隧道交叉段变形机制之探讨

The Deformation Mechanism of Tunnel Intersection

采经现地量测数据验证之数值分析模式,利用参数分析探讨岩石材料在弹性模式与弹塑性模式下,主隧道于人行聨络横坑开挖期间在交叉段附近产生之变形行为;采用参数包括不同覆岩深度、不同材料强度及不同主应力大小与方向。分析结果显示,随着联络横坑之开挖,隧道交叉段附近之变形,依材料是否已达塑性及主应力大小与方向之不同而有不同之变形趋势;在弹性模式下,主隧道交叉侧之变形随联络横坑之开挖而往开挖方向位移,在弹塑性模式下,则依主应力大小与方向之不同而呈现不同之变形行为,此结果显示,隧道交叉段之变形机制主要受现地主应力大小与方向及塑性区形成两项因素控制,依此机制可解释主隧道交叉段于联络横坑开挖时之变形行为。

A numerical model which was verified previously by field measurements was used in this study to investigate the deformation behavior of tunnel intersection during the excavation of connection adit. Parametric studies were conducted by using different cover depths, rock mass strengths, and lateral stress coefficients. Results of the numerical analyses show that the deformation mechanism of the intersection during the connection adit excavation depends on plastic zone distribution and the direction and the magnitude of the principal stress. For elastic model, the deformation of the main tunnel on the connection adit side would move towards the excavation direction of the connection adit. For elastoplastic model, the deformation behavior of the main tunnel would be influenced by the magnitude and orientation of the principal stress. According to the results of this paper, the deformation mechanism of tunnel intersection is influenced both by the release of the lateral constraint due to connection adit excavation and the loading changes due to the plastic zone.