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| Research on the Limit Supporting Force of the Shield Tunnel Excavation Face |
| WANG Guo-fu1，ZHENG Tao1，WANG Wei-ming1，LU Lin-hai2，SUN Jie-cheng2 |
| (1. Shandong University of Science and Technology, Qingdao, Shandong 266590, China；2. Jinan Rail Transit Group Co. Ltd, Jinan, Shandong 250101, China) |
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Abstract Abstract：Research purposes： There are great potential safety problems in the construction of shield tunnelling, under the influence of the over excavation of the shield cutter, the inner wall of the shield shell and the asymmetric thrust of jack, resulting in front of the excavation face deformation is complex, difficult to control the stability of the excavation face. Based on the theory of the curved surface of silo, the limit equilibrium model of the surface of the curved wedge prism was proposed, and the theoretical calculation formula of the limit supporting force was deduced; then in the engineering background of the shield tunnel of Jinan rail transit line R1 Wangfuzhuang to Dayangzhuang section, the deformation distribution characteristics of excavation face with different curvature radius were studied, to provide scientific theoretical guidance for the stability of curved tunnel excavation face. Research conclusions： (1) The damage of curved shield tunnel excavation face presented asymmetric distribution, by the influence of eccentric support pressure of excavation face, the surface gradient wedge prism balance model was formed. (2) With the decrease of the radius of curvature, the excavation surface displacement and the limit support pressure first increased then decreased, and the supporting pressure was calculated not according to the central supporting force, but rather according to the lateral side of the curve, and its value was greater than the straight line of shield tunnel. (3) Limit support pressure increased with the increase of cohesion, internal friction angle of the soil excavation surface, first showed a trend of increase with the increase of the difference in value on both sides of the rupture angle, decreases when the β1＞32.3°, and eventually flatten out. (4) The research results can provide theoretical guidance and scientific basis for the stability of the excavation face and its support in the construction of the shield tunnel.
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Received: 25 May 2017
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2017, Vol. 34 
