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| Physical model test on the stability of tunnel face in sandy soil |
| LÜ Xilin1,2, ZHAO Yucheng1,2, ZENG Sheng1,2
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1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China;
2. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China |
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Abstract According to the characteristics of shield tunnel construction and considering the hydraulic changes, a physical model test device for failure of shield tunnel face in sandy soil was designed. The displacement controlled loading of the excavation face was realized by pulling the rigid support face, and the earth pressure in front of the excavation face was measured. The high-precision digital image captured during the test was processed to track the instability process of the excavation face. 11 groups of physical model tests were carried out to investigate the failure mechanism of excavation face in isotropic and anisotropic strata and under groundwater seepage condition, and the ultimate support pressure to maintain the stability of excavation face was obtained. The results showed that with the increase of the deformation of the excavation face, the support pressure first decreased rapidly and then tended to be stable. The failure mode of the excavation face was composed of a sliding wedge and an upper prism. In anisotropic strata, the deposition direction of soil particle leaded to the variation of limit support pressure, and the height and width of loosen area in front of the excavation face changed slightly. Under seepage condition, the seepage of groundwater leaded to an obvious increase of the ultimate support pressure, the angle between the sliding surface and the horizontal in the failure state of the excavation face was small and the failure are abecomes large.
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Received: 24 January 2022
Published: 20 September 2022
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