HDD Bore Profile Calculator
Calculates the required pull force along an HDD bore profile and compares it with the allowable force per DVGW GW 321.
Notice: This quick check is for orientation purposes only. The results do not replace a project-specific design. Dimensioning and approval are the responsibility of the responsible engineering office. All information without guarantee. Full Disclaimer
Application & Background
The HDD Bore Profile Calculator answers the central planning question: “Is the planned horizontal directional drilling feasible with the selected PE pipe?”
Unlike the Pull Force Calculator, which only calculates the allowable force (= What can the pipe withstand?), this tool additionally determines the required pull force along the bore profile — and compares both values.
Calculation Model
The tool uses the estimated radius method with a simplified 4-point profile. The force calculation is based on the Euler–Eytelwein equation (capstan/belt friction) and a geometric profile model:
Surface ──── Rollers ────╲ Entry (α₁)
╲
╲── Low point ─── Bottom (L₃) ─── Low point ──╱
╱ Exit (α₂)
╱── Surface
From the entry/exit angles and cover depth, the radii are estimated:
$$R_{in} = \frac{H}{\alpha_1^2} \qquad R_{ex} = \frac{H}{\alpha_2^2}$$
The force balance along the 4 segment points considers:
| Force Component | Formula (simplified) |
|---|---|
| Roller friction | $\mu_{ground} \cdot w_a \cdot g \cdot L_{roller}$ |
| Capstan effect (curves) | $e^{\mu \cdot \alpha}$ — belt friction against the bore wall |
| Buoyancy/Weight | $w_b \cdot g \cdot H$ — net submerged weight |
| Borehole friction | $\mu_{mud} \cdot |
The required pull force $F_{req}$ is the cumulative force at exit point T₄.
Utilization Rate
$$\text{Utilization} = \frac{F_{req}}{F_{allow}} \times 100,%$$
| Range | Assessment |
|---|---|
| ≤ 70 % | ✅ Green — comfortable safety margin |
| 70–100 % | ⚠️ Amber — feasible, monitor closely |
| > 100 % | 🔴 Red — pipe overloaded, adjust SDR or measures |
Sources & Standards
- DVGW GW 321 (10/2003) — Allowable tensile force for PE pipes during HDD installation, Annex A (normative)
- DIN EN 12889:2000-07 — Trenchless construction and testing of drains and sewers
- Euler–Eytelwein equation — Capstan/belt friction (basis for force calculation at bends)
- ASTT Guideline — Geometry recommendations, angles, cover depth
All data provided without warranty. Full disclaimer