TITLE PARTICLE SHAPE QUANTITIES AND INFLUENCE ON GEOTECHNICAL PROPERTIES – A REVIEW Juan Manuel Rodriguez Zavala Division of Mining and Geotechnical Engineering Department of Civil, Environmental and Natural Resources Luleå University of Technology PREFACE The work in this report has been carried out at the Division of Mining and Geotechnical Engineering at Luleå University of Technology. In this new journey, now as a Ph.D. student I have face new questions and challenges that have improved myself not only as a student but also as a person. It has been not easy but the fellowship environment with professors, students, technicians, etc., all in general friends benefits the daily discussion and the interchange of ideas. The intention of the report is to build up a starting point from where the research on particle shape developed by the author will take place. It is also the intention to present the general overview on particle shape research and make it understandable for all readers. Particle shape research is a wide area and the author focus the report in Geotechnical Engineering. The report has been split in chapters with the intention to describe first how the measurements were developed in time and according with authors follow by the techniques used to measure the particle’s dimensions. It is also included those properties found in literature affected by the particle’s shape. Finally findings are discussed with the proper conclusion. I appreciate the time taken by my supervisors Sven Knutsson and Tommy Edeskär to address me in the right direction, the support they always gave me and they for sure will give me in the near future, I also must be grateful to my colleague Jens Johansson who previous work, experience on the image analysis and discussions has been of great value and help. I would like to thank my family by the support they gave me this last two years in the work and the joy they provide me during our spare time, I understand it has not been easy for them ether and I appreciate them effort. Juan Rodriguez Luleå 2012 i ABSTRACT It has been shown in the early 20th century that particle shape has an influence on geotechnical properties. Even if this is known, there has been only minor progress in explaining the processes behind its performance and has only partly implemented in practical geotechnical analysis. This literature review covers different methods and techniques used to determine the geometrical shape of the particles as well as reported effects of shape on granular material behaviour. Particle shape could be classifying in three categories; sphericity - the overall particle shape and similitude with a sphere, roundness - the description of the particle’s corners and roughness - the surface texture of the particle. The categories are scale dependent and the major scale is to sphericity while the minor belongs to roughness. Empirical relations and standards had been developed to relate soil properties, e.g. internal friction angle, minimum and maximum void ratio, density, permeability, strain, with the particle shape. The use of the relations and standards enhance the bulk material performance e.g. asphalt mixtures and rail road ballast. The overview has shown that there is no agreement on the usage of the descriptors and is not clear which descriptor is the best. One problem has been in a large scale classify shape properties. Image analysis seems according to the review to be a promising tool, it has many advantages. But the resolution in the processed image needs to be considered since it influence descriptors such as e.g. the perimeter. ii 1 INTRODUCTION .......................................................................................................................... 1 2 AIM AND GOAL ........................................................................................................................... 3 3 DESCRIPTION OF SHAPE PROPERTIES ............................................................................... 3 3.1 INTRODUCCTION ......................................................................................................... 3 3.2 SCALE DEPENDENCE ................................................................................................... 4 3.3 FORM (3D)....................................................................................................................... 5 3.4 FORM (2D)....................................................................................................................... 9 3.5 ROUNDNESS OR ANGULARITY ............................................................................... 11 3.6 ROUGHNESS OR SURFACE TEXTURE .................................................................... 18 4 TECHNIQUES IN ORDER TO DETERMINE PARTICLE SHAPE ..................................... 20 4.1 HAND MEASUREMENT .............................................................................................. 20 4.2 SIEVE ANALYSIS ........................................................................................................ 21 4.3 CHART COMPARISON ................................................................................................ 21 4.4 IMAGE ANALYSIS ....................................................................................................... 23 5 EFFECT OF SHAPE ON SOIL PROPERTIES ........................................................................ 25 5.1 INTRODUCTION .......................................................................................................... 25 5.2 INFLUENCE OF SIZE AND SHAPE ............................................................................ 28 5.3 VOID RATIO AND POROSITY .................................................................................... 29 5.4 ANGLE OF REPOSE. .................................................................................................... 32 5.5 SHEAR STRENGTH...................................................................................................... 33 5.6 SEDIMENTATION PROPERTIES ............................................................................... 36 5.7 HYDRAULIC CONDUCTIVITY, PERMEABILITY. .................................................. 37 5.8 LIQUEFACTION ........................................................................................................... 39 5.9 GROUNDWATER AND SEEPAGE MODELLING ..................................................... 40 6 DISCUSSION ................................................................................................................................ 40 6.1 TERMS, QUANTITIES AND DEFINITIONS. .............................................................. 40 6.2 PROPERTIES ................................................................................................................. 41 6.3 IMAGE ANALYSIS ....................................................................................................... 42 6.4 APPLICATIONS ............................................................................................................ 43 7 CONCLUSIONS ........................................................................................................................... 43 8 FURTHER WORK ...................................................................................................................... 44 9 ACKNOWLEDGMENT .............................................................................................................. 44 10 REFERENCES ............................................................................................................................. 44 iii ABBREVIATIONS Symbol Description Units A Area of the projected particle, area of the particle outline (2D) m2 A1 Area of the projected particle after “n” dilatation-erosion cycles m2 2 AC Area of the smallest circumscribed circle m 2 AC2 Area of circle with diameter equal to longest length of outline m 2 ACON Convex area m AF Sukumara angularity factor - ANGCON Angles subtending convex parts of the outline degree (º) ANGPLA Angles subtending plane parts of the outline degree (º) a Longest axes diameters of the particle m B Greatest breadth perpendicular to L m b Medium axes diameters of the particle m C Circularity - CR Convexity ratio - c Shorter axes diameters of the particle m Co Cohesion Pa CPER Convex perimeter m DA Diameter of a circle equal on area to that of the particle outline m DAVG Mean average diameter m DC Diameter of the smallest circumscribed circle in the particle outline m DCIR Diameter of circumscribed sphere m DI Diameter of the largest inscribed circle m DS Diameter of circle fitting sharpest corner (two sharper corners, DS1, DS2) m DSV Diameter of a sphere of the same volume as particle m DX Diameter of a pebble particle through the sharpest corner DS m d Grain diameter (average) m dN Nominal diameter, diameter of a sphere of the same volume as the natural m particle e Void ratio % F Angularity factor - FR Fullness ratio - g Gravitational acceleration m/s2 I Intermediate axis m k Hydraulic conductivity m/s L Longest axis of the outline m N Number of corners (items counted) or number of divisions - n Porosity - P Perimeter of the projected particle, perimeter of outline (2D) m PC Perimeter of a circle of same area as particle outline m PCON Sum of perimeter of all convex parts m PCD Perimeter of circle of same area as drainage basin m PD Perimeter of a drainage basin m PI Particle index - R Roundness - RAVG Mean average radio of the pebble m RCON Radius of curvature