Geogrid Wall• Civil Engineering Student• KKU Designed and analyzed geogrid wall which is flexible mesh used to create a reinforced coherent mass behind the retaining wall by stabilizing the soil. The stability of the soil depends greatly on the friction slope it contains. Geogrid wall prevents soil form slipping and collapse.

1. DESIGN OF GEO-GRID WALL BY
ANALYSING SLOPE ALONG ABHA-DARB
ROAD
Saad Munahi Al Shahrani ,Naif Khalid Al Zuhairi
Mazed Ali Mohammad Dajma, Abdulaziz Mohammed Saad Al Qahtani
Supervised by: Eng. Saiful Islam
Kingdom of Saudi
Arabia
Ministry of Education
King Khalid University
College of Engineering
INTRODUCTION
 Escarpment roads and mountainous areas
in Saudi Arabia are facing landslide hazards
that are frequently occurring from time to
time causing considerable damage to these
areas
 Shear escarpment highway is located along
Abha-Darb Road. It is the most important
escarpment highway in the area, where all the
light and heavy trucks and vehicle used it as
the only corridor that connects the coastal
areas
OBJECTIVE
The objective of this study is to determine
stability of slope along Abha-Darb Road
 A real case study of slope failure is chosen
in fulfilling the objective of study for the
simplicity of the analysis the soil is assumed
to be homogeneous
 Stresses of the soil mass along the critical
slip surfaces as well as the displacements are
all the three directions are determined using
finite difference scheme
 In order to judge the failure surface FOS is
calculated at critical section to show the
behaviour of failure
 The Design of Geogrid wall has to be done
alone the road side for the safety of mankind.
STUDY AREA
The study is performed on slope 20 km
away from Abha towards Darb Road at Co-
ordinate Location 184 ‘6.8”N,4230’18.6”
MATERIAL PROPERTIES
Density (kg/m3) 𝞺 1860
Poissons ratio µ 0.25
Young’s modulas (N/m2) E 137.5 x 106
Shear modulas (N/m2) G 55 x 106
Bulk modulas (N/m2) K 91.6 x 106
MODELLING GEOMETRY
The geometry of the soil domain is created using no
of brick shape element and wedge element The size
of the Slope model is considered as x = 180m y =
10m and z varies from 0 to 120m depending upon
variation of slope. At the bottom plane of the grid all
movements are restrained.
MODEL-GEOMETRY
RESULTS
DESIGN OF GEOGRID WALL
Lay
er
no
Dept
h(m)
Spaci
ng
h(m) Le
Le
min LR L
L
requi
red
1 0.75 0.75 0.42 1 3.06 4.06 5
2 1.75 1 0.39 1 2.57 3.57 5
3 2.75 1 0.35 1 2.08 3.08 5
4 3.25 0.5 0.16 1 1.83 2.83 5
5 3.75 0.5 0.16 1 1.59 2.59 5
6 4.25 0.5 0.16 1 1.34 2.34 5
7 4.75 0.5 0.15 1 1.10 2.10 5
8 5.25 0.5 0.15 1 0.85 1.85 5
9 5.75 0.5 0.15 1 0.61 1.61 5
10 6.25 0.5 0.15 1 0.36 1.36 5
11 6.75 0.5 0.15 1 0.12 1.12 5
DISCUSSIONS
From the analysis of displacement magnitude contour obtained from static
analysis, it is evident that the displacement of magnitude 9.45 cm occurs at the top of
heel side of the study area.
 Also from the figure of x-displacement contour it is clear that maximum X-
displacement occurs at the downslope just adjacent to the road. The maximum value
of X-displacement is observed to be 18.295 cm.
Moreover Y-displacement is found to be of negligible value. Also figure shows
displacement vector from which it can be conclude that the soil at downslope is
sliding forward whereas settlement is observed at upstream slope. The maximum
value of Z-displacement is found to be 9.45 cm.
From the figure of XX stress it is observed that the tensile stress occurs along the
top of the slope. The maximum observed value of tensile stress is 26.019 kPa.
Similarly it can be seen from the figure of ZZ stress contour that the tensile stress
occurs along the top of the slope whose maximum value is 5.469 kPa.
The contour of FOS wrt Elevation and Height is plotted which indicates it is
unstable at higher height and is stable at lower height showing trends of circular
failure. Also the plots of FOS vs Height at various position along X- axis from the toe
of hill confirms the same results
 The design of 7m Geogrid Wall is check for Internal and External Stability. While
Checking for sliding ,overturning bearing Capacity. The computation Shows
Geogrid Wall is Stable.
Conclusion
The Project work analyses the instability of the most vulnerable slope of study
area along the Road slope Abha-Darb Road.
 The slope was investigated for the stability using three dimensional finite
difference codes.
 The slope undergoes circular failure mechanism as obtained by the analysis. The
factors of safety of the slope at some location are coming out to be less than one,
which confirms its instability. The factor of safety along the slope is high at low
heights and slope is quite stable. It then decreases due to positive shear strain rate
and then again increases at higher heights due to negative shear strain rate. This
trend of the factor of safety confirms the path of circular failure.
 Hence what we can say on the wholistic point is that there are ongoing
deformations at the slope
 The Design of Geogrid Wall is checked for Internal & External Stability and it is
coming Safe.
Total lateral Pressure due to overburden and
surcharge at any depth z
Ph=Pa + q h=(*z*KA+ q h)
q h=qs*KA
Ta=Tu*(1/(RFID *RFCR*RFCD*RFBD)
h=Ta*Cr/ph
Embedment length of Geogrid Layer
2*Ci*Cr*Le*potan=TH*FS=ph*h*Fs
The equation for LR=(H-z)tan(45-/2)
Fig 1.Contour of Displacement Magnitude Fig. 2 Contour of X - Displacement
Fig.3.Contour of Y - Displacement
Fig. 5 Contour XX Stress Fig. 6 Contour ZZ Stress
Fig. 4 Contour of Z - Displacement
Fig. 7 Showing FOS wrt Elevation and X- axis
Fig.8 Plot of FOS vs Height at a Distance
of 175 m from Toe of Hill
Fig.9 Plot of FOS vs Height at a Distance
of 164 m from Toe of Hill
Fig.10 Plot of FOS vs Height at a Distance
of 142 m from Toe of Hill Fig.11 Plot of FOS vs Height at a Distance
of 138.5 m from Toe of Hill
Fig.12 Plot of FOS vs Height at a Distance
of 93 m from Toe of Hill
Fig.13 Plot of FOS vs Height at a Distance
of 15 m from Toe of Hill