考虑截面扁平化和翘曲的土-隧相互作用模型

Soil-tunnel Interaction Model Considering Cross-sectional Flattening and Warping

摘要:

基于广义梁理论与三维空间土抗力，将隧道视为在弹性地基梁上的具有弯曲、剪切、翘曲和扁平化4个变形模态的薄壁圆环结构，推导了横纵向相互耦合的土隧相互作用模型。结合案例验证了模型的有效性，并通过参数化分析得到了隧道厚径比、土抗力系数对隧道横纵向结构响应的影响规律。研究表明：高应力压载条件下大直径隧道翘曲和扁平化效应显著，截面呈现典型的“横鸭蛋”形式。翘曲将加剧隧道的纵向应变，增幅可达30%以上。隧道厚径比越小，其横纵向变形越大，增幅均可达30%左右。相较于法向土抗力系数，隧道纵向受力性能对切向土抗力系数更为敏感而横截面受力性能对双向抗力系数的敏感性一致。

关键词:土隧相互作用;广义梁理论;椭圆变形;翘曲;隧道横纵向力传递机制

Abstract:

The paper regards the tunnel as a thin-walled ring structure with four deformation modes， including bending， shearing， warping and flattening， on elastic foundation， by introducing the Generalized Beam Theory and three-dimensional soil reactions. The finite element solution of the proposed soil-tunnel model considering coupled transverse and longitudinal actions is derived. The effectiveness of the model is verified by two case studies. Furthermore， the effects of tunnel width-to-thickness ratio and soil resistance coefficient on the transverse and longitudinal behaviours of the tunnels are obtained by parametric analysis. The results show that： The effect of warping and flattening on tunnel with large diameter are significant under high-stress external load， where the cross-section presents a typical form of "horizontal duck egg" and the warping aggravates the longitudinal strain of the tunnel with more than 30% increasing. The smaller the thickness to diameter ratio of tunnel is， the larger the transverse and longitudinal deformation are. The increasing amplification can reach about 30%. The longitudinal behaviors of the tunnel are more sensitive to tangential soil resistance coefficient than the normal coefficient， while the cross-sectional performance is equally sensitive to bidirectional soil resistance coefficient.

Key words:soil-tunnel interaction;generalized beam theory;elliptical deformation;warping;longitudinal and transverse load transfer mechanism