DBPapers
DOI: 10.5593/SGEM2015/B12/S2.027

CONSIDERATION OF SPECIMENS SHEAR AREA CHANGES DURING DIRECT SHEAR TEST OF SOILS AND ITS EFFECTS ON A SIZE OF SPREAD FOUNDATION

G.Nguyen
Friday 7 August 2015 by Libadmin2015

References: 15th International Multidisciplinary Scientific GeoConference SGEM 2015, www.sgem.org, SGEM2015 Conference Proceedings, ISBN 978-619-7105-32-2 / ISSN 1314-2704, June 18-24, 2015, Book1 Vol. 2, 203-208 pp

ABSTRACT
The paper deals with consideration of specimens shear area changes during direct shear test of soil and its effects on a size of spread foundation. To illustrate mentioned effects, direct shear test of soil CE will be introduced. The soil CE is a nature soil from Niepołomice, Poland and had following properties: w = 61.0%; wL = 127.9% and wP = 45%. The size of specimens was 60mm x 60mm x 15mm, time of consolidation was 4 hours and shear speeds were 0.01mm/min (slow test) and 1mm/min (quick test). The specimens had been loaded by normal stresses 50kPa, 100kPa, 200kPa, 300kPa and 400kPa. The different values of shear strength parameters, obtained by taking into account specimens shear area changes during the test and different shear speed, had been used to design spread foundation by design approaches mentioned in Eurocode 7, Part 1 (DA1-C1; DA1-C2; DA2 and DA3) and also by the old and new Slovak Technical Standard STN 73 1001. The model example for the comparison of spread foundation design by various design approaches is the model introduced by Orr (2005). It will be shown that taking into account specimens shear area changes during the test reduced foundation area from 8.0% up to 9.7% (slow test) and from 8.2% up to 8.7% (quick test) which is not negligible.

Keywords: direct shear test, specimens shear area changes, Eurocode 7, STN 73 1001, spread foundation.