Kirra provides seven vibration-focused models in the analytics dialog (plus separate damage/energy models below), from empirical site laws through VOD-ramp Temporal Lifecycle to full time-domain Blair Heavy. This page summarises each model and its key parameters.
For which models can show wave interference (constructive/destructive), see the table in Blast Analytics Overview (section Wave collision and interference).
Screenshot coming soon – PPV overlay on blast pattern
The simplest model. Computes Peak Particle Velocity using the empirical scaled-distance law.
Formula: PPV = K x (D / Q^n)^(-b)
| Parameter | Default | Description |
|---|---|---|
| K | 1140 | Site constant (calibrated from blast monitoring) |
| b | 1.6 | Site exponent (attenuation slope, typical 1.5-2.0) |
| n | 0.5 | Charge weight exponent (0.5 = square-root scaling) |
| Cutoff Distance | 1.0 m | Minimum distance to avoid singularity |
| Target PPV | 0 mm/s | Black contour line at this value (0 = disabled) |
MIC Bin Mode: When the Time Window parameter is set to a value greater than 0, the model switches to Maximum Instantaneous Charge bin mode. Fixed-width bins group holes by firing time, and each bin’s combined charge mass is used instead of individual hole masses. Essential for accurate near-field PPV prediction.
Per-deck variant of the scaled-distance site law. Instead of treating each hole as a single point charge, this model evaluates PPV separately for each charged deck using that deck’s own mass and position (top / centre / base sampling in the shader).
Superposition: Like PPV Site Law, this path does not synthesise time-domain waveforms. It does not display constructive/destructive interference — it is not a coherent phase model. For coherent superposition, use Blair Heavy.
Advantages over PPV Site Law:
Contrast with Temporal Lifecycle: PPV Per-Deck does not propagate a detonation front along the column at VOD from the primer. If you need burn-front timing along the explosive column, use Temporal Lifecycle or Blair Heavy.
Same parameters as PPV Site Law, with an additional max display distance setting.
Physics-based model implementing Heelan’s (1953) analytical solution for radiation from a cylindrical charge. Divides each charge column into discrete elements and computes P-wave and SV-wave contributions with directional radiation patterns.
| Parameter | Default | Description |
|---|---|---|
| Rock Density | 2700 kg/m3 | Rock mass density |
| P-Wave Velocity | 4500 m/s | From seismic testing |
| S-Wave Velocity | 2600 m/s | From seismic testing |
| VOD | 5500 m/s | Fallback when no product VOD assigned |
| Elements | 20 | Charge discretisation count (max 64) |
| Q_p | 50 | P-wave attenuation factor (0 = elastic) |
| Q_s | 30 | S-wave attenuation factor (0 = elastic) |
Features:
Bridges the empirical site law with Heelan’s directional radiation patterns. Each element’s waveform peak is given by the site law constants K and b, while retaining directional behaviour from the Heelan model. Developed by Blair & Minchinton (2006).
Same parameters as PPV Site Law plus rock velocity parameters from Heelan Original.
Best for: Compliance prediction with directional accuracy at sites with calibrated K and b values.
Same energy summation approach as Scaled Heelan but uses Blair’s (2015) improved radiation patterns:
| Parameter | Default | Description |
|---|---|---|
| K | 1140 | Site constant |
| B | 1.6 | Site exponent |
| P-Wave Velocity | 4500 m/s | |
| Poisson’s Ratio | 0.25 | S-wave velocity derived from this |
| VOD | 5500 m/s | Fallback |
temporal_lifecycle)GPU model that treats detonation as a continuous ramp propagating from the primer along the charge column at VOD, rather than firing each deck as a simultaneous point source. At an observation point, P-wave arrivals from positions along the charge occur at different times (Mach-cone style behaviour when VOD exceeds rock P-wave speed).
Per-primer data: The shader uses a primer texture (uPrimerData) together with the deck texture. Each primer row carries deck index, primer fraction along that deck (top toward base), delay, and VOD, so multiple primers per hole can drive separate burn fronts. Deck row 2 packs primerFrac in the fractional part of the auxiliary channel for primer-aware ordering (see TemporalLifeCycleModel.js in the Kirra source).
Superposition: Contributions are still combined with incoherent (RMS) energy summation — same limitation as Scaled Heelan family on GPU: no coherent interference fringes. The model shows when energy arrives from the moving detonation front under uDisplayTime filtering, not wave cancellation.
Time Interaction: Supported — use Interact to animate firing time and watch the sequence evolve.
Full coherent time-domain waveform superposition model — the only analytics path that superposes waveforms with phase so that constructive and destructive interference can appear in the result. Runs on CPU via Web Workers (not GPU), computing PPV on a 3D voxel grid for truly volumetric output. Uses multiple workers based on your computer’s processor count.
| Parameter | Default | Description |
|---|---|---|
| K | 700 | Site constant (gamma x SITEK) |
| B | 1.5 | Site exponent |
| Charge Exponent | 0.7 | |
| Gamma | 0.0455 | Waveform scaling factor |
| Poisson’s Ratio | 0.25 | |
| Rock Density | 2500 kg/m3 | |
| P-Wave Velocity | 6000 m/s | |
| VOD | 5279 m/s | Fallback |
| Bandwidth | 10000 | Hz-like waveform parameter |
| Pulse Order | 6 | Waveform shape parameter |
| Elements per Deck | 12 |
Key differences from other models:
Computes cumulative damage index based on PPV threshold for crack initiation.
| Parameter | Default | Description |
|---|---|---|
| Rock UCS | 120 MPa | Unconfined Compressive Strength |
| Rock Tensile | 12 MPa | Typically UCS/10 |
| PPV Critical | 700 mm/s | Threshold for new crack initiation |
| K_hp | 700 | Holmberg-Persson site constant |
| Alpha | 0.8 | Charge length exponent |
| Beta | 1.4 | Distance exponent |
Output: Damage Index (0-1). Values approaching 1.0 indicate significant damage.
Combines intact rock fracture with joint-controlled failure. Evaluates both dynamic stress against tensile strength and Mohr-Coulomb failure on joints.
Additional parameters: joint set angle, joint cohesion, joint friction angle.
Output: Damage Ratio (values > 1.0 = failure).
Computes borehole wall pressure and its attenuation with distance from each charged deck.
Formula: P(R) = Pb x (a / R)^alpha
Where Pb = rho_e x VOD^2 / 8 (borehole wall pressure).
Output: MPa. Best for near-field wall damage assessment and presplit design.
Per-deck powder factor analysis. Each charged deck contributes its mass within a spherical volume at the observation distance.
Output: kg/m3 on a log scale.