Statistical Correlations between effective angle of internal friction (?’) and SPT- N value for cohesive glacial tills

Kanagaratnam Balachandran, Laifa Cao

Dans les comptes rendus d’articles de la conférence: GeoSt. John's 2019: 72nd Canadian Geotechnical Conference

Session: Reliability/Probabilistic Approaches

ABSTRACT: : This paper presents a statistical analysis of the correlation between the effective angle of internal friction (and standard penetration test blow count (SPT-N) for cohesive glacial tills in the city of Toronto. The ( values were derived from the consolidated undrained triaxial test. 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 ( and SPT-N value for cohesive glacial tills with different textures, such as silty clay, silty clay till and clayey silt till. In this paper, the correlation equations between SPT (N) 60 values and ( is suggested for cohesive glacial tills. Additionally, the range of SPT (N) 60, (suggested. RÉSUMÉ: nombre de coups par essai de pénétration standard (SPT-N) pour des tills glaciaires cohésifs dans la ville de Toronto. Les valeurs ( d'une enquête géotechnique complète réalisée dans le cadre du projet de train léger sur rail Eglinton Crosstown à Toronto. Cette étude a porté principalement sur les corrélations statistiques entre ( -N pour des tills glaciaires cohésifs de différargileux. Dans cet article, les équations de corrélation entre les valeurs SPT - (N) 60 et ( tills glaciaires cohérents. En outre, la plage de SPT - (N) 60, ( . 1.0 INTRODUCTION Statistical correlations between in-situ soil testing results have become growingly more and more poplar 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 statistical correlation between standard penetration test (SPT) and consolidated undrained (CU) triaxial test was 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 sampler 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 CU triaxial test is a common laboratory testing method widely used for obtaining shear strength parameters for a variety of soil types under undrained condition. It is a conventional laboratory test to determine the shear characteristics under undrained conditions and is applicable to field conditions where soils that have been fully consolidated under one set of stresses are subjected to a change in stress without time for further consolidation to take place (undrained condition), and the field stress conditions are similar to those in the test method. Therefore, it is widely used and much more common in geotechnical investigations. The CU triaxial test is performed in accordance with the ASTM D4767 -11 methods. This means that the specimen is allowed to consolidate under the confining pressure in the initial stage. In this consolidation stage 3 is the same as 1. Then the axial load is applied without drainage. This stage of the test is also commonly referred to as load stage, compression stage or shearing to failure stage. During the CU test, the pore pressures are typically measured so that both total and effective stress strength parameters

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