Non-Dimension Chart To Determine The Thickness of CNS Soil To Minimize The Effect of Expansive Soil Exerted On Circular Footing
Non-Dimension Chart To Determine The Thickness of CNS Soil To Minimize The Effect of Expansive Soil Exerted On Circular Footing
Non-Dimension Chart To Determine The Thickness of CNS Soil To Minimize The Effect of Expansive Soil Exerted On Circular Footing
Talal1. Masoud is with the Civil Engineering Department, University, Fig1: Model footing with the Circular Iron Plate
Jerash, Jordan (phone:0772175443, e-mail:
dr.talalmasoud@outlook.com).
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4th International Conference on Chemical, Ecology and Environmental Sciences (ICEES'2015) Dec. 15-16, 2015 Pattaya (Thailand)
The circular iron plate fixed on the top of the tank by mean expansive soil, the tank filed with expansive soil in layers of
of bolts in a condition that the vertical heave is prevent to 50 mm and compacted using the same kind of vibrator to get
take place and the only way of the soil to move is from the the same initial dry density that is ρd=1.76 gm/cm3. The high
circular hole. of the expansive soil was 27 cm (90% of the tank high). Then
The model footing was put on the circular hole so that the cohesive non-swelling soil with 3 cm high was compacted to
model footing can go up and down without any effect of the the top layer of the tank (10% of the tank high) as show in the
restrain and adjusted so as to receive the load application Fig. 3 .
point at its center. The proving ring of 200 kg capacity was hc = the thickness of CNS soil
used to the loading frame. H – hc : the thickness of expansive soil.
The loading system was allowed to come down by moving H : total high of the tank = 30 cm
the load over the lever arm till it touched the ball resting on Then the same model footing (that is 60 mm in diameter)
the center of the model footing but did not apply any load. was used.
Dial gauge was also positioned before applying any load to The circular iron plate fixed on the top of the tank by mean
record heave of the soil as shown in Fig 2. as bolts in a condition that the vertical heave is prevent to
take place except from the circular hole.
Fig. 2. Testing Tank with the Model footing in the circular Iron
Plate on Plain Expansive soil Fig.3. Testing Tank with the Model footing in the circular Iron Plate
on Plain Expansive soil with CNS Soil
Then water was allowed to come to the dry soil from the
The model footing was put on the circular hole on the top
bottom and from the sides.
layer of cohesive non-swelling soil and adjusted so as to
The heave was taken place and recorded by the dial gauge.
receive the load application point at its center. The proving
This heave was prevented by applied load to the model
ring of 200 kg capacity was used to the loading frame. The
footing so that the model footing kept in the same position,
loading system was allowed to come down by moving the load
that is zero heave zero settlement.
over the lever arm till it touched the ball resting on the center
The maximum force applied by the soil to the model as the model footing but did not apply and load. Dial gauge
footing called uplift force, and the uplift force divided by the was also positioned before applying any load to record heave
area of the model footing give the up lift pressure that the soil of the soil.
exerted to the model footing so that there is no heave take
The water was allowed to come to the dry soil [expansive
place when water come to the dry soil. The test was repeated
soil + cohesive non-swelling soil] from the bottom and from
twice to ensure the reproducibility of results. The results of
the sides. The heave was prevented by applied load to the
this test given in Table 1.
model footing so that the model footing was kept in the same
TABLE I point.
RESULTS OF UPLIFT PRESSURE TEST OF EXERTED BY PLAIN EXPANSIVE SOIL The maximum force applied by the soil to the model
Diameter model Area of the Uplift farce Uplift pressure footing called uplift force, and the uplift force divided by the
footing model
60mm 2.27cm2 52.6Kg 2.04Kg/cm2
area of the model footing give the uplift pressure that the
expansive soil with cohesive non-swelling soil exerted to the
model footing so that the model footing not effect of the
2. Uplift Pressure Exerted by Expansive Soil With (CNS)
heave.
Soil As a Layers.
The test was repeated in the same manner and with the
The tank used in this test was the same tank, that is 36 cm same condition and the model footing but after change the
in diameter and 30 cm in depth. To study the effect of thickness of cohesive non-swelling soil. The results of these
cohesive non-swelling soil (CNS) on the uplift pressure of the test were give in Table 2.
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4th International Conference on Chemical, Ecology and Environmental Sciences (ICEES'2015) Dec. 15-16, 2015 Pattaya (Thailand)
TABLE II Fig. 5shows the effect of CNS soil on the uplift pressure it
RESULTS OF THE UPLIFT PRESSURE TEST WITH (CNS) SOIL
founded that as the thickness of CNS layer increase the uplift
Thickness Total Up lift
of (CNS)mm thickness of the pressure pressure degreases.
hc(mm) expansive soil H Kg/cm2
(mm)
0 300 0 2.05
30 300 10% 1.44
60 300 20% 0.9
90 300 30% 0.35
120 300 40% 0.2
150 300 50% 0.07
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4th International Conference on Chemical, Ecology and Environmental Sciences (ICEES'2015) Dec. 15-16, 2015 Pattaya (Thailand)
Concluding Remarks
The results founded from the tests carried out on the model
footing show that the uplift pressure exerted by the plain
expansive soil on the model footing was only 70% of the
swelling pressure exerted by the same soil on constant volume
method which may be due to lateral pressure. That means that
the swelling pressure in the field less than the swelling
pressure founded on the laboratories. Also these results show
that as the thickness of (CNS) soil increase, the swelling
pressure of the soil decrease using the non-dimension chart, it
is possible to determine the thickness of CNS needed to
minimize or to eliminate the effect of expansive soil on the
footing founded on such soil.
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4th International Conference on Chemical, Ecology and Environmental Sciences (ICEES'2015) Dec. 15-16, 2015 Pattaya (Thailand)
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