The high-strength grade of a driven pipe and the type of joint They are selected based on the anticipated thrusts, the driving length, the diameter, the depth, the geotechnical conditions, the soil-pipe friction, the curvature, the external pressure, the required watertightness, and the pipeline’s operating conditions. The pipe must withstand both temporary construction loads and permanent loads once installed.
In projects of pipe ramming, microtunneling in terrestrial and subway applications o infrastructure crossings, this decision should not be based solely on the diameter or the end use of the pipeline. It must also take into account how the pipe is driven into the ground, the stresses it is subjected to during installation, and the level of leak tightness the joint must ensure.
What must a driven pipe be able to withstand?
A driven pipe is installed in two distinct phases:
| Phase | Key Efforts | What is being verified |
|---|---|---|
| Execution | Longitudinal thrust, friction, point loads, deflections, curvature, and contact pressure | Axial resistance, joints, distribution rings, cracking, deformation, and driving capacity |
| Service | Soil loads, traffic, external water, internal pressure, durability, and watertightness | Structural strength, leak tightness, corrosion, abrasion, service life, and maintenance |
For this reason, a pipe that is suitable for hydraulic operation is not always sufficient for pile driving. It must be designed to withstand the stresses of installation without damaging the pipe, the joint, or the lining.
Factors Affecting the Durable Class
The resistance class is defined based on a combination of technical variables:
1. Expected maximum thrust
The driving force is one of the most important factors. It depends on the length of the section, external friction, lubrication, diameter, geotechnical conditions, depth, and alignment. If the expected driving force is high, a pipe with greater load-bearing capacity or the use of intermediate push stations.
2. Penetration and Friction Lengths
The longer the pipe, the greater the contact area between the pipe and the ground. This increases frictional forces and can affect the pipe’s axial strength, joint design, and lubrication system.
3. Pipe Diameter and Thickness
The outer diameter determines the contact area, thrust, stiffness, hydraulic capacity, and stability against external loads. The wall thickness affects the structural strength and the ability to withstand driving forces.
4. Depth and External Loads
The covering, the weight of the soil, and loads from traffic, railways, or nearby structures all affect the strength required throughout the pipeline's service life.
5. Geotechnical Engineering and the Water Table
Abrasive, heterogeneous terrain containing boulders, rock, sand, gravel, or water can increase thrust forces, wear, external pressure, and sealing requirements.
6. Curvature and Guidance Tolerances
If the route includes a curve, the pipe and joint must be able to accommodate controlled angular deflections without losing their load-bearing capacity or watertightness.
7. End Use of the Pipeline
Sewage systems, water supply systems, drainage systems, outfalls, water intake structures, industrial pipelines, or accessible tunnels may require different criteria regarding watertightness, internal pressure, durability, chemical resistance, or maintenance.
How to Select the Type of Joint
The joint must ensure alignment, force transmission, leak tightness, and compatibility with the driving process. Its design depends on the pipe material, diameter, pressure, bend radius, tolerances, and service requirements.
| Criteria Type | What Is Reviewed | Impact on the board |
|---|---|---|
| Water Tightness | Internal pressure, external pressure, and water table | Define elastomers, geometry, and sealing system |
| Driving Force | Axial load transmitted between pipes | Conditions distribution rings and contact surfaces |
| Curvature | Permissible angular deviation between pipes | Requires joints compatible with the intended radius |
| Durability | Chemical environments, seawater, wastewater, or corrosive soils | Materials, Coatings, and Protection |
| Tolerances | Alignment, Manufacturing, and Assembly | It affects performance during planting and operation |
| Maintenance | Accessibility and End Use | It may require inspection, repairability, or greater durability |
In driven pipes, it is common to use joint systems with sealing elements and surfaces designed to distribute thrust evenly. When the forces are high, load-distribution rings or equivalent solutions are used to prevent load concentrations and damage to the pipe ends.
Role of Load-Distribution Rings
The distribution rings They help transfer thrust between pipes more evenly. Their function is to reduce stress concentrations, compensate for small tolerances, and protect the pipe ends during driving.
They are particularly relevant when the following conditions exist:
- High thrust.
- Long stretches.
- Large diameters.
- Curvature.
- Strict tolerances.
- Pipes made of reinforced concrete, FRP, steel, or other materials with specific contact requirements.
- Risk of eccentric loads or misalignments.
The selection of the ring must be coordinated with the pipe manufacturer, the project engineering team, and the driving procedure.
Common Mistakes to Avoid
When selecting pipes and joints, you should avoid:
- Select the pipe based solely on its hydraulic diameter.
- Failure to verify the maximum driving forces.
- Do not take friction or lubrication into account.
- Ignore permissible curvatures or deviations.
- Do not check the external pressure based on the water table.
- Using seals that are not compatible with the operating pressure.
- Failure to provide adequate distribution rings.
- Underestimating traffic, rail, or building loads.
- Failure to coordinate the type of soil, the excavation method, and the excavation process.
- Do not test durability against chemical exposure, abrasion, or seawater.
What information does Eurohinca need to review it?
To determine the strength class and joint type, please provide the following:
- Expected inner and outer diameters.
- Pipe material.
- Drive-in length.
- Depth and coverage.
- Plan and elevation drawings.
- Radius of curvature, if any.
- Geotechnics and water table.
- External loads.
- Internal and external pressure.
- End use of the pipeline.
- Required service life.
- Leak-tightness requirements.
- Maximum allowable thrust per tube.
- Proposed joint system.
- The Need for Intermediate Stations.
- Durability and environmental conditions.
The selection must be coordinated with the technical assistance and engineering for trenchless construction sites, the manufacturer of the piping and the overall design of the wells, the tunnel boring machine, and the driving procedure.
Minimum checklist for selecting pipes and fittings: diameter, material, driving length, design thrust, allowable thrust, friction, lubrication, geotechnical engineering, water table, depth, external loads, internal pressure, external pressure, curvature, joint, distribution ring, watertightness, durability, intermediate stations, and excavation method.
Request a Technical review of load-bearing class, driving forces, and joint type before finalizing the piping design or preparing the technical and commercial proposal.
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