逆斜切式隧道门的受力机理

采用有限元对逆斜切式隧道门的受力进行三维数值模拟分析,并用几何相似比为1∶30的模型试验结果进行验证。分析结果表明,逆斜切式隧道门结构的受力基本特征是:隧道洞口结构处于三维受力状态,按壳体结构进行设计比较合理;当进入洞内距离超过隧道洞径约2.5倍的洞身地段,纵向轴力值远小于横向轴力,且横向弯矩是纵向弯矩的6~10倍,因此在结构设计中可不必考虑纵向内力的影响,简化成平面应变问题;在衬砌突出部位与岩层的交界面上,拱顶沿隧道纵向的轴力达到最大值,而且处于受拉状态,因此对洞口段衬砌结构纵向应进行配筋设计。

Stress Mechanism of Down Bamboo-truncating Tunnel Portal

3D numerical simulation analysis with the method of FEM was carried on the mechanical behavior of down bamboo-truncating tunnel portal. The results were compared with that of the model experiment with 130 geometric similarity ratio. Analysis result indicates that down bamboo-truncating portal possesses the following basic mechanical characteristics. Its tunnel adit opening is under 3D stress so it will be reasonable to design it according to shell structure. When coming into the cave sector for about 25 times of the tunnel diameter, the axial force in longitudinal direction is far less than that in cross direction and the moment of flexion in cross direction is 6 to 10 times of that in longitudinal direction. The influence of the inner force in longitudinal direction can be neglected in structure design. It can be simplified as plane strain. On the interface between rock stratums and the projecting part of lining, the vertical axis-force of the vault under tension reaches maximum. Reinforcement design should be considered for longitudinal lining structure at tunnel portal section.