caa a22 4500 467930856 CHVBK 20180406152943.0 cr unu---uuuuu 170328e20060601xx s 000 0 eng 10.1007/s10706-004-5832-6 doi (NATIONALLICENCE)springer-10.1007/s10706-004-5832-6 The Direct Shear Strength and Dilatancy of Sand-gravel Mixtures [Elektronische Daten] [Alessandro Simoni, Guy Houlsby] A total of 87 direct shear tests in a large direct shear-box apparatus have been used to investigate the strength and dilatancy of sand-gravel mixtures. This paper focuses on the differences in behaviour between a silica sand (yellow Leighton Buzzard sand) and sand-gravel mixtures obtained by adding fractions of two kinds of gravel to the sand. The purpose is to find a relation between the grain-size characteristics of the materials and the shearing resistance. Experimental results are analysed in terms of the frictional and dilatant contributions to the strength of mixtures as a function of their relative density, and are compared with dilatancy theories and empirical equations. The addition of gravel to the mixtures, even at low fractions (less than 0.1 by volume), causes an increase in peak friction angle (Φ ′peak) which results both from higher dilatancy at failure (ψmax) and higher constant volume friction angle (Φ ′cv). Use of the minimum voids ratio (emin) of the materials allows the data for the two families of mixtures to be normalized and interpreted in terms of Φ ′cv and the ratio (Φ ′peak − Φ ′cv)/ψmax. The relationships between relative density (D r ), ψmax and Φ ′peak − Φ ′cv are only partly explained on a physical basis, so we develop empirical equations to predict the peak shear resistance of sand-gravel mixtures (up to gravel contents of 0.5) on the basis of easily measurable quantities. Such equations constitute a practical tool to overcome the problems arising from the impracticality of testing coarse material in the standard shear-box apparatus. Springer, 2006 coarse granular material nationallicence direct shear test nationallicence empirical equations nationallicence minimum voids ratio nationallicence over-size particles nationallicence relative density nationallicence Simoni Alessandro Dipartimento di Scienze della Terra e Geologico-Ambientali, Università di Bologna, Via Zamboni 67, 40126, Bologna, Italy aut Houlsby Guy Department of Engineering Science, Oxford University, Parks Road, OX1 3PJ, Oxford, UK aut Geotechnical & Geological Engineering Kluwer Academic Publishers 24/3(2006-06-01), 523-549 0960-3182 24:3<523 2006 24 10706 https://doi.org/10.1007/s10706-004-5832-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10706-004-5832-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Simoni Alessandro Dipartimento di Scienze della Terra e Geologico-Ambientali, Università di Bologna, Via Zamboni 67, 40126, Bologna, Italy aut NATIONALLICENCE 700 1- Houlsby Guy Department of Engineering Science, Oxford University, Parks Road, OX1 3PJ, Oxford, UK aut NATIONALLICENCE 773 0- Geotechnical & Geological Engineering Kluwer Academic Publishers 24/3(2006-06-01), 523-549 0960-3182 24:3<523 2006 24 10706 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer