Tutorial 06 Joint Spacing RQD Frequency

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Tutorial 6 Joint Spacing Analysis

True joint spacing RQD analysis

Joint frequency

Core loss


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Dipsv.7.0Tutorial Manual Tutorial 6: Joint Spacing

Introduction

This tutorial will demonstrate how to use the Joint Spacing, RQD and Joint Frequency

analysis options, using one of the example files installed withDips.

Select File > Recent Folders > Examples Folder and open the Joint Spacing.dips7file. Youshould see the following:

The main features of this file are:

Six Linear traverses are defined (Analysis > Traverses).

The Distance Column is enabled and Distance measurements along each lineartraverse have been entered.

In addition, for convenience, four set windows defining four joint sets, have already been

added over the main pole concentrations on the stereonet.

NOTE: if the Set Windows do not exist (e.g. sets have been deleted), then add four set

windows to define sets similar to the stereonet shown above.

Distance Units

The Unitsfor the Distance Column are selected in Project Settings, either Metric (meters) or

Imperial (feet). In this case the Units are Metric (meters).

The Unitsapply to the Distance column and all related analyses (e.g. Joint Spacing, RQD,

Joint Frequency).

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Joint Spacing

The Joint Spacingoption will convert distance measurements along a linear or borehole

traverse, into true (perpendicular) spacings between adjacent joints belonging to the same

joint set.

The following figure illustrates the geometry in 2D; the actual calculation accounts for the 3-

dimensional orientations of the planes with respect to the traverse line.

The Joint Spacing option is only enabled if THREE criteria are met:

1.

You must have at least one (or more) joint sets defined, using the options available

for creating sets (e.g. Add Set Window, Add Set Freehand).

2.

You must have at least one (or more) linear or borehole traverses defined (e.g.

Linear, Linear BH Oriented Core, Linear BH Televiewer, Curved BH Oriented Core,

Curved BH Televiewer).

3.

The Distance Column must be enabled (checkbox in Project Settings) and distance

values entered.

The Joint Spacing.dips7file that you have just opened, satisifes the above criteria, so we

will proceed to the joint spacing option.

1.

Select Joint Spacingfrom the Analysis menu.

2.

You will see the Joint Spacing dialog.

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3.

The dialog will indicate the sets and traverses currently defined, in this case 4 sets

and 6 traverses. You may only choose ONE set at a time, but you can select any or

all traverses.

4.

You can choose True or Apparent Spacing. Generally you will want to plot True

Spacing. Apparent Spacing is simply based on the raw measurements from the

Distance column.

5.

Lets use all of the default selections for now (i.e. True Spacing for Set 1 based on

measurements from All Traverses). Select OK.

You should see the following graph.

This plots the distribution of true joint spacing for Set 1, using data from all traverses. The

mean, standard deviation, min and max values are listed at the bottom of the plot.

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Once a joint spacing graph has been generated, for convenience, you can choose which Set

to plot from the sidebar Chart Settings. This will update the graph within the same view.

Choose different sets and view the resulting graphs.

If you wish to plot data using selected traverses, then you will have to return to the Joint

Spacing option in the Analysis menu. For example, in the Joint Spacing dialog, select Set 4

and Traverses 3, 4 and 5. Select OK and generate a new plot.

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0

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0.32 0.63 0.93 1.23 1.53 1.83 2.14 2.44 2.74

Quantity

Spacing (m)

True Joint SpacingSet 4

Traverse 3, 4, 5

mean=0.638 s.d.=0.713 min=0.022 max=3.043

7

6

2 2

1 1

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Info Viewer Summary of Joint Spacing

The Info Viewerpresents a summary of joint spacing statistics for each traverse / set

combination, and for each set using all traverses, as shown below.

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RQD Analysis

Now lets demonstrate the RQD Analysisoption.

TheRQD Analysisoption allows you to calculate the Rock Quality Designation (%) calculated

from distance measurements recorded along a linear or borehole traverse. When adjacentdistance measurements between joints are less than or equal to 10 centimeters (metric) or

4 inches (imperial), that length is flagged as "poor quality". RQD is a measure of the

percentage of core length pieces which are greater than this cutoff value, relative to the

total measured interval.

In order to use the RQD Analysis option:

1.

You must have at least one (or more) linear or borehole traverses defined (e.g.

Linear, Linear BH Oriented Core, Linear BH Televiewer, Curved BH Oriented Core,

Curved BH Televiewer).

2.


values entered.

Select RQD Analysisfrom the Analysismenu. You will see the following dialog.

All currently defined traverses will be listed in the dialog. NOTE that Sets are not selected in

this dialog. The calculation of RQD is based on all joint measurements along individual

traverses, and does not require selection of Sets.

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We will use the default selections (Discrete Interval, 1 meter interval length). Select OK and

you should see the following graph for Traverse 1.

With the Discreteinterval option, each interval begins at the end of the previous interval.

Lets try the MovingInterval option, which moves the interval in overlapping increments.

This may help to better identify narrow transitions in RQD value.

Select RQD Analysis from the Analysis menu. Select the Moving Interval option, and use the

default interval and increment values. Select OK.

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RockQualityDesignation(%)

Distance (m)

RQD Analysis

Traverse 1

mean=84.333 s.d.=12.726 min=57.000 max=100.000

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You can also plot multiple traverses on the same RQD plot, this is left as an optional

exercise.

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RockQualityDesignation(%)

Distance (m)

RQD AnalysisTraverse 1

mean=83.918 s.d.=12.488 min=52.000 max=100.000

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Joint Frequency

The Joint Frequencyoption is very similar to the RQD option, and allows you to plot the

linear 1D frequency of joints along the length of each traverse.

In order to use the Joint Frequency option:

1.

You must have at least one (or more) linear or borehole traverses defined.

2.


values entered.

Select Joint Frequencyfrom the Analysismenu. You will see the following dialog.

All currently defined traverses will be listed in the dialog. We will use the default selections

(Discrete Interval, 1 meter interval length). Select OK and you should see the following

graph for Traverse 1.

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You can also apply the Terzaghi Weighting to the Joint Frequency. Select Joint Frequency,

and in the dialog select the Weighting checkbox. This will apply the Terzaghi weighting to

the joint count, and plot the weighted number of joints per meter, as shown below.

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Jointspermeter

Distance (m)

Joint Frequency Analysis

Traverse 1

mean=6.636 s.d.=2.422 min=3.000 max=11.000

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WeightedJointsperm

eter

Distance (m)

Joint Frequency Analysis

Traverse 1

mean=12.894 s.d.=6.267 min=6.483 max=27.999

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Core Loss

It should be noted that the Jointing Analysis options do not account for intervals of lost or

damaged core or unlogged core. It is assumed that distance readings are from continuous

measurement of intact core.

This has the following implications:

Joint Spacing for the Joint Spacing option, if there is a gap in the Distance

measurements, it is possible that an artificially large joint spacing value may be

recorded, if joints from a given set occur on either side of a gap.

RQD for the RQD option, a gap in distance measurements would be recorded as

RQD = 100, since no joints would be recorded, which would register as intact

core.

Joint Frequency for the Joint Frequency option, frequency would be recorded as

zero over a gap in the distance record.

In conclusion, there is currently no method of specifying lost/damaged/unlogged corelengths for the Jointing Analysis options, so this should be kept in mind when interpreting

results.

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Tutorial 06 Joint Spacing RQD Frequency

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