Overview
This document details Datarock’s product Joint Roughness Coefficient (JRC).
Literature
This product is based on the following literature:
Title | Author | Year |
The Shear Strength of Rock Joints in Theory and Practice | Barton & Choubey | 1976 |
A new method estimating the 2D Joint Roughness Coefficient for discontinuity surfaces in rock masses | Zhang et al | 2014 |
Dependent Models
The outputs of the following models are used:
Model Name | Model Type |
Fracture Detection and Classification | Object Detection |
Drillers Break | Object Detection |
Fracture Binary Mask | Instance Segmentation |
Data Processing
The following steps are taken to determine the JRC:
Take the output of the fracture detection model, “simple” classes only
Run a segmentation model to extract the fracture profile (or skeleton)
Fit polyline to left, middle and right of skeleton
Fit an ellipse to each of the polylines
Check for core neatness: plot each ellipse on stereonet, if tight fit, proceed to the next step. If not, discard this joint for measurement.
Straighten out profile of ellipse, fracture profile interface
Calculate the JRC_median, JRC_lower_bound, JRC_upper_bound for each. This provides a score from 0-20.
Calculate average value across each interval.
Product Configuration Options
There are no configuration aspects to this product.
Output Intervals
Default interval length: 3.0m
Customisable interval available: No
User Data
Not currently able to upload to the platform.
Data Output
Results from this product is delivered in a batch nature.
Integration of the required technologies into Datarock production is ongoing.
The available CSV files include the following:
ProjectID_JRC_3m.csv
File Header | Description |
hole_id | Customer’s Hole ID |
depth_from | Start of interval |
depth_to | End of interval |
jrc_median | Median JRC. This is the suggested JRC |
jrc_lb_median | Lower Bound JRC, the statistical lower bound of the potential range of JRC values based on this method. |
jrc_ub_median | Upper Bound JRC, the statistical upper bound of the potential range of JRC values based on this method. |
timestamp | Time of model prediction |
version | A model version identifier |
Product Limitations
Limitations | Comments |
Measurement on “simple” fractures only | This method is limited to fractures that have one interface only, as we need a clear interface to measure. There may be intervals of broken rock that have different JRC values |
Analysing interface of fracture with edge of core | The nature of this method relies on a direct correlation between a fracture’s internal roughness and the appearance of its interface with the circumference of the core. A comparison with logged data across the customer’s range of lithology is required. |
Document Version
Version | Date | Author | Rationale |
0.1 | 7 Sep 2022 | S Johnson | Initial release |