Rock Bolt Spacing
Calculate square-grid tributary-load bolt-spacing screen; anchorage, wedges, corrosion and dynamics are not modeled or certified.
Description
A tributary-area bolt estimate compares reduced bolt capacity with factored load per unit area.
A tributary-area bolt estimate compares reduced bolt capacity with factored load per unit area. Taking a square root converts the permitted area to square-grid spacing.
The tool returns maximumTributaryAreaM2 (maximum tributary area m2); maximumSquareGridSpacingM (maximum square grid spacing m). Input measurements and model parameters are supplied by the caller; the tool computes the stated summary rather than acquiring those measurements.
When to use Rock Bolt Spacing
Use Rock Bolt Spacing when you already have designArealLoadKnPerM2, boltCapacityKn, capacityReductionFraction, designFactor and want maximumTributaryAreaM2, maximumSquareGridSpacingM. This is useful for checking a supplied calculation, documenting a measurement convention, or comparing observations prepared on the same basis.
How to use Rock Bolt Spacing and understand its results
- Enter designArealLoadKnPerM2, boltCapacityKn, capacityReductionFraction, designFactor using the field table below. Match the units, ordering and data boundaries described in the calculation.
- Run the tool after checking the stated bounds and matching paired observations or categories. A malformed request gives a tool error rather than a usable measurement.
- Read maximumTributaryAreaM2, maximumSquareGridSpacingM. Use the calculation and interpretation below to distinguish amounts, ratios, signs and decision flags where applicable.
- Review the supplied parameters and assumptions before using the result in a report or comparing it with another observation.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| designArealLoadKnPerM2 | Design areal load kn per m2 | number | Required |
| boltCapacityKn | Bolt capacity kn | number | Required |
| capacityReductionFraction | Capacity reduction fraction | number | Required |
| designFactor | Design factor | number | Required |
Require positive load and capacity, reduction in (0,1] and factor at least one.
area = boltCapacity×capacityReduction/(arealLoad×designFactor); spacing = sqrt(area) The symbols refer to the supplied quantities or generated values described above; unit conversions and comparison boundaries follow the stated implementation.
{
"input": {
"designArealLoadKnPerM2": 25,
"boltCapacityKn": 100,
"capacityReductionFraction": 0.5,
"designFactor": 2
},
"output": {
"maximumTributaryAreaM2": 1,
"maximumSquareGridSpacingM": 1
}
}Limitations and assumptions
The reduction factor is a retained-capacity multiplier. Anchorage, rock structure, load sharing and installation quality are not verified.
Numerical inputs must be finite. The tool checks its declared input shape and calculation constraints; those checks do not verify the quality, calibration or representativeness of the supplied observations.
Alternative or Complementary methods
Rock Bolt Length: Convert normal loosened-zone depth to bolt path and add caller anchorage/exposed allowances; no anchorage strength or support certification. Shotcrete Thickness: Screen ideal cylindrical shotcrete membrane thickness by pressure×radius/allowable stress; excludes bending, early-age strength, bond and buckling.
Methodological background: Pillar and Roof Span Design Guidelines for Underground Stone Mines.1
References
-
Pillar and Roof Span Design Guidelines for Underground Stone Mines — NIOSH, Centers for Disease Control and Prevention
Similar or alternative tools
- Rock Bolt Length
Convert normal loosened-zone depth to bolt path and add caller anchorage/exposed allowances; no anchorage strength or support certification.
- Shotcrete Thickness
Screen ideal cylindrical shotcrete membrane thickness by pressure×radius/allowable stress; excludes bending, early-age strength, bond and buckling.