application of automation in geotechnical testing

8/19/2019 Application of Automation In Geotechnical Testing

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Application of Automation inhni l T in

r. ac an our VP and Director of Lab Systems


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Geocomp’s BriefGeocomp’s BriefIntroductionIntroduction

Geocomp was founded in 1982 by Dr. Allen Marr a former MITresearcher, and a student of Dr.Lambe who co-wrote with Dr.

Whitman the world renowned book on Soil Mechanics.

We are actively involved with

-many subcommittees, keepingus current with changes of

proposed new standards.


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High Tech Labys ems

Three DivisionsThree Divisions

1. Products Division2. Consulting

3. erv ces v s on


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Central Arter “Bi Di ” Pro ect

We are located outside Boston, MA the center of the largest

public work in the US (over $ 14 billion).


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-


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Project Facts:Project Facts:

• 13 million cubic yards of soil

• Trucks lined end to end would

Panama Canal

• Nearly 4 million cubic yards of–

sidewalk to Tokyo

• Reinforcing steel would form 1

inch steel bar to wrap the earthsequator


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Complex Excavation Support SystemsComplex Excavation Support Systems


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Constrained & Con ested SitesConstrained & Con ested Sites

One

Center

SouthStation

NB


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New Construction Practices

Slurry Wall Construction Jet GroutingDeep Soil Mix andGround Freezing


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a ora ory es ng qu pmena ora ory es ng qu pmen

Courtesy KS-DOT-1968


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Modern Fully Automated Triaxial(UU,CU, CD) and Stress Path

All phases run

automatically

All stress paths

poss e n atriaxial cell


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Chronology and Technological

vances n eo ec n ca es ng

Decade Primary Advances Role of Lab Testing

1920s: Development of fundamental concepts of modern soil mechanics. Lab tests confirm and help extend theoretical concepts.

1930s: Application of fundamental developments to engineering practice.

Meticulous field observations explained with data from new laboratory tests.

1940s: x rapo a on o exper ence o more ar ng pro ec s

Use of laboratory tests to expand envelope of practice and to help interpret fieldmeasurements.

1950s:Major advances in concepts of shear strength culminating in ASCE BoulderConference

La bo r a t o r y i s cen t er o f geo t echn i c a l r esea r ch .

1960s:Larger scale projects (massive dams) undertaken

Field measurements of deformation and pore pressure become a key part ofgeotechnical engineering


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1970s: ocus on e av or an measur ng proper es n s u

New lab devices are more complex. Variety of devices developed to measure physical properties in situ.

1980s: Era of advanced modeling-risk, probability, constitutive relations

Models require more data and more sophisticated data but demand for lab

testing declines.

1990s: Specialized materials and methods like geosynthetics, reinforced soils,flowable fills

Era of the computer-compute and display

Laboratory measurements help make use of these new materials and methods possible

Decreased emphasis on site-specific, hard data

2000s: Automation

Remains to be seen.


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Understanding Geo-SystemsResponse-Behavior

Four major factors ( 4’S):1. Soil: sand and gravel vs. clayan s t

2. Structure: particle

3. State: Memory of soil’s pastand present stress history

4. Stress System: loadcondition from the environment

, , , vs. undrained)


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Geotechnical is a multi-disciplinedcoordination of:

to ForcesMaterial Pro erties: Particlesize, Structure composition,

Index, Compressibility, and

Fluid Flow:

See a e of water thru orous

media

Environmental Effects:Courtesy MnCourtesy Mn--DOTDOT

Climate, rainfall, chemical

Geology, and Geophysics


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Three-phasedmaterial:

airair

water

Solids

geological variability


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Problem-Design Category:

na ys s- ater a roperty

Embankments How hi h stee ?

StrengthCohesive, frictional, time-

Foundations

Deformations Ma nitude

settlements?

Ex v i n

Uniform vs. Differential

Instantaneous vs. Time

Earth RetainingSystems

Seepage Rates

How deep, support,

water?

Pressures


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Typical Sequence for a

eotec n ca es gn ro ect

Soil Mechanics Concepts(stress-strain behavior,

masses)

Geology and Exploration(composition of actual soilmasses)

Experiences ( precedents whatdesi ns have worked wellunder what conditions)

Economics and Liability Issues


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“We have lots of experience in the areaalready.”

“We have used conservative estimates of soil

parameters for design.”

“ ” .

“I had three water content measurements thatI used to estimate the design strength.”

“We do not understand the lab results.”“We don’t have time to run tests.”

“ ’ ” .


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Valid data are essential to any engineer’s work. Anal sis and desi n are based ondata.

==

Experience =Experience = ∑ KnowledgeKnowledge


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ROLE OF GEOTECHNICAL

TESTING

Establish baseline site conditions

Improve quality of analysis

Deve op more cost e ective esign

Determine feasible ways to improve existing

Develop mix formulations

Provide manufacturing quality control andualit assurance

Troubleshoot construction problems


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ROLE OF GEOTECHNICALTESTING (Cont.)

Determine cause of unacceptable performance

M n m ze r s rom a ure, surpr ses, amagesand delays

Develop new materials

Improve our understanding of material behavior


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Failure of Excavated Slo e


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-

FillContractor claimed $12,000,000 +110

+53 Clay+60+53

Till


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ONE TEST IS WORTH ONE


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y test

Terzaghi (1936)------

“I came to the United States and hoped to discoverthe philosopher’s stone by accumulating and

....

It took me two years of strenuous work to discoverthat eolo ical information must be

supplemented by numerical data which can only be obtained by physical tests carried out in a

”a ora ory.


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Terzaghi’s First Consolidation

ev ce

Istanbul, Turkey Istanbul, Turkey


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Consolidation Testing

•Terzaghi, 1925

USACE 1985


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Triaxial Testin


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u oma e es ng qu pmen

Today, we have an amazing choice of devices w t w c to equ p our a orator es.

The primary change in geotechnical lab in theas 30 years as een e n ro uc on anuse of electronics to run tests, collect data and

.

Automated geotechnical equipment run tests, .


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Fully Automated Laboratory

Systems:Hel in clients reduce their risk b offerinHel in clients reduce their risk b offerin

The most advanced fullautomated laboratory

soil testing equipmentin the world

Expert technicalsupport and assistance

w o sys ems an

testing


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Automated Testin E ui ment

Data Acquisition ( Manual Device + DAQ)

utomate Testing

Unconfined Compression

Consolidation

Direct/Residual Shear

As halt and Geos nthetics Testin

Cyclic


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ShearTrac-II

ow rac-

LoadTrac-II


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LoadTrac IILoadTrac II

Automated System Automated System

Machine

with Multiple

apabilities

Triaxial ( UU,CU,CD)Triaxial ( UU,CU,CD)

Consolidation and SwellConsolidation and Swell

apabilities

Unconfined CompressionUnconfined Compression

California Bearing RatioCalifornia Bearing Ratio

a

r ax a yc cr ax a yc c

Constant Rate of Consol .Constant Rate of Consol .

Universal Solutionniversal Solution

Resilient ModulusResilient Modulus


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TESTING CAPABILITIESTESTING CAPABILITIES

Direct Shear Direct Shear

Machineachine

ConsolidationConsolidationwith Multipleith Multiple

apabilitiesapabilities

ons an o umeons an o ume

SwellSwell

Constant StressConstant Stress

SwellSwellniversal Solutionniversal Solution


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Triaxial ( UU,CU,CD)Triaxial ( UU,CU,CD)

Consolidation and SwellConsolidation and Swell

Unconfined CompressionUnconfined Compression

California Bearing RatioCalifornia Bearing Ratio

Triaxial CyclicTriaxial Cyclic

Constant Rate of Consol .Constant Rate of Consol .

Stress PathStress Path

Resilient ModulusResilient Modulus

PermeabilityPermeability


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Common to all Geocomp Systems (LoadTrac-II, FlowTrac-II, ShearTrac-II,..)

Logic programmable chips

Embedded controller with three (03)

CPU’sFour analog channels with signalconditioning and power supplies built-in

22 bit Data Ac uisition and Control

Front panel LCD and Keypad for truemanual controls

All in 100x100 mm2 PCB

Easily removable and Upgradeable


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Control Board: All Software programmable

t roug t e eypa com nat on


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Volume and PressureMeasurements

Manual panels with air

pressure regulators

digital gages

Volumes read of graduated

burettesOperator subjectivity, not

consuming

V l d P


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Volume and Pressure

Measurements

d l


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Modern Volume Pressure Systems:

M cro- tepper r ven F ow pump


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-

Micro-stepper Motor

PS and Drive

Solenoid valves

Piston/Cylinder

Limit switches

Control Board


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-

∆V = 5.363e-4 cc/step x ∆Steps


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-ow rac- ow pump u zes :

A high speed, precision micro stepper motor to regulatepressure and volume to the cell or specimen

A built-in microprocessor to control the micro steppermotor, which drives a piston in and out of a sealed

c linder. A pressure transducer on the end of the cylinder providesthe feedback for control of pressure. The number of

.

Two two-way electronic valves are used to control thedirection of flow to the cell or sample (output valve), and

e manua ra n opera on supp y va ve .


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FlowTrac-II Ca abilities

Apply and maintain the desired. .

while monitoring volume changes

.

ow rates can e set to any va ue between 0.000006 ml/sec. and 3.0.


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a ages

Strain Gages

LVDT

Position sensors


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Position sensors employcon uct ve-p ast cresistance and collector

means of measuringosition without the need of

a solid mechanical coupling.

Position Sensors: Special


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Position Sensors: Special

ea ures

Long life – 100 x 106 movements – .

Repeatability= 0.002 mm

Double bearin s stem on shaftInsensitive to shock and vibration

Spring loaded

Price comparable or even less thanLVDT’s for 10 times superior

P M t


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Pressure Measurements:

Mercury pots

Pressure Sensors: Special


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Pressure Sensors: Special

Features

Reliable semiconductor technologyCalibrated and temperature compensated

Small size, rugged, stainless steelpackage

FS ranges up to to 25000 kPa.

Pressure non-linearity: ±0.1 %FSS

Pressure hysteresis: ±0.015 %FSSRepeatability: ±0.010 %FSS

. .

P S V


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Pressure Sensors: Vent

Load Sensor:


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Load Sensor:

Features pec cat ons

Universal:Tension

Compression

Environmentally sealed

NTEP/OIML approved


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22 bit analog to digital conversion external to the systemcontroller, which operate over an ARC-Net network.

The ARC-Net network permits much higher speedtransmission of data and commands over a longer distance

than does a serial network such as RS232.It also permits the system to be expanded to several loadframes and flow pumps operated from the same computer.

, ,

etc. can be run from one computer with the Windows XPor 2000 operating system. System can log data up to 2000

.

Daisy–chained up to 256 units with unique ID


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Daisy–chained up to 256 units with unique ID

num ers

ONE (01) PC controls several

stations

Pressure-VolumeController

FlowTrac II

Pressure-VolumeController

FlowTrac II

Geocomp

Motor Power

CPU Power

Net Tx

N etR x

Limit Empty

FlowOut

Flow In

LimitFull

OutputValve

SupplyValve

www.geocomp.com

CorporationGeocomp

7

4

1

-

Menu

8

5

2

0

9

6

3

.

Esc

Ent.

Alt

Motor Power

CPU Power

Net Tx

N etR x

Limit Empty

FlowOut

Flow In

LimitFull

OutputValve

SupplyValve

www.geocomp.com

CorporationGeocomp

7

4

1

-

Menu

8

5

2

0

9

6

3

.

Esc

Ent.

Alt

To PC

Terminator

Network line

Terminator

ona un s


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uu --

Remote access and control through


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e ote access a d co t o t oug

Virtual Network Computing (VNC)

VNC can substantially

mprove:

Efficiency

Cost-effectiveness

Fully Automated Triaxial:


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Fully Automated Triaxial:

xamp e o utomat on ene ts

The program takes intoThe program takes intoaccount the followin when itaccount the followin when itapplies the vertical stress:applies the vertical stress:

••Axial load (+) Axial load (+)••Uplift force due to theUplift force due to theconfining (cell) pressure (confining (cell) pressure (--))

•• Weight of the piston (+)Weight of the piston (+)

•• Piston frictionPiston friction --

Full Automation throughout all phases


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Full Automation throughout all phases

of a test until final report

a ura ona ura on asease

Capabilities of AutomatedS stems from the Basic to the Most


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S stems from the Basic to the Most Advanced Geotechnical Test

UC CU

CBR

Incremental

D

CKoU(L)

Consol. with Ko

o

CKoD(L)

CK D U

StrainRowe cell

Triaxial stress path

Cyclic Triaxial

consolidation Resilient Modulus

Typical Outputs: CU & CD


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yp p

r a x a e s s

Typical Stress Paths


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Stress Paths from Ko = 1 Condit ion

LoadingUnloading

40

Compression v increasing

h decreasing

0

20

,

k P a

-20

q

h increasingv decreasing

-60

-40

0 20 40 60 80 100 120

Extension

p, kPa

Stress Path applications in the real


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wor

Stress Paths


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Ko ConsolidatedExtension Test (CKoE)

o .

20

40

60 Compression

Loading Unloading

5 4

3

21 dewatering, consolidation2 Ko loading3 foundation loading

-40

-20

0

,kPa

Extension 9

8

7

5 active wall

6 pore pressure buildup7 excavation unloading

8 pure shear

9 jack reaction

-60

0 20 40 60 80 100 120

p, kPa

Consolidation with LoadTrac-II


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Swell: free and constantvolume

Fixed RingFloating Ring

With Excess Pore Water

Measurements

Consolidation with Mini-

L Tr -III


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L Tr -III

Incremental

Swell: free and constantvolume

xe ngFloating Ring

Measurements

Constant Rate of Consolidation


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Hydraulic Rowe Cell


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Consolidation

Specimen diameters up

to 250 mm

vertical, horizontal and

combined drainage

C clic Triaxial


73/101

All phases run

au oma ca y

Isotropic and

consolidation

Resilient Modulus


74/101

automaticallyaccording to thelatest AASHTOspecifications

Application of Resilient Modulus


75/101

in Pavement Design

Fully Automated


76/101

All hases run

automatically Capable of running

residual strength and

creep tests

Fully Automated Direct


77/101

mp e ear

Universal Shear System

developed by NGI All phases run automatically

and undrained ( constant

volume) shear tests

Full Automated Permeabilit


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All phases run

Ca able of runnin bothconstant gradient andconstant flow rate

ex e wa

permeability tests

Geolo 6: Data Ac uisition


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Designed asDesigned aslow cost wa tolow cost wa toadd dataadd dataacquisition toacquisition toexistingexistingequipmentequipment

Customized Systems


80/101

Large consolidometer up to280 mm (11in.) diameter

Elastic Modulus and PoissonRatio Testing of Soft Rock

Resilient Modulus of As haltCores

Fatigue Life Testing

Pressure Measurements Rowe-Barden Consolidation


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Diameter = 50 cm (20 in.)

H:D ratio = 1:1 and 2:1

Labor saved with Automated


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onso a on es ng

Soil Type Test Time, days Labor, hours

d

Silty sand 16-18 0.5-1 4-12 1

Silty Clay 16-18 1-2 8-16 1

Plastic Clay 16-18 2-3 12-32 1

Includes 12 load steps with one log cycle of secondary compression. Times include preparing specimen,

running test and reporting results. Times for conventional tests assume standard practice of applying each

increment for 24 hrs.

Labor saved with Automated


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Soil Type Test Time, days Labor, hours

d

Silty sand 1 0.5 6-8 2

Silty Clay 2 1 10-16 2

Plastic Clay 5 2 12-24 2

Times include preparing specimen, running test and reporting results.


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700+ Visi tors

Innovation and Success Through Partnership

Iowa State University: HighIowa State University: High--Tech MobileTech Mobile


87/101

eo ec n ca aeo ec n ca a

Iowa State University High-Tech Mobile


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eo ec n ca a



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eo ec n ca a

A special application of the LoadTrac-II unit for


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University of British Columbia, CanadaUniversity of British Columbia, Canada

A special application of the ShearTrac-II unit for


92/101

Scripps Institution of Oceanography: UCSDScripps Institution of Oceanography: UCSD

Research on hydraulic properties of swelling


93/101

-

Advantages of Automated

a qu pmen


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a qu pmen

Maintain and Manage Information FlowFinish Tests Faster

Provide Consistenc in Test Procedures andResults

Permit More Detailed Analysis of Test

Ma e More pec a ze Tests Poss e

Advantages of Automated

a qu pmen


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a qu pmen

Utilize Facilities Better mprove ua y

Present Data to Meet Specific Client Needs

Make Lab Work More Interesting for theTechnician

Improve Image of Lab to ClientsSave Mone :Onl ONE PC Run Several TestinStations

Problems with Automated

Systems


96/101

Systems

-

Longer time to train new users

g er now e ge eve o ec n c ans

Problems if staff turn over

Too much reliance by technician on thecomputer

Problems in Lab Testin


97/101

Shortage of people with interest in the lab and hands-on

knowledge of soil behavior

Decreased appreciation of importance of soil behavior by practitioners

ow eve o n eres n qua y es sCK oU triaxial tests – should be SOP

–

stress path – closest to reality

Future of Geotechnical Testing:

on the dark side


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on the dark side

Gross imbalance between what is taught in,

and what is actually done in practice

commodity service

Bad ast ex eriences: slow results

confusing and contradictory, expensive,resulting in practice alterations to avoid

testing

n e r g s e


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n e r g s e

Rapid demand for test results

More complex designs

requiring more detailed

models, and input parameters

,legal action

Answering public’s demand for

min. negative impact from

constructions

Strain contours from failure analysis

for reinforced slope

Guiding Principle for Test

Conditions


100/101

Conditions

laboratory test

conditions

design as closely

Thank ou for our attention


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application of automation in geotechnical testing

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