JOURNAL OF SUSTAINABLE UNDERGROUND

EXPLORATION
e-ISSN: 2821-2851 J-SUE
Vol. 3 No. 2 (2023) 29-33
https://publisher.uthm.edu.my/ojs/index.php/j-sue

Plaxis 2D Modelling of an Anchor Sheet Pile for Soil Slope

Strengthening at Segamat, Johor
Mohamed Izzad Najmi Mohamed Azam1, Mohd Fairus Yusof1*, Mohd
Khaidir Abu Talib1,2
1 Faculty of Civil Engineering and Built Environment,
Universiti Tun Hussein Onn Malaysia, Batu Pahat, 86400, MALAYSIA
2 Research Centre for Soft Soil Malaysia (RECESS),
Universiti Tun Hussein Onn Malaysia, Batu Pahat, 86400, MALAYSIA

*Corresponding Author: fairus@uthm.edu.my

DOI: https://doi.org/10.30880/jsue.2023.03.02.005

Article Info Abstract

Received: 12 December 2023 In soil engineering, the soil slope is one of the important issues in
Accepted: 19 December 2023 geotechnical and environmental engineering that can fail due to
Available online: 24 December 2023 settlement behaviour. Due to soil slope instability, roads near the
Segamat River’s slopes have seen severe settlement. Therefore, this
study was carried out to determine how the geometry of the soil slope
Keywords
and the properties of the soil affect soil stability and deformation.
Slope stability, anchor sheet pile, Because of the varying slope geometries along the river, this study used
Plaxis 2D, settlement two alternative slope geometries in its modelling. A comparison was
made between the existing slope and the slope stabilised with sheet
piling by using Plaxis 2D. Other parameters that affect slope stability are
also being investigated, such as anchor length and anchor installation
angle. The anchor sheet pile's presence is intended to improve the
slope's stability. As a result of this analysis using PLAXIS 2D software,
the optimal anchor length depends on the passive pressure of the soil
behind the sheet pile. According to the results, installing an anchor with
a 60° angle is more stable because the safety factor obtained is 3.26
which is greater than that of a 45° angle which is 1.33. It shows the
anchor is the best support of the sheet pile for the soil slope stability.

1. Introduction
As the number of deeper and broader excavations in communities grows, the usage of retaining structures to
address settlement and load carrying difficulties becomes increasingly widespread. Slope surface, landslide
stability is a key problem when movement of existing or prospective slopes impacts the safety of people and
property, or the availability and value of the area. Tie-back retaining walls are a frequent procedure in
geotechnical engineering, particularly for deep excavations [1]. Because nearby structures and buildings must be
secured, the performance of tie rods and walls used to secure deep excavations in urban areas is critical.
Slope stability is defined as assessing a soil's failure by determining if the stress in the soil paralleled the
strength of the soil, as reported by [2]. This assessment is crucial for ensuring the safety of structures built on or
near soil slopes, as a failure of the slope can lead to damage or collapse of these structures. There are many
factors that can affect slope stability, including the properties of the soil, the slope geometry, and the presence of
water or other external loads. Engineers use a variety of methods, such as limit equilibrium and finite element
analysis, to evaluate slope stability and design measures to improve it.

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J. of Sustainable Underground Exploration Vol. 3 No. 2 (2023) 29-33 30

The anchor of the sheet pile is the one of the factors to strengthening of soil slope stability. The stability of
the soil slope is influence by various of factor which are the length, spacing and geometry of the anchor that will
be installed. Thus, the soil slope of geometry and the parameter of anchor sheet pile will be design by using
software Plaxis2D to estimate the characteristics or behaviors and to proposed the best design.
The aim of this study to determine how the geometry of the soil slope and the properties of soil affect the
soil slope stability and obtain the best design of anchored sheet pile. Two locations of the chainage were
selected, which are chainage 50 and chainage 150. The stability of the soil slope is determined by the value of the
safety factor for each chainage.

2. Properties and Methods

Plaxis 2D is a computer software that provides the capabilities for analysis and simulation in geotechnical
engineering. It is important in this study as it simulate the soil, anchor, and sheet pile. Plaxis 2D enable
simulating and constructing the soil qualities, layer and profile based on the parameters obtained. This study
used the software to conduct Finite Element Analysis (FEA) which examines the load applied and the soil slope
model to obtain the factor of safety at the end simulation. Numerical analysis programs are used when
traditional problem-solving methods are insufficient [3]. This are useful for solving nonlinear problems,
optimization, parametric studies, and understanding the effect of input variations on analysis outcomes via
sensitivity analysis and uncertainty quantification. The illustration in Fig. 1 depicts the representation of the
anchor sheet pile on a soil slope to being simulated in Plaxis 2D. The design of the anchor sheet pile can be seen
in Fig. 2, which was created using Plaxis 2D.

Fig. 1 Modelling of anchor sheet pile

Fig. 2 Modelling of anchor sheet pile by using Plaxis 2D

2.1 Soil Properties for Modelling

Table 1 and Table 2 show the soil properties for each section of a slope known as chainages. These tables include
information such as soil type, density, and moisture content. These soil properties are important for determining
the stability of the slope and are considered when designing the anchor sheet pile, a structural element that
reinforces and stabilizes soil slopes. The soil properties may vary between different sections or chainages of the
slope, and it is important to consider these differences when designing the anchor sheet pile to ensure the
stability of the slope.
 31 J. of Sustainable Underground Exploration Vol. 3 No. 2 (2023) 29-33

Table 1 Soil properties for modelling at chainage 50 [4]

Parameter Sandy Silt Granite Unit
Type material behaviour Drained Non-porous -
Material model Mohr-Coulomb Elastic -
Bulk Density 1.73 - Mg/m3
Dry Density 1.10 - Mg/m3
Young’s modulus, E 12000 50000 kN/m2
Poisson’s ratio 0.20 0.1 -
Undrained shear strength, Su 42 kN/m2
Frictional angles 32 - °
SPT 8 - -

Table 2 Soil properties for modelling at chainage 150 [4]

Parameter Sandy Silt Gravel Silt Sandy Silt Granite Unit
Type material behaviour Undrained Undrained Undrained Undrained -

Material model Mohr- Mohr- Mohr- Elastic -

Coulomb Coulomb Coulomb
Bulk Density 1.7 1.71 1.722 - Mg/m3
Dry Density 1.23 1.31 1.268 - Mg/m3
Young’s modulus, E 16000 40000 18000 50000 kN/m2

Poisson’s ratio 0.3 0.28 0.35 0.1 -

Undrained shear strength, Su 25 120 60 - kN/m2

SPT 6 18 11 - -

2.2 Modelling of Anchor Sheet Pile

The obtained soil properties and parameters, simulation for modeling the anchor sheet pile was carried out
(Table 3). The main objective of anchor sheet pile is to provide additional stability for soil slope. Parameters
already determined will be compared to the selected slope geometry to produce better outcome of anchor sheet
pile modeling. These parameters such as soil properties, anchor sheet pile parameters, loads applied on the
slope, and boundary conditions will be entered in the data for simulation on Plaxis 2D software, which will result
in anchor sheet pile modeling and prediction of safety factor.

Table 2 Soil properties for modelling at chainage 150 [4]

Parameter Value
Spacing 1 metre and 2 metre
Length 10 metre and 15 metre
Angle 45° and 60°

3. Results and Discussions

The results obtained from numerical modeling of the slope using Plaxis 2D software. The objective of the study
is to understand how the slope geometry and soil properties affect soil slope stability and deformation, and to
find the best design for an anchored sheet pile to improve soil slope stability.
The study comparing angles of 45° and 60° with different lengths and spacings shows that the length and
spacing of the anchors placed on the soil slope affect the factor of safety. The results indicate that the angle of 60
degrees, in combination with the right length and spacing, makes the slope more stable and erosion more
controlled. The research demonstrates that the slope geometry has an impact on the factor of safety. The erosion
condition is used to show how the factor of safety is affected by the installation of the anchors and sheet piles.
The results indicate that angles of 60 degrees, along with the appropriate length and spacing, have a positive
influence on the factor of safety and are more cost-effective and suitable for long-term slope stability.
 J. of Sustainable Underground Exploration Vol. 3 No. 2 (2023) 29-33 32

Furthermore, the results show that increasing the length of the anchor installed can lead to an increase in the
factor of safety, making it stable and more rigid. From the Table 3 and Table 4 shows the comparison of safety
factor on chainage 50.

Table 3 The installation of a 45-degree geometry anchor results in safety factors

Angle 45°
Length, m 10 15
Spacing, m 1 2 1 2
CONDITION FOS FOS FOS FOS
Initial 2.37 2.37 2.37 2.37
Sheet Pile 2.47 2.47 2.47 2.47
Anchor and Sheet Pile 2.57 2.57 2.57 2.57
Erosion with anchor 1.33 1.32 1.34 1.32
and sheet pile

Table 4 The installation of a 60-degree geometry anchor results in safety factors

Angle 60°
Length, m 10 15
Spacing, m 1 2 1 2
CONDITION FOS FOS FOS FOS
Initial 1.41 1.41 1.41 1.41
Sheet Pile 1.57 1.57 1.57 1.57
Anchor and Sheet 1.61 1.61 1.61 1.61
Pile
Erosion with anchor 2.05 2.34 3.26 3.1
and sheet pile

The research compared the effects of different angles (45° and 60°), lengths, and spacings of anchors on soil
slopes, and found that these factors greatly impact the stability of the slope. Specifically, the study found that
using 60-degree anchors with appropriate lengths and spacings leads to increased stability and less erosion. The
results suggest that the geometry of the slope plays a significant role in determining the stability, and that using
anchors at a 60-degree angle, with appropriate length and spacing, is more effective and cost-efficient in the
long-term. Additionally, the study found that increasing the length of the anchors can improve the stability even
more. The Table 5 and 6 shows the result obtained of the comparison factor of safety on chainage 150.

Table 5 The installation of a 60-degree geometry anchor results in safety factors

Angle 45°
Length, m 10 15
Spacing, m 1 2 1 2
CONDITION FOS FOS FOS FOS
Initial 2.37 2.37 2.37 2.37
Sheet Pile 2.47 2.47 2.47 2.47
Anchor and Sheet Pile 2.57 2.57 2.57 2.57
Erosion with anchor 1.33 1.32 1.34 1.32
and sheet pile

Table 6 The installation of a 60-degree geometry anchor results in safety factors

Angle 60°
Length, m 10 15
Spacing, m 1 2 1 2
CONDITION FOS FOS FOS FOS
Initial 2.37 2.37 2.37 2.37
Sheet Pile 2.47 2.47 2.47 2.47
 33 J. of Sustainable Underground Exploration Vol. 3 No. 2 (2023) 29-33

Anchor and Sheet 2.57 2.57 2.56 2.58

Pile
Erosion with 1.40 1.41 1.40 1.42
anchor and sheet
pile

4. Conclusion
The main conclusions of this study are that the installation of piles and anchors can significantly impact the
stability of soil slopes. The results indicate that by using piles and anchors, the stability of the slope can be
increased by approximately 8%. Additionally, the length and geometry of the pile installation, as well as the soil
properties and slope conditions, all play a significant role in determining the stability of the slope. This study
also suggests that when erosion is present, the installation of anchors and sheet piles can help to maintain the
stability of the slope. The result obtained would follow the required factor of safety based on the types of slopes"
means that the outcome of a simulation or calculation will conform to a specific level of safety determined by the
characteristics of the slope, such as a higher safety level being required for a slope stability [5]. Overall, the study
highlights the importance of considering various factors when installing anchors and sheet piles to ensure
optimal stability and safety of soil slopes.

Acknowledgement
The author would like to thank the Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein
Onn Malaysia for its support.

Conflict of Interest
Authors declare that there is no conflict of interests regarding the publication of the paper.

Author Contribution
The authors confirm contribution to the paper as follows: study conception and design: Mohd Fairus Yusof; data
collection: Mohamed Izzad Najmi Mohamed Azam; analysis and interpretation of results: Mohamed Izzad
Najmi Mohamed Azam, Mohd Fairus Yusof; draft manuscript preparation: Mohamed Izzad Najmi Mohamed
Azam, Mohd Fairus Yusof, Mohd Khaidir Abu Talib. All authors reviewed the results and approved the final version
of the manuscript.

References
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[2] Kumar, M. T., & College, G. (2015). Reliability and Fuzzy Logic Concepts as Applied to Slope Stability
Analysis.
[3] Williamson, M. P. (2005). The Finite Element Method. Wiley-Interscience, (pp. 529-552). New York:
McGraw- Hill.
[4] M, B. (2000). Soil Mechanics and Foundations. Arizona: John Wiley & Sons, Inc.
[5] Volume 6- Geotechnical Manual, Site Investigation and Engineering Survey. (2009). Kuala Lumpur:
Government of Malaysia Department of Irrigation and Drainage.