Welcome to the Engineering series for GeoStudio 2012.
This tutorial introduces the options available when drawing reinforcement loads in the SLOPE/W product of GeoStudio 2012.
If you are a new user to the GeoStudio Products, it is recommended that you first view the Getting Started with GeoStudio studio video series;
in particular, the introduction to SLOPE/W tutorial.
This tutorial assumes that the viewer is already familiar with the basic setup of a model in SLOPE/W.
We will start with a SLOPE/W limit equilibrium analysis already open.
This analysis has been created to simulate the stability of a slope that does not have any reinforcement loads applied.
Before solving this analysis, let's add a second analysis to the analysis tree to simulate the
influence of the reinforcement load on the factor of safety of the slope.
We will go to KeyIn,
analyses and clone the current SLOPE/W analysis.
We will keep all of the analysis parameters the same
as the first analysis and simply change the name of the clone to help differentiate between analyses.
Next we will go to Draw, Reinforcement loads to add two anchors to the slope.
Other reinforcement options include nails, geosynthetics, and piles.
When drawing anchors, as well as nails and geosynthetics, an estimation of the pullout resistance is required.
Here, we will simulate anchors that have proper anchorage
with measures such as nuts and bearing plates.
For the anchor reinforcement load, the bond length is the grouted length and will influence the calculating
of the pullout force.
When simulating reinforcement loads, in particular when using anchors or nails,
the required inputs are the bond diameter, which is the diameter of the grounded section in contact the soil;
the resistance reduction factor,
which can be used to account for nonlinear stress reduction over the imbedded length;
spacing, or the distance in the out-of-plane dimension between the anchors and nails along the slope;
tensile capacity, or tensile strength of the reinforcement;
reduction factor, which accounts for the reduction of the ultimate tensile capacity due to physical
processes, such as installation damage, creep, and durability;
shear force to incorporate a force that represents the shear stress mobilized within the reinforcement;
shear reduction factor to reduce the input shear force; and
the apply shear, which controls the orientation of the shear force on the free body.
Here, the force is applied either parallel to the orientation of the reinforcement or parallel to this slice base.
For this example, we will assume the pullout resistance is 300 kilopascals with a resistance reduction factor of 1.5,
bond diameter of 1/PI or approximately 0.318 m,
bond length is 3 m, and spacing in the out-of-plane dimension is 2 m.
The tensile capacity is set to 2000 kilonewtons,
with a reduction factor of 2.
Using these values, we can calculate the factored pullout resistance and factored tensile capacity.
First, the factored pullout resistance per length of grouted section behind the slip surface is calculated by the equation shown.
The result is 100 kilonewtons per meter per meter of grouted section behind the slip surface.
The maximum pullout force must not exceed the factor tensile capacity, which has been calculated here
as 667 kilonewtons.
Since the bond length is only 3 m, it will not be possible for the pullout force to reach this value.
Now let's return to our analyses in SLOPE/W
and add the anchors to the slope.
We will first add two anchors in the approximate location that is desired.
Next, we will go to KeyIn, reinforcement loads,
where we can edit the information for each or both of the anchors.
When both of the anchors are highlighted in this window, the inputs can be edited for both of the anchors simultaneously.
If only one anchor requires editing, then only the anchor of interest should be highlighted in this window.
Once all of the known input parameters are defined for the anchors, we can go back to the first analysis window
and solve both of the analyses.
Once solved, we can see that the factor of safety for the slope without reinforcement is 0.965.
If we switch to the second analysis where we added the two anchors to the slope, we can see that the factor of safety
has changed to 1.330 for the most critical slip surface.
We can use a slice information button to view the free body diagram and force polygon for each of the slices for the chosen slip surface.
Remember, the factored pullout resistance per length of grouted section was calculated to be 100 kilonewtons per meter per meter of grouted section.
If we multiply this value by the 3 m grouted section,
this indicates that the pullout force should be 300 kilpnewtons concentrated at the base of the slices.
If we move to the slice whose base is intersected by the reinforcement, we can see that there is a
resistance force value of 300 kilonewtons, as expected.
If the anchors were set to have a distributed force in the KeyIn reinforcement loads,
this value would reflect this distribution over all of the slices below the anchors,
as the force will be distributed
throughout the slices influenced in each anchor.
More information on the distribution of force can be found in the SLOPE/W engineering book or the example file for the reinforcement with anchors.
It is recommended that this tool is used whenever a reinforcement is used in a slope stability analysis
to ensure that the results match the users understanding and expectations of the analysis.
More information can be seen by using the view object information command
where the input parameters used,
as well as the calculations for each individual anchor, are shown.
We have now reached the end of this introductory tutorial.
Note that not all of the powerful features of SLOPE/W 2012 have been used or discussed here.
Further information on each command can be found in the online help, supporting documentation for
SLOPE/W, as well as in other tutorial videos of the Getting Started and Engineering Series with GeoStudio.
Thank you for watching.