10th Asian Regional Conference of IAEG (2015)

Suitable Calculation of Shallow Foundation Bearing Capacity by Comparing The
Calculation of Terzaghi’s and Mayerhorf’s Concepts in Jatinangor, West Java Province,Indonesia
Ilham PINASTI(1), Dicky MUSLIM(1), Fajar FAJAR(1), Farach ABDURACHMAN(1)(1)Departement of Geological Engineering, Faculty of Geological Engineering, Padjadjaran University
E-mail: ilhampinaas@gmail.com

ABSTRACT
Jatinangor is a major educational area in West Java, Indonesia that the infrastructure
continues intensively for supporting the educational facilities. At the infrastructure
construction’s step needed a calculation of the bearing capacity. The objective of thisresearch is to determine which equation of bearing capacity that suitable for this area. TheMethods are using desk work, field work, and laboratory work. For field work using UDS(Undisturbed Sampling) and DCPT (Dutch Cone Penetration Test) in three locations. For
laboratory work using tri-axial test and basic properties test. For desk work using shallow
bearing capacity calculations by Terzhagi’s and Mayerhorf’s concepts. The material in thisarea is clay with brown color and high plasticity. The values of unit weight are 1,725gr/cm3 , 1,762 gr/cm3, and 1,715 gr/cm3, cohesions are 0,178 kg/cm2, 0,264 kg/cm2 , and0,160 kg/cm2, internal friction angles are 4,863o, 4,785o, and 3,810o, and Cones Pressure are
28 kg/cm2 , 21 kg/cm2 , and 27 kg/cm2. The results of Terzaghi’s calculation concepts are
2,37 ton/m2 in location 1, 2,64 ton/m2 in location 2, and 2,18 ton/m2 in location 3. Those
three locations are square foundations type. Meanwhile, the results of Mayerhorf’scalculation concepts are 0,7 ton/m2 in location 1, 0,525 ton/m2 in location 2, and 0,675
ton/m2 in location 3. Based on comparing the two concepts above, the calculations ofshallow foundation bearing capacity which suitable with infrastructure construction inJatinangor is Terzaghi’s calculation concept with square foundation type, because the value
is higher than Mayerhorf’s calculation.

Keywords : Soil, Bearing Capacity, Shallow Foundation, Mayerhorf’s Concept,
Terzhagi’s Concept, Infrastructure.
1. Introduction
Infrastructure in Indonesia is well developed, it
can be seen in one of the area in West Java Province,Jatinangor. Jatinangor is an education area that theinfrastructure continues intensively for supporting theeducational facilities. Therefore it needs a solid
infrastructure that can survive for a long time. Before
the construction begin, it needs some of investigation
for the built area. Geotechnics investigation is one of
method that can be done before the construction begin.
By pay attention to the materials and geologicalcondition, the value of bearing capacity in the built
area could be known to determine the feasibility of anarea on infrastructure development.
The value could be calculated by using Terzaghi’sand Mayerhorf’s concepts. The objective is todetermine which equation of bearing capacity thatsuitable for this area. The research is located in 3
locations at Jatinangor area, exactly at theconstruction area for the new building of Faculty ofGeological Engineering.
2. Method
The methods are using field work, laboratory work,and desk work.
2.1 Field Work
Field work consists of UDS (Undisturbed Sample)
and DCPT (Dutch Cone Penetration Test).
Undisturbed samples are soil samples that show theoriginal characteristics. Usually for UDS is using
Shelby Tube for sampling, the diameter of shelby tube
is about 8 cm and the length is about 50 cm, because110th Asian Regional Conference of IAEG (2015)it helps to reduce disturbance towards soil samples forgain the original characteristic of soil.
As defined by R.W Day (2001), The cone
penetration test (CPT) is an in situ testing method
usedtodetermine
thegeotechnicalengineering properties of soils and delineating soil
stratigraphy. The test method consists of pushing aninstrumented cone, with the tip facing down, into theground at a controlled rate (usually 2centimeters/second). The resolution of the CPT indelineating stratigraphic layers is related to the size ofthe cone tip, with typical cone tips having a crosssectional area of either 10 or 15 cm², corresponding todiameters of 3.6 and 4.4 cm (see in fig. 1). This test
used to determine value of cone pressure (Qc).

2.3 Desk Work
Desk work consists of literature studies andcalculating the value of shallow foundation bearing
capacity. As defined by U.S Army Corps of Engineers(1992), Bearing capacity is the ability of soil to safely
carry the pressure placed on the soil from any
engineered structure without undergoing a shear
failure with accompanying large settlements.
Applying a bearing pressure which is safe withrespect to failure does not ensure that settlement of
the foundation will be within acceptable limits.
Therefore, settlement analysis should generally beperformed since most structures are sensitive toexcessive settlement and generally accepted conceptof bearing capacity analysis is to assume that the soil
below the foundation along a critical plane of failure(slip path) is on the verge of failure and to calculate
the bearing pressure applied by the foundation
required to cause this failure condition (John E.
Bowles, 1997). This is the ultimate bearing capacity(Qu).

Fig. 1 Dutch Cone Penetrometer
2.2 Laboratory Work
Laboratory work consist of basic properties soil
test and tri-axial test. Basic properties soil test areused to get a characteristic of soil from some elements.
There are 6 elements of basic properties test, but forthis research only one element that used in theshallow foundation bearing capacity calculation. Theelement is unit weight (). Unit weight is comparison
between total weight soil and soil volume.
As defined by K.H. Head (1998), The triaxial testis one of the most versatile and widely performed
geotechnical laboratory tests, allowing the shear
strength and stiffness of soil and rock to be
determined for use in geotechnical design. Primaryparameters obtained from the test may include theangle of shearing resistance (ϕ), cohesion (c), andundrained shear strength (cu), although otherparameters such as the shear stiffness (G),compression index (Cc), and permeability (k) may
also be determined. The triaxial test typically involves
placing a cylindrical specimen of soil, ranging from
38mm to 100mm diameter, into a cell that can bepressurised (see in fig. 2). Most specimens have anapproximate 2:1 height to diameter ratio, and aresealed within a rubber membrane.

Fig. 2 General set-up of a soil specimen inside a
triaxial cell
Moreover, from this work the material of theresearch area could be known. The material of theresearch area is clay with brown color and highplasticity. For calculating the values of bearing
capacity in the area are using Terzaghi’s andMayerhorf’s concepts in Zufialdi Zakaria (2006).
There are three equations of bearing capacity (Qu) by
Terzaghi’s. The following shows an equations :=.

+ .

= 1,3. .

2.

+ .

+ 0,5 . .
.

+ 0,4 . .

(1)
(2)

10th Asian Regional Conference of IAEG (2015)= 1,3. .
Where :QuG
DfB
cNq,Nc,Ngfactors+ .

.

+ 0,4 . .

(3)

area. From the data in Table 1, show some values ofTerzhagi’s bearing capacity concept by using theformula (1) for the continuous foundation, theformula (2) for the rectangular foundation, and theformula (3) for the circular foundation as shown in
Table 2.

= Ultimate Bearing Capacity Pressure= Unit Weight= Depth of Foundation= Width of Foundation= Cohesion= Dimensionless bearing capacity

Table 2 Values of Qu by Terzhagi’s
Qu
Qu
Qu
Location(Circular)(Continues)(Square)
1
7.06
6.87
7.14
2
7.85
7.49
7.93
3
6.49
6.32
6.56

The following shows an equation of Mayerhorf’s
concept:
Qu = Qc / 40 . (B + D)

(4)

After the values of Qu determined, then withformula (5) the value of Qa can be calculated thatshown in Table 3.

Where :QuQc
B
D= Ultimate Bearing Capacity Pressure= Cones Pressure= Width of Foundation= Depth of Foundation

Table 3 Values of Qa by Terzhagi’s
Qa
Qa
Qa
Location(Circular)(Continues) (Square)
1
2.35
2.29
2.38
2
2.62
2.5
2.64
3
2.16
2.11
2.18

For both concept to know allowable bearing capacity
value (Qa) are using same formula, the following
show an equation :Qa = Qu / F

After the value of Qa determined, could be seenthat square foundation is the largest value of bearing
capacity. So the recommended foundation form forthis area is square foundation.
Furthermore, the calculation of bearing capacity
Mayerhorf’s using formula (4) and the data fromTable 1. The result of the calculation is shown in table
4.

(5)

Where :QaQu
F= Allowable Bearing Capacity= Ultimate Bearing Capacity Pressure= Safety Factor

3. Result &Discussion
From the results can be obtained the data that usedin the calculation of bearing capacity at 3 different
locations with 2 meters depth, 1 meter width
foundation, and safety factor F = 3, is shown in Table
1. Calculating data using the bearing capacity ofTerzhagi’s concept will use three different calculation,
there are circular foundation, rectangular foundation,and continuous foundation. Furthermore, aftercalculating these three different calculations, can beseen that the different values bearing capacity of eachcalculation.

Table 4 Values of Qu by Mayerhorf’sLocation
Qu1
2
3

After the values of Qu determined, then withformula (5) the values of Qa can be calculated thatshown in Table 5.
Table 5 Values of Qa by Mayerhorf’sLocation
Qa

Table 1 Variables of bearing capacityLocationc



NcN

Qc

123

0.18
0.26
0.16

4.86
4.79
3.81

1.73
1.76
1.76

6.45 1.55 0.43
6.42 1.54 0.42
6.13 1.43 0.34

28
2127

Nq

2.1
1.58
2.02

12
3

0.7
0.52
0.68

After calculating values bearing capacity withdifferent concepts, which using Terzhagi's andMayerhorf's concept, then bearing capacity ofdifferent values have been obtained (see table 3 and 5).
It can be seen that the bearing capacity values byCalculations that generate the most large value ofbearing capacity shows that the calculation is the mostsuitable calculation of bearing capacity for the study

310th Asian Regional Conference of IAEG (2015)

using the calculation of Terzhagi’s concept generatelarger Qa value than the calculation by using theMayerhorf's concept. Different values of bearing
capacity between
Terzhagi’s and Mayerhorf’s
concept happen because a lot of factors. Severals
factor are the different variables for each concepts(can be seen at formula (1), (2), (3), and (4)).
Terzhagi’s concept have some different variables thatused in the formula with Mayerhorf ‘s concept, there
are unit weight (), cohesion (c) and dimensionlessbearing capacity factors (Nq, Nc, and Ng) for
Terzhagi’s concept and for Mayerhorf’s concept there
is one different variable, conus pressure (Qc). Can beseen at table 1 that the values of conus pressure at
research area is low. So that the values of bearing
capacity by using Mayerhorf’s concept have lessvalues than the other one (Terzhagi’s concept). Low
values of conus pressure shown that material ofresearch area have a low stiffness, that matter
supported by material composition of research area isclay. Generally, clay is material with low stiffnes, that
affect to the calculation of bearing capacity. So thatthe calculation of bearing capacity by using
Mayerhorf’s concept is not suitable for research area.
Moreover, it also seen from the result of variable
by Terzhagi's concept that the cohesion values thereby
affecting the bearing capacity values of Terzhagi'sconcept have larger value. The content of the material
in the research area affect the values of cohesion,
which known as clay material with a fine grain size,
so it has a larger value of cohesion than the coarse
grain size material.

Day, R. W. (2001) Soil Testing Manual: Procedures,Classification Data, amd Sampling Practices, NewYork, McGraw-Hill.
Head, K. H. (1998) Manual of Soil Laboratory
Testing Volume 3: Effective Stress Tests,
Chichester, John Wiley & Sons Ltd.
Zakaria, Zufialdi (2006) Soil Bearing Capacity for
Shallow Foundation. Faculty of GeologicalEngineering Padadjaran University. Jatinangor.

4. Conclusions
After calculating values of bearing capacity in theresearch area obtained different values by using
Mayerhorf's and Terzhagi's concepts. Then, aftercompared the values of bearing capacity by using thedifferent concepts, Terzhagi’s concept has greater
values than the Mayerhorf's concept. So can beconcluded that the calculation of bearing capacity by
Terzhagi’s concept is more suitable for the researcharea, because: The material of research area is dominatedby clay, so the characteristic of soil is low
stiffness that show a low values of conepressure.
 The values of cohesion in the research area ishigh, because the dominated material is clay.
That affect the values of bearing capacity byusing the calculation of Terzhagi’s concept isgreater than the other one (Mayerhorf’sconcept.
ReferencesAnonym (1992) Engineering and Design BEARING
CAPACITY OF SOIL. Department of the Army
U.S. Army Corps of Engineers. Washington, DC.
Bowles, Joseph E. (1997) Foundation Analysis andDesign-5th Edition. McGraw-Hill Companies, Inc.
Singapore.

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