MATLAB Modeling of SPT and Grain Size Data in Producing Soil Profile

MATLAB MODELLING OF SPT AND GRAIN SIZE DATA IN PRODUCING SOIL PROFILE

CE 400: PROJECT AND THESIS

Submitted by-Debojit Sarker

Student ID: 0704015

Supervised by-Dr. Md. Zoynul Abedin

Professor,Department of Civil Engineering,

BUET.

Objectives:

To develop a MATLAB computer model that could

produce the soil-profile at a particular location using GPS

coordinates or chainage location.

To validate the model using known soil profile data.

To use predicted borehole log in case studies of designing

practical problems (e.g. Pile Capacity and Liquefaction).

Project Site

Jajira Approach Road of Padma Multipurpose Bridge Project in Madaripur district

Subsurface Investigation:

• Determining the nature of soil at the site and its stratification.

• Obtaining disturbed and undisturbed soil samples for visual identification and

appropriate laboratory tests.

• Determining the depth and nature of bedrock, if and when encountered.

• Performing some in situ field tests, such as Standard Penetration Test (SPT)

• Assessing any special construction problems with respect to the existing

structure(s) nearby

• Determining the position of the R.L. & water table.

Planning for Soil Exploration

Table-1 gives guidelines for initial

planning of borehole spacing. In

our study 15 borings were

conducted within 20KM chainage

at Jajira approach road of Padma

multipurpose bridge project.

Table 1: Spacing of Borings

Position of Boreholes

APBH 05

APBH 06

APB

H 0

7

APB

H 0

8

APB

H 0

9

APB

H 1

0

APB

H 1

1

APB

H 1

2

APB

H 1

3

APB

H 1

4

APB

H 1

5

APB

H 1

6

APB

H 1

7

APB

H 1

8

APB

H 1

9

Bangladesh Geological Survey indicates that the project site Jajira of Madaripur district, in

general, is underlain by recent alluvium. The Padma superficial alluvial river deposits typically

comprise normally-consolidated, low strength compressible clays, or silts and fine sands of low

density.

Applicability and Usefulness of In-situ Tests

Standard Penetration TestThe test consists of the following:Driving the standard split-barrel sampler of dimensions a distance of 460 mm into the soil at the bottom of the boring.Counting the number of blows to drive the sampler the last two 150 mm distances ( total = 300 mm) to obtain the N number. Using a 63.5-kg driving mass (or hammer) falling “free” from a height of 760 mm. several hammer configurations are available.

Standard Dimensions of Standard Split SpoonSPT arrangements

Correlations for Standard Penetration Test

Cohesive

Cohesionless

Correlations for Standard Penetration TestPrediction of pile capacity by SPT (after Shoospasha et. at. 2013)


Skin Friction of pile:

Cohesive (clay):

α Method

Qs=α*Cu*p*ΔL

Sladen (1992):

α=C * ( ϭ eff/ Cu)^0.45

C=0.5 for driven piles

Cohesionless (sand) according to mayerhof,1976:

fav=0.02*Pa*N-avg (for high displacement driven pile)

fav=0.01*Pa*N-avg (for low displacement driven pile)

Qs=p*L*fav

(p=peremeter of pile)

Pile end bearing capacity:

Cohesive (clay):

(Mayerhof)

Qp=9*Cu*Ap

(Ap=area of pile tip)

Cohesionless (sand):

Meyerhof(1976)

Qp=qp * Ap

qp=0.4*Pa*N*L/D <= 4*Pa*N

(N= avg value of SPT)

For Foundation design and analysis purpose (pile foundation)

Clay:

Visic(1977)

Qp=Ap * Cu * Nc*

Nc*=4/3*(ln(Irr) +1)+3.1416/2 +1

O'Neil & Reese (1999)

Ir=347*(Cu/Pa) - 33 <= 300

Sand:

Briaud et al. (1985)

Qp=qp*Ap

qp=19.7*Pa*(N60)^0.36

Clay:

λ method, Vijayvergiya and focht (1972)

fav= λ*(ϭ effective avg +2*Cu)

Qs=p*L*fav

p= perimeter of pile section

Sand:

Briaud et al. (1985)

fav= 0.224*pa*(N60 avg)^0.29

Pa = atmospheric pressure=100 KN/m^2


For Foundation design and analysis purpose (Seismic Soil Liquefaction)

Grain Size Distribution

Soil Type Particle Size

Range, mm

Retained on Mesh

Size/ Sieve No.

Boulder

Cobble

Gravel:

Sand:

Silt

Clay

Coarse

Medium

Fine

Coarse

Medium

Fine

>300

300-75

75-19

19-9.5

9.5-4.75

4.75-2.00

2.00-0.425

0.425-0.075

0.075-0.002

<0.002

12”

3”

¾”

3/8”

No. 4

No. 10

No. 40

No. 200

---

---

Engineering Classification (For particles smaller than 75mm and based on estimated weights)

Coarse grained soils (More than

50% of the material retained on No. 200 sieve

(0.075 mm)

Gravels (More than 50% of coarse

fraction retained on No. 4 sieve

(4.75 mm)

Clean gravelsLess than 5% fines

Gravel with finesMore than 12%

fines

Sands (over 50% of coarse fraction smaller than 4.75

mm)

Clean SandsLess than 5% fines

Sands with finesMore than 12%

fines

Fine grained soils (Over 50% of the material smaller than 0.075 mm)

Silts & ClaysWL < 50

Inorganic

Organic

Silts & ClaysWL > 50

Inorganic

Organic

Soils of high organic origin

Particle Size Distribution of Soil

Typical sieve analysis Graph [at APBH 13]

MATLAB

MATLAB® is a high-level language and interactive environment

for numerical computation, visualization, and programming.

Using MATLAB, you can analyze data, develop algorithms, and

create models and applications.

The language, tools, and built-in math functions enable you to

explore multiple approaches and reach a solution faster than

with spreadsheets or traditional programming languages, such as

C/C++ or Java™.

MATLAB R2013a Win8 screenshot:

Input method for SPT profile (MS Excel Spreadsheet):

chainage- depth

17600 18600 19600 20100 20600 21100 21600 24100 24582 25100 25600 26600 27100 27600

1.5 4 5 5 5 6 5 2 5 5 5 5 4 6 10

3 4 5 3 3 20 5 6 17 17 3 4 7 1 12

4.5 6 6 26 16 18 33 5 10 9 13 3 2 9 11

6 10 7 27 31 12 31 24 6 10 14 11 15 5 3

7.5 11 7 31 26 28 30 19 8 11 12 13 16 18 11

9 11 8 30 15 29 9 23 11 26 16 13 11 16 12

10.5 12 2 32 17 24 12 32 12 22 14 24 18 9 32

12 17 15 33 15 21 13 35 22 24 9 23 38 14 14

13.5 15 37 32 14 20 14 20 24 18 4 19 31 19 16

15 29 29 31 26 32 11 18 23 21 5 23 14 13 21

16.5 27 30 38 24 43 23 25 7

18 30 16 42 23 34 22 22 42

19.5 26 21 46 22 39 21 19 25

SPT contour profile:

Figure : SPT contour profile from chainage 17600 [APBH 05] to 27600 [APBH 19], up to 19.5m depth

Input method for soil-profile (MS Excel Spreadsheet):

APBH-05 APBH-06 APBH-07 APBH-08 APBH-09 APBH-10 APBH-11 APBH-12 APBH-13 APBH-14

Start End Avg

Chainage 17600 18600 19600 20100 20600 21100 21600 24100 24582 25100

Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine % Sand % Fine %

1.35 1.8 1.35 D1 86 14 92 8 94 6 90 10 86 14 94 6 15 85 18 82 8 92 14 86

2.85 3.3 3.075 D2 93 7 83 17 94 6 92 8 93 7 94 6 87 13 86 14 94 6 4 96

4.35 4.8 4.575 D3 94 6 84 16 86 14 93 7 87 13 82 18 94 6

5.85 6.3 6.075 D4 91 9 92 8 89 11 92 8 92 8 91 9 94 6 83 17

7.35 7.82 7.585 D5 84 16 88 12 88 12 94 6 90 10 94 6 93 7 87 13

8.85 9.3 9.075 D6 87 13 87 13 88 12 91 9 95 5

10.35 10.8 10.575 D7 88 12 89 11 91 9 87 13 90 10 92 8 88 12 2 98

11.85 12.3 12.075 D8 90 10 85 15 92 8 94 6 91 9 90 10 91 9 63 37 92 8 20 80

13.35 13.8 13.575 D9 85 15 89 11 87 13 89 11 91 9 86 14 63 37 17 83

14.85 15.3 15.075 D10 89 11 90 10 87 13 90 10 89 11 88 12 84 16 94 6 17 83

16.35 16.8 16.575 D11 92 8 90 10 92 8 90 10 90 10 84 16 10 90

17.85 18.3 18.075 D12 96 4 95 5 67 33 92 8 87 13 89 11 90 10

19.35 19.8 19.575 D13 94 6 88 12 88 12 92 8

Soil-profile (from chainage 17600 to 27600, up to 19.5m depth)

Predicted Borehole Log (At chainage 26100)

Location

Latitude (deg) 23.4009

Longitude (deg) 90.1735

0 0 cohesive very soft N/A 0 0

1.5 5 cohesive soft N/A 46.2 23

3 6 cohesive soft N/A 48.8 42

4.5 3 cohesive soft N/A 39.9 54

6 13 cohesionless medium 0.63 N/A 66

7.5 15 cohesionless medium 0.64 N/A 79


10.5 21 cohesionless dense 0.7 N/A 103

12 31 cohesionless dense 0.83 N/A 115

13.5 25 cohesionless dense 0.72 N/A 128


16.5

18

19.5

effe

ctiv

e s

tress

γ (kN/m 2̂) 15

γ sat (kN/m 2̂)

18

Rela

tive D

en

sit

y

Un

dra

ined

Sh

ear

Str

en

gth

(kP

a)

Gra

ph

ic L

og

Dep

th (

mete

r)

Sam

ple

Typ

e

Sam

ple

Nu

mb

er

Blo

w C

ou

nts

(b

low

s/f

oo

t)

So

il T

yp

e

Co

ns

iste

nc

y

Groundwater Depth (m):

2.5

Elevation(m) PWD:

5.804

Total Depth of Boring:

15

Project Number:Project: Client: Boring No.

Address: Madaripur

Position:

Chainage: 26100

0

5

6

3

13

15

12

21

31

25

19

0

1.5

3

4.5

6

7.5

9

10.5

12

13.5

15

16.5

18

19.5

The ultimate load-carrying capacity Qu of a pile is given by the equation :

Qu = Qp +Qs

Where ,

Qp = Load carrying capacity of the pile point

Qs = Frictional resistance (skin friction) derived from the soil-pile interface.

Allowable pile capacity,

Qa = Qu/ F.S.

Estimating pile capacity (at chainage 21100)

Liquefaction Potential Index (at chainage 21100)

Summary

The developed MATLAB model can predict an intermittent borehole log with

reasonable accuracy.

The developed model gives SPT contours that may be used to identify the soil

spatial stiffness.

The program yields grain size surface plots that may be used to identify the soil

profile.

The estimation of pile capacity suggests that the predicted borehole estimates the

SPT values well.

The variation in liquefaction potential suggests that the model be refined for grain

size estimation.

Thank You