September 2015 Indianapolis IN Gerald Verbeek 1 The disclaimers Im Dutch Im a Conehead But I will try not to be biased 2 Practical Experiences using the CPT 3 Theory Equipment Mindset ID: 802486
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FHWA CPT workshop Practical Experiences using the CPT--September 2015 - Indianapolis, IN--Gerald Verbeek
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Slide2The disclaimersI’m DutchI’m a Conehead
But I will try not to be biased
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Slide3Practical Experiences using the CPT3
Theory Equipment Mindset
Slide4The Theory4
The same theory is used around the world to interpret CPT results
Slide5The Equipment5
The same equipment is used around the world to obtain CPT results
whether for electrical CPT (ASTM D5778)
Slide6The Equipment6Or mechanical CPT (ASTM D3441)
Slide77The Mindset
Slide88The Mindset - US
Slide99The Mindset - US
Slide1010The Mindset - US
Slide1111
Vs.
The Mindset – Aspect 1
Slide1212
The Mindset – Aspect 1
Vs.
Feeling is believing…..or is it?
Slide1313
The Mindset – Aspect 1
Soil Classification according to CUR
(Center for Civil Engineering Project Execution Research and Regulations)
Slide14The Mindset – Aspect 2Vs.
Trust …..but verify?
Slide1515The Mindset – Aspect 2In 2014 ADSC and DFI developed the workshop“Bored Piles / Drilled Shafts Best Practices: Design, Construction, Contracting Methods”5 aspects were reviewed from a North American perspective and from a European perspective:DesignConstructionContracting MethodsInnovations and technologiesQuality Control
Slide1616The Mindset – Aspect 2Typical findings regarding foundation testing:Germany It is possible to calculate the piles bearing capacity based on empirical data. Therefore, there is generally no load test on piles.SpainIt is very unusual to do a Load Test on a drilled shaft.
The Netherlands
It is very unusual to do a load test on a drilled shaft (“maybe for 1 % of the projects one or two piles may be tested”).
Or maybe just trust
Slide17The Mindset – The NetherlandsCPT: “It has always been there”
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1932 -1934
Pieter
Barentsen
develops the first internationally recognized cone model for Cone Penetration Testing (CPT). All testing and production was performed at GMF Gouda.
The Dutch Cone was born and also the first patent in CPT history, applied in 1934 and granted in 1938 to
Goudsche
Machinefabriek
and Pieter
Barentsen
. GMF Gouda became the first manufacturer of CPT equipment on an industrial scale.
1959
GMF Gouda introduces the first hydraulic pushing rigs for 10 ton and later also 20 ton capacity setting a new standard for efficient CPT soundings.
1965
H.K.S.
Begemann
improved the Dutch cone and added an extra sliding shaft for measuring the sleeve friction, resulting in the Friction Jacket Cone, also known as
Begemann
Cone.
1971
After a period of testing, failing and improving the electric cone
penetrometers
with strain gauged measuring bodies become more reliable and popular.
Slide1818One of the first CPT devices (around 1940)The Mindset – The Netherlands“It has always been there”
Slide191950 kN hand operated CPT deviceThe Mindset – The Netherlands“It has always been there”
Slide202050 kN hand operated CPT deviceThe Mindset – The Netherlands“It has always been there”
Slide2121Hand operated 50 kN pusher installed on old army truckThe Mindset – The Netherlands“It has always been there”
Slide2222Manual pusher inside a truckThe Mindset – The Netherlands“It has always been there”
Slide23The Mindset – The Netherlandsthere is only 1 university in The Netherlands where you can get an MSc in Civil Engineering
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Slide2424The Mindset – The Netherlands“Under Ground”Manual geotechnical soil investigation
Slide25The Mindset – The Netherlands25
18 pages – CPT
10 pages – boreholes
6 pages – other soil investigations
Slide26The Mindset – The Netherlands26
Manual geotechnical soil investigation
TOTAL 34 pages
18 pages – CPT
10 pages – boreholes
6 pages – other soil investigations
Geotechnical Engineering Circular 5
TOTAL 42 pages
8 pages – CPT
17 pages – boreholes
17 pages – other soil investigations
Vs.
Slide27. The next slides are taken from presentations by a premier Dutch geotechnical consulting company. They show how CPT is marketed by Dutch firms within The Netherlands and abroad.
The Mindset – The Netherlands
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Slide28. For site investigations CPT’s are usually carried out in combination with a few boreholes for soil sampling. Next to an almost continuous profile is speed another advantage. Per unit 200 to 300 meter of soil profile can be collected per day.
The Mindset – The Netherlands
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Slide29CPT data are used for soil stratigraphy and soil classification , and correlations can also provide information regarding: State characteristics soil unit weight, overconsolidation ratio, in-situ horizontal stress Strength characteristics
undrained shear strength, sensitivity, effective stress strength parameters
Deformation characteristics
constrainted
modulus,
undrained
Young’s Modulus, small strain shear modulus.
Consolidation and flow characteristics
consolidation and permeability coefficients
The Mindset – The Netherlands
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Slide30CPT’s used for geotechnical profiles
The Mindset – The Netherlands
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Slide31An alternative approach is to apply the in situ test results directly to engineering problems as :Determination of pile bearing capacities and load settlement responseBearing capacities for shallow foundationsQuality control for ground improvementEvaluation of the potential for soil liquefactionThe Mindset – The Netherlands
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What mostly happens
Slide32Some examples of geophysical measurements that can be carried out using CPT equipment:Magnetic measurements : to determine the length of (sheet) piles, soil anchors and the presence of unexploded ordnance;Seismic measurements : to determine the potential of liquefaction and elastic soil parameters for dynamic loading;Conductivity measurements : to assist in the interpretation of (airborne) electromagnetic and geo-electric measurements and to determine the fresh- salt water interface in groundwater. Presently used e.g. in a European project aimed at predicting effects of climate change to coastal areas.
The Mindset – The Netherlands
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Slide33Magnetic measurements
The effect of a piece of steel reinforcement steel measured at different distances
showing the
vertical, horizontal
and derivative component of the magnetic field
The Mindset – The Netherlands
Slide34Conductivity measurements Standard CPT graph - soil classification - conductivity - chloride mg/l
The Mindset – The Netherlands
Slide35Comprehensive coverage using the Dutch Eurocode 7 standards and guidelines for accurate design of vertically loaded bearing piles and tension piles and shallow foundations with both horizontal and vertical loading.Easy soil data definition by importing CPT data, which can be done in several formats, including the Geotechnical Exchange Format (GEF). The automatic CPT interpretation tool provides soil-type dependent suggestions for all applicable parameters.The Mindset – The Netherlands
Work in progress
Questionable
Slide36Eurocode 7 applies to geotechnical aspects of the design of buildings and civil engineering works.part 1 covers the general basis for the geotechnical aspects of the design of buildings and civil engineering works, assessment of geotechnical data, use of ground improvement, ground reinforcement, dewatering and fill. It also includes calculation rules for spread foundations, piles, retaining structures, embankments and slopes. part 2 covers requirements for the execution, interpretation and use of results of laboratory tests to assist in the geotechnical design of structures.It is the national standard in 33 European countries since 2010.The Mindset – Europe
Slide37The Mindset – Europe CEN member states
Slide38The Mindset – Europe
CEN member states
Slide39The Mindset – Europe
Slide40Cone penetration tests are extensively used in soil mechanics to determine the layer structure and the bearing capacity of the subsoil. Data from the cone penetration test is stored digitally and supplied to the client in the format they request. The result is a large variety of formats which makes mutual exchange problematic and hinders durable storage of penetration test data. The standard Geotechncial Exchange Format brings an end to this confusing situation.The Mindset – The Netherlands
Slide41In summary:CPT is known to every civil engineerCPT is the test method of choice for soil investigationsCPT is generally accepted as a reliable method for soil investigations (clients – contractors – consultants – regulatory agencies)The CPT results are generally accepted as direct inputs for the design of any foundation type.The Mindset – The Netherlands
It is just what you do
Slide42Thank you!Questions?42