soil dynamics3 test - KNTU homepage webFTP client

K.N. Toosi University of Technology 5/31/2010

Dr. H. Ghasemzadeh 1

رفتار ديناميكي خاك ها

Hasan Ghasemzadeh

Soil dynamics1

آزمايشات آزمايشگاهي

آزمايشات صحرايي

رفتار خاک ها تحت بار سيکلی

2

آزمايشات آزمايشگاهيآزمايش برش مستقيم σ

e

3

آزمايشات آزمايشگاهيآزمايش برش نوساني ساده

σ

N

كمبريج -رسكو و همكاران

پتانسيل روانگرايي–مدول برشي –ميرايي

تعداد نوسانات متناظر با شكست

تنش قائم ثابتدوران محور هاي تنش هاي اصلي

شرايط كرننش مسطح4

آزمايش سه محوريآزمايشات آزمايشگاهي

σd

N

تعداد نوسانات متناظر با شكست

σd= σ1 –σ3

13 12 33

دوران نود درجه محور هاي تنش هاي اصلي در هر سيكل

5

آزمايش سه محوريآزمايشات آزمايشگاهي

واقعيآزمايش سه محوري

استوانه تو خاليآزمايش سه محوري

6



آزمايش ستون تشديدآزمايشات آزمايشگاهي

a column of soil is subjected to an oscillating longitudinal or torsional load. The frequency is varied until resonance occur. From the frequency and amplitude at resonance the modulus and damping of the soil can be calculated. A further measure of the damping can be obtained by observing the decay of oscillations when the load is cut off.

Resonant-Column

مدول برشي–ميرايي T = A sin ωt

Apply harmonic torqueMeasure angular rotationSweep across frequencies

7

There are several advantages of the bender element technique: it is non-destructive, allows for unlimited number of tests during the experiment and it is relatively simply to use.

- Testing apparatus is triaxial, consolidometer, resonant column or etc. equipped with bender elements.

آزمايشات آزمايشگاهي

سرعت موج برشيمدول برشي در تغيير مكانهاي كم

Bender elements

8

In-Situ Tests

0.0001 0.001 0.01 0.1 1 10 100 1000

Grain Size (mm)

In-S

itu

Test

Met

hod

SPT

CPT

DMT

PMT

VST

Geophysics

CLAYS SILTS SANDS GRAVELS Cobbles/ Boulders

آزمايشات صحرايي

9

Soil Dynamics Tests (Geophysical Methods)

Mechanical Wave Measurements• Seismic Refraction• Crosshole Tests (CHT)• Downhole Tests (DHT)• Spectral Analysis of Surface Waves• Suspension Logging

Electromagnetic Wave Techniques• Ground Penetrating Radar (GPR)• Electromagnetic Conductivity (EM)• Surface Resistivity (SR)• Magnetometer Surveys (MT)

10

Mechanical Wave Nondestructive measurements (s < 10-4%) Both borehole geophysics and non-invasive

types (conducted across surface). Measurements of wave dispersion:

velocity, frequency, amplitude, attenuation. Determine layering, elastic properties,

stiffness, damping, and inclusions Four basic wave types: Compression (P),

Shear (S), Rayleigh (R), and Love (L).11

Mechanical Body Waves

SourceReceiver (Geophone)

OscilloscopeP

S RTime

Amplitude

R S12



Mechanical Waves (Compression)

0 1000 2000 3000 4000 5000 6000 7000 8000

Compression Wave Velocity, Vp (m/s)

Fresh Water

Sea Water

Clay

Sand

Till

Ice

Weathered Rocks

Intact Rocks

Steel

P - Wave Velocities

13

Mechanical Waves (Shear)

0 1000 2000 3000 4000

Shear Wave Velocity, VS (m/s)

Fresh Water

Sea Water

Clay

Sand

Till

Ice

Weathered Rocks

Intact Rocks

Steel

S - W ave V elocities

} V s = 0

14

Geophysical Equipment

Seismograph Spectrum Analyzer

Portable Analyzer Velocity Recorder15

Seismic Refraction

Vertical GeophonesSource(Plate)

Rock: Vp2

ASTM D 5777

Soil: Vp1

oscilloscope

x1x2x3x4

t1t2

t3t4

Note: Vp1 < Vp2

zR

Determine depthto rock layer, zR

16

Seismic Refraction

0.000

0.005

0.010

0.015

0.020

Tra

vel T

ime

(sec

on

ds)

0 10 20 30 40 50 Distance From Source (meters)

Horizontal Soil Layer over Rock

Vp1 = 1350 m/s

1

Vp2 = 4880 m/s

1z

x2

V VV Vc

c p2 p1

p2 p1

Depth to Rock:zc = 5.65 m

xc = 15.0 m

x values

t va

lues

17

Shear Wave Velocity, Vs

Fundamental measurement in all solids (steel, concrete, wood, soils, rocks)

Initial small-strain stiffness represented

by shear modulus: G0 = Vs2

(alias Gdyn = Gmax = G0) Applies to all static & dynamic problems at

small strains (s < 10-6) Applicable to both undrained & drained

loading cases in geotechnical engineering. 18



CrossholeSeismic Testing

Equipment

19

Crosshole TestingOscilloscope

PVC-cased Borehole

PVC-cased Borehole

DownholeHammer(Source) Velocity

Transducer(GeophoneReceiver)

t

x

Shear Wave Velocity:Vs = x/t

TestDepth

ASTM D 4428

Pump

packer

Note: Verticality of casingmust be established by

slope inclinometers to correctdistances x with depth.

SlopeInclinometer

SlopeInclinometer

© Paul Mayne/GTx = fctn(z)

from inclinometers

20

Downhole SeismicTesting Equipment

21

Downhole TestingOscilloscope

Cased Borehole

TestDepth

Interval

HorizontalVelocity

Transducers(GeophoneReceivers)

packer

PumpHorizontal Plank

with normal load

Shear Wave Velocity:Vs = R/t

z1z2

t

R12 = z1

2 + x2

R22 = z2

2 + x2

x

Hammer

© Paul Mayne/GT

22

SensorsSource

SignalAnalyzer

Accelerometer

RayleighSurfaceWaves

In-Situ Surface Wave Testing

Layer 1

Layer 2

Layer 3

Layer 4

23

Shear Wave Measurements

24



Seismic Piezocone Test (SCPTu)

25

60o

fs

qc

Vs

u1

u2

Cone Tip Stress, qt Penetration Porewater Pressure,u Sleeve Friction, fs Arrival Time of Downhole Shear Wave, ts

Obtains Four Independent Measurements with Depth:Hybrid of Penetrometerwith Downhole Geophysics

Seismic Piezocone Test

26

• Electronically-actuated

• Self-contained

• Left and right polarization

• Modified beam uses fin to enhance shear wave generation

• Successfully tested to depths of 20m

• Capable of being used with traditional impulse hammer

Automated Seismic Source

27

Downhole Shear Wave Velocity

Anchoring System Automated Source Polarized Wave Downhole Vs with excellent soil coupling.

28

Complete Set of Shear Wave TrainsMud Island Site A, Memphis TN

29

Sounding

0

5

10

15

20

25

30

35

0 10 20 30 40

qt (MPa)

Dep

th (

m)

0

5

10

15

20

25

30

35

0 100 200 300

fs (kPa)

0

5

10

15

20

25

30

35

0 1000 2000 3000u2 (kPa)

0

5

10

15

20

25

30

35

0 100 200 300 400

Vs (m/sec) d = 35.7 mm

qt

fs

u2

Vs

30



Seismic Flat Dilatometer (SDMT)

31

Seismic DMTs at UMASS, Amherst

0

2

4

6

8

10

12

0 2 4 6 8

Lift-off Pressure po (bars)

De

pth

(m

)

0

2

4

6

8

10

12

0 20 40 60 80

Travel Time of Shear Wave (ms)

SDMT1

SDMT4

SDMT5

6

8

10

12

DMT 2

DMT 3

SDT 4

0

2

4

6

8

10

12

0 5 10 15

Expansion Pressure p1 (bars)

SDMT 1

DMT 2

DMT 3

SDMT 4

SDMT 5

32

More Better

More Measurements is

33

Soil Dynamics Tests (Geophysical Methods)

Electromagnetic Wave Techniques

34

Electromagnetic Wave

Nondestructive methods Non-invasive; conducted across surface. Measurements of electrical & magnetic

properties of the ground: resistivity (conductivity), permittivity, dielectric, and magnetic fields.

Cover wide spectrum in frequencies (10 Hz < f < 1022 Hz).

35

Electromagnetic Wave

Surface Mapping Techniques:• Ground Penetrating Radar (GPR)• Electrical Resistivity (ER) Surveys• Electromagnetic Conductivity (EM)• Magnetometer Surveys (MS)

Downhole Techniques• Resistivity probes, MIPs, RCPTu • 2-d and 3-d Tomography

36



Ground Penetrating Radar (GPR)

GPR surveys conducted on gridded areas Pair of transmitting and receiver antennae Short impulses of high-freq EM wave Relative changes in dielectric properties

reflect differences in subsurface. Depth of exploration is soil dependent (up

to 30 m in dry sands; only 3 m in wet saturated clay)

37

Ground Penetrating Radar (GPR)

Xadar Sensors & Software GeoRadar

38

Illustrative Results from Ground Penetrating Radar (GPR)

Crossing an underground utility corridor

39

Illustrative Results from Ground Penetrating Radar (GPR)

40

Illustrative Results of Ground Penetrating

Radar (GPR)

Geostratigraphy

41

Examples of Ground Penetrating Radar (GPR)

Useful in Locating Underground Utilities

42



Results from Ground Penetrating Radar (GPR)

43

Results from Ground Penetrating Radar (GPR)

44

Electrical Resisitivity Measurements

45

Electrical Resistivity (ER) Surveys

Resisitivity R (ohm-m) is an electrical property. It is the reciprocal of conductivity

Arrays of electrodes used to measure changes in potential.

Evaluate changes in soil types and variations in pore fluids

Used to map faults, karst features (caves, sinkholes), stratigraphy, contaminant plumes.

46

Electrical Resisitivity

Measurements

What will be gained by changing electrodespacing?

Depth of ER survey:i.e., greater spacing influences deeper

47


48




1 10 100 1000 10000

Bulk Resistivity, (ohm-meters)

Clay

Loam

Loose Sands

Sands & Gravels

Glacial Till

Weathered Rocks

Resistivity Values (ConeTec & GeoProbe, 1997)

49

Electrical Resistivity

50

Electromagnetic Conductivity (EM)

51

Magnetometer Surveys (MS)

Measure relative changesin the earths' magneticfield across a site.

52

In-Situ Testing - Objectives

Select in-situ tests for augmenting, supplementing, and even replacing borings.

Realize the applicability of various in-situ methods to different soil conditions.

Recognize the complementary nature of in-situ direct push methods with conventional rotary drilling & sampling methods.

Recognize values for utilizing these methods and quality implications for their underuse.

53

A.P. Van den Berg Track Truck

54



55

Boreholes Data CollectionProperty Method

Shear (s) and compression (p) wave velocity

Suspension (p-s) logging

Downhole logging (impulsive and vibratory sources)

Density Gravity-density logging

Compensated density (- logging)

Geometry of contact (depths/thicknesses)

Geologic logs (examination of core/cuttings)

Geophysical logging suite–Compensated density (-)–Neutron porosity

–Dual induction resistivity

–Full waveform sonic

Modulus reduction and damping

Resonant column and torsional shear tests

Sediment particle size Gradation testing

Borehole condition Acoustic televiewer

Caliper logging

Gyroscope surveys

Shear ModulusMeasurement of Gmax

Correlation to (N1)60

56

بارگذاری صفحه ای

ماده سازی حفر گالریٓ و ا

زمايشٓ نصب سيستم ا

زمايشٓ انجام ا

زمايشٓ ارائه نتايچ ا

بارگذاری وبار برداری می شود بار و تغییر مکانها ثبت می 30در 30صفحه

گردد

زمايش ٓمراحل انجام ا

57

δe1 δe3

σ

δe

/sk

1

sk

بارگذاری صفحه ای

58

بلوک تشديد

Vertical

Concrete Block

Pit bottom

4.51.5

0.7

0.75

2.75

Horizontal

حرکت دورانی

شتاب سنچ

224 f

aA z

z

شتاب قائمدامنه ارتعاش قائم

فرکانس ارتعاش59

بلوک تشديد

فرکانس ھای متفاوت تشديد فرکانس طبيعی

uCضريب فشار يکنواخت الاستيک خاک

z

z

zus A

AAfM

A

AFCk

224

zz AfMMaF 224

A

MfCu

224

جرم سيستم

سطح مقطع بلوک

11 A

ACC uu 2

1 10mA ضريب فشار يکنواخت الاستيک خاکبرای پی به سطح مقطع

1A

Az

fnz

f

Am2/mA

f2f1

nzf

ff

212

60



مقادير تجربی

Cبرشی يکنواخت الاستيک خاکضريب

روابط تجربی ضريب فشار يکنواخت الاستيک خاک

C برشی يکنواخت

جابجايی برشی

uCC 5.0

)1( 2 s

u

EC

)1(

13.12

A

EC s

u

uCC3

3

تنش غير يکنواخت ارتعاش گھواره ای

Cبرشی غير يکنواخت الاستيک خاکضريب

Cضريب فشار غير يکنواخت الاستيک خاک

CC3

2

uCC 2Barkan

Barkan

توصيه موسسه استاندارد ھندوستان

پراکاش

Vesic

61 62

آزمايشات در آزمايشگاه

1. Shear Box Test

Motor drive

Load cell to measure Shear Force

Normal load

Rollers

Soil

Porous plates

Top platen

Measure relative horizontal displacement, dx

vertical displacement of top platen, dy

63

Tests to measure soil strength2. The Triaxial Test

Cell pressure Pore pressure

and volume change

Rubber membrane

Cell water

O-ring seals

Porous filter disc

Confining cylinder

Deviator load

Soil

64

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