Correletion Between Standard Penetration Test with Unconfined Compressive Strength and Index Properties of Fine-Grained Soil

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Addis Ababa University


The properties of soil play an important role in many practices for geotechnical engineering. To determine the real values of these properties special techniques should be followed such as undisturbed samples and initial overburden pressures should be taken into consideration. Actually, it is difficult to obtain 100 % undisturbed samples due to handling, transportation, release of overburden pressure and poor laboratory conditions. So, prediction of some properties such as shear strength parameters (cu) for hard and dry silty clay and sandy silt soil with the help of standard penetration test (SPT) and index properties provides a good opportunity to obtain these parameters without great using of more laboratory tests. Standard penetration tests (SPT), rough measure the strength of soil. The merit of this test and the main reason for its widespread use is that it is simple and inexpensive. The shear strength parameters which can be indirect are approximate, but may give a useful guide in ground conditions where it may not be possible to obtain borehole samples of adequate quality like clay containing sand or gravel. This study was undertaken in order to study the reliability of using standard penetration test (SPT) and index properties (IL, ILM, PI and PL) in predicting some properties, (such as shear strength parameters (qu & cu) of silty clay and sandy silt. For purpose of this investigation I utilized the borehole samples data that have been carried out for Addis Ababa Housing Development Program office at Bole Arabsa Condominium Building site 6. The results of the research indicated that the undrained shear strength of fine grained soil strongly related with the SPT number and liquidity index. Empirical equations to identify the shear strength parameters of fine grained soil using corrected SPT number (N’70) and liquidity index have been proposed. Keyword: Silty clay & sandy silt, (qu & cu), LL, PL, PI, IL, Modified Plasticity Index from laboratory result & SPT from the field



Silty clay & sandy silt; (qu & cu); LL; PL; PI; IL;Modified Plasticity Index from laboratory result & SPT from the field