cell with 250kg capacity was used to measure the entering
loads. In this case study, load cell was fastened by the bolt
in the metal plate center that formed solid system. This
solid system was placed exactly under vessel and under
forcing system. For measuring the foundation settlement
one displacement sensor (LVDT) was used that placed on
and center of metal plate. The present research includes
four loading tests.
To reinforce soil foundation two reinforced geogride
and geotextile were used. The various tests parameters
include: reinforced types (geogride and geotextile),
reinforcement layer (N), depth of first layer (U),
reinforcement wide (b) and space between reinforcement
layers (h). Table 2 shows the features of testing models.
Figure 2. Failure mechanism the Wide-slab of reinforced
soil under the foundation strip.
MATERIAL AND METHODS
Characteristics of the physical model
On the research of the soil dry sand was used as a
test case. To determine the profile of gravel, particle
experiments in accordance with the standard ASTM D
422-87, Specific gravity in accordance ASTM D 854-87
Were done. The sand contains. 002% decline from the
number 200 sieve, as Sandy has been classified a bad
seed. Other soil parameters is given in table 1. In relation
to how to sand r, to create uniform models for use with
loose gravel, sand and rain from a height of about 25 cm
was poured.
Table 1. Specifications of used sand
gr /cm3
Cu
Cc
Gs
27
2.67
1.5
1.25
0.992
Figure 3A shows the model and test case parameters
and shows the manner of reinforcing soil foundation. For
entering load, one rigid frame was designed and installed
in the laboratory. First, one reinforced concrete bond
foundation with 1.8m length, 0.40m width and 0.50m
height was made and at the two ends of this foundation.
The column base plate besides the six built were placed to
stablish the columns. In this way, beam and column nodes
were designed. As you can see in the figure 3 for
connecting columns two UNP160 hopper was used and
for beam, two UNP200 hopper node. Has been used and
then, beam and column we strengthen by the band. Figure
(3B) shows the supported structure of forcing system. For
building the laboratory vessel that soil should be put on it,
the metal plates with 3.9mm thickness and dimension of
(1.0*0.3*0.6) m was used. Because of the photography,
this system was formed with the case that has 3cm
transparent talc to take photo in successive loadings.
The tool for loading in system is force controlling
that by increasing the weights until interruption time, the
sample has been increased. Due to the decreasing of
loading from forcing system, lever load practice was used
that has 1.1m*0.03m arm and has 0.03m thickness which
the 3kg weight was installed at one side to make
equilibrium of the system. The space between weights to
loading place is 0.75cm; therefore, the amount of loads
9.3 times increases in every loading. Figure 4 shows the
schematic picture of loading system and types of supports.
To transfer the entering force to tested soil, one rigid
plate with the size of 0.3m*0.061m was used that work as
a surface band foundation on soil bed. One digital load
Calibration point
A)
B
b
Surface
P
u
Reinforcement layer No.1
Reinforcement layer No.2
Reinforcement layer No.3
h
h
H
Rigid base
B)
Figure 3. A) the model and test case parameters; B) the
supported structure of forcing system and laboratory
vessel
To cite this paper: Ashkan F (2018). The Study of Failure Mechanism of Reinforced Soil under Strip Foundation by PIV Method. J. Civil Eng. Urban., 9 (1): 01-06. www.ojceu.ir
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