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INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
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ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XV, Issue VI, June 2026
Numerical Investigation of Geogrid-Reinforced Strip Foundations
Subjected to Adjacent Excavation Using PLAXIS 2D
Uday Shankar S
1
, Manoj Kumar H R
2
, Skanda D
3
1, 2
Assistant Professor, Department Civil Engineering, SJCE, JSS STU, Mysore
3
Student, Department Civil Engineering, SJCE, JSS STU, Mysore
DOI:
https://doi.org/10.51583/IJLTEMAS.2026.150600206
Received: 08 July 2026; Accepted: 13 July 2026; Published: 22 July 2026
ABSTRACT
Excavation activities carried out near existing foundations can significantly alter the stress state of the
surrounding soil, resulting in reduced bearing capacity and increased settlement that may compromise the
stability and serviceability of structures. This issue is particularly important in urban areas, where new
construction is frequently undertaken adjacent to existing buildings with limited available space. The present
study evaluates the effectiveness of geogrid reinforcement in improving the performance of strip foundations
subjected to the influence of nearby excavations through numerical modelling using PLAXIS 2D. A series of
finite element analyses was performed by varying the excavation depth and horizontal distance from the existing
strip foundation to assess their effects on foundation behaviour. Both reinforced and unreinforced soil conditions
were analysed under identical loading and boundary conditions to enable a systematic comparison of their
performance. The response of the foundation system was evaluated in terms of ultimate bearing capacity and
settlement. The numerical results demonstrate that the incorporation of geogrid reinforcement effectively
mitigates the adverse effects of adjacent excavation by improving the load-carrying capacity of the foundation
soil and limiting excessive deformation. Depending on the excavation geometry, the reinforced soil exhibited an
increase in ultimate bearing capacity ranging from 14% to 27%, while the corresponding settlement decreased
by approximately 11% to 16% compared with the unreinforced condition. The improvement is attributed to the
ability of the geogrid to provide tensile reinforcement, enhance stress distribution, and improve soil confinement
beneath the foundation. Overall, the study demonstrates that geogrid reinforcement is an effective ground
improvement technique for maintaining the stability and performance of existing strip foundations subjected to
nearby excavation, thereby providing useful guidance for the design and rehabilitation of foundation systems in
urban construction projects.
Keywords: Bearing Capacity, Settlement, Geogrid, Foundation soil, Excavation.
INTRODUCTION
Generally, foundations are made to meet bearing capacity and settling requirements. Despite this, contemporary
research has continued to focus on the issue of foundation soil bearing capacity for various conditions. Most
people agree that the settlement condition is because of the degree of structure performance. The settlement is
typically viewed as a sum of two parts, namely immediate (short term) and consolidation (long term). When the
settlement limit is exceeded, the footing size and geometry must be altered, or the soil must be strengthened in
foundation settlement calculations.
The temporal occurrence of the vertical deflection beneath the foundation, which is dependent on the rate of
loading in relation to the permeability of the soil, is what separates these two components. The first is incorrectly
called "elastic. “Settlement", as the elasticity theory has been widely used in computations. The conduct of the
earth is not malleable or even changeable. However, because of its simplicity, elasticity theory has been generally
accepted and used in geotechnical engineering for the computation of rapid settlement.
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It is very necessary to understand the behavior of soil below ground level due to external load coming from
super structure directly or adjacent structure. The distribution of load should be assessed below ground level in
the form of stress.
Geogrid
Geogrids are made with high-modulus polymer materials, such as polypropylene and polyethylene through
tensile drawing. Geogrids are made of a net-like material with big openings known as apertures and high tensile
stiffness. These holes allow the earth to connect with the surrounding soil, strengthening it. There are two main
types of geogrids: biaxial, triaxial and geocell. The nominal rib thickness of the commercial geogrids that are
now on the market for soil reinforcement is between 0.5 and 1.5 mm, and the junctions are between 2.5- and 5-
mm. Apertures in soil reinforcement grids are typically elliptical or rectangular in shape. The apertures range in
size from roughly 25 to 150 mm. The aperture dimensions range from around 25 to 150 mm. Geogrids is designed
so that the open portions of the grids exceed 50% of the overall area. Because of their high tensile stiffness, these
geogrids produce reinforcing strength at strain rates as low as 2%. Fig. 1 indicates the different types of geogrid
used in construction.
Fig. 1: Different types of Geogrids (Source: Google)
Problem Definition
PLAXIS 2D is a widely used finite element software for analyzing the behaviour of soil and geotechnical
structures under different loading conditions. It enables realistic simulation of soil–structure interaction, making
it an effective tool for predicting deformation, settlement, and stability in geotechnical engineering problems.
Ground improvement method by using geogrid has been extensively used from last few decades. A biaxial
geogrid with a length of 4 m was used as the reinforcing material beneath the footing. A total of five geogrid
layers were provided at a vertical spacing of 1.0 m between successive layers. The first geogrid layer was placed
at a depth of 0.5 m below the footing, while the remaining layers were positioned at regular intervals of 1.0 m.
The footing had a width (B) of 2.0 m, excavation depth (Y) and the horizontal distance between the edge of the
footing and the excavation was represented by X, which was varied from 2m to 5m to investigate its influence
on the footing response. This reinforcement configuration shown in Fig. 2 and 3 was adopted to evaluate the
effectiveness of geogrid reinforcement in improving soil stability and mitigating the adverse effects of adjacent
excavation.
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Fig. 2: Schematic representation of excavation near foundation supported with geogrid.
Fig. 3: Plaxis2D model with geogrid
RESULT AND DISCUSSION
Effect of Neighbouring excavation at X=2m on Bearing capacity and Settlement of Existing Foundation
Soil with and without Geogrid.
Table 1 and Fig.4 represents the effect of using geogrids by comparing the results of bearing capacity of existing
foundation soil for various depth of excavation at a horizontal distance of X=2m from edge of footing to
excavation.
Table 1: Effect of excavation at X=2m on Bearing capacity of foundation soil
Y
Unreinforced soil (kN/m
2)
Reinforced soil (kN/m
2
)
% of increase in
bearing capacity
Y=2m
106
147
27
Y=3m
104
134
22
Y=4m
104
127
18
Y=5m
103
124
17
Fig.4: Effect of excavation at X=2m on Bearing capacity of foundation soil
50
100
150
200
250
300
Y=2m Y=3m Y=4m Y=5m
Bearing Capacity (kN/m2)
Excavation depth (m)
Unreinforced soil (kN/m2) Reinforced soil (kN/m2)
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Table 2 and Fig.5 represents the effect of using geogrids by comparing the results of settlement of existing
foundation soil for various depth of excavation at a horizontal distance of X=2m from edge of footing to
excavation.
Table 2: Effect of excavation at X=2m on Settlement of foundation soil
Y
Reinforced soil (mm)
% of decrease in
settlement
Y=2m
19.09
11
Y=3m
17.5
12
Y=4m
15
13
Y=5m
14.6
16
Fig.5: Effect of excavation at X=2m on Settlement of foundation soil
From Fig. 4 and Fig. 5 it is clearly observed the effect of using geogrid for the existing foundation soil. Ultimate
bearing capacity values are enormously increased by using geogrids as reinforcement to the soil in an average
of 25%. Similarly maximum settlement values are decreased by using geogrids in an average of 13%.
Effect of Neighbouring excavation at X=3m on Bearing capacity and Settlement of Existing Foundation
Soil with and without Geogrid.
Table 3 and Fig.6 represents the effect of using geogrids by comparing the results of bearing capacity of existing
foundation soil for various depth of excavation at a horizontal distance of X=3m from edge of footing to
excavation.
Table 3: Effect of excavation at X=3m on Bearing capacity of foundation soil
Y
Unreinforced soil (kN/m
2)
Reinforced soil (kN/m
2
)
% of increase in
bearing capacity
Y=2m
113
152
26
Y=3m
112
140
20
Y=4m
112
129
13
Y=5m
111
127
12
10
20
30
40
50
Y=2m Y=3m Y=4m Y=5m
Settlement in mm
Excavation Depth in m
Unreinforced soil (mm) Reinforced soil (mm)
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Fig. 6: Effect of excavation at X=3m on Bearing capacity of foundation soil
Table 4 and Fig.7 represents the effect of using geogrids by comparing the results of settlement of existing
foundation soil for various depth of excavation at a horizontal distance of X=3m from edge of footing to
excavation.
Table 4: Effect of excavation at X=3m on Settlement of foundation soil
Y
Reinforced soil (mm)
% of decrease in
settlement
Y=2m
17.1
13
Y=3m
16.8
12
Y=4m
15.4
14
Y=5m
14.9
16
Fig. 7: Effect of excavation at X=3m on Settlement of foundation soil
From Fig. 6 and 7 it is clearly observed the effect of using geogrid for the existing foundation soil. Ultimate
bearing capacity values is enormously increased by using geogrids as reinforcement to the soil in an average of
18%. Similarly maximum settlement values are decreased by using geogrids in an average of 14%.
50
100
150
200
250
300
Y=2m Y=3m Y=4m Y=5m
Bearing Capacity (kN/m2)
Excavation depth (m)
Unreinforced soil (kN/m2) Reinforced soil(kN/m2)
10
12
14
16
18
20
22
Y=2m Y=3m Y=4m Y=5m
Settlement in mm
Excavation Depth in m
Unreinforced soil (mm) Reinforced soil (mm)
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Effect of Neighbouring excavation at X=4m on Bearing capacity and Settlement of Existing Foundation
Soil with and without Geogrid.
Table 5 and Fig.8 represents the effect of using geogrids by comparing the results of bearing capacity of existing
foundation soil for various depth of excavation at a horizontal distance of X= 4m from edge of footing to
excavation.
Table 5: Effect of excavation at X=4m on Bearing capacity of foundation soil
Y
Unreinforced soil (kN/m
2)
Reinforced soil (kN/m
2
)
% of increase in
bearing capacity
Y=2m
121
156
22
Y=3m
120
144
16
Y=4m
120
133
10
Y=5m
120
129
7
Fig. 8: Effect of excavation at X=4m on Bearing capacity of foundation soil
Table 6 and Fig.9 represents the effect of using geogrids by comparing the results of settlement of existing
foundation soil for various depth of excavation at a horizontal distance of X=4m from edge of footing to
excavation.
Table 6: Effect of excavation at X=4m on Settlement of foundation soil
Y
Reinforced soil (mm)
% of decrease in
settlement
Y=2m
15.1
13
Y=3m
15.8
14
Y=4m
14.4
15
Y=5m
13
15
50
100
150
200
250
300
Y=2m Y=3m Y=4m Y=5m
Bearing Capacity (kN/m2)
Excavation depth (m)
Unreinforced soil (kN/m2) Reinforced soil(kN/m2)
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Fig. 9: Effect of excavation at X=4m on Settlement of foundation soil
From Fig. 8 and 9 it is clearly observed the effect of using geogrid for the existing foundation soil. Ultimate
bearing capacity values is enormously increased by using geogrids as reinforcement to the soil in an average of
14%. Similarly maximum settlement values are decreased by using geogrids in an average of 14%.
Effect of Neighbouring excavation at X=5m on Bearing capacity and Settlement of Existing Foundation
Soil with and without Geogrid.
Table 7 and Fig.10 represents the effect of using geogrids by comparing the results of bearing capacity of existing
foundation soil for various depth of excavation at a horizontal distance of X= 5m from edge of footing to
excavation.
Table 7: Effect of excavation at X=5m on Bearing capacity of foundation soil
Y
Unreinforced soil (kN/m
2
)
Reinforced soil (kN/m
2
)
% of increase in
bearing
capacity
Y=2m
121
159
24
Y=3m
121
149
18
Y=4m
120
137
12
Y=5m
120
132
9
Fig. 10: Effect of excavation at X=5m on Bearing capacity of foundation soil
10
12
14
16
18
20
Y=2m Y=3m Y=4m Y=5m
Settlement in mm
Excavation Deptin m
Unreinforced soil (mm) Reinforced soil (mm)
50
100
150
200
250
300
Y=2m Y=3m Y=4m Y=5m
Bearing Capacity (kN/m2)
Excavation depth (m)
Unreinforced soil (kN/m2) Reinforced soil(kN/m2)
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Table 8 and Fig.11 represents the effect of using geogrids by comparing the results of settlement of existing
foundation soil for various depth of excavation at a horizontal distance of X=5m from edge of footing to
excavation.
Table 8: Effect of excavation at X=5m on Settlement of foundation soil
Y
Reinforced soil (mm)
% of decrease in
settlement
Y=2m
15.4
14
Y=3m
15.8
15
Y=4m
14.2
13
Y=5m
13.6
12
Fig. 11: Effect of excavation at X=5m on Settlement of foundation soil
From Fig. 10 and 11 it is clearly observed the effect of using geogrid for the existing foundation soil. Ultimate
bearing capacity values is enormously increased by using geogrids as reinforcement to the soil in an average of
16%. Similarly maximum settlement values are decreased by using geogrids in an average of 14%.
CONCLUSIONS
The present study investigated the influence of adjacent excavation on the behaviour of existing strip foundations
reinforced with geogrids using finite element modelling in PLAXIS 2D. Based on the numerical investigation,
the following conclusions can be drawn:
1. Adjacent excavation significantly influenced the response of strip foundations by reducing the ultimate
bearing capacity and increasing foundation settlement, particularly at smaller excavation distances and
greater excavation depths.
2. Geogrid reinforcement effectively improved the engineering performance of the foundation soil by
increasing the ultimate bearing capacity by approximately 14–27% while reducing settlement by 11–
16% under the excavation conditions considered.
3. The improvement in performance is attributed to the tensile reinforcement provided by the geogrid,
which enhanced stress redistribution within the soil and improved confinement beneath the foundation.
4. The effectiveness of geogrid reinforcement was observed for all excavation configurations, indicating its
suitability as a practical ground improvement technique for protecting existing foundations during nearby
excavation activities.
12
13
14
15
16
17
18
19
Y=2m Y=3m Y=4m Y=5m
Settlement in mm
Excavation Depth in m
Unreinforced soil (mm) Reinforced soil (mm)
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5. Overall, the numerical study demonstrates that geogrid reinforcement can substantially improve the
stability and serviceability of existing strip foundations, providing a reliable solution for foundation
rehabilitation and safe urban excavation practices.
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