Kinematic possibilities
Combine applicable outcrops from the current project. All selected structural measurements are paired, including across outcrops. Results screen orientations only; persistence and connections are left to detailed analysis.
One friction angle applies to all selected planes. Lateral limits apply to planar sliding and flexural toppling. Exact boundary cases are excluded. No factor of safety or failure probability is calculated.
Circles are poles perpendicular to measured planes. Diamonds represent the trend/plunge of intersection lines, not connecting lines between poles. The highlighted mode uses red rings for critical poles or red diamonds for critical wedge intersections. Set colors remain visible underneath. Black is the slope great circle; orange dashed lines show friction/slip limits. Pale red shading is the selected mode’s critical region.
Lower hemisphere, equal area. Plot and record list show up to 1,000 examples per mode; totals include all tests. Download includes inputs, source measurements, counts and the same capped examples. Results are held in memory until inputs change or this tab is reopened; download to retain them.
Methods and current scope
This first version evaluates planar daylighting and friction, two-plane wedge sliding along intersections, and flexural toppling using the slope-minus-friction slip limit. Direct toppling and wedge sliding on a single bounding plane are not yet evaluated. This is not a complete DIPS replacement.
Method references: Planar, Wedge, Flexural toppling.
Outcrop notebook
Project details
Fields follow the project header on the discontinuity field sheet. Magnetic declination is also used by the browser sensor mode.
Active outcrop
This is the parent record for structural sets and discontinuity observations.
RMR 1989: choose a description for each rating. Strength descriptions follow Marinos & Hoek (2000), Table 1; the remaining ratings follow Bieniawski (1989), as reproduced in Hoek's Rock Mass Classification, Table 4. GSI and RMR are different systems. Lengths below are in feet; UCS is pressure, expressed in MPa.
Measured values are optional and stored separately; selecting a range does not invent an exact measurement. Choose the matching rating when entering a measurement. All five base ratings are required; orientation is optional and must be assessed relative to the intended excavation.
Spacing boundaries are rounded conversions to feet. At a shared boundary, choose the lower rating. Overall condition categories include aperture, weathering, continuity and infill together; do not rate surface roughness alone. Orientation choices identify slopes, tunnels/mines or foundations; they are not a slope stability calculation.
RMR reference, Table 4 (online)
Attach a photographed field sketch or image. Add captions below.
No outcrop selected
Measurement population
Contact orientation
Hold the back of the phone flush to the rock. For steep surfaces (70–90°), rotate the phone sideways within the plane so its top points across the face, not straight up. Near vertical, opposite dip directions can represent nearly the same plane; check the strike line. Browser compass heading is magnetic; the active project's declination is applied when entered.
Compass / verified measurement
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New discontinuity
Field names mirror the uploaded “Rock Slope Evaluation: Ground-Level Discontinuity Data Sheet.”
Legacy JCS(R) values are retained verbatim. They are not treated as compressive strength or used in calculations.
Barton–Bandis joint characterization
Record the roughness profile in the expected shear direction, joint-wall strength, friction basis, and test sources. Lengths are feet; stresses and strengths are psi. JRC and rebound numbers are dimensionless.
Barton–Bandis field reference
JRC: compare the measured profile in the expected shear direction with the Barton–Choubey reference profiles (bands 0–2 through 18–20). Select a supported calculation value from 0–20; the app does not silently choose a midpoint. Profile length matters. Use “Enter exact value” for a decimal estimate or test result.
JCS: joint-wall compressive strength, not a rebound number or automatically the intact-rock UCS. Enter psi from a documented test or suitable correlation. The hammer type, orientation, surface condition and calibration belong in the record.
Friction: select the angle supported by your test or estimate, and identify residual versus basic friction. A dropdown number is not a recommended default. Record the source and assumptions; roughness alone does not determine friction.
Scale and stress: L₀ and Lₙ are lengths in feet. JCS and effective normal stress use psi. Apply scale correction only once. Effective normal stress is total normal stress minus water pressure. Record externally calculated stresses or clearly identify an assumed sensitivity range.
References: Hoek, Practical Rock Engineering — Chapter 4: Shear Strength of Discontinuities (JRC profiles, JCS and scale corrections); Rocscience: joint properties, Barton–Bandis criterion and friction basis. Based on Barton (1973, 1976), Barton & Choubey (1977), and Barton & Bandis (1982). Links require internet; this field guidance is available offline.
Save discontinuity retains all inputs and a recalculated result in the record. Backups, GIS properties and the discontinuity CSV include these fields. Partial observations can be saved without a strength result.
Calculation assumptions and reference
τ = σ′n tan[φ + JRC log₁₀(JCS/σ′n)]. Use residual friction for the Barton–Choubey formulation; basic friction is an explicit alternative for fresh, unweathered surfaces. Use an independently supported JCS value. Hammer readings are summarized only: hammer type, orientation, calibration, moisture and the chosen correlation must be documented before estimating strength.
Optional scale correction: JRCₙ = JRC₀(Lₙ/L₀)^(−0.02 JRC₀); JCSₙ = JCS₀(Lₙ/L₀)^(−0.03 JRC₀). Use compatible reference scales and do not correct already scaled values twice. No strength is calculated for nonpositive effective stress, stress above JCS, or an apparent peak angle above 70°. Infill-dominated surfaces need another model. These outputs are not a factor of safety or a constant friction angle for kinematics.
Hoek: Shear strength of discontinuities, Chapter 4Field display
End-of-day review
Confirm only after checking the file in Files or Downloads. Slope assessments have a separate backup in Slope rating.
Data safety & status
No project selected
CSV files include project and outcrop identifiers so the tables can be joined later in Excel, GIS, Leapfrog, or a database.
All projects on this device
Current v1 backups and legacy v0.2/v0.3 JSON backups are accepted. Legacy unlinked observations are preserved under an imported “UNASSIGNED” outcrop.
Project packages always merge by record ID and cannot replace unrelated projects.
Erase local field database
Export a full backup first. This removes projects, outcrops, structural sets, measurements, and discontinuity records from this browser.
The data-collection and manual-entry portions of this application are functional offline. Browser-derived strike/dip remains explicitly experimental until checked against known planes and a trusted compass. See FIELD_VALIDATION.md in the download package.
Slope hazard rating
Standalone calculator based on the supplied USMP rating sheet. It does not read or change projects, outcrops, measurements, or backups.