# Soldier Pile Calculator

Pile count, concrete and reinforcement - with jet-grout cut-off, a full retaining line.

- Page: https://jianzhujisuan.com/en/soldier-pile
- Category: Construction (https://jianzhujisuan.com/en/c/construction)
- Chinese version: https://jianzhujisuan.com/zh/soldier-pile.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Wall length 60 m, Pile diameter 800 mm, Pile length 18 m, Pile spacing 1.2 m): **Number of piles 51 bars**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Wall length | number | 60 | m |  |
| Pile diameter | select | 800 mm | — |  |
| Pile length | number | 18 | m |  |
| Pile spacing | number | 1.2 | m | Usually 1.2-1.5× diameter; interlock where watertight |

## Formula

- **Pile count**: n = ⌊length ÷ spacing⌋ + 1
- **Per pile**: V₁ = π×(d/2)² × length
- **Concrete**: V = n × V₁
- **Reinforcement**: ≈ concrete × 90 kg/m³

## Worked example

A 60 m wall, 800 mm piles, 18 m long at 1.2 m spacing: 51 piles, 9.05 m³ each, 461.6 m³ of concrete and about 41.5 t of reinforcement.

## Questions

### How wide can soldier pile spacing be?

Two things cap it: soil arching between piles (too wide and soil squeezes through the gaps) and the cut-off (wider gaps are harder for jet grout to seal). Common practice is 1.2-1.5× diameter, so 800 mm piles at 1.0-1.2 m. Soft ground, sand and a high water table call for tighter spacing, or interlocking (tangent) or double-row piles.

### How is pile length set?

Excavation depth plus embedment, set by stability. The toe must penetrate stable ground below formation, usually 0.3-1.0 times the excavation depth (more in soft ground), and satisfy overall stability and base heave checks. So length is dig depth plus embedment, not just to formation. Too long is wasted, too short kicks out at the toe - the design must set it from soil parameters.

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