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Deflection of multilayer soil systems
ABSTRACTS
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77. James H. Taylor. A n annular shear device. Trans. A S A E 10 (2), 164-169 (1967). A subject of great interest to many people in soil dynamics is the relationship between forces and deformations in soils. In studies of this relationship, an interaction has been observed between the horizontal and vertical displacements. A plate or an annulus resting on a particular soil and loaded to some selected normal pressure will sink into the soil a given distance. However, if sufficient torque is then applied to produce tangential or horizontal displacement, additional sinkage will usually occur. This is a manifestation of the phenomenon sometimes called "slip sinkage." A n annular shear device was designed and built which measures soil shearing stress (S), normal pressure (P), sinkage (Z), and horizontal displacement (J) simultaneously and continuously. For the sake of convenience, this device was given the name "desometer" derived from the three words, displacement, energy, and stress. Normal pressure and horizontal displacement were selected as independent variables, and experiments were designed to facilitate the determination of the functions f and g where S : f ( P . J ) and Z = g (P,J) for given soil conditions. 78. J. H. Taylor, G. E. Vanden Berg and I. F. Reed. Effect of diameter on performance of powered tractor wheels. Trans. A S A E 10 (6), 838-842 (1967). Total weight carried on a tire is an important factor affecting tractive performance. A larger diameter tire is capable of carrying a larger static weight than a smaller diameter tire of the same cross section at the same inflation pressure. Because of this the effects of diameter have usually been confounded with the effects of weight and inflation pressure. Isolating the effects of diameter is complex for, if tires having varying diameters carry the same static weight, either inflation pressure or static deflection or both must vary. Static deflection is known to correlate with the life of a tire. Static deflection also changes the shape of a tire in the mutual contact area and thus probably influences tractive performances. The factors of diameter, weight, inflation pressure, and deflection are interrelated such that any two can be kept constant independent of the "other two", but the "other two" are then singularly related by a one-to-one correspondence rule. In a research program designed to determine the effects of diameter on performance of powered wheels tires were selected as similar as possible, except for varying diameters. Lug spacing, lug height, rubber compounding, tire width, etc., were constant within production accuracy while rim diameters varied from 24 to 42 in. 79. J. J. Thomas and C. J. Anderson. A method of showing soil movement. J. agric. Engng Res. 13 (2), 196-200 (1968). Most methods used to demonstrate soil deformation due to earth moving, pile driving or cultivation are of limited value. In general they are two dimensional and only reveal the movement at a soil-glass or soil-air interface. A common method is to use coloured layers of soil which are photographed after deformation. In addition high-speed cine films have been taken of the soil surface during deformation. Measurements within the bulk of the soil have been made using radio-active tracer techniques. It appeared that some of the analogies used to show gross deformations in metal working investigations could be used if modified. For example Holmquist used wax billets with longitudinal coloured filaments or transverse coloured layers. The billets were warmed until they had the desired plasticity and were then extruded. When cool, they were hard enough to be sectioned to reveal the internal deformation which had occurred. Further details of this method are given by Blazynski and Cole. In similar investigations Green used plasticine as a working medium and built blocks of alternate layers of different coloured plasticine. The model billet was made of two or more such blocks separated by a parting layer of french chalk or silicone grease. After deformation, the blocks could be separated at the parting layers. Collacott shows the use of plasticine in glass-sided boxes to demonstrate two-dimensional flow around plungers forced into the layered blocks. Both wax and plasticine are highly cohesive but some material with low cohesion is also desirable. One of the settables and mixes for foundry moulds appeared to be a suitable medium. The shell mould process uses a sand coated with a thermo-setting resin The other method in common use is the silicate/CO2 process; this appeared to show the most promise for further investigation. 80. K. Ueshita and G. G. Meyerhof. Deflection of multilayer soil systems. J. Soil Mech Fdns Div. Am. Soc. cir. Engrs 93, 257-282 (Sept. 1967). This paper presents the results of theoretical and experimental investigations of deflections of a
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ABSTRACTS three layer soil system under a loaded circular area. The evaluation of these deflections on the basis of the theory of elasticity shows that a reasonable approximation for a three layer soil system gives Odemark's method. Model tests are performed to check the validity of the theory of elasticity in this problem. The most important difference between the theory and the real behaviour of layered subgrade appears in the relationships between pressure and deflection, which theoretically being of straight form, in fact are of exponential one, even for small deflection ranges. The relationship between loading plate size and pressure, necessary to produce a certain deflection is consistent with the theory. Paper brings (in an appendix) basic theoretical equations and solutions of the problem, describes the tests performed, and (in another appendix) discusses the properties of materials used in experimental investigations. The results of investigations are graphically presented. Reviewer believes the paper is of significance for designers of highways and airports, when estimating the deflection of a pavement under a wheel load, or for designers of structures with circular spread foundation such as tanks, smokestacks, and blast furnaces, founded on multilayer subgrades. (Applied Mechanics Review, April 1968).
81. A . S . Vesie and G. W. Glough. Behavior of granular materials under high stresses. J. Soil Mech. Fdns Div., Am. Soc. cir. Engrs 94, 661-688 (May 1968). Triaxial tests at mean normal stresses up to 1200 kg per cm 2 on a medium-grained, uniform quartz sand show that the nature of sand deformation varies with pressure. As mean normal stress increases, crushing becomes more pronounced and dilatancy effects gradually disappear. Beyond breakdown pressure, at which all effects of initial void ratio disappear, sand behaves essentially as a linearly deformable solid with modulus of deformation E proportional to meart normal stress q. In the same range, sand strength is characterized by a constant angle of internal friction 0, equal to the angle of interparticle friction from the low pressure tests. Below breakdown pressure, E increases as a power function of q; however the exponent of this function varies with pressure and, to a certain degree, with the initial void ratio of sand. The strength envelopes in this range are all curved and depend on the initial void ratio of sand. Relative compressibility of granular materials generally increases with pressure and may be responsible for scale effects in a number of passive pressure phenomena. (Author's Summary). 82. S. Woelke. Kinematics and dynamics of a track chain. J. agric. Engng Res. 13 (2), 168-186 (1968). Considerations concerning the mechanics of motion of a track chain are presented. The complex theory has made it necessary to introduce a number of simplified assumptions by means of which kinematics and dynamics of a track chain and of its links have been determined, using Lagrangian functions. The stresses on the links and their relative motions during a period of time are illustrated for the four forward speeds of a given tractor and for turning in first gear. (Author's Summary). These abstracts have been collected by T. Kurtay of the Department of Agricultural Engineering, The University of Newcastle upon Tyne. The following is a list of publications searched. (1) British Technology Index, The Library Association, London. (2) Monthly Summaries, Motor Industry Research Association, Lindley. (3) Applied Mechanics Review, Am. Soc. Mech. Eng., New York. (4) U.S. Govt. Research Development Reports, Dept. of Commerce, Springfield. (5) J. Soil Mech and Found. Div., Am. Soc. Civil Eng., New York. (6) Geotechnique, Inst. Civil Eng., London. (7) Civil Eng. and Public Works Review, London. (8) Soils and Fertilizers, Commonwealth Bureau of Soils, Harpenden. (9) J. Agric. Eng. Res., N.I.A.E., Bedford. (10) Civil Engineering, Am. Soc. Civil Engnr, New York. (11) Soil Science Proceedings, Am. Soc. of Soil Science, Washington. (12) J. Engng. Education, Am. Soc. Eng. Education, Washington. (13) Materials Research and Standards, Am. Soc. Testing Materials. (14) J. Strain Analysis, Inst. Mech. Engr., London. (15) Agricultural Engineering, Am. Soc. Agr. Eng., Michigan. (16) Trans. A.S.A.E., Am. Soc. Agr. Eng., Michigan.
91
77. James H. Taylor. A n annular shear device. Trans. A S A E 10 (2), 164-169 (1967). A subject of great interest to many people in soil dynamics is the relationship between forces and deformations in soils. In studies of this relationship, an interaction has been observed between the horizontal and vertical displacements. A plate or an annulus resting on a particular soil and loaded to some selected normal pressure will sink into the soil a given distance. However, if sufficient torque is then applied to produce tangential or horizontal displacement, additional sinkage will usually occur. This is a manifestation of the phenomenon sometimes called "slip sinkage." A n annular shear device was designed and built which measures soil shearing stress (S), normal pressure (P), sinkage (Z), and horizontal displacement (J) simultaneously and continuously. For the sake of convenience, this device was given the name "desometer" derived from the three words, displacement, energy, and stress. Normal pressure and horizontal displacement were selected as independent variables, and experiments were designed to facilitate the determination of the functions f and g where S : f ( P . J ) and Z = g (P,J) for given soil conditions. 78. J. H. Taylor, G. E. Vanden Berg and I. F. Reed. Effect of diameter on performance of powered tractor wheels. Trans. A S A E 10 (6), 838-842 (1967). Total weight carried on a tire is an important factor affecting tractive performance. A larger diameter tire is capable of carrying a larger static weight than a smaller diameter tire of the same cross section at the same inflation pressure. Because of this the effects of diameter have usually been confounded with the effects of weight and inflation pressure. Isolating the effects of diameter is complex for, if tires having varying diameters carry the same static weight, either inflation pressure or static deflection or both must vary. Static deflection is known to correlate with the life of a tire. Static deflection also changes the shape of a tire in the mutual contact area and thus probably influences tractive performances. The factors of diameter, weight, inflation pressure, and deflection are interrelated such that any two can be kept constant independent of the "other two", but the "other two" are then singularly related by a one-to-one correspondence rule. In a research program designed to determine the effects of diameter on performance of powered wheels tires were selected as similar as possible, except for varying diameters. Lug spacing, lug height, rubber compounding, tire width, etc., were constant within production accuracy while rim diameters varied from 24 to 42 in. 79. J. J. Thomas and C. J. Anderson. A method of showing soil movement. J. agric. Engng Res. 13 (2), 196-200 (1968). Most methods used to demonstrate soil deformation due to earth moving, pile driving or cultivation are of limited value. In general they are two dimensional and only reveal the movement at a soil-glass or soil-air interface. A common method is to use coloured layers of soil which are photographed after deformation. In addition high-speed cine films have been taken of the soil surface during deformation. Measurements within the bulk of the soil have been made using radio-active tracer techniques. It appeared that some of the analogies used to show gross deformations in metal working investigations could be used if modified. For example Holmquist used wax billets with longitudinal coloured filaments or transverse coloured layers. The billets were warmed until they had the desired plasticity and were then extruded. When cool, they were hard enough to be sectioned to reveal the internal deformation which had occurred. Further details of this method are given by Blazynski and Cole. In similar investigations Green used plasticine as a working medium and built blocks of alternate layers of different coloured plasticine. The model billet was made of two or more such blocks separated by a parting layer of french chalk or silicone grease. After deformation, the blocks could be separated at the parting layers. Collacott shows the use of plasticine in glass-sided boxes to demonstrate two-dimensional flow around plungers forced into the layered blocks. Both wax and plasticine are highly cohesive but some material with low cohesion is also desirable. One of the settables and mixes for foundry moulds appeared to be a suitable medium. The shell mould process uses a sand coated with a thermo-setting resin The other method in common use is the silicate/CO2 process; this appeared to show the most promise for further investigation. 80. K. Ueshita and G. G. Meyerhof. Deflection of multilayer soil systems. J. Soil Mech Fdns Div. Am. Soc. cir. Engrs 93, 257-282 (Sept. 1967). This paper presents the results of theoretical and experimental investigations of deflections of a
92
ABSTRACTS three layer soil system under a loaded circular area. The evaluation of these deflections on the basis of the theory of elasticity shows that a reasonable approximation for a three layer soil system gives Odemark's method. Model tests are performed to check the validity of the theory of elasticity in this problem. The most important difference between the theory and the real behaviour of layered subgrade appears in the relationships between pressure and deflection, which theoretically being of straight form, in fact are of exponential one, even for small deflection ranges. The relationship between loading plate size and pressure, necessary to produce a certain deflection is consistent with the theory. Paper brings (in an appendix) basic theoretical equations and solutions of the problem, describes the tests performed, and (in another appendix) discusses the properties of materials used in experimental investigations. The results of investigations are graphically presented. Reviewer believes the paper is of significance for designers of highways and airports, when estimating the deflection of a pavement under a wheel load, or for designers of structures with circular spread foundation such as tanks, smokestacks, and blast furnaces, founded on multilayer subgrades. (Applied Mechanics Review, April 1968).
81. A . S . Vesie and G. W. Glough. Behavior of granular materials under high stresses. J. Soil Mech. Fdns Div., Am. Soc. cir. Engrs 94, 661-688 (May 1968). Triaxial tests at mean normal stresses up to 1200 kg per cm 2 on a medium-grained, uniform quartz sand show that the nature of sand deformation varies with pressure. As mean normal stress increases, crushing becomes more pronounced and dilatancy effects gradually disappear. Beyond breakdown pressure, at which all effects of initial void ratio disappear, sand behaves essentially as a linearly deformable solid with modulus of deformation E proportional to meart normal stress q. In the same range, sand strength is characterized by a constant angle of internal friction 0, equal to the angle of interparticle friction from the low pressure tests. Below breakdown pressure, E increases as a power function of q; however the exponent of this function varies with pressure and, to a certain degree, with the initial void ratio of sand. The strength envelopes in this range are all curved and depend on the initial void ratio of sand. Relative compressibility of granular materials generally increases with pressure and may be responsible for scale effects in a number of passive pressure phenomena. (Author's Summary). 82. S. Woelke. Kinematics and dynamics of a track chain. J. agric. Engng Res. 13 (2), 168-186 (1968). Considerations concerning the mechanics of motion of a track chain are presented. The complex theory has made it necessary to introduce a number of simplified assumptions by means of which kinematics and dynamics of a track chain and of its links have been determined, using Lagrangian functions. The stresses on the links and their relative motions during a period of time are illustrated for the four forward speeds of a given tractor and for turning in first gear. (Author's Summary). These abstracts have been collected by T. Kurtay of the Department of Agricultural Engineering, The University of Newcastle upon Tyne. The following is a list of publications searched. (1) British Technology Index, The Library Association, London. (2) Monthly Summaries, Motor Industry Research Association, Lindley. (3) Applied Mechanics Review, Am. Soc. Mech. Eng., New York. (4) U.S. Govt. Research Development Reports, Dept. of Commerce, Springfield. (5) J. Soil Mech and Found. Div., Am. Soc. Civil Eng., New York. (6) Geotechnique, Inst. Civil Eng., London. (7) Civil Eng. and Public Works Review, London. (8) Soils and Fertilizers, Commonwealth Bureau of Soils, Harpenden. (9) J. Agric. Eng. Res., N.I.A.E., Bedford. (10) Civil Engineering, Am. Soc. Civil Engnr, New York. (11) Soil Science Proceedings, Am. Soc. of Soil Science, Washington. (12) J. Engng. Education, Am. Soc. Eng. Education, Washington. (13) Materials Research and Standards, Am. Soc. Testing Materials. (14) J. Strain Analysis, Inst. Mech. Engr., London. (15) Agricultural Engineering, Am. Soc. Agr. Eng., Michigan. (16) Trans. A.S.A.E., Am. Soc. Agr. Eng., Michigan.