Structural Characteristics
Tunnel steel perforated pipes are manufactured using seamless steel pipes or straight-seam steel pipes as the base material. Grouting perforations (typically with a diameter ranging from 8mm to 12mm) are fabricated on the pipe wall at pre-designed intervals, with hole patterns available in circular or quincunx (plum blossom) configurations. The pipe ends may be processed into a tapered shape (to facilitate penetration into rock formations) or equipped with threaded connections (to enable secure attachment to grouting equipment). For select products, a filter screen is installed on the exterior of the perforations to mitigate grout leakage and prevent hole blockage caused by sand and gravel particles during the grouting operation.
2. Core Functions
As a critical component of tunnel advance support systems, the product is primarily utilized in the advance small-diameter pipe grouting support technique: Prior to tunnel excavation, the steel perforated pipes are driven into the front-line surrounding rock along the contour of the tunnel arch. Cement-based grout, chemical grouting agents, and other specialized materials are injected into the surrounding rock mass through the perforations in the pipe body. The injected grout then diffuses and solidifies within the fractures of the surrounding rock, forming a "reinforcement ring" that effectively restricts surrounding rock deformation and mitigates risks such as collapse and water ingress during the excavation process.
3. Typical Application Scenarios
Applicable to tunnel construction projects in weak and fractured surrounding rock formations (e.g., sand layers, fault fracture zones), shallow-buried tunnel sections, or water-rich geological strata;
Commonly employed in excavation support for highway tunnels, railway tunnels, and metro interval tunnels, with extensive application particularly in complex geological conditions involving Class V and Class VI surrounding rocks;
Also suitable for reinforcement works following tunnel collapse incidents, as well as for the remediation of defects and deterioration in existing tunnel structures