Journal of Civil Engineering and Urbanism  
Volume 8, Issue 5: 59-65; September 25, 2018  
The Analysis of Reinforced Soil under Strip Foundation  
by Measurement of the Displacement Vectors by the  
Means of Image Processing  
Forough Ashkan  
Department of Civil Engineering, Faculty Member of Engineering, University of Maragheh, Iran  
Corresponding author’s Email:  
Reinforcing soil for solving the geotechnical problems is a very useful and economical technique. Soil as a grainy  
environment has a very good resistance under pressure and when it is cut, but is not that much resistant when being  
pulled. Being reinforced due to increase of the friction, it will be more resistant when being cut. I this survey we  
leveled our focus on the analysis of modeling loose sand and using image process for measuring the displacement  
Vectors and also, investigating the effect of different factors such as reinforced type and layer on the soil failure  
mechanics and we compared consequences with unreinforced status of the soil. The results convey this very  
message that the surfaces of the soil which were failed and also the depth of mentioned surfaces in reinforced model  
compared to unreinforced one increase and cover more loading capacity.  
Keywords: Reinforced soil, displacement vectors, soil mechanics, image processing.  
1. Triangular area immediately below the Foundation  
(wedge disruptive).  
One of the very important elements when designing  
foundation of structures such as such as buildings,  
followed by bridge and dam, is properly evaluated the role  
of stress-deformation behavior of soil under the  
Foundation (Bowles 2003). This factor is dependent on  
soil’s mechanical features. The first person deciding to  
purpose a theory about the calculation of the ultimate  
bearing capacity of shallow foundation was Terzaghi in  
1943. He assumed the shear failure surface under the final  
strip load like what u see in picture 1.  
2. Radial shear regions of the ADF and the CDE  
with curved fissures DF and DE.  
3. Two Rankin-triangular area AFH and CEG.  
Terzaghi (1943) deemed that angels of CAD and  
ACD is equal to inner friction angel to Ø.  
Huang and Meng (1997) suggested a theory about  
the reinforced soil failure mechanics according to cutting  
mechanics of wide-slab in soil which was recommended  
by and or Schlosser et al. (1983) which is illustrated  
this very theory failure separation force after reinforced  
layer is (B+Δ B) and failure areas of resistance increase  
even to soil surface.  
= Special weight; C= Cohesion; Ø= Friction angel  
Figure 1. The ultimate in bearing shear fissures a rigid  
rough contact surface with tape infrastructure  
He also substituted the existing soil above the  
surface which was under the foundation with overload in  
degree of  
(in which  
is the special weight of  
q Df  
Picture 2. Slab-wide mechanism in reinforced soil under  
the soil.).  
the strip base  
The failure area under the foundation can be divided  
into areas as goes below:  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing.  
J. Civil Eng. Urban., 8 (5): 59-65.  
Techniques proffered up until now are based on  
analytic research and modeling experiments. Almost of  
the physical models are in line with force - displacement  
information of the foundation and usually it is a real  
burden and a very tough challenge to observe failure  
mechanism. Because of the complex nature of the soil  
behavior which in turn leads to the complication of the  
arms and soil action? The analysis of the changed  
behavior of the appearance of the soil beneath trip bases in  
the experimental ways will enables us to perceive soil’s  
changed appearance or failure well. This research will  
equip us with better understanding of different parameters  
and their effects on slip surface when loading, likewise.  
Picture 3B. the base holder of Jak, and the experimental  
like box.  
Features of physical model:  
In this research dried sand was utilized for  
experiment. For determining sand’s features, grain size  
experiments were in compliance with ASTM, D 422-87  
special weight according (ASTM D 854-87). The intended  
sand included 0.02% was sieved with 200 was categorized  
as bad sand (Asadpour Estiar, 2006(.). Other soil  
parameters are included in table 1. About the precipitation  
method of the sand for creating homogenous models for  
loose sand by rain method, sand was poured from the  
height about 25 cm. In Table1, Features of used sand is  
Picture 3 A Exhibits parameters of the model,  
experiment box and the way by which the foundation of  
the soil was enhanced for implementing the load. A rigid  
frame was designed and used in laboratory.  
First, a trip basis with 1.8 m length 0.40 width and  
0.50 height was made and in two extremes of this base,  
the plate was installing the bases accompanying with  
In this vein the installation and attaching points  
were designed. As picture conveys the message, for bases  
we employed attachment of the two pipe UNP160 and for  
the beam attachment of the two pipe UNP200 are utilized  
and later on the beam and the columns were fortified by  
the belt and bracket.  
Pic 3. B. reveals force system of the base holder.  
For building experimental plate which was supposed  
to contain the soil. We used iron pages with thickness of  
3.9mm with the size of (1*0.3*0.6m).  
Table 1. Specifications of used sand  
gr /cm3  
For photographing the system while loading  
continuously, outside of the box was planned out of talc  
with thickness of 3cm.  
For the purpose of the force controlling there is a  
system by adding Kent ledges tries to monitor the force  
and adds to the force till the failure point of the system.  
Due to the reduction of the loading operation, a  
system like a lever was taken advantage of which has an  
arm in size about 1.1*0.03 m and thickness of 0.03m and  
a load of 3 kg in order to balance the system was added.  
The schematic picture of loading system and types of  
supports has been presented in Figure 4. The space  
between weights to loading place is 0.75cm and in each  
loading the load will be 9.3 times added to the previous  
load of the system.  
Calibration point  
Reinforcement layer No.1  
Reinforcement layer No.2  
Reinforcement layer No.3  
Rigid base  
Picture 3A.Parameters of model and experiment box  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing. J.  
Civil Eng. Urban., 8 (5): 59-65.  
Hang the frames reaction  
Load cell  
110 cm  
75 cm  
9 cm  
Loading by weight  
Figure 4. The schematic picture of loading system and types of supports  
For passing the force of the load to the soil  
These places are exhibited on observation widow  
with black color in particular distances in millimeter.  
Calibration points are findable by means of the  
Close- range photogrammetry and as a result of clear  
distances from each other and the stable location of the  
Calibration points during the experiment, it was possible  
to apply locations of the Meshes. The displacement  
vectors reached by near board photogrammetry and are  
transferable from the picture site to the real one. So the  
displacement field of the soil plate is achieved.  
experimented, a rigid frame in 0.3m*0.061m dimensions  
was deployed as a surface of trip base on the soil bed. For  
estimating the load, digital local cell of 250 kg capacity  
was in place. In experimental model, the load cell was  
located precisely at center of the iron plate and  
compromised the whole consistent system. In order of  
calculating of the settlement of the bases a displacement  
sensor or LVDT was used which was a plate right in the  
center. Present research comprises 4 experiments of  
loading. In order to reinforcing soil foundation  
exploitation of a particular reinforced called Geotextile  
was work.  
The altering parameters goes as; number of  
reinforced layers (N), the depth of the reinforced layer  
(U), The width of the reinforced layers (B), The distance  
between the reinforced layers (H). In table 2 You may  
explore features of the experimental models.  
In this study, analyses were drawn by Meshing of the  
taken photos  
and nice picture structures were  
gained and accordingly the shift of the sites of the Meshes  
in soil mass was evaluated.  
In picture5 displacement vectors of the settlement of  
the trip base located on loose sand in loading plate is  
The levels of the settlement are S/B=0.2, 0.35, 0.5.  
The settlement diagram are horizontal and pressure  
on one layer has been chosen as Geogrid.  
In this diagram, the status of the loading plate are  
shown according to settlement. The dark line exhibits the  
Geogrid layer before the deformation (Saket, 2006).  
Table 2. the features of testing models  
Test number  
Calibration factor  
The shift of the soil elements for every status from  
the beginning till the intended settlement are displayed.  
It is clear that in all the cases displacement vectors  
beneath the foundation is inclined to downward and  
toward the sides. Since the soil is loose the willingness for  
condensation under the base is observable and the  
displacement vectors under the base are bigger than the  
rest causing the reinforce under the base to change  
appearance and the other discernable issue is the  
movement of the elements of the soil when increasing  
amount of the loading is heightened.  
Image processing:  
While carrying out the experiment by PIV pictorial  
method which was first exploited by Adrian1991 in the  
experimental studies in fluid mechanics and recently has  
been employed in studying and examining changes of the  
appearance of the soil which is changing by White et al.  
Pictures are taken by the means of the digital camera  
with 7.1 mega pixel clarity  
and are saved to  
be processed afterwards by Geopiv8 software.  
When displacement vectors extended failure wedge  
and shear zone are formed beneath the base and in these  
areas the vectors inclined upwards. Above the reinforced  
layer, the angel of the displacement vectors is not in line  
with the vectors under the reinforced layer and also above  
the reinforced layer local failure areas are shaped.  
In order to process the pictures by PIV method, all  
pictures should be divided into Mesh and each of these  
Meshes has special picture structure and this will aid in  
other pictures to find the exact location of other Mesh.  
The displacement of every Mesh is clear and compared to  
first is calculable. These are in pixel so one may need to  
turn them into millimeter so the Calibration points are  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing. J.  
Civil Eng. Urban., 8 (5): 59-65.  
In which:  
In this picture one can behold that The amassed  
strain which has been made is expanded by the increase of  
the settlement of the loading plate in width and length  
direction and in 30 mm settlement there is strain up until  
the depth of Z/B=2 and in width -0.5<X/B<0.5. In the  
Geogrid also there is shear strain.  
While in S/B=0.2 amass of the maximum shear  
strain is distinct in sides of the base. It is due to the  
looseness of the soil and there is an inclination of  
condensation in the soil and so base settles in the soil and  
cutting failure of the Punch takes place and amass of the  
maximum cutting strain explanatory of the existence of  
slip surface in that very location.  
Picture 5. Displacement vectors in soil (a S/B=0.2 ، (b  
S/B=0.35 ، (c S/B=0.5 .Test 1  
In picture 6, The shear strain induced with the  
loading plate’s settlement in settlement levels in S/B=0.2,  
0.35, 0.5. Has been showed. The maximum of which is  
going to be achieved through below equation:  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing. J.  
Civil Eng. Urban., 8 (5): 59-65.  
The dark line shows Geotextile reinforced before  
deformation. It is so discernable that the direction of the  
displacement vectors in the reinforced layer is downward.  
In this section, the size of the vectors is bigger and  
resulting in deformation the reinforced layer under the  
foundation. In half right of the soil model in depth of  
Z/B=1, and 3.72<X/B<2.11 is gradually shifting upward.  
Failure wedge increasingly after the reinforced layer of  
the Geotextile started to form. Above the reinforced  
layers, the angle of the displacement vectors is not in line  
with reinforced layers’ vectors.  
Also above the Geotextile layer surface of the local  
failure has been shaped which are conspicuous with red  
color in the picture. The slip layers caused in reinforced  
foundation does not corresponds with the suggested slip  
layers. According to the wide-slab failure mechanism in  
Z/B=0.5 depth, the size of the triangle area under the  
reinforced layer is ( B ( ،and also is B  B bigger  
Picture 6. S/B=0.2 ، (b S/B=0.35 ، (c S/B=0.5( .Test 1 .  
maximum shear strain  
Gradually by expanding the depth shift vectors is  
downward and their sizes reduced. For the analysis of the  
failure wedge and shear zone and resistant formed in soil,  
one and two reinforced layer and foundation of the  
displacement vectors , the experiments numbers12,19,20  
are compared and completely schematical images of how  
these reinforces have effect on the failure mechanics of  
the soil have been depicted. Picture 7, shows displacement  
vectors in an unreinforced foundation.  
than the width and likewise the area of  
2.11   2.11  
Z/B=1 is in the shear zone and active triangle Rankin area.  
In these areas the direction of the displacement  
vectors is toward down and horizontal, also in an  
enhanced cases, the failure surfaces reached to the  
reinforced under layers and are not transferred to the  
surface of the earth. Agreeing with the diagram the  
incorrectness of the Huang and Meng theory has been  
Picture 7. Failure surfaces of unreinforced soil.  
Due to the looseness of the soil, no complete  
Terzaghi failure mechanics of the soil is seen, but a  
mechanics in between of failure and settlement  
simultaneously occur.  
Picture 8. Failure surfaces in an enhanced sol with a layer  
of (S/B=0.5). Test3  
By adding to the depth, Vectors toward down is  
observable and their sizes is reduced.  
Picture 9 happens to show displacement vectors in  
an enhanced foundation with two reinforced layers. Dark  
lines are showing two layers before the deformation. The  
thing which transparent is that the direction of the  
displacement vectors under the reinforced layer is upward.  
The displacement vectors in shear zone and the  
resistant areas gradually shift to up. The failure wedge is  
beginning to be formed under the second reinforced layer.  
In between of two reinforced layers the failure surfaces  
which are depicted by red color vectors.  
Area of  
in Z/B=0.5, is in Active  
0.9   0.9  
triangle Rankin area and shear zone.  
In these areas the direction of the displacement  
vectors is first toward down and then upward.  
In picture 8, you can see the displacement vectors in  
enhances foundation with one layer of reinforce.  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing. J.  
Civil Eng. Urban., 8 (5): 59-65.  
The slip surface in the reinforced soil foundation  
with 2 layers does not comply with the slip surface of  
Terzaghi. According to the failure wide- slab in Z/B=1  
depth, the size of the triangle areas under the reinforced  
Authors’ Contributions  
All authors contributed equally to this work.  
layer is  
and (  
) times increases compared to  
B  B  
Competing interests  
The authors declare that they have no competing  
the base, furthermore the area of  
1.91   1.91  
Z/B=1.52 is part of active triangle Rankin area and shear  
In the mentioned areas the direction of the  
displacement vectors is to down and also is horizontal.  
Besides, in enhanced cases with the short reinforced  
width. The failure areas reached up to the reinforced layer.  
This survey makes it known that when loading increased  
the tip of the failure wedge turned to the left and the soil  
beneath the base merely is scattered from one side.  
This experiment was repeated several times and  
probable conclusion are below:  
The force system was not balanced. This system was  
installed to the rigid frame by two buckles. It is possible to  
check its balance with the eyes but errors may occur while  
balancing it with the eyes. The force on the base was out  
of the center. The force of the base is on the Load cell  
which is in center of the iron plate. Due to the  
implementing it by hands, there may be some imprecision.  
So, the load may be was not exactly at center.  
Asadpour Estiar R )2006(. Experimental study of the  
effect of reinforcement on the mechanical behavior  
of sand. MSc Thesis, Faculty of Engineering,  
University of Tabriz.  
Bowles, Joseph E. (2003). Foundation analysis and  
design, McGraw-Hill Inc.  
Chen Q and Abu-Farsakh M (2015). Ultimate bearing  
capacity analysis of strip footings on reinforced soil  
foundations. Original Research Article Soil and  
Foundations, Volume 55, Pages 74-85.  
El Sawwaf M and Nazir AK (2012). The effect of deep  
excavation-induced lateral soil movements on the  
behavior of strip footing supported on reinforced  
sand. Original Research Article. Journal of  
Advanced Research, Volume 3, Issue 4, Pages 337-  
Inconsistency of the soil beneath the base which is  
of least important compared to the two previously  
mentioned cases above.  
Huang CC and Menq FY (1997). Deep footing and wide-  
slab effects on reinforced sandy ground. Journal of  
Geotechnical and Geoenvironmental Engineering,  
ASCE 123 (1), 3036.  
Lackner C and Bergado DT and Semprich S (2013).  
"Prestressed reinforced soil by geosynthetic-concept  
and experimental investigations". Original Research  
Article Geotextiles and Geomembranes, Volume 37,  
Pages 109-123.  
Saket A )2006(. Geogrid and its application", the Ministry  
of Industry and Mines, Geological and Mineral  
Schlosser F, Jacobsen HM and Juran I. (1983). Soil  
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Terzaghi K (1943). Theoretical Soil Mechanics.  
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Picture 9. Test 4. Failure surfaces in soil reinforced with  
two layers.(S/B=0.5)  
White DJ and Take WA and Bolton MD (2003). Soil  
deformation measurement using particle image  
By comparing the two pictures of 7- 9 we can  
conclude that increase of the reinforced layers results in  
failure of the surface and makes it (failure surface) to be  
wider and deeper when we reinforced the soil with two  
layers meaning that failure surface in enhanced cases with  
two reinforced layers is longer and huge mass of  
reinforced soli are in action and more loading capacity is  
being covered in this very case.  
Géotechnique 53, No. 7, 619-631.  
White DJ and Richards and Lock AC (2004). The  
measurement of landfill settlement using digital  
imaging and PIV analysis. Schofield Center,  
Department of Engineering, University of  
Cambridge, UK.  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing. J.  
Civil Eng. Urban., 8 (5): 59-65.  
Conference on Soil Mechanics and Foundation  
Engineering, Balkema, Helsinki, 83-101.  
To cite this paper: Ashkan F (2018). The Analysis of Reinforced Soil under Strip Foundation by Measurement of the Displacement Vectors by the Means of Image Processing. J.  
Civil Eng. Urban., 8 (5): 59-65.