Civil Infrastructure ; 2014 ; Yichang, Hubei, China
2014-06-23
Conference paper
Electronic Resource
English
Internal Sand Deformation around a Tunnel Boring Machine
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