The Role of the Pipe Arch

The role of the pipe arch in the pre-supporting before tunnel excavation primarily includes the following two aspects:

(1) Enhance the strength of surrounding rock soil, increase the soil bearing capacity of the excavation line arch, reinforce the tunnel surrounding rock, and ensure the safety of tunnel construction. The role of the pipe shed is even more pronounced when the tunnel passes through areas such as fractured zones, loose zones, weak strata, water inrush, and sand inrush.

(2) Ground settlement control. When tunnels pass beneath existing lines and structures, the primary role of the pipe shed is to control ground subsidence, preventing damage to the existing lines, buildings, and structures due to tunnel excavation. This ensures the safety of the existing lines, buildings, and structures, as well as the smooth progress of tunnel excavation. In such cases, the diameter of the steel pipes in the pipe shed may be too large (φ299).

Section 2: Working Principle of the Pipeline Shelter

The working principle of the pipe canopy primarily involves two aspects:

(1) Utilizing the simply supported beam principle; due to the larger diameter and stiffness of the pipe shed, they are also arranged more densely. At this point, the pipe shed acts as a simply supported beam, obstructing the release of stress from the surrounding rock during the tunnel excavation process.

(2) By utilizing the fluidity of cement slurry and the cracks or pores in the surrounding rock, the injected cement slurry can combine with the soil to form a concrete-like solid, thereby reinforcing the surrounding rock and soil. It also serves as a waterstop for strata with low water content.