Zhuojin Pipe Fitting Co., LtdSteel Pipe Concrete Support Technology Application in Deep High-Stress Roadways
Literature Overview
This paper published in Modern Mining (2025, Vol. 41, Issue 10, pp. 182-186) presents a case study of steel pipe concrete (RPC) support technology applied to a deep high-stress roadway at Shihe Coal Mine, operated by Jinneng Holding Equipment Manufacturing Group. The research addresses the persistent challenge of roadway support in deep mining environments where traditional support methods have proven inadequate against the combined effects of high in-situ stress, large deformation, and rapid initial deformation rates.
Failure Analysis of Original Support System
The study begins with a systematic analysis of failure phenomena observed in the roadway under the original support conditions. The deep roadway exhibited the following characteristic failure modes typical of high-stress mining environments:
| Failure Characteristic | Description | Root Cause |
|---|---|---|
| Large deformation volume | Cumulative deformation exceeding support design capacity | Insufficient support stiffness and strength |
| High initial deformation rate | Rapid convergence within first days after excavation | High stress relief rate and weak surrounding rock |
| Roof and floor heave | Asymmetric deformation pattern | In-situ stress anisotropy |
| Rib spalling | Progressive failure from free face inward | Lack of confinement pressure |
| Support element failure | Bolt pull-out, steel arch deformation | Support strength exceeded load demand |
The failure analysis confirms that the original support system lacked the necessary load-bearing capacity and adaptability to accommodate the large deformations characteristic of deep high-stress roadways.
Optimized Support Design
The proposed solution employs steel pipe concrete (RPC) arch supports designed in a straight-wall semi-circular arch configuration with an inverted arch (reverse bottom arch). This design fully leverages the high load-bearing capacity and good adaptability of RPC support systems.
| Design Parameter | Specification | Design Basis |
|---|---|---|
| Support configuration | Straight-wall semi-circular arch + inverted arch | Matches roadway cross-section geometry |
| Steel pipe specification | High-strength structural steel pipe | Provides primary structural framework |
| Concrete fill | High-strength concrete (C40 or higher) | Fills voids and provides composite action |
| Inverted arch | Concrete-filled steel pipe at floor level | Prevents floor heave and provides lateral confinement |
| Load calculation method | Based on actual roadway cross-section and surrounding rock stress | Ensures adequate safety margin |
The load calculation demonstrated that the optimized support system provides a bearing capacity exceeding the required capacity for the deep high-stress roadway. The inverted arch component is particularly important as it addresses the floor heave problem that is often the primary failure mode in deep roadways.
Engineering Practice Considerations
From a pipe welding and fabrication perspective, the application of steel pipe concrete supports in mining roadways presents several practical considerations:
- The steel pipe arches must be fabricated with precise geometry to ensure proper fit with the roadway cross-section and to allow uniform concrete fill.
- Welding quality of the steel pipe arch segments is critical, as the welded joints represent potential weak points in the support structure.
- The connection between the steel pipe arch and the inverted arch must be designed to accommodate differential movement while maintaining structural integrity.
- Concrete placement inside the steel pipe arch requires careful attention to avoid voids that would compromise the composite action between steel and concrete.
Study Insights and Reflections
This research exemplifies the practical application of pipe fabrication technology in a non-traditional domain. The steel pipe concrete support system is essentially a composite structure that combines the tensile strength and ductility of steel pipe with the compressive strength and confinement effect of concrete. The design philosophy mirrors that of steel-reinforced concrete in civil engineering, adapted to the specific geometric and loading requirements of underground roadways.
The innovation lies in the combination of the semi-circular arch with the inverted arch configuration. Traditional roadway support designs often neglect the floor, treating it as a passive boundary. In deep high-stress roadways, however, the floor is an active structural element that must resist heave forces. The inverted arch provides this resistance while also improving the overall structural stability by creating a closed load path.
For pipe fabrication shops supplying steel pipe arches for mining applications, this research highlights the need for precise dimensional control, high-quality welding, and the ability to produce complex curved geometries. The tolerance requirements for pipe arch fabrication in this application are stringent, as dimensional deviations can compromise the fit with the roadway profile and the effectiveness of concrete confinement.