www.rocscience.com Open in urlscan Pro
76.223.77.128  Public Scan

Form analysis
2 forms found in the DOM

Name: searchForm — POST

<form method="post" name="searchForm" accept-charset="utf-8" style="padding: 0">
  <label for="searchQuery" class="d-block">What are you looking for?</label>
  <div class="input-group w-100">
    <input id="searchQuery" class="top-nav-search-input search-input w-100" autocomplete="off" data-provide="typeahead" dir="ltr" spellcheck="false" aria-label="Main search bar" aria-describedby="topnav-search-button">
    <button class="input-group-append" type="button" id="topnav-search-button" onclick="doSearch();">search</button>
  </div>
</form>

Name: searchForm — POST

<form method="post" name="searchForm" accept-charset="utf-8" style="padding: 0">
  <label for="searchQuery" class="d-block mb-0">Search all user guides</label>
  <div class="input-group w-100">
    <input id="headerHelpSearchQuery" class="search-user-guides search-input" autocomplete="off" data-provide="typeahead" dir="ltr" spellcheck="false" aria-label="Main search bar" aria-describedby="topnav-search-button">
  </div>
</form>

Text Content

The Rocscience International Conference 2021 Proceedings are now available. Read
Now



Home

Products
Learning
Support
Events
About
Products

All Products
Plans & Pricing
Maintenance+
Pricing Table
Academic Bundle
All Products

Slide2
Slide3
RS2
RS3
EX3
Settle3
RocFall
SWedge
UnWedge
RSPile
RSData
Dips
RocPlane
RocSupport
RocTopple
CPillar
RSLog
Browse all
Learning

Learning Resources
User Guides
Hoek's Corner
Training
Tutorials, Documentation and more

Slide2
Slide3
RS2
RS3
EX3
Settle3
RocFall
SWedge
UnWedge
RSPile
RSData
Dips
RocPlane
RocSupport
RocTopple
CPillar
RSLog
Browse all
Support

Program Downloads
Install & Activate
License Support
Support Policy
Events

Webinars & Courses
Rocscience International Conference
About

Company
Global Resellers
Careers
Contact Us
Buy Now

Free Trial


Products
Products
All Products Slope Stability Excavation Design Settlement & Foundation
Licenses & Pricing
All Products & Plans Maintenance+ Pricing Table Academic Bundle
All Products Browse all
Slide2
Slide3
RS2
RS3
EX3
Settle3
RocFall
SWedge
UnWedge
RSPile
RSData
Dips
RocPlane
RocSupport
RocTopple
CPillar
RSLog

Learning
Learning Resources User Guides Hoek's Corner Training
Tutorials, Documentation and more Browse all
Slide2
Slide3
RS2
RS3
EX3
Settle3
RocFall
SWedge
UnWedge
RSPile
RSData
Dips
RocPlane
RocSupport
RocTopple
CPillar
RSLog

Support
 * Program Downloads
 * Install & Activate
 * License Support
 * Support Policy
 * Get Support

Events
 * Webinars & Courses
 * Rocscience International Conference

About
 * Company
 * Global Resellers
 * Careers
 * Internships
 * Contact Us


Buy Now
What are you looking for?
search


ALL USER GUIDES

Search all user guides

 


SEARCH RESULTS

Close search




All Learning Resources
Home Learning 2D Finite Element Analysis of a Reinforced Soil Embankment
Constructed on a Cellular Foundation Mattress


2D FINITE ELEMENT ANALYSIS OF A REINFORCED SOIL EMBANKMENT CONSTRUCTED ON A
CELLULAR FOUNDATION MATTRESS

Oct. 19, 2021 21 minutes read


By Ian Williams, Ph.D. & Dan Simpson




Introduction

This article presents a brief summary of a 2D finite element analysis carried
out using RS2 to model a proposed reinforced soil embankment supported on a
cellular foundation mattress. The analysis is based on a series of analyses
carried out by Remedy Geotechnics Limited for a project involving the
construction of a temporary haul road and piling platforms on formations of soft
alluvial clay to facilitate the construction of a new viaduct for a major UK
rail project.

RS2 Model

The 2D idealisation used for the RS2 embankment model is shown in Figure 1.

Figure 1: 2D idealisation used for RS2 embankment model

The in-situ soil formations comprise a 5 m depth of soft alluvial clay underlain
by mudstone bedrock. To mitigate the risk of instability and control
settlements, the embankment is supported on a TensarTech Stratum cellular
foundation mattress system constructed to a depth of 1 m within the surficial
horizons of the in-situ alluvial clay. The 2.5 m high embankment has a face
angle of 45° and incorporates five horizontal layers of Tensar RE560 uniaxial
soil reinforcement geogrids at a vertical spacing of 0.6 m. The groundwater
regime is hydrostatic with the groundwater table coincident with the initial
ground surface.

All soils were represented using elastic-perfectly plastic constitutive models
with the Mohr-Coulomb yield criterion and non-associated plastic flow with zero
dilation.

The elastic stiffness and Mohr-Coulomb shear strength parameters for the geocell
mattress were calibrated against the results of more sophisticated 3D finite
element models to derive equivalent parameter values for use in the 2D analyses.

The embankment geogrid reinforcement was represented in the RS2 model using
elastic geogrid elements. A database of various geosynthetic products is
built-in to RS2 and can be used to expedite the entry of the reinforcement
properties (see screenshot presented in Figure 2).

Figure 2: Screenshot of RS2 geosynthetic reinforcement database

Piling rig loads were approximated by applying vertical pressures to the ground
surface at the top of the embankment.


The analysis was carried out in a sequence of four stages as shown in Figure 3.

Figure: 3 Modelling sequence

To examine likely modes of failure for the embankment without and with the
imposed piling rig loads, shear strength reduction (SSR) analyses were performed
at stages 3 and 4 respectively.

Analysis Results


A selection of results from the analysis are presented in Figures 4 to 8. For
reasons of confidentiality, the values of some results are not given and
attention is focused on modes of behaviour.

Figure 4 shows contours of soil strain in the horizontal direction together with
plots of axial tensile load in the geogrids at modelling Stages 3 and 4. These
visualisations show that the peak tensile loads in the geogrids coincide with
regions of peak tensile strains in the soil.

Figure 4(a) shows that at Stage 3 the development of a slip surface at the
embankment toe is being resisted by the mobilisation of axial tensile loads in
the lower geogrids where they pass through regions of the embankment within
which the horizontal soil strains are tensile. The axial tensile loads in the
geogrids reduce to zero in regions where the horizontal soil strain remains
compressive. Tensile horizontal soil strains are also developing upwards from
the base of the geocell mattress where it is ‘sagging’ under the surcharge of
the embankment fill.

Figure 4(b) shows a different pattern of horizontal soil strain and axial
tensile loads in the geogrids when the piling rig loads are imposed. Now the
dominant tensile strains in the soil and tensile axial loads in the geogrids
occur beneath the imposed piling rig loads. These dominant tensile soil strains
coincide with zones of high shear strain and are consistent with the onset of
punching shear through the embankment/geocell mattress and ultimate bearing
failure of the underlying formation soils.

The maximum axial tensile loads in the geogrids did not exceed the tensile
capacity at any stage.

Figure 4a: Contours of horizontal soil strain and plots of axial tensile load in
the geogrids - At Stage 3 when embankment is constructed Figure 4b Contours of
horizontal soil strain and plots of axial tensile load in the geogrids - At
Stage 4 when piling rig loads are imposed

Figure 5 shows contours of vertical displacements together with plots of axial
tensile load in the geogrids at modelling Stages 3 and 4. For this particular
model, the maximum settlement due to embankment loading is around 28 mm and the
additional settlement induced when the piling rig loads are imposed is around 48
mm.

Figure 5a: Contours of vertical displacement and plots of axial tensile load in
the geogrids - At Stage 3 when embankment is constructed Figure 5b: Contours of
vertical displacement and plots of axial tensile load in the geogrids - At stage
4 when piling rig loads are imposed

Visualisations of the failure modes based on the SSR analyses are presented in
Figures 6 to 8.

These visualisations suggest that at Stage 3 the predicted failure mechanism
comprises a slope failure with the slip surface passing through the embankment
toe. Localised face bulging between the horizontal geogrids is also predicted.

At Stage 4, when the piling rig loads are imposed, a punching mechanism through
the embankment and geocell mattress together with a bearing capacity failure in
the underlying subgrade is predicted. Due to the proximity of the rig loads to
the embankment crest, the failure mechanism is asymmetric with an anticlockwise
rotational movement. The primary mode of failure, however, is a bearing capacity
failure due to punch through.

Figure 6a: Contours of maximum shear strain and plots of axial tensile loads in
the geogrids at failure - At stage 3 when embankment is constructed Figure 6b:
Contours of maximum shear strain and plots of axial tensile loads in the
geogrids at failure - At stage 4 when piling rig loads are imposed Figure 7a:
Animated failure mechanisms with contours of absolute horizontal displacement -
At stage 3 when embankment is constructed Figure 7b: Animated failure mechanisms
with contours of absolute horizontal displacement - At stage 4 when piling rig
loads are imposed Figure 8a: Displacement vectors at the onset of failure - At
stage 3 when embankment is constructed Figure 8b: Displacement vectors at the
onset of failure - At stage 4 when piling rig loads are imposed




Back to top





Founded in 1996, Rocscience is a world leader in developing 2D and 3D software
for civil, mining, and geotechnical engineers. As engineers ourselves, we know
the importance of having reliable and easy-to-use software. That’s why we
constantly develop and refine our programs to make expert solutions that work
for you.


Products
 * Slope Stability
 * Excavation Design
 * Settlement & Foundation
 * All Products
 * Plans & Licenses
 * Maintenance+
 * Pricing Table
 * Academic Bundle
 * Free Trial

Learning
 * Resources
 * User Guides
 * Hoek's Corner
 * Training

Learning
 * Resources
 * User Guides
 * Hoek's Corner
 * Training

About
 * Company
 * Global Resellers
 * Careers
 * Contact Us

Support
 * Program Downloads
 * Install & Activate
 * License Support
 * Support Policy
 * Get Support

About
 * Company
 * Global Resellers
 * Careers
 * Contact Us

Events
 * Courses & Webinars
 * Conferences

Terms & Conditions | Privacy Policy | Cookies
© 2021 Copyright Rocscience Inc.
Terms & Conditions | Privacy Policy | Cookies | © 2021 Copyright Rocscience Inc.
Rocscience logo, click here to return to the homepage Account Icon - click here
to log in or out of your account Shopping Cart icon Click here to search our
site Click here to close Learning Tech Support Documentation Info Chevron Delete
Back to Top View More" PDF File Calendar Location Language Fees Video Click here
to visit Rocscience's LinkedIn page Click here to visit Rocscience's YouTube
page Click here to visit Rocscience's Twitter page Click here to visit
Rocscience's Facebook page Click here to visit Rocscience's Instagram page
Bookmark Network Scroll down for more Checkmark Download Print Back to top
Single User Multiple Users RSLog RocFall3 CPillar Dips EX3 RocFall RocPlane
RocSupport RocTopple RS2 RS3 RSData RSPile Settle3 Slide2 Slide3 SWedge UnWedge
Commercial License Education License Trial License Shop safe & secure Money-back
guarantee


YOUR CHOICE REGARDING COOKIES ON THIS SITE

We use cookies to optimise site functionality and give you the best possible
experience.

I AcceptI Do Not AcceptSettingsCookie Control Close Icon
May we use cookies to track your activities? We take your privacy very
seriously. Please see our privacy policy for details and any questions.Yes No