Charge Design
Beta
A complete guide to building, visualizing, and validating explosive columns in BlastCAD.
Table of contents
- Activating Charge Mode
- Charge Segments
- Building a Charge Column
- Explosives Database
- Inert Materials
- Mass Calculation Summary
- Proximity Analysis (Burden Circles)
- Applying a Charge Design to Multiple Holes
Activating Charge Mode
Charge Mode is a specialized camera and UI state optimised for designing explosive columns. To activate it:
- Select a hole in the viewport or Explorer Panel.
- Click Charge in the Ring Workflow panel, or open the Charge Design tab in the Properties Panel.
- The camera locks orthogonally to the selected hole’s axis, providing a perfect side-on section view of the borehole.
In Charge Mode:
- The hole is rendered as a large 3D cylinder in the center of the viewport.
- All charge segments are displayed as stacked, colour-coded cylinders inside the hole body.
- Advanced polygon offset rendering eliminates z-fighting artifacts between segments.
- The Properties Panel switches to the Charge Inspector.
Charge Segments
A charge column is built from one or more segments stacked from toe to collar. Each segment has three properties:
| Property | Options | Description |
|---|---|---|
| Type | explosive, stemming, air_deck | Determines how mass and volume are calculated |
| Length | meters | Segment height within the hole |
| Material | From Explosives Database | Assigns density and colour |
Segment Types
Explosive — An energised column segment. The mass is calculated as:
\[m_{seg} = \pi \left(\frac{d}{2000}\right)^2 \times L_{seg} \times \rho_{exp}\]Where $d$ is hole diameter in mm, $L_{seg}$ is segment length in m, and $\rho_{exp}$ is the explosive density in kg/m³.
Stemming — An inert confinement material (typically drill cuttings or crushed stone). Renders as a grey segment. Does not contribute to explosive mass. Stemming is placed at the collar and sometimes between decks.
Air Deck — An empty void in the explosive column. Used to reduce the specific charge (kg/t) while maintaining confinement above and below the air gap. Renders as a translucent blue segment. Does not contribute to explosive mass.
Building a Charge Column
Manual Segment Entry
In the Charge Inspector panel:
- Click Add Segment.
- Set the segment type, length, and material.
- The segment appears at the toe end of the column by default.
- Drag segments to reorder them (or use the up/down arrows).
- Click the length field and type a new value — the column updates in real-time.
The collar stemming and toe stemming fields at the top of the inspector set stemming lengths applied automatically at the top and bottom of the explosive column.
Using a Charge Template
Charge Templates store pre-built segment sequences. To apply a template:
- Click Apply Template in the Charge Inspector.
- Select a template from the Charge Templates database.
- BlastCAD scales the template’s proportions to fit the current hole’s charged length.
Templates are particularly useful for standardized decked charges repeated across all holes of the same diameter and length.
Explosives Database
The material dropdown in each segment lists all explosive products in your project’s Explosives & Detonators database.
Explosive properties used in charge calculations:
| Property | Description |
|---|---|
| Density (kg/m³) | Used to compute explosive mass per segment |
| Type | bulk, packaged, detonator, or surface_delay |
| Color | Hex color used to render the segment in Charge Mode |
| RWS | Relative Weight Strength (vs. ANFO = 100). Used by the Kuz-Ram fragmentation model. |
| Nominal Delay (ms) | For delay-type detonators |
| Scatter (%) | Timing scatter percentage for detonation timing analysis |
See Explosives & Detonators for the full database management guide.
Inert Materials
Two material types are treated as inert (zero mass contribution):
| Material | Represented as | Use case |
|---|---|---|
| Stemming (Gravel) | Grey segment | Collar and inter-deck confinement |
| Air Deck | Translucent blue segment | Charge ratio reduction, wave reflection decoupling |
Mass Calculation Summary
The Charge Inspector displays a running summary at the bottom:
| Metric | Calculation |
|---|---|
| Charge Length (m) | Sum of explosive segment lengths |
| Stemming (collar, m) | Collar stemming segment length |
| Total Column (m) | Sum of all segments (should ≤ hole length) |
| Explosive Mass (kg) | Sum of mass across all explosive segments |
| Explosive Factor (kg/m) | Total mass ÷ hole length |
Unit check: BlastCAD displays all mass values in kilograms and lengths in metres regardless of the unit setting, to avoid confusion in mixed-unit environments.
Proximity Analysis (Burden Circles)
The Proximity Circle Editor is a critical QA tool for preventing underloading near free faces and preventing holes from being too close to each other.
Activating Proximity Circles
In the Charge Inspector, toggle Show Proximity Circles.
BlastCAD projects up to 5 concentric circles onto the active ring plane, all centered on the selected hole’s collar position. Each circle represents a specified radial distance — a visual burden gauge.
Configuring Circles
| Setting | Description |
|---|---|
| Circle count | 1 to 5 circles |
| Radii (m) | One radius per circle (e.g., 1.5, 2.0, 2.5, 3.0, 4.0 m) |
| Color | Each circle has an independent display color |
Interpretation:
- If adjacent hole collars fall inside the innermost circle, they may be too close — risk of sympathetic detonation or overloading.
- If the free face (drive boundary) falls outside the outermost circle, the hole may be underloaded for that section of the blast.
Distance Readout
Hover over any other hole in the ring section view while Proximity Circles are active — a dashed line appears from the active hole to the hovered hole, with the 3D distance annotated in the viewport.
Applying a Charge Design to Multiple Holes
Once a single hole is charged, you can propagate the design:
- In the Charge Inspector, click Apply to Ring — copies the charge column to all holes in the same ring.
- Click Apply to All — copies to every hole in the blast pattern.
- Use Primer Rules to apply initiation logic on top of the base charge design. See Primer Rules.
Mass is recalculated per hole based on each hole’s actual diameter and charged length — the proportions are preserved but the absolute values are scaled.