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Transcript of 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
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آزمايشات آزمايشگاهيآزمايش برش مستقيم σ
e
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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
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دوران نود درجه محور هاي تنش هاي اصلي در هر سيكل
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آزمايش سه محوريآزمايشات آزمايشگاهي
واقعيآزمايش سه محوري
استوانه تو خاليآزمايش سه محوري
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K.N. Toosi University of Technology 5/31/2010
Dr. H. Ghasemzadeh 2
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
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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
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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
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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)
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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
K.N. Toosi University of Technology 5/31/2010
Dr. H. Ghasemzadeh 3
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
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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
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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
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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
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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
K.N. Toosi University of Technology 5/31/2010
Dr. H. Ghasemzadeh 4
CrossholeSeismic Testing
Equipment
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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
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Downhole SeismicTesting Equipment
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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
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SensorsSource
SignalAnalyzer
Accelerometer
RayleighSurfaceWaves
In-Situ Surface Wave Testing
Layer 1
Layer 2
Layer 3
Layer 4
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Shear Wave Measurements
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Dr. H. Ghasemzadeh 5
Seismic Piezocone Test (SCPTu)
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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
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• 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
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Downhole Shear Wave Velocity
Anchoring System Automated Source Polarized Wave Downhole Vs with excellent soil coupling.
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Complete Set of Shear Wave TrainsMud Island Site A, Memphis TN
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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
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0 1000 2000 3000u2 (kPa)
0
5
10
15
20
25
30
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0 100 200 300 400
Vs (m/sec) d = 35.7 mm
qt
fs
u2
Vs
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Dr. H. Ghasemzadeh 6
Seismic Flat Dilatometer (SDMT)
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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
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More Better
More Measurements is
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Soil Dynamics Tests (Geophysical Methods)
Electromagnetic Wave Techniques
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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).
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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
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K.N. Toosi University of Technology 5/31/2010
Dr. H. Ghasemzadeh 7
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)
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Ground Penetrating Radar (GPR)
Xadar Sensors & Software GeoRadar
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Illustrative Results from Ground Penetrating Radar (GPR)
Crossing an underground utility corridor
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Illustrative Results from Ground Penetrating Radar (GPR)
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Illustrative Results of Ground Penetrating
Radar (GPR)
Geostratigraphy
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Examples of Ground Penetrating Radar (GPR)
Useful in Locating Underground Utilities
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Dr. H. Ghasemzadeh 8
Results from Ground Penetrating Radar (GPR)
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Results from Ground Penetrating Radar (GPR)
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Electrical Resisitivity Measurements
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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.
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Electrical Resisitivity
Measurements
What will be gained by changing electrodespacing?
Depth of ER survey:i.e., greater spacing influences deeper
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Electrical Resisitivity Measurements
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K.N. Toosi University of Technology 5/31/2010
Dr. H. Ghasemzadeh 9
Electrical Resisitivity Measurements
1 10 100 1000 10000
Bulk Resistivity, (ohm-meters)
Clay
Loam
Loose Sands
Sands & Gravels
Glacial Till
Weathered Rocks
Resistivity Values (ConeTec & GeoProbe, 1997)
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Electrical Resistivity
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Electromagnetic Conductivity (EM)
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Magnetometer Surveys (MS)
Measure relative changesin the earths' magneticfield across a site.
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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.
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A.P. Van den Berg Track Truck
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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
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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
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δe1 δe3
σ
δe
/sk
1
sk
بارگذاری صفحه ای
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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
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Dr. H. Ghasemzadeh 11
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
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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
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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
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