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Analytical investigation on the arching effect of tunnel face in sandy ground
Highlights An analytical solution to the arching effect at the tunnel face in sand was developed. Horn method was modified by considering the soil-cutter friction and face displacement. The proposed method is proved to be closer to the model tests than the Horn method. The propagation law of the loosening zone at tunnel face in sand was revealed.
Abstract Owing to lack of consideration of the effects of soil particle flow and sand-cutter friction in mechanized tunneling in sandy ground, the traditional methods for considering the arching effect at a tunnel face generally produce discrepancies from model tests and field observations. To remedy this deficiency, in this study, the sand particle flow was investigated by following gravity flow principles to define the shape and size of the loosening zone at the tunnel face (LOZF). Then, by considering the sand-cutter friction and face extrusion displacement, a modified Horn method was developed to determine the loosening pressure at the tunnel face and propagation extent of the LOZF. Finally, the proposed method was verified based on parametric studies and a detailed comparison with a series of model tests. The results indicate that the shape of the loosening zone is semi-ellipsoidal or a part of a semi-ellipsoid, and is affected by the face displacement. Through a detailed comparison with model tests and the Horn method, the proposed method is proven to be closer to the model tests than the Horn method. Thus, the proposed method can predict the support pressure and loosening state at a tunnel face in sandy ground.
Analytical investigation on the arching effect of tunnel face in sandy ground
Highlights An analytical solution to the arching effect at the tunnel face in sand was developed. Horn method was modified by considering the soil-cutter friction and face displacement. The proposed method is proved to be closer to the model tests than the Horn method. The propagation law of the loosening zone at tunnel face in sand was revealed.
Abstract Owing to lack of consideration of the effects of soil particle flow and sand-cutter friction in mechanized tunneling in sandy ground, the traditional methods for considering the arching effect at a tunnel face generally produce discrepancies from model tests and field observations. To remedy this deficiency, in this study, the sand particle flow was investigated by following gravity flow principles to define the shape and size of the loosening zone at the tunnel face (LOZF). Then, by considering the sand-cutter friction and face extrusion displacement, a modified Horn method was developed to determine the loosening pressure at the tunnel face and propagation extent of the LOZF. Finally, the proposed method was verified based on parametric studies and a detailed comparison with a series of model tests. The results indicate that the shape of the loosening zone is semi-ellipsoidal or a part of a semi-ellipsoid, and is affected by the face displacement. Through a detailed comparison with model tests and the Horn method, the proposed method is proven to be closer to the model tests than the Horn method. Thus, the proposed method can predict the support pressure and loosening state at a tunnel face in sandy ground.
Analytical investigation on the arching effect of tunnel face in sandy ground
Wu, Jun (author) / Liao, Shao-Ming (author) / Liu, Meng-Bo (author) / He, Jun-Zuo (author)
2021-09-27
Article (Journal)
Electronic Resource
English