mechanical parameters and bearing capacity of soils ...the soil-structure, which, in turn depends on...

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 2 (2018) pp. 1075-1094

© Research India Publications. http://www.ripublication.com

1075

Mechanical Parameters and Bearing Capacity of Soils Predicted from

Geophysical Data of Shear Wave Velocity

Qassun S. Mohammed Shafiqu a, Erol Güler

b and Ayşe Edinçliler

c

aAssistant Professor, Dr., Civil Engineering Department, Al-Nahrain University, College of Engineering, Baghdad, Iraq. Professor, Dr, Civil Engineering Department, Bogazici University, College of Engineering, Istanbul, Turkey.

Professor, Dr, Earthquake Engineering Department, Bogazici University, College of Engineering, Istanbul, Turkey.

aORCID: 0000-0002-0389-6872

Abstract

The analysis of foundation vibrations and earthquake

problems in geotechnical engineering demands

characterization of dynamic soil properties by geophysical

techniques. Also the dynamic structural analysis of the

superstructures needs knowledge of the dynamic response of

the soil-structure, which, in turn depends on dynamics

properties of soil. The estimation of seismic velocities,

modulus of elasticity and structural properties of soils is not

enough in the design of engineering projects. Therefore, an

ultimate bearing capacity has been predicted using the seismic

shear wave velocity. It is indicated that the allowable bearing

pressure and the coefficient of subgrade reaction together with

many other elasticity parameters may be obtained rapidly and

reliably once the seismic wave velocities are determined in

situ by convenient geophysical survey. In this study, the data

for S and P-waves velocities collected from seismic

investigation reports in the different soil deposits of Iraq. Use

was made of the mathematical correlations connecting several

parameters and wave velocities for studying the layers of soil

presented in Iraqi areas. The soil elastic constants together

with the allowable bearing capacity, and other parameters

were obtained and discussed. It was indicated that for

cohesive and cohesionless soils, up to a shear wave velocity of

300 m/s and 400 m/s respectively, the shear wave velocity

may predicts the bearing capacity relatively well.

Keywords: Bearing capacity, soil parameters, shear wave

velocity, seismic technique, shear modulus.

INTRODUCTION

A footing is the supporting base of a building which forms the

interface across which the loads are transmitted to the

sublayers. Shallow footing represents the foundation were the

structural loads are transmitted to the near-surface soil.

Earthquakes may cause a reduction in bearing capacity and

increase in settlement and tilt of shallow foundations due to

seismic loading. The foundation must be safe both for the

static as well for the dynamic loads imposed by the

earthquakes. Soil-foundation-structure system should work

together in a coherent manner. In particular, if the site is

exposed to high seismic loadings it is highly desirable that the

soil-foundation part of the system should play an appropriate

role in delivering the required overall performance.

In the design of shallow foundation one of the main factors

related to soil is bearing capacity and the other is settlement or

in other words the subgrade reaction. As stated in Grant and

West [1], the seismic "S-wave velocity" is effectiveness

property for estimating the soils capacity. Elastic parameters

are related to shear wave velocity providing allowable bearing

capacity estimating for shallow footings [2].

For the calculation of allowable bearing capacity, the

geophysical methods, utilizing seismic wave velocity

measuring techniques with absolutely no disturbance of

natural site conditions, may yield relatively more realistic

results than those of the geotechnical methods, which are

based primarily on bore hole data and laboratory testing of so-

called undisturbed soil samples [3].

Many researchers have extensively studied to obtain a relation

between the various parameters of soil mechanics and the

seismic wave velocities. Depending upon many experimental

results, Hardin and Black [4], and Hardin and Drnevich [5]

established indispensable relationship between void ratio,

shear rigidity of soils with shear wave velocity. Also, Ohkuba

and Terasaki [6] supplied different expressions relating the

seismic wave velocities to density, permeability, water

content, unconfined compressive strength and modulus of

elasticity. Also the use of geophysical methods in foundation

engineering has been extensively investigated [7, 8, 9, 10, 11

and 12].

Keçeli [10 and 13] indicated that the determination of the

allowable bearing capacity could be obtained by means of the

seismic technique. Tezcan et al. [2]; Kaptan et al. [14] has

defined an allowable bearing capacity and a settlement as

depending on the layer thickness. But, it is well known that

the soil bearing capacity, settlement and modulus of elasticity

cannot be dependent on the layer thickness. Nevertheless, they

obtained also an allowable bearing capacity by changing the

notation of the relations in the article of Keçeli [13].

THEORY

The response of soils to dynamic loading is controlled mostly

by the mechanical properties of the soil. Many types of

geotechnical engineering problems are associated with

dynamic loading, such as: machine vibrations, seismic

loading, liquefaction and cyclic transient loading, etc. The

dynamic soil parameters related with dynamic loading are

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1076

shear wave velocity (Vs), damping ratio (D), shear modulus

(G), and Poisson’s ratio (ν), which are also used in many non-

dynamic type problems. The problem of predicting the

bearing capacity of soils from wave propagation properties is

that the soil undergoes only very low strain during the wave

propogation. However when soils are subjected to earthquake

loads or static loads upto failure, they undergo large strains.

The waves S via P velocities have been symbol as Vs and Vp respectively. At the time they are measured, G, K or E, ν, Ec

with other elasticity parameters can be estimated from Eqs (1)

to (8). Using the equations will help in finding the allowable

bearing capacity.

1) Shear modulus (G) connect with Vs by Equation (1):

G = ρ Vs2

(1)

Where ρ is the mass density equal to ρ = γ/g , γ is the unit

weight of the soil and gis the acceleration due to gravity

which isgiven as 9.8g m.s2.

The unit mass density relates with P-wave velocity Vpas

shown in Equation (2)

γ = γ0+ 0.002 Vp (2)

Tezcan et al., [2] shows that γo is reference unit weight and

equal to γo= 16 kN/m3 for loose soils. With respect to [15],

few parameters (i.e., elastic) were given in Eqs (3) to (9):

2) Elasticity modulus (Ed)

E = ρ Vp2

(3)

3) The (Ec) which is Oedometric modulus presented as in

Equation (4)

Ec = E (1-v)/(1+v)(1-2v) (4)

4) Bulk modulus (K) is expressed in Equation (5) as

K =2(1+v)G / 3(1-2v) (5)

5) Poisson’s ratio (ν) is given as in Equation (6) as

ν=(α -2) / 2(α-1) (6)

where α= Ec / G= (Vp / Vs)2 (7)

6) Coefficient of Subgrade ks, bearing capacities qult and qall are obtained by Eqs (8) to (10) as in [16] and [17] by,

ks = 4 γ Vs = 40 qult (8)

7) Ultimate Bearing Capacity (qult)

qult=ks/40= 4 γ Vs/40=0.1 γ Vs (9)

8) As allowable Bearing Capacity (qall)

qall=qult / n =0.1 γVs / n (10)

For soils the safety factor n is (n = 4.0)

Small compressible and large capacities are necessary in

footing construction obtained by the reciprocal amounts of E

and K respectively. G and Vs of a soil deposit is decreased

with enlarging shear strain [18].

MATERIALS AND METHODS OF DATA ANALYSIS

Resources of Geophysical and Geotechnical Data

For many projects in Iraq the engineering parameters of the

different strata from many geophysical and geotechnical

investigation reports are collected [19], and a data base is

prepared for static, shear and compression wave velocities

parameters of different soils for most zones in Iraq as shown

in Table (1) and Figures (1 and 2), where the zones borders

are according to the governorate boundaries. These

parameters are evaluated from field and laboratory tests

results of the available geotechnical and geophysical

investigation reports collected from different resource such

National Center of Construction Laboratories and Research

(NCCLR), engineering consulting bureaus of Baghdad and

Al-Nahrain universities together with some private companies

and laboratories such as Andrea Engineering Test labs, AL-

Ahmed Engineering Test lab and others.

When the seismic wave velocities, Vs and Vp, are obtained,

the elastic parameters are estimated by the Eqs (1) to (7). Also

the subgrade modulus ks, ultimate and allowable bearing

capacities are onbtained depending on the Eqs (8), (9) and

(10) respectively and as will be presented in Table (2).



1077

Figure 1. Map study of seismic zones in Iraq [19] Figure 2. Map study of projects locations in Iraq [19]

Table 1: Iraq seismic zones and sites symbols according to [19]

NO. Zone Governorate Site

symbol

Map

symbol

NO. Zone Governorate Site

symbol

Map

symbol

1

North

Dohuk N1 1 26 Middle Babylon M10 26

2 Dohuk N2 2 27

East

Diyala E1 27

3 Irbil N3 3 28 Diyala E2 28

4 Irbil N4 4 29 West Anbar W2 30

5

Eastern

North

Sulaymaniyah EN1 5 30

Western

south

Karbala WS1 31

6 Sulaymaniyah EN2 6 31 Karbala WS2 32

7 Kirkuk EN3 7 32 Karbala WS3 33

8 Kirkuk EN4 8 33 Karbala WS4 34

9 Kirkuk EN5 9 34 Najaf WS5 35

10 Kirkuk EN6 10 35 Najaf WS6 36

11 Kirkuk EN7 11 36 Eastern Missan ES1 37



1078

12

Western

North

Mosul WN1 12 37 South Missan ES2 38

13 Mosul WN2 13 38 Missan ES3 39

14 Mosul WN3 14 39 Missan ES4 40

15 Salah Al-den WN4 15 40

South

Al Dewaniya S1 41

16 Salah Al-den WN5 16 41 Al Dewaniya S2 42

17 Baghdad M1 17 42 Al Nasiriya S3 43

18

Middle

Baghdad M2 18 43 Al Nasiriya S4 44

19 Baghdad M3 19 44 Al Nasiriya S5 45

20 Baghdad M4 20 45 Al Basrah S6 46





25 Babylon M9 25

Investigated Soil Parameters

The data for soil parameters investigated were taken from

geotechnical and geophysical investigation reports for most

Iraqi soil. Soil parameters such as; γwet ,γdry, c and ϕ which are

given in the geotechnical reports had evaluated by the field or

laboratory tests, also the depth of the water table and

description of the soil types according to borehole logs were

presented in these reports. While the seismic wave velocities

Vs, Vp values are listed in the geophysical reports that been

evaluated from the cross hole and down hole tests. The

geotechnical bore hole should be the same for the geophysical

bore hole or might be different bore hole but they should be

near to each other or collected either from the same borehole

or two adjacent ones which have the same soil layers profile.

The soil strength parameters (c or ϕ ) were evaluated by the

correlations from N value (SPT) according to the type of soil

when their values are not mentioned or evaluated in some of

the soil investigation reports.

Soil Parameters Evaluation

As mentioned earlier the soil parameters γwet ,γdry , c, ϕ

determined from field and laboratory tests results are

presented in the geotechnical investigation reports, and the

dynamic parameters Vs and Vp are prepared from geophysical

investigations reports. Once seismic wave velocities, Vp and

Vs , together with the density are measured, many parameters

of elasticity, such as shear modulus G, oedometric modulus of

elasticity Ec , modulus of elasticity E (Young’s modulus),

bulk modulus K, and Poisson’s ratio ν may be obtained from

the Eqs (1) to (7). Also the subgrade modulus ks, ultimate and

allowable bearing capacities are obtained depending on the

Eqs (8), (9) and (10) respectively.

able (2) presents the geotechnical and geophysical parameters

collected and evaluated together with the values of ks, qult and

qall estimated.



1079

Table 2: Soil properties and bearing capacity in different locations and zones of Iraq.

no. site

depth soil type W.T γwet γdry c ϕ Vp Vs E×103 G×103 ν K×106 Ks×108 qult

1×102 qall

1×102 qult

2×102 qall

2×102 qall

2×102

m m kN/m3 kN/m3 kN/m2 (o) m/s m/s kN/m2 kN/m2 kN/m2 N/m2.s kN/m2 kN/m2 kN/m2 n=4 n=3

1 N1 0-3 Brown silty clay

with little fragment

NO

W.T

18.4 15.3 32 17 992 302 501.95 171.55 0.463 6.62 0.2223 5.56 1.39 4.87 1.22 1.62

3-10 Dense grey gravel

with sand to gravel

with silt and sand

(GP,GP-GM)

19 14.9 0 42 1445 468 1233.6 422.46 0.46 5.14 0.3557 8.89 2.22 16.34 4.08 5.45

2 N2 0-7.5 Reddish brown rock

fragment of

limestone with silty

sand

>25 19.6 16.8 0 39 1623 832 3642.64 1354.1 0.345 39.17 0.6523 16.31 4.08 9.31 2.33 3.1

3 N3 4-10 Brown silt/clay with

few sand & trace of

gravel,(CL-ML)

No

W.T

21.3 18.1 49 28 807 354 706.4 248.56 0.421 1.5 0.3016 7.54 1.89 16.95 4.24 5.65

4. N4 0-6 Brown silt/clay with

few sand,(CL)

21.4 18.1 43 21 988 296 517.13 178.32 0.45 1.72 0.2534 6.33 1.58 8.6 2.15 2.87

6-10 Brown silt/clay with

little sand& few

gravel,(CL-ML)

21.2 17.8 35 34 1460 462 1204.83 413.75 0.456 4.56 0.3918 9.79 2.45 22.45 5.61 7.48

5. EN1 0-4 Unknown 19.9 16.6 94 0 1745 262 419.05 144 0.486 5.13 0.2086 5.21 1.30 5.36 1.34 1.79

4-15 Unknown 20.9 18.4 0 44 2606 576 1963.11 670.6 0.463 8.84 0.4815 12.04 3.01 27.33 6.83 9.11

6 EN2 0-5 Unknown 19.4 17.6 81 3 1485 233 336.53 113.62 0.481 2.95 0.1808 4.52 1.13 4.62 1.16 1.54

5-10 Unknown 21.6 18.1 4 42 2313 384 932.18 283.48 0.467 4.2 0.3318 8.29 2.07 18.57 4.64 6.19

7 EN3 0-4 Brown (CH, CL) 3.9 19.7 16.8 55 0 535 219 253.86 90.6 0.401 0.43 0.1726 4.31 1.08 3.14 0.79 1.05

4-6 Medium brown silty

Sand (SM)

19.6 17.2 21 33 679 301 477.75 172.47 0.385 0.69 0.2359 5.9 1.48 3.13 0.78 1.04

6-12 Dense grey gravel

with sand to gravel

with silt and

sand(GP, ,GP-GM)

19.5 16.8 0 42 1384 733 2760.89 991.7 0.392 4.26 0.5717 14.29 3.57 16.77 4.19 5.59

8

EN4

0-2 Brown silt with

(ML)

2.9 19.4 17.7 5 37 360 145 124.2 44.25 0.403 0.21 0.1125 2.81 0.7 6.33 1.58 2.11

2-6 Stiff brown lean clay

(CL)

17.3 15.8 80 0 514 212 284.06 98.44 0.392 0.42 0.1467 3.67 0.92 4.56 1.14 1.52

6-15 Stiff brown to grey

lean clay (CL)

19.4 17.5 21 39 1065 323 663.2 229.3 0.424 1.43 0.2506 6.27 1.57 9.22 2.3 3.07

9

EN5 2.5 (ML) being Stiff >25 19 16.8 0 32 1125 225 290.15 98.09 0.479 2.3 0.1710 4.28 1.07 2.55 0.63 0.85

2.5-15 (CH, CL) with

consistency very stiff

to hard

20.6 18.2 227 0 1250 321 634.86 216.38 0.467 3.21 0.2645 6.61 1.65 12.94 3.24 4.31

15-20 Very dense silty

gravel with sand

(GM)

20.6 18.2 0 42 2500 476 1409.8 475.9 0.481 12.37 0.3922 9.81 2.45 17.71 4.43 5.9

1seismic method [15]

2conventional method [16]



1080

Table (2): Continue

no. site

depth soil type W.T γwet γdry c ϕ Vp Vs E×103 G×103 ν K×106 Ks×108 qult1×102

qall1×102

qult2×102

qall2×102

qall2×102

m m kN/m3 kN/m3 kN/m2 (o) m/s m/s kN/m2 kN/m2 kN/m2 N/m2.s kN/m2 kN/m2 kN/m2 n=4 n=3

10 EN6 0-10 (CL,CH) very stiff

brown to stiff

2.6 21.0 18.1 120 0 1541 304 585.82 197.91 0.48 4.88 0.2554 6.39 1.6 6.84 1.71 2.28

11 EN7 0-10 Very stiff to hard

brown lean clay (CL)

3.8 20.1 17 130 0 1250 312 585.43 199.53 0.467 2.96 0.2508 6.27 1.57 7.41 1.85 2.47

12 WN1 0-15 moderately gypseous

(CL,CH)

2.8 19 17.3 65 0 1330 459 1069.8 378.56 0.413 2.05 0.3488 8.72 2.18 3.71 0.93 1.24

13 WN2 0-7.5 Dark brown sand silt

with rock fragments

>25 18.3 16 0 37 773 319 542.6 189.3 0.432 1.33 0.2335 5.84 1.46 5.97 1.49 1.99

7.5-20 Brown sand gravel 17.8 15.3 0 42 1113 348 600.3 202.5 0.416 1.14 0.2478 6.2 1.55 15.3 3.83 5.1

14 WN3 4-15 (GM,GP) medium to

very dense

2.3 19.4 16.3 0 38 1057 362 584.6 217.2 0.424 1.36 0.2809 7.02 1.76 7.63 1.91 2.54

15 WN4 0-2 Grey gravel with silt

sometimes with

sand(GM)

No

W.t

18.3 16.8 0 36 714 292 445.39 160.21 0.39 0.67 0.2137 5.34 1.34 4.57 1.14 1.52

2-5 Medium stiff to hard

brown lean clay

sometimes with sand

and gravel to

silt(CL,ML)

20.1 15.3 46 34 1055 346 676.62 238.08 0.421 1.43

0.2782

6.96

1.74

28.03 7.0 9.34

5-10 Dense to very dense

grey gravel with silt

and sand to gravel

17.8 16.1 0 43 1335 606 2009.1 714.45 0.406 3.56 0.4315 10.79 2.7 18.83 4.71 6.28

16 WN5 0-4 Highly gypseoussilty

sand to sandy silt

with little gravel

16 18.4 15.9 0 37 942 451 1030.4 374.97 0.374 1.36 0.3319 8.3 2.07 6 1.5 2

4-20 Silty sand with

gravel to sand with

gravel

19 14.8 0 41 1373 701 2559.4 916.7 0.396 4.1 0.5328 13.32 3.33 13.35 3.34 4.45

17 M1 0-10 slightly

gypseousmarly (CH,

CL,CL-ML)

2.1 18.7 14.8 76 12 544 186 187.1 64.84 0.446 0.578 0.1391 3.48 0.87 4.33 1.08 1.44

10-16 Loose to medium

grey to green silty

sand (SM)

20 16.3 0 36 736 258 381.9 140.42 0.433 1.0 0.2064 5.16 1.29 5.44 1.36 1.81

18

M2 0-8 (CL) stiff to medium

consistency

2.65 20.1 17 125 0 820 265 414.42 144.1 0.438 1.11 0.2131 5.33 1.33 6.42 1.61 2.14

8-15 clayey silty sand to

silty sand loose to

dense

19.1 15.5 0 36 1150 395 815.79 283.26 0.44 2.27 0.3018 7.55 1.89 5.19 1.3 1.73

19 M3 0-10 Soft to stiff brown

lean or fat clay or silt

sometimes lean clay

with sand to sandy

silt (CL,CH,ML)

0.8 18.7 14.9 52 12 443 153 146.53 45.52 0.43 0.31

0.1144 2.86 0.72 2.67 0.67 0.89

10-18 Medium to very

dense grey silt sand

or clayey sand

(SM,SC)

19 14 0 39 769 215 263.34 91.12 0.445 0.8 0.1634 4.1 1.02 9.03 2.26 3

20

M4

0-10 Lean clay stiff to

very stiff

1.55 19.78 17.43 180 0 761 298 538.8 191.5 0.408 0.98 0.2358 5.9 1.47 9.25 2.31 3.08

10-15 Stiff to very stiff

grey to brown to

black lean clay

sometimes with sand

1.55 20.2 17.1 68 16 1113 428 995.34 373.2 0.415 2.1 0.3458 8.65 2.16 9.48 2.37 3.16



1081

(CL)

15-20 Medium grey silty

sand (SM)

20.89 17.02 0 34 1351 507 1388.6 511.6 0.417 2.9 0.4236 10.59 2.65 3.97 0.99 1.32

21 M5 10-15 Loose to medium

grey silty sand (SM)

3.1 18.4 15.6 0 38 1191 430 977.68 336.2 0.454 3.5 0.3165 7.91 1.98 7.23 1.81 2.41

22 M6 0-1 (ML) with filling

materials

1.3 19.00 15.8 28.7 0 322 140 251.99 91.1 0.383 0.36 0.1064 2.66 0.67 1.48

0.37 0.49

1-15 Brown to grey silty

clay to clayey silt

(ML,CL,CH)

18.88 14.7 31.5 0 776 219 403.34 138.51 0.456 1.53 0.1654 4.14 1.03 1.62 0.41 0.54

15-20 (SM,GP) 22.31 17.04 0 38 1504 408 941.3 321.92 0.462 4.13 0.3641 9.10 2.28 8.77 2.19 2.92

23 M7 0-6 (CH) which is stiff

to medium stiff

0.6 19.8 15.8 50 0 641 189 209.16 72.13 0.45 0.7 0.1497 3.74 0.94 2.57 0.64 0.86

6-12 Very stiff brown lean

clay (CL)

19.0 14.5 100 0 675 248 338.44 119.17 0.42 0.71 0.1885 4.71 1.18 5.14 1.29 1.71

12-15 (SM) to Silty Sand

with gravel, medium

stiff to stiff

19.0 15.0 0 37 750 225 284.46 98.09 0.45 0.95 0.1710 4.28 1.07 6.2 1.55 2.07

24 M8 (CH) stiff to very

stiff

19.8 17.1 65 10 841 165 162.7 54.97 0.48 1.36 0.1307 3.27 0.82 6.3 2.1

0-7.5 1.58

7.5-12 (SM) being medium

dense to very dense

2.2 19.0 16.5 0 38 1025 279 440.3 150.8 0.46 1.83 0.2120 5.3 1.33 7.47 1.87 2.49

25 M9 0-5 (CL,CH) sometimes

with sand

1.41 21.26 17.85 90 0 735 260 406.11 145.35 0.397 0.66 0.2211 5.53 1.38 4.63 1.16 1.54

5-15 Losse to dense grey

silty SAND(SM)

18.6 15.4 0 38 1503 369 682.46 242.5 0.403 1.17 0.2745 6.86 1.72 7.31 1.83 2.44

26 M10 0-2.4 Grayish sandy silty

clay soil, medium

consistency

1.5 16.18 14.5 144 0 306 111 57.9 20.33 0.424 0.13 0.0718 1.8 0.45 7.4 1.85 2.47

2.4-15 Grayish medium

silty sand

18.44 16.5 0 38 450 183 176.33 62.98 0.4 0.29 0.1350 3.38 0.84 7.25 1.81 2.42

27 E1 0-10 Very stiff to hard

brown to grisg

brown marl lean clay

(CL)

1.72 21.1 18.3 83 0 976 372 835.49 298.82 0.398 1.37 0.3140 7.85 1.96 4.27 1.07 1.42

28 E2 0-15 Stiff brown clay

(CL)

1.46 20.3 17.1 76 0 1076 398 945.39 331.95 0.424 2.07 0.3232 8.08 2.02 3.9 0.98 1.3

29 W2 0-5 (CL) of very stiff to

stiff consistency

1.75 20.4 17.07 120 0 730 257 386.09 135.85 0.421 0.81 0.2097 5.24 1.31 6.17 1.54 2.06

5-10 Loose to dense grey

to dark grey silty

sand and clayey silty

sand sometimes with

gravel (SM,SC-SM)

18.2 15.2 0 33 1513 379 809.19 282.34 0.433 2.01 0.2759 6.9 1.72 2.91 0.73 0.97

30 WS1 0-5 Stiff brown to green

lean clay

1.2 19.5 15.6 77 0 688 198 223.14 72.87 0.458 0.84 0.1544 3.86 0.97 3.96 0.99 1.32

5-9 Loose to medium

brown to grey silty

sand (SW-SM)

18.4 14.8 0 33 948 265 401.85 137.62 0.46 1.67 0.1950 4.88 1.22 2.94 0.73 0.98



1082

9-15 Very dense grey silty

sand

19.1 15.3 0 36 1370 497 1329.6 463.92 0.433 2.29 0.3797 9.49 2.37 5.19 1.3 1.73

31 WS2 0-18 Loose to very dense

off white yellow,

light brown to grey

sometimes

moderately

gypseoussilty sand or

sand with silt or sand

(SM,SP-SM,SP)

NO

W.T

19.6 17.93 0 38 986 417 958.17 340.98 0.405 1.68 0.3270 8.18 2.04 7.7

1.93 2.57

32 WS3 0-10.5 (CH) gypseous stiff 1.5 18.5 14.7 100 0 1416 312 541.76 183.65 0.475 3.61 0.2309 5.77 1.44 5.14 1.29 1.71

33 WS4 0- 4.5 (SP,SM) yellow to

white dense slightly

to moderately

gypseous sand

0.8 18.8 18 0 37 1433 284 457.0 154.6 0.478 3.46 0.2136 5.34 1.34 6.14 1.53 2.05

4.5-12 (SP,SM) dense to

very dense

19.4 18 0 35 1733 550 1727.2 598.46 0.443 5.05 0.4268 10.67 2.67 4.4 1.1 1.47

12-22 (SP,SM) which is

very dense

19.4 18 0 35 1650 563 1801 627.1 0.436 3.71 0.4369 10.92 2.73 4.4 1.1 1.47

34 WS5 0-10 Very loose grading

to very dense slightly

to moderately

gypseous sand (sm)

or sand with silt (SP-

SM)

2.1 17.5 14.9 0 41 1613 618 1975.9 696.75 0.4185 4.04 0.4326 10.82 2.70 12.29 3.07 4.1

35 WS6 0-1.2 (SM) slightly

gypseous silty sand

0.9 19.1 17 0 43 805 268 412.33 143.37 0.438 1.11 0.2048 5.12 1.28 20.15 5.03 6.71

1.2-7 Medium- dense to

very dense light

brown sand (SP)

19.5 18 0 40 1450 557 1743.5 616.95 0.413 3.34 0.4345 10.86 2.72 11.24 2.81 3.75

7-10 (SM) very dense 19.6 18 0 39 1812 659 2472.2 868.03 0.424 5.42 0.5167 12.92 3.23 9.31 2.33 3.1

36 ES1 0-6 (CL,CH) being stiff

to very stiff

0.41 19.2 14.8 53 4 451 111 69.32 23.67 0.464 0.32 0.08525 2.13 0.53 3.7 0.93 1.23

6-14 Loose grey silty sand

(SM)

20.45 17.8 0 36 605 152 167.53 57.49 0.457 0.65 0.1243 3.11 0.78 5.56 1.39 1.85

14-20 (CH) stiff to very

stiff

19.9 15.6 63 0 690 211 254.57 89.07 0.429 0.61 0.1680 4.2 1.05 3.24 0.81 1.08

37

ES2 0-5 (CL,CH) as stiff to

medium stiff

0.6 18.0 14.6 65 0 377 131 90.15 31.5 0.431 0.22 0.0943 2.36 0.59 3.34 0.84 1.11

5-8

(CL,CH) stiff 19.5 15.8 60 0 604 250 347.98 124.28 0.4 0.58 0.1950 4.88 1.22 3.08 0.77 1.03

8-17 (CL) stiff 20.8 15.9 60 8 1362 420 1082.8 374.17 0.447 3.41 0.3494 8.74 2.18 5.2 1.3 1.73

38 ES3 0-9 (CL,CH) medium

stiff to stiff

0.6 19.7 15.7 80 0 696 179 188.5 64.37 0.464 0.87 0.1411 3.53 0.88 4.11 1.03 1.37

9-18 (CL) stiff 20.9 16.1 60 0 1167 380 886.78 307.76 0.44 2.46 0.3177 7.94 1.99 3.08 0.77 1.03

39 ES4 0-7.5 (CL,CH) stiff to

medium stiff

0.6 19.5 15.1 80 0 500 176 175.96 61.57 0.429 0.41 0.1373 3.43 0.86 4.11 1.03 1.37

7.5-9 Loose grey silty sand 19.5 15.7 0 29 600 200 228.51 79.51 0.437 0.6 0.1560 3.9 0.98 1.58 0.39 0.53

9-10 (CL) stiff 19.5 15.7 60 8 600 250 346.6 124.23 0.395 0.55 0.1950 4.88 1.22 5.2 1.3 1.73

40 S1 0-5 (CL,CH) very stiff

to stiff

0.3 19.6 15 42 8 685 225 281.99 99.02 0.424 0.62 0.1764 4.41 1.10 3.64 0.91 1.21

5-6.5 Loose grey silty sand

(SM)

20.7 17.2 0 33 814 243 340.53 117.34 0.451 1.16 0.2012 5.03 1.26 3.31 0.83 1.1



1083

6.5-10 (CH) very stiff to

stiff

19.3 14.9 65 0 1224 333 645.63 220.2 0.466 3.16 0.2571 6.43 1.61 3.34 0.84 1.11

41 S2 0-1.5 Brown lean clay(CL) 0.3 18.5 14.4 94 0 625 188 193.28 66.65 0.450 0.64 0.1391 3.48 0.87 4.83 1.21 1.61

1.5-2 (SM) loose 20.0 15.0 0 30 909 185 213.45 72.21 0.478 1.62 0.1480 3.7 0.93 1.91 0.48 0.64

2-10 (CL,CH) very stiff

to stiff

19.3 14.7 60 5 909 200 232.17 78.73 0.475 1.55 0.1544 3.86 0.97 4.41 1.1 1.47

42 S3 0-8 Medium stiff to hard

brown or grey or

dark grey lean to fat

clay sometimes with

sand to sandy lean

clay or silt or sandy

silt(CL,CH,ML)

1.2 19.1 15.8 78 0 646 185 198.82 68.72 0.458 0.79 0.1413 3.53 0.88 4.0 1.0 1.33

8-15 Dense to very dense

grey or dark grey or

brown silty sand

otsilty clayey sand or

sand with silt

(SM,SC-SM,SP-SM)

17.7 14.6 0 40 1094 321 562.51 198.94 0.464 2.7 0.2273 5.68 1.42 10.2 2.55 3.4

43 S4 0-12 (CL,CH) medium to

soft

1.7 19.5 15.2 90 3 434 110 70.54 24.06 0.466 0.35 0.0858 2.15 0.54 5.96 1.49 1.99

12-14 Loose grey silty sand

(SM)

20.8 18 0 41 500 145 129.7 44.6 0.454 0.47 0.1206 3.02 0.75 14.61 3.65 4.87

14-15 (CL) very stiff

20.8 17 191 0 600 166 170.56 58.45 0.459 0.69 0.1381 3.45 0.86 9.82 2.46 3.27

44 S5 0-4 (CL) very stiff 4 19.07 15.1 34 0 600 200 223.45 77.75 0.437 1.7 0.1526 3.82 0.95 1.75 0.44 0.58

4-10 (CL,CH) stiff to

hard

19.93 15 112 0 750 240 337.6 117.1 0.442 0.97 0.1913 4.78 1.2 5.76 1.44 1.92

45 S6 0-3 Medium light brown

gypseous soil

1.6 20.3 16.8 0 35 803 329 780.35 258.63 0.397 1.17 0.2671 6.68 1.67 4.61 1.15 1.54

3-10 Medium to very

dense light brown to

grey slightly to

highly gypseoussilty

sand or sand with silt

or sand (SM,SP)

18.9 16.01 0 34 1811 627 1797.46 737.98 0.446 6.59 0.4740 11.85 2.96 3.59 0.89 1.19

46 S7 0-3.7 Grey gypseous

sand (SM)

1.8

18.18 16.1 5.33 39 566 230 269.05 96.012 0.401 0.45 0.1673 4.18 1.05 8.63 2.16 2.88

3.7-15 Grey gypseous silty

sand (SM)

19.16 15.3 8.4 40 1404 365 750.38 256.45 0.463 3.38 0.2797 6.99 1.75 11.04 2.76 3.68

47 S8 0-6 Very soft to stiff

brown lean clay (CL)

5 21.1 16.4 60 0 434 166 168.06 59.47 0.412 0.32 0.1401 3.50 0.88 3.08 0.77 1.03

6-15 Very loose grey

clayey silty sand

(SC-SM)

19 15.3 0 37 510 194 250.53 88.4 0.417 0.50 0.1474 3.69 0.92 6.2 1.55 2.07

48 S9 0-6 (CL,CH) stiff to

medium

1.1 19.7 15.7 80 0 294 117 82.58 29.47 0.401 0.14 0.0922 2.31 0.58 4.11 1.03 1.37

6-12 (CL) stiff 20.9 16.1 60 0 381 198 239.08 83.77 0.427 0.55 0.1655 4.14 1.03 3.08 0.77 1.03

49 S10 0-10 (CL,CH) very soft

to stiff

1.0 18.37 13.92 40 0 550 138 104.6 35.7 0.466 0.51 0.1014 2.54 0.63 2.06 0.52 0.69

10-13 Grey silty sand (SM) 19.63 15.54 0 37 334 103 61.8 21.23 0.455 0.23 0.0801 2 0.5 6.4 1.6 2.13

13-15 (CL) very soft to

stiff

20.02 16.03 48 0 450 102 62.57 21.24 0.473 0.39 0.0817 2.04 0.51 2.47 0.62 0.82



1084

RESULTS AND DISCUSSION

Evaluation of the Allowable Bearing Capacity

In this research, and for each layer of the areas of study the

elastic parameters, were calculated from Eqs (1) to (8). The

relations also provide obtaining of the bearing capacities both

ultimate and allowable according to the Eqs (9) and (10)

respectively. The results obtained are presented in Table (2).

Also, following the classical procedure of [16], the ultimate

and allowable bearing capacities were determined, by

assuming the factor of safety equal to n=3 and 4 and as given

in Table (2) for the purpose of comparison. The numerical

values of the ultimate and allowable bearing capacities

determined in accordance with the conventional Terzaghi

theory and seismic technique (Tezcan et al., 2006) for

cohesive soils are plotted in Figures (3 and 4 respectively).

And the results of ultimate and allowable bearing capacities

estimated from both methods for cohesionless soils are plotted

in Figures (5 and 6 respectively).

Two separate linear regression lines were also shown in the

Figures (3 and 5), for the purpose of indicating the average

values of ultimate bearing pressure determined by ‘seismic’

and ‘conventional’ methods. For cohesive and cohesionless

soils it can be indicated that up to a shear wave velocity of

300 m/s and 400 m/s respectively, the shear wave velocity

predicts the bearing capacity relatively well. Above 300 m/s

and 400 m/s the scatter is large and it looks like there are quite

many points that are falling below the bearing capacity

estimated by the shear wave velocity. The linear regression

line indicates for Vs values smaller than 300 m/s and 400 m/s

a narrow band, which should be regarded as quite acceptable.

The ‘seismic’ method proposed herein yields allowable

bearing cabacities (on the order of 10 to 20%) greater than

those of the ‘conventional’ method for Vs values smaller than

400 m/s. In fact, the ‘conventional’ method fails to produce

reliable and consistent results for relatively strong soils,

because it is difficult to determine the appropriate soil

parameters c and ϕ for use in the ‘conventional’ method [20].

Therefore, from the results the use of ‘seismic’ method can

give an order of magnitude for such strong soils with Vs > 300

m/s for cohesive soils and >400 m/s for cohesionless soils.

The allowable bearing capacity has been obtained at different

sites in various regions of Iraq as shown in Table (2) and

Figures (4 and 6) for cohesive and cohesionless soils

respectively. Factor of safety used for allowable bearing

capacity estimated from shear wave velocity is 4 (Tezcan,

2006), and allowable bearing capacity is estimated from

Terzaghi equation using factor of safety, n=3 and 4, it can be

indicated that values from shear wave velocity are close to

that from conventional method till Vs=300 m/s for cohesive

soils and 400 m/s for cohesionless soils and above these

velocities the scatter is large. It can be concluded from these

graphs that allowable bearing capacity estimated from shear

wave velocity may be obtained for n less than 4 for soils that

have Vs less and equal than 400 m/s. Table (3) shows the

range of values for seismic wave velocities and allowable

bearing capacity for different types of soil with various

description. In order to demonstrate that the technique used

covers all soils types, the values of seismic velocities and

allowable bearing capacity given in Table (3) are compared

with the values for foundation materials given in building

codes with entire seismic velocities covering all soils and

rocks types and with the values calculated by using seismic

velocities of soils and rocks [21] which has been obtained at

thousands of construction sites in various regions of Turkey

since 1990. The comparison shows that the allowable bearing

capacity values obtained from hard through loose soils were in

agreement with the building codes and Keçeli [21] values.

Thus, allowable bearing capacity values obtained by the

technique proposed here are evaluated for accuracy. Table (3)

also demonstrated awide range for soil types description.

Allowable bearing capacity for cohesive and cohesionless

soils is drawn via shear wave velocity for each of the layers as

given in Figures (4 and 6 respectively) which shows linear

empirical relationships between qall and Vs. This is clarified in

Eqs (11 and 12):

For Cohesive Soils qall (kN/m2) =(0.0053Vs - 0.073)×10

2

(11)

For Cohesionless Soils qall(kN/m2)=(0.0048Vs + 4.0E-6)×10

2

(12)

Expressions give slopes which are dimensionless constant

predicting elastic deformability coefficient of shallow footing

caused by load on the considered footings. The slopes of qall

and Vs plots considering impulse/driving load gives

deformability of layers over m3 of foundation layers which is

about 0.5 kNs·m−3

. From Eqs (11 and 12), sublayers are

considered less susceptible to deformation than that near

surface depending on the magnitudes of qall and shear

modulus G which is plotted against Vs for cohesive and

cohesionless soils as shown in Figures (7 and 8 respectively).

As it increases, the degree of elastic deformation decreases.

Although through depth and because of compaction which

cause increasing subsurface consolidation, other tectonically

induced secondary structures like divide, fault lineament and

fold within the sedimentary facies could cause voids in the

subsurface thereby leading to elastic deformation of

subsurface.

The layers also show polynomial relationships between qall and G as shown in Figures (7 and 8) for cohesive and

cohesioless soils respectively. The soil layer density and thus

unit weight provides determination shear wave velocity and

the shear modulus in Equation (1) explaining the influential

variation shown in the relation between allowable bearing

capacity qall and shear modulus G in the layers which is given

by Eqs (13 and 14):

For Cohesive Soils qall (kN/m2) =(-4E-06G2 + 0.0061G + 0.4843)×102

(13)



1085

For Cohesionless Soils qall (kN/m2) = (-1E-06G2 + 0.0043G + 0.6675)×102

(14)

The highest value of qall for sublayers is seen on north zone

and reduces through middle and south of Iraq. In the zones

that are greatly undrained with water the behavior shows less

allowable bearing capacity while higher bearing capacity is

related to unsaturated zones. The higher allowable bearing

capacity value with depth is due to cementation/compaction

which increases with depth.

The larger value of the allowable bearing capacity is obtained

in North of Iraq (i.e., N1) with a value of about 408 kN/m2 and

the lowest is at Middle and South regions (i.e., M10 and S10

respectively) with avalue of about 50 kN/m2. According to the

depths of investigation and soil descriptions shown in Table

(2), three layers with approximate depths can be considered

for investigation, layer one extends to about 6m from the

ground surface, while layer two extends for a depth 6m to

10m and third one for depth between 10m to 15m. qall value

has an average value of about 142 kN/m2 for layer one, while

the average bearing capacity for layer two is about 176

kN/m2and about 162 kN/m

2 for layer three. With respect to

cohesive and non-cohesive soils, the results of the minimum,

maximum and average values of shear modulus, G, and

allowable bearing capacity, qall appears for the layers to a

depth of about 15m from ground surface in the study areas are

as shown in Table (4).

Table 3: Allowable bearing capacity for different soil descriptions.

Soil type Vp -range (m/s) Vs -range

(m/s)

qall ×102

(kN/ m2)

Rock Fragment of Limestone with Silty Sand to Gravel

with Sand or Gravel with Silt and Sand

Silty Sand (Loose)

Silty Sand (Medium)

Silty Sand (Dense)

Gypseous Sand to Silty Sand

Clay (Very Soft to Soft)

Clay (Medium)

Clay (Stiff)

Clay (Very Stiff to Hard)

714-2500

334-909

450-1191

1025-1733

803-1811

294-550

377-820

381-1076

675-1541

292-733

103-243

183-507

279-659

268-627

102-153

131-265

198-398

248-459

1.34-4.08

0.5-1.26

0.84-2.65

1.33-3.23

1.28-2.96

0.5-0.88

0.59-1.33

0.97-2.02

1.18-2.18

Table 4: Shear modulus and allowable bearing capacity for different depths in cohesive and cohesionless soils.

Soil type

Depth

Approx.

(m)

G×103 –value

(kN/m2)

qall×102-value

(kN/m2)

Min. Avg. Max. Min. Avg. Max.

Cohesive

soil

0-6 21.24 105.5 374.17 0.45 1.06 1.96

6-10 83.77 206 413.75 1.03 1.54 2.45

10-15 21.24 207.6 374.17 0.51 1.47 2.18

Cohesionless soil 0-6 44.25 387.76 1354.1 0.7 1.78 4.08

6-10 57.49 693.8 4142.8 0.78 1.97 3.57

10-15 21.23 464.1 3370 0.5 1.76 3.33



1086

Figure 3: Ultimate bearing capacity against shear wave velocity for cohesive soils.

Figure 4: Allowable bearing capacity against shear wave velocity for cohesive soils.

0

5

10

15

20

25

30

0 50 100 150 200 250 300 350 400 450 500

qult(×

10

2 kP

a)

Vs(m/sec)

conventional method [16]

seismic method [15]

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 50 100 150 200 250 300 350 400 450 500

qal

l (×1

02 k

Pa)

Vs (m/sec)

seismic method-n=4 [15]

conventional method-n=3 [16]




1087

Figure 5: Ultimate bearing capacity against shear wave velocity for cohesionless soils.

Figure 6: Allowable bearing capacity against shear wave velocity for cohesionless soils.

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900

Vs (m/sec)

seismic method [15]

conventional method [16]

qal

l(×10

2kP

a)

0

5

10

15

20

25

30

0 100 200 300 400 500 600 700 800 900

qall

(×10

2 k

Pa)

Vs (m/sec)

2.22

4.08

5.45

seismic method-n=4 [15]





1088

Figure 7: Allowable bearing capacity against shear modulus for cohesive soils.

Figure 8: Allowable bearing capacity against shear modulus for cohesionless soils.

Evaluation of the Soil Parameters

This study aimed also at obtaining model equations from the

correlations of the shear wave velocities and the different

geotechnical parameters studied. This was to obtain direct

relationships between the S-wave velocity and the

geotechnical parameters. These equations can be used for a

quick evaluation and inexpensive estimation of the various

soil parameters.

The graphs of the parameters were plotted against the shear

wave velocities. Also, the relations and correlations have been

investigated between seismic velocities and geotechnical

parameters using the best fit curve. The relations give obvious

variations in the geotechnical properties affecting the

velocities differently in different parts of the velocity ranges.

The graphs of modulus of elasticity, E, bulk modulus, K, and

subgrade modulus, ks, against the S-wave velocity (Figures 9,

11 and 13 respectively) gave the empirical equations defined

0

0.5

1

1.5

2

2.5

3

0 50 100 150 200 250 300 350 400 450

qal

l (×

10

2 k

N/m

2 )

G(×103 kPa)

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 200 400 600 800 1000 1200 1400 1600

qal

l (×

10

2 k

N/m

2)

G(×103 kPa)



1089

in Eqs (15, 16 and 17) for cohesive soils. And the plots of

modulus of elasticity, E, bulk modulus, K, and subgrade

modulus, ks, against the S-wave velocity (Figures 10, 12 and

14 respectively) gave the empirical equations defined in Eqs

(18, 19 and 20) for cohesionless soils. The equations shows

polynomial relationships between E with Vs and exponential

relationship between K and Vs and linear relationship between

ks with Vs. The minimum, maximum, and average values of

modulus of elasticity, E, bulk modulus, K, and subgrade

modulus, ks for the cohesive and cohesionless soils estimated

to a depth of about 15m from ground surface in the study

areas are given in Table (4).

This result shows that the lower layers are more compressed

than the first layer. This may be as a result of the geologic

formation of these layers, their level of saturation and the

level of cementation of the geomaterial. It was also indicated

that the Young modulus of the subsurface increased in direct

proportion with the seismic wave velocity and the two

parameters generally increased with depth. This also shows

that the second layer has more strength than the other layers.

The results also shows that the first layer would deform more

easily under shear stress than the lower layers. The bulk

modulus results further confirmed that the second geologic

layer to be more competent than the first layer. The subgrade

modulus ranges also reveals that the second geologic layer is

more competent than the first layer.

For Cohesive Soils

E (kN/m2) = (0.0047Vs

2 + 0.5284Vs-47.13) ×10

3 (15)

K (kN/m2) = (0.1566e

0.0074Vs) ×10

6 (16)

ks (N/m2.s)= (0.0008Vs - 0.0119) ×10

8 (17)

For Cohesionless Soils

E (kN/m2) = (0.0047 Vs

2 – 0.4619Vs

-50.866) ×10

3 (18)

K (kN/m2) = (0.2789e

0.005Vs) ×10

6 (19)

ks (N/m2.s) = (0.0008Vs - 0.0002) ×10

8 (20)

Table 4: Soil parameters for different depths in cohesive and cohesionless soils in the study areas.

Soil type

Depth

Approx.

(m)

E×103 -value

(kN/m2)

K×106-value

(kN/m2)

ks ×108-value

(N/m2.s)

Min. Avg. Max. Min. Avg. Max. Min. Avg. Max.

Cohesive

soil

0-6 57.9 304.14 835.5 0.13 1.34 6.62 0.072 0.169 0.314

6-10 239.1 592.7 1204.8 0.55 1.88 4.56 0.165 0.247 0.392

10-15 62.57 588 1082.8 1.58 1.58 3.41 0.082 0.236 0.35

Cohesionless

soil

0-6 124.2 1057.6 3642.6 0.21 2.28 5.14 0.113 0.303 0.65

6-10 167.5 1926.5 11343 0.29 3.64 14.43 0.124 0.39 1.191

10-15 61.8 1313 9397 0.23 3.43 14.62 0.08 0.316 0.953



1090

Figure 9: Young’s modulus against shear wave velocity for cohesive soils.

Figure 10: Young’s modulus against shear wave velocity for cohesionless soils.

0

200

400

600

800

1000

1200

1400

0 50 100 150 200 250 300 350 400 450 500

E(×

10

3 k

Pa)

Vs(m/sec)

0

500

1000

1500

2000

2500

3000

3500

4000

0 100 200 300 400 500 600 700 800 900

E(×

10

3 k

Pa)

Vs(m/sec)



1091

Figure 11: Bulk modulus against shear wave velocity for cohesive soils.

Figure 12: Bulk modulus against shear wave velocity for cohesionless soils.

0

1

2

3

4

5

6

7

8

9

10

0 50 100 150 200 250 300 350 400 450 500

K(×

10

6 k

Pa)

Vs(m/sec)

0

5

10

15

20

25

30

35

40

0 100 200 300 400 500 600 700 800 900

K(×

10

6 k

Pa)

Vs(m/sec)



1092

Figure 13: Subgrade modulus against shear wave velocity for cohesive soils.

Figure 14: Subgrade modulus against shear wave velocity for cohesionless soils.

CONCLUSION

The conclusions that can be drawn from this study can be

summarized as follows:

1. Ranges for values of seismic wave velocities and

allowable bearing capacity for different types of soil

with various description are presented, extending the

knowledge for the limit of theses values. Also the

values of qall determined for hard through loose soil

types were found to be in agreement with references

values and the building codes.

2. Correlations between seismic velocity Vs and

allowable bearing capacity has been obtained. This

relationship show direct proportionalities between Vs

with qall. The results show that the range of bearing

capacity for the study area was between 50 and 408

kN/m2, being highest at north regions and reduces

through middle and south regions of Iraq.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0 50 100 150 200 250 300 350 400 450 500

k s(×

10

8 N

/m2.s

ec)

Vs(m/sec)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 100 200 300 400 500 600 700 800 900

k s(×

10

8 N

/m2.s

ec)

Vs(m/sec)



1093

3. The cross and down hole tests results revealed three

geologic layers with the second layer being more

competent. qall value has an average value of about

142 kN/m2 for layer one, while the average bearing

capacity for layer two is about 176 kN/m2and about

162 kN/m2 for layer three.

4. As the bearing capacity is a mechanism where large

shear strains develop and the measured shear wave

velocity is based on very small strains, thus the

bearing capacity estimated from the shear wave

velocity may be used to check the values calculated

by other means.

5. The obtained empirical expressions may be taken

into consideration when evaluating and predicting

the parameters of the study area.

6. For wide range of ground conditions, empirical

expressions estimated for the qall using Vs measured

at small shear strains, are appropriate to give reliable

results.

7. Allowable bearing capacity being larger with higher

shear modulus improved by higher shear wave

velocity. For cohesive and cohesionless soils it was

indicated that up to a shear wave velocity of 300 m/s

and 400 m/s respectively, the shear wave velocity

may predicts the bearing capacity relatively well.

8. Based on the empirical formulations obtained from

the data of the sites, top layer show less bearing

capacity comparing with layers two and three

depending on the elastic deformability coefficients of

shallow foundation from the graphs of qall against G.

Also the layers show relationships of seconed order

between qall and G.

9. Correlations between seismic velocity Vs and

geotechnical properties have been derived. These

relations show polynomial relationships between E

with Vs and exponential relationship between K and

Vs and linear relationship between ks with Vs.

REFERENCES

[1] Grant S.and West G. F., 1965, “Interpretation Theory

in Ap- plied Geophysics,” McGraw-Hill, New York, p.

583.

[2] Tezcan, S. S., Ozdemir, Z. and Keceli, A. 2009,

“Seismic Tech- nique to Determine the Allowable

Bearing Pressure for Shallow Foundations in Soils

Sand Socks,” Acta Geophy- sica, Vol. 57, No. 2, pp. 1-

14. http://dx.doi.org/10.2478/s11600-008-0077-z.

[3] Schulze, W.E., 1943, “Grundbau, Deutsche

Forschungsgesellschaft für Bodenmechanik,” 7th ed.,

B.G. Taubner Publishers, Leipzig, Germany. Also

available: Technical University of Istanbul, Issue 48,

No DK624-15, Uçler Printing House, Istanbul, Turkiye.

[4] Hardin, B. O., and Black, W.L., 1968, “Vibration

modulus of normally consolidated clays,” Journal of

the Soil Mechanics and Foundation Division, ASCE,

Vol.94, No. SM2, pp.353-369.

[5] Hardin B. O. and Drnevich V. P., 1972, “Shear

Modulus and Damping in Soils,” Journal of Soil

Mechanics and Foun-dation Division ASCE, Vol. 98,

pp. 667-692.

[6] Ohkubo, T., and Terasaki, A., 1976, “Physical property

and seismic wave velocity of Rocks,” OYO

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