Statistical correlations between undrained shear strength (CU) and both SPT- N value and net limit pressure (PL) for cohesive glacial tills

Kanagaratnam Balachandran, Jinyuan Liu, Laifa Cao, Scott Peaker

In the proceedings of: GeoOttawa 2017: 70th Canadian Geotechnical Conference; 12th joint with IAH-CNC

Session: Field Investigation I - CPT, Geophysics, etc.

ABSTRACT: : This paper presents a statistical analysis of the correlation between the undrained shear strength (CU) and both standard penetration test blow count (SPT-N) and net limit pressure (PL) value for cohesive glacial tills in the city of Toronto. The Cu values were derived from the field vane shear test (FVST) and PL values were derived from SPT-N. This study is based on the results of a comprehensive geotechnical investigation for the Eglinton Crosstown Light Rail Transit (LRT) project in Toronto. This study focused primarily on the statistical correlations between CU and both SPT-N and PL value for cohesive glacial tills with different textures, such as silty clay till and clayey silt till. In this paper, the correlation equations between SPT (N) 60 values and CU, PL values and CU are suggested for cohesive glacial tills. Additionally, the range of SPT (N) 60, CU, PL and the pressuremeter constant () factor for cohesive glacial tills is suggested. RÉSUMÉ: Cet article présente une analyse statistique de la corrélation entre la force de cisaillement non découpée/ drainée(CU) et le taux de détection de pénétration standard (SPT-N) et la pression de limite nette (PL) pour les calculs glaciaires cohésifs dans la ville de Toronto. Les valeurs de Cu ont été dérivées du test de cisaillement de la piste de champ (FVST) et les valeurs de PL ont été dérivées de SPT-N. Cette étude est basée sur les résultats d'une enquête géotechnique globale pour le projet Eglinton Crosstown Light Rail Transit (LRT) à Toronto. Cette étude portait principalement sur les corrélations statistiques entre la CU et la SPT-N et la valeur PL pour les labies glaciaires cohésives avec différentes textures, telles que la till d'argile et le till de limon argileux. Dans cet article, les équations de corrélation entre SPT - (N)60 valeurs et CU, PL valeurs et CU sont suggérées pour les cultures glaciaires cohésives. En outre, la gamme de SPT - (N)60, CU, PL et le facteur de constante de pressionmètcohésifs est suggérée. . 1.0 INTRODUCTION Statistical correlations between in-situ soil testing results have become growingly more and more popular during the site investigations especially for being practical and economical. Hence, estimations of geotechnical parameters from in situ test results hold a significant place in the geotechnical design practice. Keep that in mind, in this study also the statistical correlation between undrained shear strength (CU) from the field vane shear test (FVST) and both standard penetration test blow count (SPT-N) and net limit pressure (PL) value for cohesive glacial tills were performed. The SPT is a well-established method for soil investigation. As many forms of the test are in use worldwide, standardization is essential in order to facilitate the comparison of results from different investigations, even at the same site (Thorburm 1986). In this paper, SPT was performed in accordance with the ASTM D 1586 method. This means that the test was standardized using a 50 mm O.D. split spoon sampler, driven into the soil with a 64 kg weight having a free fall of 760 mm auto hammer was used exclusively on the project. The blows required to drive the split barrel sample a distance of 305 mm, after an initial penetration of 152 mm, is referred to as the SPT N value. This method has been accepted internationally and is useful in field investigation. The FVST is a moderately rapid and economical in situ method for determining the undrained shear strength of fully saturated clays without disturbance. The test is relatively simple, quick, and provides a cost-effective way of estimating the soil shear strength. Therefore, it is widely used and much more common in geotechnical investigations. The results of the test are not reliable if clay contains silt or sand. In this paper, FVST is performed in accordance with the ASTM D 2573 (1) method. This means that the test

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Kanagaratnam Balachandran; Jinyuan Liu; Laifa Cao; Scott Peaker (2017) Statistical correlations between undrained shear strength (CU) and both SPT- N value and net limit pressure (PL) for cohesive glacial tills in GEO2017. Ottawa, Ontario: Canadian Geotechnical Society.

@article{geo2017Paper202,author = Kanagaratnam Balachandran; Jinyuan Liu; Laifa Cao; Scott Peaker,title = Statistical correlations between undrained shear strength (CU) and both SPT- N value and net limit pressure (PL) for cohesive glacial tills,year = 2017}