Hiley Formula calculator for pile foundation

Hiley Formula - Pile Driving Calculator

Units: weight = tonne, drop height h = mm, c = mm, Ru in tonne (same units as used in your image).

Working load (tonne) — used to compute Ru = 2 × working load

Or enter Ultimate driving resistance R_u (tonne)

Hammer weight W_h (tonne)

Pile weight W_p (tonne)

Hammer drop height h (mm)

Temporary compression (helmet+packing) c (mm)

Friction constant k (winch/other losses)

Coefficient of restitution e

Formula reference (Hiley): \( \displaystyle R_u = \frac{W_h\,h\,\eta}{S + \tfrac{1}{2}c} \). Rearranged for set per blow \(S\): \( \displaystyle S = \frac{W_h h \eta}{R_u} - \frac{c}{2} \).

🏗️ Hiley Formula – Pile Driving Calculator User Guide

📌 Introduction

This tool is used to estimate the set per blow (S) of a pile during driving using the Hiley formula. It helps evaluate pile capacity and driving efficiency based on hammer properties, pile characteristics, and energy losses.

💡 The calculator supports both:

• Working Load → Automatically converted to Ultimate Resistance
• Direct Ultimate Resistance input (R_u)

⚙️ Step 1: Input Load Parameters

• Working Load (tonne) – Used to compute ultimate resistance:

Ru = 2 × Working Load

• Ultimate Resistance R_u (tonne) – Direct input (optional)

💡 Use either Working Load OR R_u, depending on your data.

🔨 Step 2: Input Hammer & Pile Properties

• W_h – Hammer weight (tonne)
• W_p – Pile weight (tonne)
• h – Drop height of hammer (mm)

These values determine the driving energy applied to the pile.

🧱 Step 3: Input Loss & Interaction Parameters

• c – Temporary compression (helmet, cap, packing) in mm
• k – Friction/efficiency factor (typically 0.7–0.9)
• e – Coefficient of restitution (0 to 1)

💡 These parameters account for energy losses during pile driving.

▶️ Step 4: Run Calculation

• Compute (Working Load) → Uses R_u = 2 × Working Load
• Compute (R_u) → Uses directly entered ultimate resistance
• Toggle Steps → Shows detailed calculations

📐 Step 5: Formula Used

Hiley Equation:

Ru = (Wh · h · η) / (S + c/2)

Rearranged for set per blow (S):

S = (Wh · h · η / Ru) − c/2

Efficiency factor (η):

η = k × (Wh + e² Wp) / (Wh + Wp)

📊 Step 6: Output Results

The calculator provides:

• Ultimate resistance (R_u)
• Efficiency factor (η)
• Driving energy (W_h · h · η)
• Set per blow (S) in mm

💡 Smaller S → Higher resistance (hard driving) 💡 Larger S → Lower resistance (easy penetration)

📉 Step 7: Interpretation of Results

• Low S (e.g., < 5 mm) → Strong soil / high resistance
• Moderate S (5–15 mm) → Normal driving conditions
• High S (> 15 mm) → Weak soil / low resistance

⚠️ Input Validation Rules

• All inputs must be positive values
• Efficiency factor k should be between 0 and 1
• Restitution coefficient e should be between 0 and 1
• Drop height and compression must be realistic

⚠ Invalid inputs may produce unrealistic results.

📐 Engineering Significance

• Pile Driving Control → Ensures safe installation
• Energy Transfer → Evaluates hammer efficiency
• Capacity Estimation → Predicts pile resistance
• Quality Check → Detects driving issues

💡 Practical Tips

• Use realistic efficiency factor (k ≈ 0.75–0.85)
• Avoid excessive compression values
• Verify results with field observations
• Combine with dynamic/static pile testing