Level 4 Training – Experienced User

 

Welcome to Level 4 of the mXrap software training programme. You should now be pretty familiar with how mXrap works. In the previous levels you have learnt the most commonly used apps. No we will look at some advanced settings and go through the remainder of the apps relevant to your site. There might be some apps mentioned below that are not relevant to your site. You can go through the videos if you like, it will give you a sense of what else is available, but feel free to skip the apps that are not available.

 

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Global variables

 

Global variables are general settings that effect various calculations in mXrap. Probably the most common global variables to adjust are the magnitudes that you denote as “Large” and “Significant”.

 

 

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Local Magnitude settings

 

Local magnitude is a calculated (derived) parameter. Normally its either based on Seismic Energy, Moment/Potency, or a combination of both. This video shows where the local magnitude settings are located.

 

This blog post discusses some common questions raised regarding local magnitude settings.

 

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Mine coordinate orientation

 

There are some places in mXrap where the mine orientation must be specified for calculations. For example the plane fitting app needs to know the direction of north.

 

 

 

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Change event marker style

 

The default event local magnitude marker might not suit everyone. After all, a ML+1.0 might mean something completely different to you compared with the site next door. This video will run you through how to make a site specific event marker. There are a couple of other marker styles you can adjust too.

 

 

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Variable overrides

 

Similarly to marker styles, the default variables don’t suit everybody. The MT chart for example sets the magnitude threshold at M-1.0. This video shows you how to modify some variable defaults.

 

 

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Drag + Drop Series

 

You already know you can split the window and drag and drop charts and tables around the screen. You can also drag and drop series between different tools.

 

 

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Monitoring Setup

 

The Basic Seismic Monitoring application is intended for mine control room operators to monitor the latest seismicity and communicate event alerts and exclusion areas depending on site specific rules. This video goes through the process of setting up the monitoring window for your site.

This blog post is about the introduction of the monitoring app.

 

 

Rockburst Damage Potential

 

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RDP

 

This app is based on the Rockburst Damage Potential (RDP) system developed by Dan Heal (2010). This app provides an environment to edit the E1, E2, E3 and E4 components of RDP system as well as to display and interrogate these components, the Excavation Vulnerability Potential (EVP), the PPV factor and the RDP.

 

You can find more information about the RDP app in the following paper.

Heal, D., Hudyma, M. and Potvin, Y. (2006) Evaluating rockburst damage potential in underground mining. InGolden Rocks 2006, The 41st US Symposium on Rock Mechanics (USRMS) 2006 Jan 1. American Rock Mechanics Association.

 

Exercises

  1. Editing UCS
    1. Choose two different geotechnical zones and change the UCS values for them.
  2. Stress values
    1. Export minodes to be used in Map3D analysis
    2. Import map3D stress values back into RDP app
  3. Editing E2
    1. Edit the Ground support standard for minodes in the lower region of the mine
    2. Add a new support standard called GS01 and assign an E2 value
    3. Change the E2 value for the newly defined Standard
    4. Remove some of the applied Ground support standards as they are wrong and you would rather have nothing than the wrong value
  4. Editing E4
    1. Show a seismically active fault/dyke for your operation and change the E4 values accordingly.
  5. Plot the following results
    1. EVP
    2. RDP

 

 

Seismic-production Balance

 

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Seismic-production balance

 

The Seismic-Production Balance app focuses on investigating the link between seismicity and production, specifically the balance between the two. Adjustment of certain seismic parameters enables the user to view the Energy Balance chart and view the influence of increasing production volume on the energy in the system. In addition to Potency charts, the app also includes some other parameters plotted as a function of production volume for further analysis. These parameters include: Cumulative Number of Events vs Production Volume, Displacement vs Production Volume and Potency vs Production Volume.

 

Exercises

  1. Is the current slope of the CNE vs Production line steeper or shallower than normal?
    1. What about potency or displacement vs. production
  2. Plot the Balance chart
    1. Adjust the magnitude indicator to show roughly 10 large events
    2. Adjust the potency conversion factor to make the balance line as close to 0 as possible without going over
    3. How does the current balance look? Close to 0? Far from 0?
    4. Note how the expected magnitude varies with balance.

 

 

Large Event Analysis

 

The large event analysis app provides the user with an easy and quick first assessment of the distribution of strong ground motion at excavations for a given event. Plots are given for a uniform and a double couple shear mechanism. Users can choose events from the database performing “what-if” analyses by overriding some or all the parameters. The app is limited to a linear distance analysis using a given strong ground motion relationship and does not take into account any wave-medium and wave-excavation interaction.

Unfortunately we don’t have any videos for the Large Event Analysis or System Design apps. We will try and make some training videos for these soon but it is a good chance for you to try and learn an app without training wheels. Explore the app and try and complete the exercises below.

 

Exercises

  1. Plot the theoretical distribution of the max. ppv on the mine excavations FOR:
    1. Largest event
      1. Assume a uniform radiation pattern
    2. How sensitive is this plot to the magnitude?
      1. What if the magnitude was ML3?
      2. What if the magnitude was ML1?
  2. Plot the theoretical distribution of the max. ppv on the mine excavations assuming the radiation pattern for a double couple shear mechanism
    1. Assume slip was on a nearby fault or foliation/bedding/orebody plane
    2. What influence does the rake angle have on the resulting ppv distribution?

 

 

System Design

 

The seismic system design app provides tools to assess the system sensitivity in 3D space. The app uses the seismic database and sensor file for a chosen stable period to derive the Dx-mmin relationship. Where Dx is the distance to the Xth sensor, typically X = 5 mmin is the system sensitivity. This relationship is then used to plot the system sensitivity in 3D space for a given array of seismic sensors. A general indication of the location quality for different magnitudes is also provided based on given sensor arrays. The effect of losing or adding sensors in the array can be evaluated interactively.

Although further development was done since the publication of the following paper, it still provides a summary of the concepts used in this app: Wesseloo, J. (2011) Empirical methods for assessment of seismic system sensitivity, Transactions of the Institutions of Mining and Metallurgy: Section A, Mining Technology, vol. 120 (2), pp. 105–111.

 

Exercises

  1. Establish trend line
    1. Look at the “sensors hit” chart
      1. Establish a time period where the seismic system were constant
      2. Set this time period
    2. Set “X” to the min sensors that should be used
      1. Based on the sensors hit chart what should you use?
    3. Fit a mmin – Dx relationship
      1. What is the influence of
        1. “floor fraction”
        2. Min number of events
        3. Dx Upper
        4. Relative bin size
    4. Establish trend line
      1. What trend-line is being used?
      2. Commit your trend line parameters to disk
      3. Why commit to disk?
    5. Establish trend line
      1. Plot the system sensitivity assessment in space for the back analysis period
      2. Filter the volume to show the mmin < -1
      3. Use dynamic clipping to show a slice through the isos
  2.  Design
    1. Open System sensitivity assessment
      1. What trend line is used?
      2. What sensors are used in the assessment?
      3. Add/remove planned sensors to the assessment and see what the influence is
      4. Add a new sensor to the list and remove the one with the least influence
      5. What will you do to transfer the planned sensor to the sensors file once it is installed?
        1. There is an easier way than to add a line to the sensors table view and punch it in
      6. What would the influence be of losing a sensor or a box?
        1. Investigate this by excluding some of the existing sensors from the assessment
      7. Plot the CQI for
        1. ML-1
        2. ML1
      8. Plot the relative location error

 

 

Instrumentation

 

Convergence pins

 

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Convergence pins

 

The main focus of the app is to create a 3D (effectively 2D) plot of convergence pin readings. This is achieved through surface contours of interpolated values from the pin reading locations.

 

 

 

Extensometers

 

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Extensometers app

 

The app provides the tools import and evaluate various formats of extensometer data. Data is assessed over the life of the instrument and for a period of interest. Displacement is expressed as a cumulative value over the instrument length and per node values. Instruments are plotted in 3D with markers displaying displacement measurement along with nearby seismic events and blasts. Cumulative and Per node displacement values are charted over time and summarised in tables.

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Data import and quality

 

This video explains the data import process for the extensometer app and some quality control features.

 

 

Prism Monitoring

 

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Prism Monitoring

 

The Prism Monitoring app provides the tools to import and evaluate prism data which is routine used to monitor ground movements, for example, slopes in open pits or subsidence zones associated with caving. Prism data is assessed as displacement and rates in 3D, 2D, and X, Y and Z directions. Displacement and rate data is plotted in 3D as a vector and interpolated values on survey surfaces, charted over time, and summarised in tables. Data from period of interest can be selected for individual, multiple, or predefined zones of prisms. Additional analysis options include piecewise linear fitting to assess rates of deformation (Figure 3), persistent quality tags for excluding erroneous data, and plotting of rockfall data with respect to surveys and prism results.

 

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Data import and quality

 

This video explains the data import process for the prism monitoring app and some quality control features.

 

 

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Velocity and deformation

 

Additional analysis can be conducted using piecewise linear fitting to assess rates of deformation.

 

 

In-situ stress monitoring

 

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Stress Cells

 

Continual monitoring of in-situ stress are done by installing stress measurement devices like the CSIRO stress cell, and monitoring the measured changes over time. This app receives the strain measurement recorded by the stress measurement device and invert for the in-situ stress state. This allows for the analysis of changes in stress magnitude and orientation over time.

 

 

Caving

 

Cave draw height

 

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Cave estimation

 

In caving, determining the position of the cave front is difficult and several methods can be used to estimate its position. This app is one of those methods. It estimates the position of the cave front from the amount of rock drawn from each drawpoint. Based on an assumed bulk factor and draw area, one as able to estimate what the cave front might look at any point in time.

 

Fragmentation

 

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Fragmentation

 

This app analyses and displays caving fragmentation data. The particle size distributions for different drawbells or drawpoints for different dates can be viewed. Chosen particle size percentile values can be displayed in 3D for different dates and as a column representing the change over time.

 

Cave hydraulic radius

 

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Hydraulic radius app

 

Using the undercut blasting data, this app calculates the hydraulic radius (HR) of the undercut over time. The app provides functions to correlate the seismic response with the hydraulic radius.

 

 

 

If you are familiar with the content above and completed the exercises, congratulations! You have completed the Level 4 user training in mXrap and are an experienced user. You now know all the apps available at your site. The next training level will start to look behind the apps and into the inner workings of mXrap.

Start Level 5