某地铁横通道掌子面失稳原因分析

Instability Causes Analysis of the Tunnel Face of a Subway Cross Passage

为研究小导管支护下隧道掌子面的稳定情况,结合小导管受力特点,基于Winkler地基模型得到的地基反力,建立掌子面稳定性分析模型,将地基反力作用于掌子面上部,通过刚体极限平衡理论,推导掌子面稳定安全系数。结合某工程实例,分析有无小导管下掌子面的稳定性,并讨论掌子面前方小导管长度对掌子面稳定性的影响。结果表明,当隧道围岩由中风化变为强风化板岩时,施工过程中掌子面失稳,验证了计算方法的可靠性;掌子面稳定性系数随小导管长度的增加先增大后趋于平稳。

In order to study the stability of tunnel face supported by small pipe, combined with the stress characteristics of small pipe, based on the foundation reaction force obtained by Winkler foundation model, the stability analysis model of tunnel face is established, and the foundation reaction force is applied to the upper part of tunnel face. Based on the rigid body limit equilibrium theory, the stability safety factor of tunnel face is derived.Combined with an engineering example, the stability of the tunnel face is analyzed under the with or without small pipe, and the effect of the length of small pipe in front of the tunnel face on the stability of the tunnel face is discussed.The results show that when the surrounding rock of the tunnel changes from moderately weathered to strongly weathered slate, the tunnel face is unstable in the construction process, which proves the reliability of the calculation method. The stability safety factor of the tunnel face increases firstly and then tends to be stable with the increase of the length of small pipe.