Blast Design Workflow
BlastCAD provides three dedicated blast design wizards covering the major underground and surface mining blast types. Each wizard guides you through a structured workflow to generate production-ready drill patterns.
Choosing the Right Workflow
| Blast Type | Wizard | Where to Find |
|---|---|---|
| Underground ring blast (longhole stoping, sublevel caving) | Ring Wizard | Canvas Toolbar → Ring Design |
| Open-pit bench blast | Bench Blast Wizard | Canvas Toolbar → Bench Blast |
| Underground tunnel / development face | Tunnel Blast Wizard | Canvas Toolbar → Tunnel Blast |
All three wizards create HoleData entries in the project, which are then available for charging, delay assignment, analytics, and export.
Underground Ring Design (Ring Wizard)
The Ring Wizard guides engineers through placing ring planes along a drive baseline, then populating those rings with drill holes constrained by the rig database.
Workflow Overview
Setup & Place Rings
Select DTM surfaces, choose baseline polyline, configure rig and burden. Place rings along the baseline.
Drill Section Editor
Design hole geometry within each ring plane using templates or manual placement.
Open the Ring Wizard via Canvas Toolbar → Ring Design. A step-by-step panel appears in the left sidebar.
See Ring Workflow for the complete walkthrough.
Open-Pit Bench Blast (Bench Blast Wizard)
The Bench Blast Wizard generates surface blast patterns for open-pit bench blasting. Access it from Canvas Toolbar → Bench Blast.
Step 1 — Bench Parameters
Configure the key design parameters:
| Parameter | Description |
|---|---|
| Bench Height (m) | Vertical height from crest to floor. Used to compute hole depth (= bench height + subdrill). |
| Subdrill (m) | Extra depth below bench floor for fracture continuity. Typically 0.3–0.5 × burden. |
| Hole Diameter (mm) | Drill bit diameter. Select from your rig database or enter manually. |
| Burden (m) | Distance from front row of holes to the free face. |
| Spacing (m) | Distance between holes in the same row. Often 1.15 × burden. |
| Dip (°) | Drill angle from vertical. 0° = vertical, positive = toward face. Inclined holes produce better fragmentation and less backbreak. |
| Stagger (%) | Stagger offset between rows as a % of spacing. 50% = equilateral triangle pattern (recommended). 0% = square grid. |
| Row Count | Number of hole rows from the face. |
Step 2 — Area Definition
Two methods for defining the blast area:
Bounding Box (automatic)
- BlastCAD reads the current scene extents or asks you to click two corner points.
- Holes are generated to fill the entire bounding box at the configured burden/spacing.
From CAD Polyline
- Draw a closed polyline in the viewport defining the exact blast boundary.
- BlastCAD generates holes only inside that polygon, automatically handling irregular perimeters.
- The polyline must be a closed polygon (last point connected to first).
Step 3 — Generate & Adjust
Click Generate Pattern. BlastCAD creates all holes and adds them to the current project layer. You can:
- Individually move holes in the Hole Table
- Delete holes outside the desired zone
- Adjust the delay pattern via Auto Tie-Up
Underground Development Blast (Tunnel Wizard)
The Tunnel Wizard generates drill patterns for underground development faces — drives, crosscuts, raises, and production headings. Access it from Canvas Toolbar → Tunnel Blast.
Step 1 — Tunnel Shape
| Shape | Description |
|---|---|
| Horseshoe | Standard development drive profile. Flat floor, arched roof. |
| Circular | Circular cross-section (raises, shafts). |
| Rectangular | Box-shaped tunnel (e.g., ore passes, rooms). |
Set Width, Height (floor to crown), and Collar Elevation (world Z coordinate of the tunnel floor).
Step 2 — Cut Type
The cut is the central group of holes that creates the initial free face for the rest of the blast to relieve into.
| Cut Type | Geometry | Best For |
|---|---|---|
| Burn Cut | Parallel large-diameter reamer holes surrounded by tightly spaced production holes | Hard rock, high advance rates |
| Wedge Cut | V-shaped angled holes converging at the centre of the face | Moderate rock, older equipment |
| Fan Cut | Fan-shaped holes radiating from a central point | Soft rock, narrow headings |
Step 3 — Zone Layout
The tunnel pattern is organised into concentric zones working outward from the cut:
| Zone | Typical Function |
|---|---|
| Cut | Creates initial void / free face |
| Easers (1st ring) | Breaks rock to the cut cavity |
| Easers (2nd ring) | Expands the broken volume |
| Stoppers | Upper holes working to the roof |
| Contour / Perimeter | Perimeter holes defining the final excavation profile (pre-split or smooth blasting) |
| Lifters | Bottom holes working to the floor |
For each zone, configure:
- Number of holes in the zone
- Hole diameter
- Dip angle relative to the tunnel axis
Step 4 — Generate
Click Generate Pattern. BlastCAD:
- Distributes holes in each zone according to the geometry.
- Assigns ring labels (all holes share ring
FACE). - Adds holes to the project with correct collar/toe coordinates in world space.
After generation, assign delays using the Auto Tie-Up workflow or manually in the Hole Table.
Delay Assignment — Auto Tie-Up
Once holes are generated (by any wizard), assign detonation delays:
- Click Assign Delays in the top bar (or in the Canvas Toolbar).
- The Auto Tie-Up panel opens.
- Select the start hole (the hole that fires first — typically a cut hole or the hole closest to the free face).
- Choose a delay pattern:
| Pattern | Delay Propagation Rule |
|---|---|
| Chevron | Delays increase outward from the center of each ring. Center holes fire first, wingtip holes fire last. Creates a V-shaped firing sequence seen from above. |
| Zigzag | Alternate holes in each row fire at offset intervals, creating a staggered timing sequence. Reduces ground vibration by spreading energy release. |
- Set Hole Increment (ms) — the time step between adjacent holes in the same ring.
- Set Ring Increment (ms) — the time step between successive rings (overrides hole increment when moving to the next ring plane).
- The live preview table shows the resulting delay assignment for every ring before you apply it.
- Click Apply Tie-Up to write the delays to all holes.
- If the result is not as expected, click Undo to revert to the previous delays.
Blast Animation
Once delays are assigned, verify the firing sequence visually:
- The Blast Animation button appears in the Canvas Toolbar.
- Click it to open the animation playback.
- Each hole fires at its assigned delay — the mesh expands in an animated detonation pulse.
- Use the speed slider to slow down or speed up playback.
- Toggle Sound to add explosion audio feedback.
See Navigation & Viewport — Blast Animation for full controls.
Sections in this Chapter
- Ring Workflow — Detailed guide to each step of the ring design process.
- Hole Parameters — All hole data fields, their engineering meaning, and how they are calculated.