modeling and simulation of compression strength for firm clay in swampy area of ahoada east

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International Journal of Advanced Research in Engineering and Technology

(IJARET) Volume 6, Issue 12, Dec 2015, pp. 73-85, Article ID: IJARET_06_12_008

Available online at

http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=6&IType=12

ISSN Print: 0976-6480 and ISSN Online: 0976-6499

© IAEME Publication

___________________________________________________________________________

MODELING AND SIMULATION OF

COMPRESSION STRENGTH FOR FIRM

CLAY IN SWAMPY AREA OF AHOADA

EAST

Eluozo. S. N

Subaka Nigeria Limited Port Harcourt Rivers State of Nigeria

Director and Principal Consultant Civil and Environmental Engineering,

Research and Development

Ode T

Department of Civil Engineering, faculty of Engineering

Rivers State University of Science and Technology Port Harcourt

ABSTRACT

The behaviuor of firm clay should be observed in design and construction

of any projects, the deposition of firm clay were monitored to determined its

compressive strength in swampy area of Ahoada east, these type of formation

are observed to be influenced by other environmental changes, it definitely

generate vertical and horizontal shrinkage on drying and expansion of wetting

during seasonal variation, the tendency of seasonal volume changes under

vegetation covers that extend to about one metre or more, the study of firm has

been observed to be influenced by seasonal variation, these conditions are

most influences observed in firm clay, the study of predicting compressive

strength for firm clay were imperative to monitor the rate of increment in

various depth at the study environment, several determination of compression

index has been produced through experimental data and empirical solutions,

these concept has not been thorough applied to determined its effective in

predicting compression strength on its index for firm clay, These applied

concepts has generated theoretical valued from simulation process, these

results were subjected to comparative test, both parameters developed

faviourable fits validating the generated model for firm clay

Key words: Modeling and Simulation, Compressive Strength, and Firm Clay

Eluozo. S. N and Ode T


Cite this Article: Eluozo. S. N and Ode T, Modeling and Simulation of

Compression Strength for Firm Clay in Swampy Area of Ahoada East.

International Journal of Advanced Research in Engineering and Technology,

6(12), 2015, pp. 73-85.

http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=6&IType=12

1. INTRODUCTION

The surface settlement resulting from consolidation settlement may range from a few

centimeters up to several meters, depending on the thickness of the clay deposit, its

previous loading history and the magnitude of the increased stress caused by the new

embankment load. In contrast to primary consolidation, secondary consolidation is

long-term form of settlement that occurs under a constant vertical effective stress (i.e.,

the vertical effective stress is not changing with time). In secondary consolidation, the

excess pore pressure dissipation associated with primary consolidation has essentially

dissipated, thus secondary consolidation is a decrease in void ratio change that occurs

after primary consolidation and progresses under a constant vertical effective stress.

Secondary consolidation is characterized by a continuing decrease in void ratio

resulting from rearrangement of the soil fabric with time Steven and Hap 2004.

Many experimental studies have shown that natural fine grained soils are

anisotropic and that anisotropy is related to the K0 stress conditions associated with

the process of sedimentation and the plastic straining during consolidation. Initial and

induced anisotropy of natural soils have been also investigated according to the shape

and the inclination of yield curves plotted in p’:q plan (Mitchell and Wong, 1973,

Tavenas and Leroueil, 1979, Graham et al., 1983, Leroueil and Vaughan, 1990,

Wheeler et al., 2003).

The mechanical response of natural clays strongly depends on changes in

microstructure; in particular when the initial preferential orientation is modified by

further loading paths having a different orientation with respect to the initial principal

stresses (Hicher et al., 2000). They stressed that the main difficulty was the

experimental determination of accurate model parameters. Various authors (Dafalias,

1986, Whittle and Kavvadas, 1994 among others) have proposed to model the initial

anisotropy by considering an inclined yield curve and a hardening law depending on

the volumetric plastic strain, with possible rotation of the yield curve (Wheeler et al.,

2003). Pietruszczak and Pande (2001) have described the inherent anisotropy within

the framework of multi-laminate model. Cudny and Vermeer (2004) have shown the

limitation of Pietruszczak and Pande’s model and they proposed a modified multi-

laminate model by considering, in addition to the strength anisotropy, the

destructuration of natural clays. Pestana and Whittle (1999) extended the model of

Whittle and Kavvadas (1994) with significant changes in the form of the bounding

surface and hardening laws to provide a unified model for sands and clays. They

checked the validity of this model in clays in Pestana et al. (2002). More recently,

Wheeler et al. (2003) have demonstrated that the use of the plastic volumetric strains

alone to consider the development and erasure of plastic anisotropy may lead to

unrealistic predictions under certain stress paths. Wheeler et al. (2003) proposed an

anisotropic elastoplastic model for soft clays by relating the change of the yield curve

inclination to volumetric and shear plastic straining. As both volumetric and shear

plastic straining are related to the stress loading path and to the stress history,

Modeling and Simulation of Compression Strength For Firm Clay In Swampy Area of

Ahoada East


2. GOVERNING EQUATION

02

2

dx

dc

dx

dcV

dx

cd

P

p

L

I

(1)

Nomenclature

PI = Plastic Index

PL = Plastic Limit

V = Void Ratio

= Porosity

Z = Dept

The developed system generated the equation that progress the following expressions

bellow

02

2

dx

dcV

dx

cd

P

P

L

I

(2)

Let

0n

n

n xaC

1

11

n

n

n xnaC

2

211 1n

n

n xannC

011

1

2

2

n

n

n

n

n

n

L

I xnaVxannP

P

(3)

Replace n in the 1st term by n+2 and in the 2nd term by n+1, so that we have;

01120

1

0

2

n

n

n

n

n

n

L

I xanVxannP

P

(4)

i.e.

12 112 nn

L

I anVannP

P

(5)

12

1 1

2

nnP

P

anVa

L

I

n

n

(6)

2

1

2

nP

P

aVa

L

I

n

n

(7)



These derivations generated the developed model as it is express bellow,

(8)

Subject equation (8) to the following boundary condition

HoCandoC 10

x

P

P

V

L

I

aaxC

10

010 aaoC

i.e. 010 aa

(9)

x

P

P

V

L

I

L

I

a

P

P

VxC

1

01

!2

Ha

P

P

VoC

L

I

1

1

!2

V

P

PH

a L

I

1

(10)

Substitute (9) into equation (10)

01 aa

V

P

PH

a L

I

0 (11)

Hence, the particular solution of equation (8) is of the form: subject to this

generated model, we have these expressions further from t5he derived solution

considering other condition in system as it produced the final model considering every

parameters expressed bellow.

x

P

P

V

L

I

L

I

L

I

V

P

PH

V

P

PH

xC

0

1

x

P

P

V

L

I

L

I

V

P

PH

xC

(12)

x

P

P

V

L

I

aaxC

10


Ahoada East


3. MATERIALS AND METHOD

Standard laboratory experiment where performed to monitor compression index of

firm clay at different formation, the soil deposition of the strata were collected in

sequences base on the structural deposition at different locations, this samples

collected at different location generated variations at different depth producing

deposition of stiff clay compression at different strata, the experimental result are

applied to be compared with the theoretical values to determined the validation of the

model.

4. RESULTS AND DISCUSSION

Results and discussion are presented in tables including graphical representation of

compression index for firm clay

Table 1 Predictive Values of firm clay compression index at Different Depth

Depth [M] Predictive of Firm Clay Cc

0.2 0.004

0.4 0.0084

0.6 0.0126

0.8 0.0168

1 0.021

1.2 0.0252

1.4 0.0294

1.6 0.0356

1.8 0.0378

2 0.042

2.2 0.0462

2.4 0.0504

2.6 0.0546

2.8 0.0588

3 0.06

Table 2 Predicted and Measured of compression index for firm clay at Different Depth

Depth [M] Predictive of Firm Clay Cc Measured Values of firm Clay Cc

0.2 0.004 0.0056

0.4 0.0084 0.0102

0.6 0.0126 0.0148

0.8 0.0168 0.0194

1 0.021 0.024

1.2 0.0252 0.0286

1.4 0.0294 0.0286

1.6 0.0356 0.0378

1.8 0.0378 0.0424

2 0.042 0.047

2.2 0.0462 0.0516

2.4 0.0504 0.0562

2.6 0.0546 0.0608

2.8 0.0588 0.0654

3 0.06 0.07




Depth [M] Predictive of Stiff Clay Cc

0.2 0.00287

0.4 0.0056

0.6 0.0084

0.8 0.011

1 0.014

1.2 0.0168

1.4 0.0196

1.6 0.0224

1.8 0.0252

2 0.0287

2.2 0.0308

2.4 0.0336

2.6 0.0364

2.8 0.0372

3 0.042

3.2 0.0448

3.4 0.0476

3.6 0.0504

3.8 0.0532

4 0.056

4.2 0.0588

4.4 0.0616


Depth [M] Predictive of firm Clay Cc Measured Values of firm Clay Cc

0.2 0.00287 0.002602

0.4 0.0056 0.005206

0.6 0.0084 0.007824

0.8 0.011 0.01043

1 0.014 0.01304

1.2 0.0168 0.0157

1.4 0.0196 0.0183

1.6 0.0224 0.0209

1.8 0.0252 0.0235

2 0.0287 0.0262

2.2 0.0308 0.0288

2.4 0.0336 0.0314

2.6 0.0364 0.0341

2.8 0.0372 0.0367

3 0.042 0.0394

3.2 0.0448 0.042

3.4 0.0476 0.0447

3.6 0.0504 0.0473

3.8 0.0532 0.0499

4 0.056 0.0526

4.2 0.0588 0.0553

4.4 0.0616 0.0579


Ahoada East



Depth [M] Predictive of firm Clay Cc

0.2 0.017

0.4 0.032

0.6 0.048

0.8 0.06


Depth [M] Predictive of firm Clay Cc Measured Values of firm clay

0.2 0.017 0.0189

0.4 0.032 0.0385

0.6 0.048 0.061

0.8 0.06 0.0843


Depth [M] Predictive of firm Clay Cc

0.2 0.0031

0.4 0.006

0.6 0.009

0.8 0.015

1 0.017

1.2 0.018

1.4 0.021

1.6 0.024

1.8 0.027

2 0.03

2.2 0.033

2.4 0.036

2.6 0.039

2.8 0.042

3 0.045

3.2 0.048

3.4 0.051

3.6 0.054

3.8 0.056

4 0.06



0.2 0.0031 0.0028

0.4 0.006 0.0056

0.6 0.009 0.0084

0.8 0.015 0.0112

1 0.017 0.014

1.2 0.018 0.0168

1.4 0.021 0.0196

1.6 0.024 0.0224

1.8 0.027 0.0252

2 0.03 0.028

2.2 0.033 0.031

2.4 0.036 0.034




2.6 0.039 0.037

2.8 0.042 0.0392

3 0.045 0.042

3.2 0.048 0.045

3.4 0.051 0.048

3.6 0.054 0.05

3.8 0.056 0.053

4 0.06 0.056

Figure 1 Predictive Values of firm clay compression index at Different Depth

Figure 2 Predicted and Measured of compression index for firm clay at Different

Depth

y = -0.0008x2 + 0.0233x - 0.001 R² = 0.9985

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 1 2 3 4

Pre

dic

ted

val

ues

fo

r Fi

rm C

lay

Depth [m]

Predictive of Firm Clay Cc

Poly. (Predictive of Firm Clay Cc)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 1 2 3 4

pre

dic

tive

val

ues

fo

r fi

rm c

lay

Depth [M]

Predictive of Firm Clay Cc

Measured Values of firm Clay Cc


Ahoada East




Depth

y = 4E-05x2 + 0.0138x + 0.0001 R² = 0.9994

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 1 2 3 4 5

pre

dic

tive

val

ues

fo

r fi

rm c

lay

Depth [M]

Predictive of Stiff Clay Cc

Poly. (Predictive of Stiff Clay Cc)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 1 2 3 4 5

pre

dic

tive

an

d m

easu

red

val

ues

fo

r fi

rm c

lay

on

co

mp

ress

ion

ind

ex

Depth [M]

Predictive of firm Clay Cc

Measured Values of firm Clay Cc





Depth

y = -0.0187x2 + 0.0912x - 0.0008 R² = 0.9988

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 0.2 0.4 0.6 0.8 1

pre

dic

tive

val

ues

fo

r fi

rm c

lay

Depth [M]


Poly. (Predictive of firm Clay Cc)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0 0.2 0.4 0.6 0.8 1

pre

dic

tive

an

d m

easu

red

val

ue

s fo

r fi

rm c

lay

on

co

mp

ress

ion

ind

ex

Depth [M]


Measured Values of firm clay


Ahoada East




Depth

The figure presented express various deposition of firm clay under compression

pressured in construction processes, figure one and two express the behaviour of firm

clay in swampy environment, the trend from the figure express gradual increment of

firm clay to the optimum level at three metres but slight fluctuation on gradual

increase of the firm soil compressibility were observed in the figure stated above,

while figure three and four maintained linear increase but at three metres sudden

slight vacillation were observed, thus linear increment of compressibility continued to

the optimum level at four metres, figure five and six expressed the progressive

condition of firm clay compressibility in linear state, but the predictive values

experiences variation compared to other deposited compression parameters expressed

y = 0.0147x + 0.0008 R² = 0.9981

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 1 2 3 4 5

pre

dic

tive

val

ues

fo

r fi

rm c

lay

Depth [M]


Linear (Predictive of firm Clay Cc)

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0 1 2 3 4 5

pre

dic

tive

an

d m

easu

red

val

ues

fo

r fi

rm

clay

on

co

mp

ress

ion

ind

ex

Depth [M]


Measured Values of firm clay



in previous figure, the parameter predicted the compressibility at the optimum level of

less than one metres. While figure seven and eight express fluctuation between

[0.8and 1.2M] thus maintained linear compressibility from [1.3-4m] the experimental

date were compared with the predictive values from figure one to eight, both

parameters expressed best fits validating the developed model values for firm soil

compression in the study environment

5. CONCLUSION

Firm, clays are soil that compact shrink formations, definitely they suffer substantial

vertical and horizontal shrinkage through the process of drying and expansion on

wetting due to seasonal changes. These formations that experiences seasonal volume

changes under grass extend to about one metre below the surface. Most developed

nations, it is observed to extend up to 4 m or more below large trees. Definitely the

degree or volume changes, particularly in firm clay soils are determined on change

through seasonal influences variations including closeness of trees and shrubs. The

behaviour of firm can be pressured by environmental change, these implies that the

greater the seasonable variation, the greater the volume change in the formation. The

behaviour firm clay are observed in terms of foundations design and construction

subjected to it variation, these are expressed in the developed model that generated the

predictive values. The determination of compression index for firm clay are normally

generated from experimental data or empirical solutions, but for this study the

application of mathematical modeling method has not been applied in any current

literature, the developed model has definitely generated theoretical values from

simulation carried out, these were compared with experimental data, both parameters

developed faviourable fits. The figure developed various increment of firm soil

compressibility at different depths under the specification for firm soil compression

index.

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[1] Steven F. B; Hap S. L 2004 Estimation of Compression Properties of Clayey

Soils Salt Lake Valley, Utah Report Prepared for the Utah Department of

Transportation Research Division Civil and Environmental Engineering

Department University of Utah

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destructuration of soft clays within the multi-laminate framework. Computers

and Geotechnics 31, No. 1, 1-22.

[3] Hicher, P. Y., Wahyudi, H. & Tessier, D. (2000). Microstructural analysis of

inherent and induced anisotropy in clay. Mechanics of Cohesive-Frictional

Materials 5, No. 5, 341-371.

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