FHWA CPT workshop Practical Experiences using the CPT

FHWA CPT workshop Practical Experiences using the CPT -September 2015 - Indianapolis, IN -Gerald Verbeek 1

The disclaimers • I’m Dutch • I’m a Conehead 2

Practical Experiences using the CPT Theory Equipment Mindset 3

The Theory The same theory is used around the world to interpret CPT results 4

The Equipment The same equipment is used around the world to obtain CPT results whether for electrical CPT (ASTM D 5778) 5

The Equipment Or mechanical CPT (ASTM D 3441) 6

The Mindset 7

The Mindset - US 8

The Mindset - US 9

The Mindset - US 10

The Mindset – Aspect 1 Vs. 11

The Mindset – Aspect 1 Vs. 12

The Mindset – Aspect 1 13

The Mindset – Aspect 2 Vs.

The Mindset – Aspect 2 In 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: Design Construction Contracting Methods Innovations and technologies Quality Control 15

The Mindset – Aspect 2 Typical 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. Spain It 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”). 16

The Mindset – The Netherlands • CPT: “It has always been there” 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. 17

The Mindset – The Netherlands “It has always been there” One of the first CPT devices (around 1940) 18

The Mindset – The Netherlands “It has always been there” 50 k. N hand operated CPT device 19

The Mindset – The Netherlands “It has always been there” 50 k. N hand operated CPT device 20

The Mindset – The Netherlands “It has always been there” Hand operated 50 k. N pusher installed on old army truck 21

The Mindset – The Netherlands “It has always been there” Manual pusher inside a truck 22

The Mindset – The Netherlands • there is only 1 university in The Netherlands where you can get an MSc in Civil Engineering 23

The Mindset – The Netherlands “Under Ground” Manual geotechnical soil investigation 24

The Mindset – The Netherlands 18 pages – CPT 10 pages – boreholes 6 pages – other soil investigations 25

The Mindset – The Netherlands Manual geotechnical soil investigation TOTAL 34 pages 18 pages – CPT 10 pages – boreholes 6 pages – other soil investigations Vs. Geotechnical Engineering Circular 5 TOTAL 42 pages 8 pages – CPT 17 pages – boreholes 17 pages – other soil investigations 26

The Mindset – The Netherlands. The next slides are taken from presentations by a premier Dutch geotechnical consulting company. They show CPT is marketed by Dutch firms within The Netherlands and abroad. 27

The Mindset – The Netherlands. 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. 28

The Mindset – The Netherlands CPT 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 29

The Mindset – The Netherlands CPT’s used for geotechnical profiles 30

The Mindset – The Netherlands An alternative approach is to apply the in situ test results directly to engineering problems as : • Determination of pile bearing capacities and load settlement response • Bearing capacities for shallow foundations • Quality control for ground improvement • Evaluation of the potential for soil liquefaction 31

The Mindset – The Netherlands Some 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. 32

The Mindset – The Netherlands Magnetic 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 Conductivity measurements Standard CPT graph - soil classification - conductivity - chloride mg/l

The Mindset – The Netherlands • Comprehensive 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 – Europe Eurocode 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 CEN member states

The Mindset – Europe CEN member states

The Mindset – Europe

The Mindset – The Netherlands Cone 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 In summary: • CPT is known to every civil engineer • CPT is the test method of choice for soil investigations • CPT 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.

Thank you! Questions? 42