The Use of Full Flow The Use of Full Flow Penetrometers in an Penetrometers in an

Intermediate Soil;Intermediate Soil;SiltSilt

By: Alan Abad By: Alan Abad & &

Mark JonesMark Jones

The Motivation for this Quest The Motivation for this Quest toto

DiscoveryDiscovery• This study focused in the use of three types This study focused in the use of three types

of in situ penetrometers in order to identify of in situ penetrometers in order to identify the behavior of intermediate soils and their the behavior of intermediate soils and their susceptibility to liquefactionsusceptibility to liquefaction

• Testing with these tools was done at multiple Testing with these tools was done at multiple penetration rates and with cyclic penetration penetration rates and with cyclic penetration

• Prior to this study little was known about the Prior to this study little was known about the implementation of full flow penetrometers in implementation of full flow penetrometers in situ in intermediate soils situ in intermediate soils

Our Path to DiscoveryOur Path to Discovery

• The scope of the project required a The scope of the project required a background in both civil and background in both civil and mechanical engineeringmechanical engineering

• In a combined effort to get the In a combined effort to get the desired results, MJ focused on the desired results, MJ focused on the geotechnical aspects while AA geotechnical aspects while AA focused on the mechanical toolsfocused on the mechanical tools

What is Silt?What is Silt?

• It is a type of soil produced by It is a type of soil produced by the mechanical weathering of the mechanical weathering of rockrock

• It could happen due to grinding It could happen due to grinding of glaciers, sandblasting by the of glaciers, sandblasting by the wind and water erosion on the wind and water erosion on the beds of rivers and streamsbeds of rivers and streams

• It displays clay-like and sand-It displays clay-like and sand-like propertieslike properties

• It feels like flour and it’s hard to It feels like flour and it’s hard to work withwork with

LARGEST

Gravel

Sand

Silt

Clay

Smallest

Silt Sample PreparationSilt Sample PreparationMJ’s GoalMJ’s Goal

• The best sample preparation method is one The best sample preparation method is one that, when completed, best resembles an that, when completed, best resembles an actual undisturbed sample from the fieldactual undisturbed sample from the field

• Two samples of uniformly deposited Two samples of uniformly deposited commercially available silt where prepared:commercially available silt where prepared:

One in a dense state by air pluviation, One in a dense state by air pluviation, and and the other in a looser state by pluviation the other in a looser state by pluviation

through waterthrough water

Silt and the PluviatorSilt and the Pluviator

The Pluviator

The Mold

The Silt

The wet pluviated sample

The Need for ToolsThe Need for ToolsAA’s GoalAA’s Goal

• Penetrometers are devices used to measure Penetrometers are devices used to measure the firmness or resistance to penetration of the firmness or resistance to penetration of soilsoil

• T-Bar, Ball and Cone penetrometers are tools T-Bar, Ball and Cone penetrometers are tools used during in situ investigations of soft clays used during in situ investigations of soft clays offshoreoffshore

• With the use of these tools, we attempted to With the use of these tools, we attempted to characterize the uniformity, undrained and characterize the uniformity, undrained and remolded strength and liquefaction resistance remolded strength and liquefaction resistance of siltsof silts

The Penetrometers Journey The Penetrometers Journey

• With the use of Solidworks the first With the use of Solidworks the first sketches of the tools were drawn to sketches of the tools were drawn to scale to fit the hydraulic actuator scale to fit the hydraulic actuator with which they will be used with which they will be used

• By using a lathe and welder the By using a lathe and welder the different types of penetrometers and different types of penetrometers and with their different ratios were with their different ratios were brought to lifebrought to life

The Tools that made the The Tools that made the ToolsTools

The Solidworks Design

The Final Outcome

The Lathe- what made them

Hydraulic Actuator- what they were designed for

How it all came togetherHow it all came together

• Once the specimen preparation method had been Once the specimen preparation method had been developed, and the penetrometers fabricated and developed, and the penetrometers fabricated and calibrated, we were able to test the siltcalibrated, we were able to test the silt

• Important information that we needed to perform Important information that we needed to perform quality reduced scale testing:quality reduced scale testing:

Area Ratios; Projected area/ push rod area. We Area Ratios; Projected area/ push rod area. We used 2/1, 5/1, 10/1 and 15/1 ratios for our probesused 2/1, 5/1, 10/1 and 15/1 ratios for our probes

Rates; Velocity/diameter of probe = rate. In our Rates; Velocity/diameter of probe = rate. In our tests we used 0.005, 0.05, 0.5 and 5.0 ratestests we used 0.005, 0.05, 0.5 and 5.0 rates

Test Profile; initial penetration, cycling, final Test Profile; initial penetration, cycling, final penetration and extractionpenetration and extraction

Cycling; 10 up and down cycles within a specified Cycling; 10 up and down cycles within a specified height height

The Testing ProcessThe Testing Process

• For the actual testing there were many other For the actual testing there were many other variables that needed to be fixed such as:variables that needed to be fixed such as:

Learning how to properly use and manipulate Learning how to properly use and manipulate Labview to control the testing systemsLabview to control the testing systems

Learning how to calibrate amplifiers and loadcells Learning how to calibrate amplifiers and loadcells for accurate data measuring for accurate data measuring

Learning how to operate the hydraulic pumps Learning how to operate the hydraulic pumps with cautionwith caution

• Network failures, limited availability of some of Network failures, limited availability of some of the equipment and undesirable results were the equipment and undesirable results were some of the problems we had to overcome along some of the problems we had to overcome along the waythe way

Our DiscoveryOur Discovery• After all the testing was concluded and all the data After all the testing was concluded and all the data

carefully analyzed we were able to determine that carefully analyzed we were able to determine that penetration resistance tends to increase with increased penetration resistance tends to increase with increased penetration ratepenetration rate

Such behavior was expected based on the characteristics Such behavior was expected based on the characteristics of both sands and claysof both sands and clays

• Cyclic penetration of the penetrometers resulted in rapid Cyclic penetration of the penetrometers resulted in rapid strength degradation of the silt, most likely due to the strength degradation of the silt, most likely due to the quick increase in pore water pressure resulting from quick increase in pore water pressure resulting from penetrationpenetration

Such strength degradation is similar to that of sensitive Such strength degradation is similar to that of sensitive claysclays

• There is minimal or almost no resistance during extractionThere is minimal or almost no resistance during extraction Very different from clayVery different from clay

Our ResultsOur Results

Graph of test conducted with a 10/1 T-bar at a ratio of 5.0

Graph of test conducted with a 10/1 T-bar at a ratio of 0.05

▪ For visual purposes different scales were used on both graphs. The test with the 0.05 ratio is almost 100X smaller than that of the test with the 5.0 ratio.

Tbar 3

0

20

40

60

80

100

120

140

160

-5000 0 5000 10000 15000 20000 25000

Penetration Resistance (kPa)

Dep

th (m

m)

Tbar 1

0

20

40

60

80

100

120

140

160

-100 0 100 200 300 400 500 600

Penetration Resistance (kPa)

Depth

(m

m)

How it applies to Earthquake How it applies to Earthquake EngineeringEngineering

• The results of this study are important for The results of this study are important for the evaluation of site response to the evaluation of site response to earthquake motions through:earthquake motions through:

Characterization of intermediate soilsCharacterization of intermediate soils Evaluation of their behavior Evaluation of their behavior • The rapid loss of strength resulting from The rapid loss of strength resulting from

cyclic loading is of particular importance cyclic loading is of particular importance when evaluating the potential of ground when evaluating the potential of ground movement resulting from an earthquakemovement resulting from an earthquake

Future Plans Future Plans

• We hope to see our findings being of some We hope to see our findings being of some help and use for in situ studies help and use for in situ studies

• And some day down the road…..And some day down the road…..

Acknowledgements Acknowledgements

Special thanks to:Special thanks to: Jason DeJongJason DeJongNick Yafrate Nick Yafrate Chad Justice Chad Justice

And all the others who contributed intoAnd all the others who contributed into

making this quest to discovery making this quest to discovery possiblepossible

Any Questions?Any Questions?

Thank you.Thank you.