| 1. |
If you are getting errors and you're running an older operating system (Windows 9x/NT), then the reason is most likely to do with an incompatibility between Rocscience software and older operating system files. Rocscience software requires up to date operating system files in order to run properly. As a rule, Rocscience does NOT change or alter your operating system files and puts the onus on you to maintain up to date operating system software.
This problem can easily be fixed by downloading the latest Microsoft system file updater from our website: http://www.rocscience.com/downloads/general/vcredist.exe
Download the file by clicking on the above link. Save the vcredist.exe file to your computer and then run it. Follow the directions. Note: It is always advisable to make a backup before installing software that modifies system files.
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| 2. |
The following links will take you to a site where you can find information about the algorithm and the equations that are used in the calculation:
Verification Manual and Explanation of Algorithms used by RocFall
Dr. Hoek's chapter on rockfalls
Overview of RocFall
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| 3. |
For a list of helpful rock fall references, please follow this link:
Rock Fall References
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| 4. |
The current calculation engine behaves as if each rock is an extremely small circle traveling down the slope. It's not possible in RocFall to change the shape from circular to something else, however the circular shape is often the worst-case (in general, non-circular shapes will not travel as far as circular shapes).
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| 5. |
After a rock stops "bouncing" down the slope, it can enter a rolling-sliding state. By choosing the correct parameter for the friction angle it is possible to model rolling.
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| 6. |
The mass does NOT change the falling behavior of the rocks.
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| 7. |
The friction angle is used in conjunction with the rock properties and the slope geometry to determine if (and how far) a rock will slide along a segment of the slope. The friction angle is NOT used to calculate the motion of the rocks when they are "bouncing", only when sliding.
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| 8. |
There are no explicit material properties for the rock in RocFall. This should be accounted for in RocFall by changing the material properties of the different slope segments. The material properties for the slope (e.g coefficient of normal restitution) are for the rock-slope interaction (i.e. how much energy is lost in the collision) and implicitly depend on both the rock material and the slope material.
If you have different types of rocks that are likely to become the "rockfall rocks" you could account for this by entering a larger standard deviation in the material properties, or by running the simulation a number of times with the different values you expect to occur.
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| 9. |
If you load a file into RocFall (vertex.fal, for example) you will find that RocFall has two methods for considering the variation in the slope (this example is also included in the demonstration version).
i. Choose Slope->Material Editor from the menu. This allows you to enter a normal distribution for the coefficients of (normal and tangential) restitution and the friction angle of the material. Entering larger values for the standard deviations can be used to take into account the roughness / variability / uncertainty about the slope material.
(The number of materials is unlimited and each segment of the slope can be assigned a different material)
ii. Choose Slope->Slope Editor from the menu. This allows you to enter standard deviations for the coordinates of the slope vertices to simulate the 3-D nature of the slope. Before each rock is "thrown" the slope coordinates are sampled.
(Changing the actual values is disabled in the demonstration version)
If you zoom in on the third vertex you will see a yellow ellipse that denotes the area where the samples are most likely to be generated (the ellipse measures 2 standard deviations in each direction).
You may also find it informative to read the tutorials that come with RocFall dealing with the creation of "vertex.fal": From the RocFall menu pick Help->Help Topics and then pick Tutorials->Vertex Variation Tutorial from the "Contents" Table.
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| 10. |
RocFall does not actually deal with the Rockfall Hazard Rating System (RHRS), but my understanding of the system is that its use is mainly to answer questions like "is this slope reasonably safe" or "of these two slopes which is more dangerous". Since two very different slopes (e.g. (slope height=25ft, road width=20ft) and (slope height=100ft, road width=44ft)) can yield the same RHRS value, the actual remedial measures you will use can vary widely.
As it says in chapter 9 of Dr. Hoek's notes "However, in personal discussions with Mr Lawrence Pierson, the principal author of the RHRS, I was informed that in the State of Oregon, slopes with a rating of less than 300 are assigned a very low priority while slopes with a rating in excess of 500 are identified for urgent remedial action"
For more information you may want to read some of the papers referenced in Chapter 9 of Dr. Hoek's notes. e.g. the paper by "Pierson" (listed in the references section of Dr. Hoek's notes)
Your request for information on rockfall remedial measures has been Passed on to me and I am happy to provide the following information. The Rockfall Hazard Rating System and the Risk Analysis process Described in the chapter on "Analysis of Rockfall Hazards" in my notes are not intended for use in deciding what remedial measures to apply to a slope to minimize rockfall hazards. These systems are simply a means of determining whether or not there is a hazard to be dealt with. In most countries this is a serious problem since there may be hundreds of kilometers of mountain highway and only a limited budget to deal with rockfall hazards. Hence it is absolutely necessary to determine which slopes are in urgent need of attention to rank these in some order of priority.
Once it has been determined that a slope needs to be dealt with, the methods of reducing the risk of rockfalls depend upon the particular circumstances of the slope. I have discussed a few of these methods in Section 9.3.3 of the notes and illustrated some options in Figures 9.4
To 9.7. These remedial measures are not related in any way to the results obtained from the Rockfall Hazard Rating or the Risk Analysis.
In designing the remedial works to minimize the rockfall hazard from a slope, the nature of the rockfall problem and the geometry of the slope and adjacent roadway are the primary considerations. Where there is a wide roadway at the toe of the slope, a catch ditch is almost always the most effective and the most economical remedial measure (see Figure 9.7).
Where there is not sufficient room for a catch ditch, consideration has to be given to the use of draped mesh, catch fences or retaining walls. Removal or stabilization of unstable areas at the top of the slope can also be a great help in reducing the frequency and severity of rockfalls. From these comments you will see that each slope is unique and has to be treated differently. This is a practical engineering problem and any attempt to relate remedial measures to some sort of classification is totally inappropriate.
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