CD法开挖隧道的顶板破坏机理分析

Analysis on Roof Failure Mechanism of Tunnel Excavation by CD Method

摘要:

在隧道修建过程中，CD法被广泛用于软弱围岩隧道和大断面隧道的修建。工程经验表明，CD法比全断面法更能够减少对隧道的扰动，降低顶部围岩塌陷的可能性，但目前对该经验的认识仍缺乏足够深入的了解。比如，CD法隧道顶部的塌陷机理，相比全断面法的定量优势比较等。为此，提出了一种预测CD法开挖隧道顶板破坏机理的运动学方法。推导了确定塌块形状的理论解。所提出的方法与全开挖方法进行了比较，证明了方法的合理性和CD法开挖的优越性。研究发现，与全断面开挖的结果相比，CD法开挖可以显著降低顶板坍塌的高度，提高顶板稳定性的安全系数。

Abstract:

In the process of tunnel construction, the central diaphragm (CD) method is widely used in the construction of weak surrounding rock tunnel and large cross-section tunnel. The engineering experience shows that the CD method can reduce the disturbance to the tunnel and the possibility of collapse of the top surrounding rock more than the full section method. However, there is still a lack of in-depth understanding of this experience. For example, the collapse mechanism of the tunnel top by CD method has the quantitative advantage compared with the full section method. Therefore, a kinematic method to predict the failure mechanism of the roof of tunnels excavated by CD method is proposed. The theoretical solution for determining the shape of collapse block is derived. Compared with the full excavation method, he proposed method proves the rationality of the method and the superiority of the CD method. The study shows that compared with the results of full-section excavation, CD method can significantly reduce the height of roof collapse and improve the safety factor of roof stability.