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Glossary of terrain-vehicle terms—part IV
Journal of Terrameehanics, 1975, Vol. 12, No. 1, pp. 33 to 38. Pergamon Press
Printed in Great Britain.
GLOSSARY
OF TERRAIN-VEHICLE
TERMS--PART
IV
Summary--This is the fourth part of the report of the Standardization Committee of the ISTVS, consisting of Standards for Terrain Characteristics--Soils. Readers" comments are invited before submission to the next international Conference of the Society for adoption. INTRODUCTION THE STANDARDIZATIONCommittee of the International Society for Terrain-Vehicle Systems (ISTVS) has been working on a set of standard terms to be used by investigators in the field of off-road operations, so that better communication might result. Terms are grouped in categories as follows:
Glossary of terms I. Terrain characteristics A. Soils B. Geometry C. Vegetation lI. Vehicle physical characteristics IlI. Vehicle performance characteristics IV. Soil test devices associated with soil-vehicle tests V. Standard symbols. Standards for two categories, Terrain Geometry and Vehicle Physical Characteristics, were published in the Journal ofTerramechanics, Vol. 5, No. 2 (1968), and were adopted by the Society in 1969; standards for Vehicle Performance Characteristics were published in the Journal of Terramechanics, Vol. 8, No. 2 (1971) and were adopted by the Society in 1972; and a list of Soil Test Devices Associated with SoilVehicle Tests was published in the Journal of Terramechanics, Vol. l I, No. 2 (1974). Standards for Terrain Characteristics--Soils are presented here for comment by members of the Society. All appropriate changes will be incorporated into this list, and the final version will be submitted to the next International Conference of the Society for adoption. The Committee, members of which are listed below, therefore, welcomes all suggestions, corrections, or additions. MARVIN P. MEYER, Chairman Mobility and Environmental Systems Laboratory U.S. Army Engineer Waterways Experiment Station P.O. Box 631 Vicksburg, Mississippi 39180 I. ROBERT EHRLICH
Davidson Laboratory Stevens Institute of Technology Castle Point Station Hoboken, New Jersey 07030 33
34
GLOSSARY OF TERRAIN-VEHICLE TERMS--PART IV DAVID SLOSS Stevens Institute of Technology Castle Point Station Hoboken, New Jersey 07030 NEWELL R. MURPHY, JR. Mobility and Environmental Systems Laboratory U.S. Army Engineer Waterways Experiment Station P.O. Box 631 Vicksburg, Mississippi 39180 ROBERT D. WISMER Technical Center Deere and Co. Moline, Illinois 61265 TIBOR CZAKO Mobility Systems Division U.S. Army Tank-Automotive Command Warren, Michigan 48090. TERRAIN CHARACTERISTICS--SOILS
The following list of terms is adopted from SAE Recommended Practice SAE J991, [22*] Soil-Vehicle Terminology. Some additional terms have been added and others deleted. In general, the committee has adopted the terminology of the Unified Soil Classification System (USCS) [23]. Other systems, notably the U.S. Department of Agricultural (USDA) Textural Soil Classification System [24] or the International Society of Soil Science Textural Soil Classification System [25] can be used but should be specifically noted. 197. Adhesion, C,. The portion of shearing resistance between soil and another material that is independent of the normal stress [22]. 198. Angle of internal friction, ?. A measure of the shearing strength of soil on an internal surface that is proportional to the normal pressure [22]. 199. Angle of repose, ct. The maximum slope which a pile of cohesionless soil can assume [22]. 200. Atterberg limits. Moisture content limits used for separating the solid, semisolid, plastic, and semiliquid phases of soil. For a complete description of Atterberg limits see [19] and [20]. 201. Bearing capacity, ultimate. The average load per unit of area on a footing required to produce failure by rupture of a supporting soil mass [20]. 202. Bulk density. Same as dry density. 203. Coarse-grained snow. Snow crystals having a mean diameter larger than 2 mm [13]. *Reference numbers are compatible with those used in previously published standards.
GLOSSARY OF T E R R A I N - V E H I C L E T E R M S - - P A R T IV
35
204. Coarse-grained soil A soil containing 50 per cent or less material smaller in diameter than 0.074 mm (No. 200 US standard sieve) [23]. 205. Coejficient of(external)friction, F. Ratio between the shearing resistance due to friction and the normal stress acting on the contact area between the soil and another material [22]. 206. Coefficient of uniformity, Co. The numerical ratio of the soil particle size (diameter) corresponding to 60 per cent passing, to the size (diameter) corresponding to 10 per cent passing, on the cumulative grain-size curve [23]. 207. Cohesion, c. The shearing strength of soil on an internal surface that is independent of the normal stress [22]. 208. Cohesionless soil. A soil that has shearing strength due primarily to internal friction and has negligible cohesion. This soil can be identified as having little or no cohesion when submerged (ISTVS).* 209. Cohesive-frictional soil. A soil that has shearing strength attributable both to cohesion and to internal friction (ISTVS). 210. Cohesive soil. A soil that has shearing strength due primarily to cohesion and negligible internal friction. This soil can be identified as having significant cohesion when submerged (ISTVS). 211. Compaction. The densification of soil by means of mechanical manipulation which results in the reduction of air voids in the soil (ISTVS). 212. Cone index, CI. An index of soil strength generally obtained with the WES cone penetrometer [26]. 213. Consistency. The relative ease with which a soil can be deformed [22]. 214. Consolidation. The gradual reduction in volume of a cohesive soil mass due to the expulsion of water under load [22]. 215. Coulomb's equation. The relationship between the shearing strengths of soil and the effective stress, 6", on an internal surface. The equation is written s = c + 6 tan q~ where c is cohesion and ~ is angle of internal friction [22]. 216. Critical layer. The soil layer which is considered most significant in terms of trafficability. Its depth varies with weight and type of vehicle and soil profile (ISTVS). 217. Dry density (unit dry weight or bulk density), Yd" The weight of soil solids, Ws, per unit of total volume of soil mass, VT; that is Ya = Ws/Vr (see Fig. 17) [20].
Air Water
vT = ½ + V . + V ~ V~
W~
WT -- W.+ Ws
Solids
FIG. 17.
Unit volume of soil divided into its components.
218. External frictional res&tance, f,. The portion of shearing resistance between soil and another material which is proportional to the normal stress [22]. 219. Field-maximum moisture content. The naturally recurring average highest moisture content of a soil layer in its natural position (ISTVS). *(ISTVS) following a definition indicates that the definition was composed by the ISTVS Standardization Committee.
36
GLOSSARY OF TERRAIN-VEHICLE TERMS--PART IV
220. FieM-minimum moisture content. The naturally recurring average lowest moisture content of a soil layer in its natural position (ISTVS). 221. Fine-grained snow. Snow crystals having a mean diameter of 2 mm or less [I 3]. 222. Fine-grained soil. A soil containing more than 50 per cent material smaller in diameter than 0.074 mm (No. 200 U.S. standard sieve) [23]. 223, Humus. The organic portion of soil formed by the partial decomposition of vegetable or animal matter (ISTVS). 224. bTternational Society o f Soil Science Textural Soil Classification System. A system which identifies soils according to the following textural classes: Stones: greater than 20 mm diameter Gravel: 20 to 2 m m diameter Coarse sand: 2 to 0.2 mm diameter Fine sand: 0.2 to 0.02 mm diameter Silt: 0.02 to 0.002 mm diameter Colloidal particles or clay: smaller than 0.002 m diameter (see [25]). 225. Liquid limit, LL. The Atterberg limit separating the plastic and semiliquid phases of soil [19]. 226. Moisture content. Same as water content. 227. Muskeg (peatland). An organic soil consisting of a surface layer of living vegetation and a sublayer of peat of any depth and existing in association with various hydrological conditions (ISTVS). 228. Organic soil. Soil with a high (usually above 20 per cent) organic content. In general, organic soils are very compressible and have poor load-sustaining properties [20]. 229. Peatland. Same as muskeg. 230. Per cent saturation, S. The ratio, expressed as a percentage, of the volume occupied by water in a given soil mass, V,., to the total volume of void space; that is S = (Vw/(V,~. q V,)] 100 (see Fig. 17) [20]. 231. Plasticity. The property of a soil which allows it to be permanently deformed without cracking or appreciable volume change [20]. 232. PlasticiO' index, PI. The numerical difference between the liquid limit, EL, and the plastic limit, PL [19]. 233. Plastic limit, PL. The Atterberg limit separating the semisolid and plastic phases of soil [19]. 234. Porosity, n. The ratio, expressed as a percentage, of the volume of voids of a given soil mass to the total volume of the soil mass, V-r; that is n : [( V, ! V,,)/Vr] 100 (see Fig. 17) [20]. 235. Rating cone index, RCI. The measured cone index multiplied by the remolding index; it expresses the soil-strength rating of soil subjected to sustained traffic (ISTVS). 236. Relative density, D+t. The ratio of the difference between the void ratio of a cohesionless soil in the loosest state, e...... and any given void ratio, e, to the difference between the void ratios of the soil in the loosest state, em,~, and in the densest state, e m i n ; that is, D d -- (emax e)/(e .... -- emi~) [20]. 237, RemoMed soil. Soil that has had its in situ structure modified by manipulation [20].
GLOSSARY OF TERRAIN-VEHICLE TERMS--PART IV
37
238. Remolding. The manipulation or working of a soil by traffic or other means (ISTVS). 239. Remolding index, RL The ratio of remolding soil strength to original strength, determined by the standard remold test (see [26]). 240. Shear strengtk, T~. The maximum resistance of a soil to shearing stresses [20]. 241. Shrinkage limit, SL. The Atterberg limit separating the solid and semisolid phases of soil [19]. 242. Sinkage constant, k. The coefficient of the sinkage term in the Bekker plate pressure-sinkage equation (ISTVS). 243. Sinkage exponent, n. The exponent of the sinkage term in the Bekker plate pressure-sinkage equation (ISTVS). 244. Snow density. The weight of snow solids per unit of total volume of snow mass (ISTVS). 245. Soil. Sediments and other unconsolidated accumulations of solid particles produced by the mechanical and chemical disintegration of rocks. In the context of terrain--vehicle mechanics literature, the term soil usually includes snow, peat, and other surface materials (ISTVS). 246. Soil strength. The resistance of a soil to an applied stress. The strength varies with moisture content and the nature, arrangement, and size distribution of the soil particles, and the test itself (ISTVS). 247. Soil trafficability. The capacity of soil to withstand the passage of vehicles (ISTVS). 248. Sticky limit, Tw. The lowest water content at which a soil will stick to a metal blade drawn across the surface of the soil mass [20]. 249. Tkixotropy. The property of a soil that enables it to increase in soil strength with time and unchanged water content. The process is reversible in that agitation or manipulation will cause a decrease in strength (ISTVS). 250. Unconfined compressive strengtk, q,,. The load per unit area at which an unconfined cylindrical specimen of soil will fail in a simple compression test [20]. 251. Unified Soil Classification System. A system which identifies (classifies) soils according to their textural and plasticity qualities and to their grouping with respect to their performances as engineering construction materials [23]. 252. Uniformity coefficient. Same as coefficient of uniformity. 253. Unit dry weight. Same as dry density. 254. Unit wet weight. Same as wet density. 255. U.S. Department of Agriculture Textural Soil Classification System. A system which identifies (classifies) soils according to the properties of three basic soil-texture classes. These classes are: Sand: 2.0 to 0.05 mm diameter Silt: 0.05 to 0.002 mm diameter Clay: smaller than 0-002 m diameter (see [24]). 256. Void ratio, e. The ratio of the volume of void space to the volume of solid particles in a given soil mass, V~; that is, e ~- (V~ + Vw)/V~, (see Fig. 17) [20]. 257. Water content (moisture content), w. The ratio, expressed as a percentage, of the weight of water in a given soil mass, IV,., to the weight of solid particles, We; that is w ~ ( Ww/Ws) 100 (see Fig. 17) [20].
38
GLOSSARY OF TERRAIN-VEHICLE TERMS
PARF IV
258. W e t densiO' (unit wet weight), T,,. W e i g h t o f the soil solids a n d water, W r p e r unit o f total v o l u m e o f soil mass, VT; t h a t is ~{,,, ~ W,r,/V T (see Fig. 17) [20]. REFERENCES [13] U.S. ARMY ENGINEERWATERWAYSEXPERIMENTSTATION,CE, Trafficability of snow. Technical Memorandum No. 3414, Rep. 3, Greenland Studies, 1955 and 1957, May (1960). [19] U.S. DEPARTMENT OF THE ARMY, Engineering and design, laboratory soils testing. Engineer Manual, EM 1110-2-1906, 10 May (1965). [20] AMERICANSOCIETYFOR TESTING MATERIALS, 1972 Annual Book o['ASTM Standards, Part I I, Bituminous Materials .[or Highway Construction Waterproo[ing, and Roo[ing; Soils, Peats, Mosses, and Humus; Soil Resistance. [22] SOCIETYOE AUTOMOTIVEENGINEERS, Soil vehicle terminology. SAE Handbook J991 (1972). [23] U.S. ARMY ENGINEER WATERWAYS EXPERIMENTSTATION, CE, The unified soil classification system. Technical Memoran&tm No. 3-357, Vicksburg, Mississippi. April 1960 (reprinted May 1967). [24] U.S. DEPARTMENT OF AGRICULTURE, Soil survey manual. U.S. Department o[" Agriculture Handbook No. 18, August (1951). [25] INTERNATIONALSOCIETY FOR SOIL SCIENCE, Report of Meeting of International Commission .lot Mechanical and Physical Soil Investigations on October 31, 1913, Vol. 4, No. 1 (1914). [26] AMERICANSOCIETY OE AGRICULTURALENGINEERS, Measurement of soil trafficability characteristics. Trans. Ant. Soc. agric. Engnrs 5 (2), 121 124 (1962).
Printed in Great Britain.
GLOSSARY
OF TERRAIN-VEHICLE
TERMS--PART
IV
Summary--This is the fourth part of the report of the Standardization Committee of the ISTVS, consisting of Standards for Terrain Characteristics--Soils. Readers" comments are invited before submission to the next international Conference of the Society for adoption. INTRODUCTION THE STANDARDIZATIONCommittee of the International Society for Terrain-Vehicle Systems (ISTVS) has been working on a set of standard terms to be used by investigators in the field of off-road operations, so that better communication might result. Terms are grouped in categories as follows:
Glossary of terms I. Terrain characteristics A. Soils B. Geometry C. Vegetation lI. Vehicle physical characteristics IlI. Vehicle performance characteristics IV. Soil test devices associated with soil-vehicle tests V. Standard symbols. Standards for two categories, Terrain Geometry and Vehicle Physical Characteristics, were published in the Journal ofTerramechanics, Vol. 5, No. 2 (1968), and were adopted by the Society in 1969; standards for Vehicle Performance Characteristics were published in the Journal of Terramechanics, Vol. 8, No. 2 (1971) and were adopted by the Society in 1972; and a list of Soil Test Devices Associated with SoilVehicle Tests was published in the Journal of Terramechanics, Vol. l I, No. 2 (1974). Standards for Terrain Characteristics--Soils are presented here for comment by members of the Society. All appropriate changes will be incorporated into this list, and the final version will be submitted to the next International Conference of the Society for adoption. The Committee, members of which are listed below, therefore, welcomes all suggestions, corrections, or additions. MARVIN P. MEYER, Chairman Mobility and Environmental Systems Laboratory U.S. Army Engineer Waterways Experiment Station P.O. Box 631 Vicksburg, Mississippi 39180 I. ROBERT EHRLICH
Davidson Laboratory Stevens Institute of Technology Castle Point Station Hoboken, New Jersey 07030 33
34
GLOSSARY OF TERRAIN-VEHICLE TERMS--PART IV DAVID SLOSS Stevens Institute of Technology Castle Point Station Hoboken, New Jersey 07030 NEWELL R. MURPHY, JR. Mobility and Environmental Systems Laboratory U.S. Army Engineer Waterways Experiment Station P.O. Box 631 Vicksburg, Mississippi 39180 ROBERT D. WISMER Technical Center Deere and Co. Moline, Illinois 61265 TIBOR CZAKO Mobility Systems Division U.S. Army Tank-Automotive Command Warren, Michigan 48090. TERRAIN CHARACTERISTICS--SOILS
The following list of terms is adopted from SAE Recommended Practice SAE J991, [22*] Soil-Vehicle Terminology. Some additional terms have been added and others deleted. In general, the committee has adopted the terminology of the Unified Soil Classification System (USCS) [23]. Other systems, notably the U.S. Department of Agricultural (USDA) Textural Soil Classification System [24] or the International Society of Soil Science Textural Soil Classification System [25] can be used but should be specifically noted. 197. Adhesion, C,. The portion of shearing resistance between soil and another material that is independent of the normal stress [22]. 198. Angle of internal friction, ?. A measure of the shearing strength of soil on an internal surface that is proportional to the normal pressure [22]. 199. Angle of repose, ct. The maximum slope which a pile of cohesionless soil can assume [22]. 200. Atterberg limits. Moisture content limits used for separating the solid, semisolid, plastic, and semiliquid phases of soil. For a complete description of Atterberg limits see [19] and [20]. 201. Bearing capacity, ultimate. The average load per unit of area on a footing required to produce failure by rupture of a supporting soil mass [20]. 202. Bulk density. Same as dry density. 203. Coarse-grained snow. Snow crystals having a mean diameter larger than 2 mm [13]. *Reference numbers are compatible with those used in previously published standards.
GLOSSARY OF T E R R A I N - V E H I C L E T E R M S - - P A R T IV
35
204. Coarse-grained soil A soil containing 50 per cent or less material smaller in diameter than 0.074 mm (No. 200 US standard sieve) [23]. 205. Coejficient of(external)friction, F. Ratio between the shearing resistance due to friction and the normal stress acting on the contact area between the soil and another material [22]. 206. Coefficient of uniformity, Co. The numerical ratio of the soil particle size (diameter) corresponding to 60 per cent passing, to the size (diameter) corresponding to 10 per cent passing, on the cumulative grain-size curve [23]. 207. Cohesion, c. The shearing strength of soil on an internal surface that is independent of the normal stress [22]. 208. Cohesionless soil. A soil that has shearing strength due primarily to internal friction and has negligible cohesion. This soil can be identified as having little or no cohesion when submerged (ISTVS).* 209. Cohesive-frictional soil. A soil that has shearing strength attributable both to cohesion and to internal friction (ISTVS). 210. Cohesive soil. A soil that has shearing strength due primarily to cohesion and negligible internal friction. This soil can be identified as having significant cohesion when submerged (ISTVS). 211. Compaction. The densification of soil by means of mechanical manipulation which results in the reduction of air voids in the soil (ISTVS). 212. Cone index, CI. An index of soil strength generally obtained with the WES cone penetrometer [26]. 213. Consistency. The relative ease with which a soil can be deformed [22]. 214. Consolidation. The gradual reduction in volume of a cohesive soil mass due to the expulsion of water under load [22]. 215. Coulomb's equation. The relationship between the shearing strengths of soil and the effective stress, 6", on an internal surface. The equation is written s = c + 6 tan q~ where c is cohesion and ~ is angle of internal friction [22]. 216. Critical layer. The soil layer which is considered most significant in terms of trafficability. Its depth varies with weight and type of vehicle and soil profile (ISTVS). 217. Dry density (unit dry weight or bulk density), Yd" The weight of soil solids, Ws, per unit of total volume of soil mass, VT; that is Ya = Ws/Vr (see Fig. 17) [20].
Air Water
vT = ½ + V . + V ~ V~
W~
WT -- W.+ Ws
Solids
FIG. 17.
Unit volume of soil divided into its components.
218. External frictional res&tance, f,. The portion of shearing resistance between soil and another material which is proportional to the normal stress [22]. 219. Field-maximum moisture content. The naturally recurring average highest moisture content of a soil layer in its natural position (ISTVS). *(ISTVS) following a definition indicates that the definition was composed by the ISTVS Standardization Committee.
36
GLOSSARY OF TERRAIN-VEHICLE TERMS--PART IV
220. FieM-minimum moisture content. The naturally recurring average lowest moisture content of a soil layer in its natural position (ISTVS). 221. Fine-grained snow. Snow crystals having a mean diameter of 2 mm or less [I 3]. 222. Fine-grained soil. A soil containing more than 50 per cent material smaller in diameter than 0.074 mm (No. 200 U.S. standard sieve) [23]. 223, Humus. The organic portion of soil formed by the partial decomposition of vegetable or animal matter (ISTVS). 224. bTternational Society o f Soil Science Textural Soil Classification System. A system which identifies soils according to the following textural classes: Stones: greater than 20 mm diameter Gravel: 20 to 2 m m diameter Coarse sand: 2 to 0.2 mm diameter Fine sand: 0.2 to 0.02 mm diameter Silt: 0.02 to 0.002 mm diameter Colloidal particles or clay: smaller than 0.002 m diameter (see [25]). 225. Liquid limit, LL. The Atterberg limit separating the plastic and semiliquid phases of soil [19]. 226. Moisture content. Same as water content. 227. Muskeg (peatland). An organic soil consisting of a surface layer of living vegetation and a sublayer of peat of any depth and existing in association with various hydrological conditions (ISTVS). 228. Organic soil. Soil with a high (usually above 20 per cent) organic content. In general, organic soils are very compressible and have poor load-sustaining properties [20]. 229. Peatland. Same as muskeg. 230. Per cent saturation, S. The ratio, expressed as a percentage, of the volume occupied by water in a given soil mass, V,., to the total volume of void space; that is S = (Vw/(V,~. q V,)] 100 (see Fig. 17) [20]. 231. Plasticity. The property of a soil which allows it to be permanently deformed without cracking or appreciable volume change [20]. 232. PlasticiO' index, PI. The numerical difference between the liquid limit, EL, and the plastic limit, PL [19]. 233. Plastic limit, PL. The Atterberg limit separating the semisolid and plastic phases of soil [19]. 234. Porosity, n. The ratio, expressed as a percentage, of the volume of voids of a given soil mass to the total volume of the soil mass, V-r; that is n : [( V, ! V,,)/Vr] 100 (see Fig. 17) [20]. 235. Rating cone index, RCI. The measured cone index multiplied by the remolding index; it expresses the soil-strength rating of soil subjected to sustained traffic (ISTVS). 236. Relative density, D+t. The ratio of the difference between the void ratio of a cohesionless soil in the loosest state, e...... and any given void ratio, e, to the difference between the void ratios of the soil in the loosest state, em,~, and in the densest state, e m i n ; that is, D d -- (emax e)/(e .... -- emi~) [20]. 237, RemoMed soil. Soil that has had its in situ structure modified by manipulation [20].
GLOSSARY OF TERRAIN-VEHICLE TERMS--PART IV
37
238. Remolding. The manipulation or working of a soil by traffic or other means (ISTVS). 239. Remolding index, RL The ratio of remolding soil strength to original strength, determined by the standard remold test (see [26]). 240. Shear strengtk, T~. The maximum resistance of a soil to shearing stresses [20]. 241. Shrinkage limit, SL. The Atterberg limit separating the solid and semisolid phases of soil [19]. 242. Sinkage constant, k. The coefficient of the sinkage term in the Bekker plate pressure-sinkage equation (ISTVS). 243. Sinkage exponent, n. The exponent of the sinkage term in the Bekker plate pressure-sinkage equation (ISTVS). 244. Snow density. The weight of snow solids per unit of total volume of snow mass (ISTVS). 245. Soil. Sediments and other unconsolidated accumulations of solid particles produced by the mechanical and chemical disintegration of rocks. In the context of terrain--vehicle mechanics literature, the term soil usually includes snow, peat, and other surface materials (ISTVS). 246. Soil strength. The resistance of a soil to an applied stress. The strength varies with moisture content and the nature, arrangement, and size distribution of the soil particles, and the test itself (ISTVS). 247. Soil trafficability. The capacity of soil to withstand the passage of vehicles (ISTVS). 248. Sticky limit, Tw. The lowest water content at which a soil will stick to a metal blade drawn across the surface of the soil mass [20]. 249. Tkixotropy. The property of a soil that enables it to increase in soil strength with time and unchanged water content. The process is reversible in that agitation or manipulation will cause a decrease in strength (ISTVS). 250. Unconfined compressive strengtk, q,,. The load per unit area at which an unconfined cylindrical specimen of soil will fail in a simple compression test [20]. 251. Unified Soil Classification System. A system which identifies (classifies) soils according to their textural and plasticity qualities and to their grouping with respect to their performances as engineering construction materials [23]. 252. Uniformity coefficient. Same as coefficient of uniformity. 253. Unit dry weight. Same as dry density. 254. Unit wet weight. Same as wet density. 255. U.S. Department of Agriculture Textural Soil Classification System. A system which identifies (classifies) soils according to the properties of three basic soil-texture classes. These classes are: Sand: 2.0 to 0.05 mm diameter Silt: 0.05 to 0.002 mm diameter Clay: smaller than 0-002 m diameter (see [24]). 256. Void ratio, e. The ratio of the volume of void space to the volume of solid particles in a given soil mass, V~; that is, e ~- (V~ + Vw)/V~, (see Fig. 17) [20]. 257. Water content (moisture content), w. The ratio, expressed as a percentage, of the weight of water in a given soil mass, IV,., to the weight of solid particles, We; that is w ~ ( Ww/Ws) 100 (see Fig. 17) [20].
38
GLOSSARY OF TERRAIN-VEHICLE TERMS
PARF IV
258. W e t densiO' (unit wet weight), T,,. W e i g h t o f the soil solids a n d water, W r p e r unit o f total v o l u m e o f soil mass, VT; t h a t is ~{,,, ~ W,r,/V T (see Fig. 17) [20]. REFERENCES [13] U.S. ARMY ENGINEERWATERWAYSEXPERIMENTSTATION,CE, Trafficability of snow. Technical Memorandum No. 3414, Rep. 3, Greenland Studies, 1955 and 1957, May (1960). [19] U.S. DEPARTMENT OF THE ARMY, Engineering and design, laboratory soils testing. Engineer Manual, EM 1110-2-1906, 10 May (1965). [20] AMERICANSOCIETYFOR TESTING MATERIALS, 1972 Annual Book o['ASTM Standards, Part I I, Bituminous Materials .[or Highway Construction Waterproo[ing, and Roo[ing; Soils, Peats, Mosses, and Humus; Soil Resistance. [22] SOCIETYOE AUTOMOTIVEENGINEERS, Soil vehicle terminology. SAE Handbook J991 (1972). [23] U.S. ARMY ENGINEER WATERWAYS EXPERIMENTSTATION, CE, The unified soil classification system. Technical Memoran&tm No. 3-357, Vicksburg, Mississippi. April 1960 (reprinted May 1967). [24] U.S. DEPARTMENT OF AGRICULTURE, Soil survey manual. U.S. Department o[" Agriculture Handbook No. 18, August (1951). [25] INTERNATIONALSOCIETY FOR SOIL SCIENCE, Report of Meeting of International Commission .lot Mechanical and Physical Soil Investigations on October 31, 1913, Vol. 4, No. 1 (1914). [26] AMERICANSOCIETY OE AGRICULTURALENGINEERS, Measurement of soil trafficability characteristics. Trans. Ant. Soc. agric. Engnrs 5 (2), 121 124 (1962).