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A study of the correlation between soil-rock sounding and column penetration test data
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
2011 (English)Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

Lime-cement columns have been used in Sweden to improve poor soil conditions since the

1970’s. The method is inexpensive and flexible, but is difficult to test since the columns are

manufactured in-situ. Many test-methods have been developed for testing the column strength

during the years. Most of them need to be evaluated using an empirical correction-factor

known as the cone factor. The column penetration test, KPS, is the most commonly used

method in Sweden, it is considered to be reliable since a large part of the column cross-section

is tested. The problem is that the probe easily deviates out of the column to the softer

surrounding soil. Today a pre-drilled guiding-hole, a soil-rock sounding, helps the probe to

stay vertical. Although the soil-rock sounding is commonly not used for evaluation of column

strength, the penetration resistance is recorded. A visual comparison between the plotted

penetration resistances from the two methods shows similarities in both hard and soft areas of

the columns.

The relation can be measured using statistics, such as the correlation coefficient. A strong

correlation was also found, suggesting that a similar equation used to evaluate the undrained

shear strength from the column penetration tests can be applied with the data from the soilrock

soundings. The statically pushed column penetration test probe and the rotated soil-rock

sounding bit bore are likely to cause different failure modes in the column. This means that

different empirical cone factors are needed when the undrained shear strength is evaluated.

By evaluating the ratio between the cone factors of the column penetration test and the data

from the soil-rock soundings from three sites, E-road E18 north of Stockholm, E-road E45

outside Gothenburg and at a construction site at Lidingö, the following aspects of the ratio

was investigated: if the ratio was site-specific; the sensitivity to the binder content; the sleeve

friction and; the sensitivity to rotational speed and rate of penetration. Average columns

formed from the penetration resistance at depth from each site were used during the


The Swedish geotechnical society has standardised two methodologies that can be used for

pre-drilling. The soil-rock sounding methodology which has no fixed rate of penetration or

rotational speed, and the total sounding methodology, based on the Norwegian total sounding

methodology which has fixed rate of penetration and rotational speed. The latter is to prefer

when comparing results between sites.

To remove the sleeve friction, the data from the soil-rock soundings needed to be de-trended.

The amount of de-trending needed to find a constant cone factor varied at the sites between

0.5 kN/m and 1.0 kN/m. This however caused high interference, partly from scaling the

variation. The cone factor for the total sounding methodology was found to be between 0.30-

0.45 times the cone factor for the column penetration test.

Place, publisher, year, edition, pages
2011. , 55 p.
Examensarbete Jord- och bergmekanik, ISSN 1652-599X ; 11/04
Keyword [en]
soil-rock sounding, column penetration, correlation
National Category
Geotechnical Engineering
URN: urn:nbn:se:kth:diva-40853OAI: diva2:442492
Subject / course
Soil and Rock Mechanics
Educational program
Master of Science in Engineering - Urban Management
Life Earth Science
Available from: 2011-09-21 Created: 2011-09-21 Last updated: 2011-09-21Bibliographically approved

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