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PLAXIS 2D and 3D applications in geotechnical earthquake engineering

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Author:
Published on:
November, 2015
Application:

In current design practice, geotechnical earthquake engineers are often responsible for providing the appropriate design ground motions for structural analysis, studying the effects of earthquakes and elaborating methods to mitigate these effects. A site response analysis is required to investigate the complex interaction between the seismic waves and the local site conditions. Morphology, stratigraphy, water conditions and soil properties have a high influence not only on the characteristics of the earthquake (for example in terms of duration, peak acceleration and frequency content) but also on the modelling strategy.


2D FEM analysis compared with the in-situ deformation measurements

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Published on:
November, 2015
Application:

Small-strain stiffness is seen as a fundamental property that almost all soils ranging from colloids to gravels, and even rocks exhibit. This is the case for static and dynamic loading, and for drained and undrained conditions. In literature, small-strain stiffness is assumed to exist due to inter-particle forces within the soil skeleton. Therefore, it can be altered only if these inter-particle forces are rearranged (Benz et al., 2009).
The deformation behaviour as a result of the excavation of a building pit in the inner city of Amsterdam is studied using the small strain stiffness model in PLAXIS 2D. The numerical results of deformations on the sheet pile wall during the different excavation stages obtained using PLAXIS are compared with the measured data. The objective of this study is to investigate the differences in computed deformation of the sheet pile wall when using the Hardening Soil Model (HS) and the Hardening Soil Small Strain Stiffness model (HSsmall) employing the correlations of Alpan (1970) and Benz & Vermeer (2007) compared with the inclinometer data to assess their performance in an actual design process.

Changing temperature unit in Chinese/Japanese Windows OS will give an error

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Known Issue ID:
23328

Problem description

In the 2D 2015 version it is possible to specify a model unit for Temperature. This is relevant for applications, which include the 2D Thermal module in their analysis.
The possible options for temperature units are: K, ºC and ºF. By default, the unit of Kelvin (K) is selected.

However, when using a Chinese/Japanese Windows Operating System (OS), and you try to change the default unit of temperature, the system gives an error message:

In the bug report information, the exception message is similar to the following:
Unknown project unit and no getter specified: °C.

Solution

For now, please use the default unit of temperature set to Kelvin, to avoid any problems in the behaviour of the program.

This issue will be solved in the next released version of PLAXIS.

[Solved] Volume strain could be activated unexpectedly

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Solved since:
Known Issue ID:
23579

Problem description

Normally, when you want to have an item activated you need to activate the checkmark in front of the item and set the values accordingly.
However, for the volume strain settings in PLAXIS 2D AE, PLAXIS 2D 2015.00 and PLAXIS 2D 2015.01 this does not always work as expected: whenever a value is set for one of the volume strain components (εxx, εyy, εzz and εvol), this will be applied in the calculation, independent of the activation state. This happens even if the volume strain components are not visible when the Apply checkbox is unchecked.

Solution

This issue is already solved since PLAXIS 2D 2015.02

When using an older version, you can manually check the behaviour of the volume strain settings by using the tabulate command to see if in any of the phases the volume strain values are not equal to zero:
tabulateSoils"VolumeStrain.epsvol"

With this, you could encounter a reply like this:

0091> tabulateSoils"VolumeStrain.epsvol"Object	VolumeStrain.epsvol Soil_1_Soil_2_1	   InitialPhase: 0   Phase_1: 0   Phase_2: 0   Phase_3: 0   Phase_4: 1   Phase_5: 1   Phase_6: 1 Soil_1_1	   InitialPhase: 0   Phase_1: 0   Phase_2: 0   Phase_3: 0   Phase_4: 0   Phase_5: 0   Phase_6: 0 

Here we can see that for the Soil object Soil_1_Soil_2_1 that the volume strain is set to 1 in Phases 4, 5 and 6. Now to conclude if the value is activated correctly, we should check the volume strain settings for this soil object in the selection explorer, see the examples below.

In these examples we see:

  • Phase_4: Volume strain activated + applied is checked + values set. Now the volume strain is applied in the calculation
  • Phase_5: Volume strain deactivated + applied is checked + values set. Now in PLAXIS 2D 2015.01 and earlier these values are incorrectly applied. 2D2015.02 and later works correctly: the volume strain is not applied as expected.
  • Phase_6: Volume strain deactivated + applied is unchecked + values set (see command line results above). Now in PLAXIS 2D 2015.01 and earlier these values are incorrectly applied. 2D2015.02 and later works correctly: the volume strain is not applied as expected.

To summarize the behaviour:

Volume strain activatedApply checkedVolume strain value2D2015.01 and earlier2D2015.02 and later
YesYesε ≠ 0appliedapplied
YesNoε ≠ 0✘ appliednot applied
NoYesε ≠ 0✘ appliednot applied
NoNoε ≠ 0✘ applied not applied

 

In order to not have a volume strain applied in PLAXIS 2D 2015.01 and earlier, please manually set the values for the strain to zero for the individual clusters. To do so:

  • check the Apply value to make the εxx, εyy, εzz and εvol parameters visible
  • set these values to zero
  • uncheck the Apply button

Custom level water condition might be reset after loading

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Known Issue ID:
24031

Problem description

In the above mentioned versions, the Custom level water condition for the InitialPhase on a loaded project may be reset to Global when switching from Green (mesh/flow conditions/ staged construction) to Blue modes (soil/structures) and back again.

The water conditions will be reset to "Global" condition for this option. This issue only happens for the “Custom level” option condition after (re)loading the Plaxis file if the cluster’s water condition is set to Custom waterlevel for the InitialPhase.

Solution

In order to avoid this issue you could use as an alternative the "Head" option instead of this “Custom level” option by specifying a reference head level. In this case, the pore pressures will be generated according to the specified head.

The model water conditions for all phases can be reviewed with:

  • Individual check of the Water Conditions in the selection explorer for each polygon;
  • Visualization of Water Conditions for all polygons in Flow conditions mode: the Custom waterlevel setting is visualized in a slightly lighter blue:
  • the use of the echo command for the polygon of interest, for example:
    echoBoreholePolygon_1_1.Soil.WaterConditions.ConditionsechoPolygon_1_1.Soil.WaterConditions.Conditions
  • the use of the tabulate command for the polygon of interest, for example:
    tabulateSoilPolygons"Soil.WaterConditions.Conditions"tabulatePolygons"Soil.WaterConditions.Conditions"

This issue will be solved in the next version of PLAXIS.

Install latest 2D version and 2D AE for converting older files

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How to have the latest PLAXIS 2D version and PLAXIS 2D AE simultaneously installed in your computer for converting older files


The procedure of converting projects created with PLAXIS 2D Classic, PLAXS 2D 2012 or an earlier version (with extension .P2D) can only be done with PLAXIS 2D AE. Since it is inconvenient to constantly switch between installed versions, you may use this tip to have both versions (2D AE and latest 2D 2015) are available in your system:

  1. open PLAXIS Connect to see which version is installed
  2. if PLAXIS 2D AE.02 is not yet installed: click to see the Available versions (see the figure below)
  3. select PLAXIS 2D AE.02 and click to Install
  4. go to the installation folder of PLAXIS 2D; by default this is in:
       C:\Program Files (x86)\Plaxis\PLAXIS 2D
  5. copy the folder to a different location (this folder should now contain the full 2D AE.02 version) and rename the copied folder properly, e.g. to PLAXIS 2DAE
  6. open PLAXIS Connect again to update to the latest version
  7. PLAXIS 2D AE and the latest PLAXIS 2D version should now be available in two separate locations with default being the latest version.
  8. In order to use the 2D AE version, PLAXIS Input should be launched from the separate folder, created in previous steps by starting PLAXIS2DXInput.exe

Notes

  • In order to use a PLAXIS 2D version, you must have access to the appropriate licence;
  • Any shortcuts, or file extension association (e.g. when double clicking a file) will always refer to the latest fully installed location.
  • For converting even older files with the extension *.plx, you can use the 2D Classic version,which can be found in the subfolder called classic, located inside the 2D AE program folder. See here for more details.

How to downgrade your PLAXIS 2D version

By using PLAXIS Connect it is easy to change versions:

Conversion of PLAXIS 2D files

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Due to adding more features and improving the program’s data structure for stability and performance, the data structure of the PLAXIS data files has evolved over time.

PLAXIS 2D 2015

PLAXIS 2D 2015 can only read PLAXIS *.p2dx files created with PLAXIS 2D 2015 or PLAXIS 2D AE.

PLAXIS 2D 2015 cannot use the 2D Classic to 2D AE converter to convert older Plaxis *.P2D files into the data format needed for PLAXIS 2D 2015. In order to use *.P2D files (2D Classic and earlier) in PLAXIS 2D 2015, these files first need to be converted to the PLAXIS 2D AE format using a PLAXIS 2D AE installation in combination with the 2D Classic to 2D AE converter installation, see below.
After this, you can open these 2D AE files in PLAXIS 2D 2015.

Tip: The procedure of keeping both versions of 2D AE and 2D 2015 installed in the same computer is described in the related article of how to Install latest 2D version and 2D AE for converting old files.

PLAXIS 2D AE

With PLAXIS 2D AE, the file extension was changed from *.P2D to *.p2dx. PLAXIS 2D AE can only read files made with PLAXIS 2D AE (*.p2dx). Plaxis project files created with the PLAXIS 2D 2012 version or earlier (with extension .P2D) cannot be opened directly in PLAXIS 2D AE: they first need to be converted using the 2D Classic to 2D AE converter.

The 2D Classic to 2D AE converter is an add-on program for PLAXIS 2D AE. In PLAXIS 2D AE when opening a 2D classic file (*.P2D) this converter program will be called, and it will transform the old PLAXIS 2D project via 2D AE's command line into the new format. Note that this Converter is intended to only work directly from PLAXIS 2D AE, and it is not intended to start the Converter manually. Please follow these steps to convert the older PLAXIS data to the new version:

  • Start PLAXIS 2D AE Input
  • Select Open an existing file
  • Go to the location of the old file
  • Select the file type PLAXIS 2D files (*.p2d) from the drop down item in the lower right corner:
  • And then select your PLAXIS 2D Classic file and click Open
  • Make sure to read the conversion notes about changed options in the program
  • Then click OK, and the PLAXIS 2D AE model will be built up using the Commands Runner (Note that this requires a PLAXIS VIP licence/subscription)

Please note that in order to perform all the above mentioned procedures, you need to have the PLAXIS 2D Classic to 2D AE converter installed. This tool comes with the full setup of PLAXIS 2D AE as an option during the installation procedure of the PLAXIS software. Next to this, it is also available as a separate program via PLAXIS Connect.

For older PLAXIS files (PLAXIS 2D V8 and V9): these files first need to be converted to PLAXIS 2D Classic before it can be converted into the 2D AE data format, see below or the related page:
Conversion from 2D Version 8/9

PLAXIS 2D 2010 - 2011 - 2012 - Classic

With PLAXIS 2D 2010, the file extension was changed from *.PLX to *.P2D. PLAXIS 2D 2010 to PLAXIS 2D Classic was capable of reading in files created with earlier versions starting from Version 8.2 (with extension *.plx).
To convert PLAXIS 2D V8/V9 files, it is recommended to use PLAXIS 2D Classic.

PLAXIS 2D Version 9

PLAXIS 2D Version 9 can read *.PLX files made with PLAXIS 2D Version 8 and PLAXIS 2D Version 9.

PLAXIS 2D Version 8

PLAXIS 2D Version 8 was the only program available that could convert PLAXIS 2D Version 7 files into the newer file structure for the *.PLX file.

Incorrect external water pressures could be applied inside a tunnel (PLAXIS 3D AE)

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Known Issue ID:
24015

Problem description

In some cases when using a PLAXIS 3D AE model with tunnels, it can happen that the external water pressures (water loads from a water body acting on a free surface) are not applied correctly on the tunnel circumference. This is important for when for instance modelling a grout pressure by using a user defined pore pressure.
This, of course, will not give the expected results of an analysis.

You can see this happening when inspecting a phase’s preview or its result, for which part of the geometry does not have external water loads applied at all.

 

Figure 1. Example of missing external water loads

Solution

When the above happens in your model, it can be solved by splitting the existing polycurve of the tunnel into two parts. The following can be done, for example:

  1. go to Structures mode and select to edit the specific tunnel
  2. add a horizontal subsection line
  3. intersect the horizontal line with the existing tunnel
  4. delete the just created horizontal line (not needed in the geometry, we only need to create two sections here)
  5. do not forget to Regenerate the tunnel!

Figure 2. Horizontal subsection line to intersect the existing tunnel


We are investigating this issue so we can fix it for an upcoming version

 


Application of commands: Groupfiltered and Apply

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groupfiltered (grpf)

The groupfiltered command (with grpf being the alternative,short version of the command) operates like the normal filter command followed by a group command on the result. This is useful for parametrization, as it can be used to store intermediate results of queries. For example if you would want to get all points with 0 < x < 2, you can do this:

0003> point (0 0 0) (1 1 1) (2 2 2)
Added Point_1
Added Point_2
Added Point_3

0004> groupfiltered Points "x<2"# expect only the first two points
Added group Group_1 containing 2 items
0005> echo Groups[-1]
Group named "Group_1"
  Contents (2): Point_1, Point_2

0006> groupfiltered Groups[-1] "x>0"# only those items in the last created group that fulfill this condition
Added group Group_2 containing 1 items
0007> echo Groups[-1] # should contain Point_2, which is the only with 0 < x < 2
Group named "Group_2"
  Contents (1): Point_2

0008> ungroup Groups[-2]# throw away the intermediate group
Disbanded group Group_1

apply (map)

The apply command (with map being the alternative command) applies a command to multiple objects at once. This takes as parameters any list-like object, a command name and a set of parameters. It then loops over the contents of the list-like object and fires the specified command with the provided parameters on that object.

For example if you want to set the "x" value of all points to some value, you can do this:

0007> point (0 0 0) (1 1 1) (2 2 2)
...
0008> apply Points"setproperties""x"3
OK
0009> tabulate Points "x"
Object   x
Point_1  3
Point_2  3
Point_3  3

In order for this to work, the object itself must implement the command in question (see the commands reference for this, or run cms MyObject to check which commands are available for any given object). For example the delete command is NOT implemented by a point, but by some higher-level object. You can therefore not use apply with delete in order to remove points.

Note: Undo stack: when you run apply it's as if you run multiple commands individually: there will be multiple undos.

The apply command will succeed if any of its subcommands succeeds. All outputs are however gathered in one big output: if one subcommand fails and some others do not, the entire result will be successful, but the feedback will contain information on the failure.

Example: Change material properties

In some cases, one wants to change one parameter for all (soil) materials. This can easily be done using the apply command:

apply Materials "sps""psi" 2

This will apply the sps (setproperties) command to all Materials in the current model in order to change the value for ψ (psi) to 2° .

 

Combining the two: Groupfiltered and Apply

Let's say you have a large project with many phases and want to switch all of them except the initial one to use a max. of 2 CPUs (cores) and you want to store 10 steps for each phase. You can write this macro (see menu item Expert> Macro library) for it:

groupfiltered Phases "PreviousPhase!="# all except the initial phase
apply Groups[-1] "setproperties""MaxCores"2"MaxStepsStored"10
ungroup Groups[-1] # get rid of temporary group to leave model clean

This will work regardless of how many phases and/or groups you already have. It will only fail if you only have the initial phase, as that would try to create an empty group at the beginning.

Apply to groups from Structures mode

When defining a group in Structures mode, this group is accessible in the green modes (Mesh, Water/Flow conditions, Staged Construction). However, the apply command does not work directly on these groups from Soil/Structures mode in the green modes. Note: it does work correctly on groups made in the same (green) mode though.
Since PLAXIS 2D 2015, we can now use the apply command to easily set a parameter for the entire Structures mode- group using the command line, by calling the apply command on the apply command.

Settings mesh coarseness for a group

Say we made a group of polygons and lines in Structures mode, called Group_1, and in Mesh mode we want to change the local mesh coarseness for all group members to 0.75, we need to call the apply command on the group members, like this:

apply Group_1 "apply""sps""CoarsenessFactor" 0.75

Changing materials for a group

When you make a group of volumes in Structures mode called Group_X, and you want to apply the same material, e.g. Concrete1, in a phase, say Phase_X, this is how the command should look:

mapGroup_X"map""setmaterial"Phase_XConcrete1

 

Incorrect rounding of small values (e.g. permeability) when using Sensitivity Analysis

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Known Issue ID:
24357

Problem description

When using the Sensitivity Analysis and Parameter Variation application (SensiPar), this application will send the parameter values that will be varied to the Input application. Unfortunately, in PLAXIS 2D 2015, the SensiPar application will send the new parameter value to Plaxis Input in a rounded format with two digits.

Table 1. Examples of rounding in SensiPar 2015
value in SensiParvalue send to Input
1E31000.00
1.8E5180000.00
0.50.50
0.4950.50
1E-30.00

 

As you can see above, values smaller than 0.01 will be rounded to zero. This will be problematic for small values (< 0.01), for example these parameters:

  • permeability values for low permeable soils;
  • HS small’s threshold shear strain: γ0.7 ;
  • stiffness parameters for the Soft Soil and Soft Soil Creep model: κ*, λ* and μ* .

Also other small parameter values, like Poisson's ratio and K0nc, can be rounded incorrectly because of this issue.

Solution

Currently no workaround is available. We are working on a solution for this rounding issue.

Modifying boundary conditions

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Application:

Fixities are very flexible: by default we have standard fixities, which fix the bottom of the model in all directions and the vertical sides in the horizontal directions.

In addition to this, a user can specify the boundary conditions for each side independently according to the following options:

  • Free
  • Normally fixed
  • Horizontally fixed
  • Vertically fixed
  • Fully fixed

The option to apply different fixities by manually creating prescribed displacement surfaces (or lines/points) and specifying different conditions for these is still possible.

A prescribed displacement can be - per direction - fixed, free or have some specific displacement value (for lines and surfaces it can also be a function of the position). Activated user-defined prescribed displacements (set to fixed or with specific displacement value) will overrule the default deformation boundary conditions.

In the case of setting a prescribed displacement to free, the following rules exist (in decreasing order of priority):

  1. point prescribed displacement wins for all directions
  2. line prescribed displacement wins for all directions, with the exception of:
    • a point prescribed displacement
    • boundaries of the line (i.e. its two end points)
  3. surface prescribed displacement wins for all directions, with the exception of:
    • a point prescribed displacement
    • line prescribed displacement (even its end points)
    • boundaries of the surface (edge lines and edge points)
  4. default fixities (if none of the above is applied)

It is also possible to disable the automatic default fixities completely for one or more phases and rely completely on manually defined fixities. The latter is done by deactivating the Deformations group (checkbox) in the Model Explorer or via the command line.

PLAXIS 3D AE

The default boundary conditions in the Model conditions section of the Model Explorer under the Deformations tree-menu should look like this:

Examples of commands to change them can be found below.

To deactivate the entire Deformations item (so no fixity applied):

deactivateDeformationsPhase_1

To change one of the model sides:

setDeformations.BoundaryXMinPhase_1"Free"setDeformations.BoundaryXMaxPhase_1"Normally fixed"setDeformations.BoundaryYMinPhase_1"Horizontally fixed"setDeformations.BoundaryYMaxPhase_1"Vertically fixed"setDeformations.BoundaryZMinPhase_1"Fully fixed"

PLAXIS 3D 2013

Since PLAXIS 3D 2013, the boundary conditions are now stored in the new Model Conditions section of the Model Explorer under the Deformations-node:

The command to change it, is now:

setDeformations.UseDefaultFixitiesPhase_1False

PLAXIS 3D 2012

The format for PLAXIS 3D 2012 is:

setPhase_1.Deform.UseDefaultBCsFalse

In PLAXIS 3D 2012, this setting is also available in the improved phases window.

PLAXIS 3D 2011

The format for PLAXIS 3D 2011 is:

setPhase_1.DefaultDeformationBCsFalse

Fully coupled flow and staged construction issue

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Known Issue ID:
24322

Problem description

When conducting a fully coupled flow-deformation analysis Plaxis will solve the full interaction between deformations, consolidation and groundwater flow simultaneously in the same phase. In this calculation, the calculation uses Staged Construction and transient groundwater flow combined.

Staged construction

In a (mechanical) staged construction calculation, any change in load or displacement will result in so called out-of-balance forces that during the Finite Element calculation will be solved in several calculation steps to reach equilibrium. In this Staged Construction loading type, the ΣMstage multiplier indicates the amount of out-of-balance that is solved. Once ΣMstage reaches one [1], the full weight and loads are fully applied in the model.

In a Staged construction phase, the time and the ΣMstage parameter are linearly coupled, this implies that the out-of-balance solving is done linearly in time.

Transient groundwater flow

In a Fully coupled flow-deformation analysis the groundwater flow can change in time: the (total) active pore pressures will then change in time. In each time step (calculation step), equilibrium of pore pressures must be reached. This takes into account the amount of flow that may develop within this step which is based on the changing or fixed hydraulic conditions and the generation of pore pressures due to undrained behaviour of the soil.

Coupling staged construction and flow

When coupling the staged construction calculation approach with this transient groundwater flow, there is a discrepancy in the way the equilibrium is reached: on one hand the full out-of-balance for forces and stresses is solved evenly over the entire phase time interval (mechanical equilibrium) and on the other hand the equilibrium for the flow field is considered per calculation step. However, the influence of the change in pore pressures and (external) waterloads on the deformation is currently solved in the same manner as the mechanical out-of-balance forces.

Since (undrained) soil behaviour is highly nonlinear, the solution for rapid changes in the hydraulic conditions might deviate from the real soil behaviour.

 

Solution

We are currently working on a solution to handle this correctly.

For the current version when using a fully coupled flow - deformation analysis you are advised to calculate the situation split in several phases with sufficiently small changes in the (hydraulic) boundary conditions, instead of one phase with larger changes. This limits this discrepancy caused by the way the out-of-balance is solved.

Remote Scripting API: Drivemining

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Application:

Since PLAXIS 3D 2013 it is possible to run scripts written in the Python programming language. This functionality enables us to automate the workflow of an iterative design process. We can make quick changes to a model, using pre-defined design parameters.

In this video, we will create a Python script that generates a model for drivemining. The script includes soil, structure, mesh, staged construction and calculation.

This remote scripting functionality is now also available in PLAXIS 2D.

Downloads

Drivemining_fixed_width.p3dae.py.txtPython script example file for PLAXIS 3D 2013. Save as .pyother| 5.38 KB
Drivemining_fixed_width.py.txtPython script example file for PLAXIS 3D 2013. Save as .pyother| 5.2 KB

How to use a user defined soil model in PLAXIS

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How to create a model for ground response analysis in PLAXIS 2D


Seepage around a pressure tunnel

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Application:

This movie demonstrates how to set-up a model to predict the development of seepage around a pressure tunnel, where the groundwater table is situated far below the pressure tunnel.

Create rock bolts accurately in PLAXIS 3D AE

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Introduction

In the PLAXIS 3D AE version it is not directly possible to intersect lines with surfaces. This is because of the parametric definition of the PLAXIS 3D AE surface objects, which is not compatible yet for line objects.

This makes the process of designing rock bolts for a tunnel project cumbersome, since the created lines might not be accurately snapped on the lining (surface) of the tunnel. Manual snapping of the end point to the tunnel lining can be done, however this might change the angle of the rockbolt slightly, which may be undesired. A manual intersection of the line and surface could solve the problem. However, this is not currently possible.

Alternative rock bolt definition

Depending on the desired geometry, different approaches are suggested. In this article the following cases are explained, related to the reference point that is given for designing the rock bolts:

  • reference point is inside the tunnel geometry
  • ending point of rock bolt

Reference point inside the tunnel geometry

In this case, the reference point is located inside the tunnel geometry. This point and a given angle assists in providing the direction of the rock bolt.
The following steps describe how to create a rock bolt accurately snapped on the surface of the tunnel lining:

  1. create the reference point
  2. find the name of the surface from which the rock bolt will be created
  3. use the lineangles command to create a line starting from the reference point towards this surface
  4. the newly created point is the starting point of the rock bolt
  5. (optional) delete the created line as not needed
  6. use the lineangles command to create the rock bolt by specifying the length (instead of a target surface)

For this example the following assumptions are taken:

  • reference point is: (25 1 -20)
  • angle of the rock bolt with respect to the xz-plane is: 60º for x-axis

Commands used:

point(251-20) # reference point lineanglesPoint_1060Surface_2deleteLines[-1]  # optional lineanglesPoints[-1]  0604 # same command with length embeddedbeamLines[-1] "Behaviour""Rockbolt""ConnectionPoint""First"

Ending point of rock bolt

In this case, the suggested alternatives are given below using two available commands: lineangles and the line command using "vector" parameters.

lineangles command

The following steps describe how to create a rock bolt accurately snapped on the surface of the tunnel lining:
create the reference point

  • find the name of the surface towards which the rock bolt will be created
  • use the command lineangles to create a line starting from the reference point towards this surface (remember to adjust the angle to find the correct value for the command)

For this example the following assumptions are taken:

  • reference point is: (32 1 -7.5)
  • angle of the rock bolt with respect to the xz-plane is: 60º for x-axis (240º for x-axis at the opposite direction)

Commands used

point(321-7.5) # reference point lineanglesPoint_10240Surface_2 # adjust angle 

line command with "vector" parameters

The line command can be used in different ways. One way to create a line is using a vector to define the direction of the line towards a surface. The structure of this command is the following:

line|referencepoint(x,y,z)|"vector"|direction(a,b,c)|targetobject

Example:

line250.2"vector"0-10Surface_1

Creates a line from a new point with coordinates (2, 5, 0.2) with a direction of (0, -1, 0) onto Surface_1.

For this example the following assumptions are taken:

  • reference point is: (32 1 -7.5)
  • angle of the rock bolt with respect to the xz-plane is: 60º for x-axis (30º for z-axis)

The following steps describe how to create a rock bolt accurately snapped on the surface of the tunnel wall:

  1. find the name of the surface towards which the rock bolt will be created
  2. use the line command to create a line starting from the reference point towards this surface (the vector in this case is calculated accordingly based on the angle given)

Commands used:

line321-7.5"vector"-0.50-0.866Surface_2embeddedbeamLines[-1] "Behaviour""Rockbolt""ConnectionPoint""Second"

( vector is calculated based on the following: [-0.5, 0, -0.866] = [cos60 , cos0 , cos30] )

These commands can also be written in a single line so it can easily be used when the rock bolt generation is prepared in for instance a spreadsheet program (see example here[]link]). The command would look like this:

embeddedbeam(321-7.5)"vector"-0.50-0.866Surface_2"Behaviour""Rockbolt""ConnectionPoint""Second""Material"”RockboltBeamMaterial

For more information on the structure of the commands used, please check the Command reference, under Help menu in Input.

How does Reset displacements to zero work?

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Application:

When we apply the option Reset displacements to zero, we reset the displacements at the BEGINNING of the phase. This means that any displacement in the model due to changes, e.g., load changes, structural elements being activated, soil activated/deactivated, can still occur in this phase: the phase just starts with zero displacements.

This option should be selected when irrelevant displacements of previous calculation steps are to be disregarded at the beginning of the current calculation phase, so that the new calculation starts from a zero displacement field. For example, deformations due to gravity loading are physically meaningless. Hence, this option may be chosen after Gravity loading to remove these displacements. If the option is not selected, the incremental displacements occurring in the current calculation phase will be added to those of the previous phase. The selection of the Reset displacements to zero option does not influence the stress field.

The use of the Reset displacements to zero option may not be used in a sequence of calculations where the Updated mesh option is used. However, if an Updated mesh analysis starts from a calculation where the Updated mesh option is not used, then the Reset displacements to zero option MUST be used in this Updated mesh analysis.

Reset small strain

This option should be selected when an existing state of the small-strain tensor in the HS small model, as reached at the end of the previous phase, is to be disregarded. As a result, the soil will behave as a 'virgin soil' without strain history. Other state parameters are not affected by this option. If it is the user's intention to reset all state parameters, then the option Reset State Variables should be used.

Note: this option to Reset small strain is automatically checked when you select the Reset displacements to zero option.

Reset state variables

This option should be selected when the values of the state parameters in advanced soil models, as reached at the end of the previous phase, are to be disregarded. As a result, the soil will behave as 'virgin' soil. The reset parameters for the Plaxis models are given in the table below.

Material modelParameter
Soft soil, Soft soil creep, Modified Cam-Clay,
Hardening soil, Hardening soil small-strain
pp reset to current effective stress state
Hardening soil small-strainStrain history tensor reset to zero
Hardening soil, Hardening soil small-strainMobilised shear reset to current
effective stress state

 

How to model segmental tunnel lining in PLAXIS 2D

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Application:

This movie shows how users can assign hinges or springs to tunnels modelled with the Tunnel designer, in order to model segmental tunnel liner.

Codemeter Drivers

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Application:

All PLAXIS products require the CodeMeter dongle with current drivers and active licences for PLAXIS 2D and/or PLAXIS 3D in order to run.

The driver package can be used for 32-bits and 64-bits Windows.

  • Local installation: install drivers on the local computer
  • Network installation: install drivers on both server and local computer, see also the related article on Network installation.

Note:
When updating the drivers, it could be that the CodeMeter key is not recognized. This can be seen in the system tray: the CodeMeter icon is grey and not green. In order to make it work again: first remove the CodeMeter key, and then reboot the computer/server. Finally, when the computer/pc is rebooted, plug in the CodeMeter key in the USB port.

inactive CodeMeter system tray icon

active CodeMeter system tray icon

Downloads

CodeMeterRuntime.exeCodeMeter Runtime-Kit 5.22a for Windows 32 & 64 Bit (February 2016)exe| 27.96 MB
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