- Email: [email protected]
Dynamic loadings
104
ABSTRACTS
39.
J. L. Bogdanoff, F. Kozin and L. J. Cote. Atlas of off-road ground roughness p.s.d.'s and report on data acquisition technique. 292 pp. (Sept. 1966). Power spectral densities, in one (line) and two (area) dimensions, are presented for off-road ground in eleven sites in the United States. Methods of acquiring, recording, and processing the data are described in detail. (U.S. Gov. Res. Dep. Rep., 10.8.69, AD-802503.)
40.
M. Bouche. Physical and mechanical properties of fine compacted soils. Annls. Inst. Tech. Batiment Tray. Publ., 20, 240, 1705-1727 (Dec. 1967). Following a general review of the physicochemical viewpoint of the microscopic behaviour of soils, author discusses several aspects of the behaviour of compacted soils, relating them to the state of a dispersed soil (inter-particle forces repel) or flocculated soil (forces attract). This is done by discussing 24 sets of graphs, many taken from the work of Seed and Chan, with extensions showing results with an Orly mud. Attention is focused on the influence of structure, which is shown to depend on the w/c of compaction and method (static, vibratory, impact or kneading), and on wetting. Swelling shearing and rigidity are examined. On the dry side of optimum (flocculated soil), or with increased energy of compaction, swelling pressures and rigidity are often higher. Likewise, statically and kneaded compacted soils may have equal early rigidities if compacted dry, but static compaction may give greater rigidity when compacted wet. A drooping characteristic against dry density was noted for low deformations when compacted wet. At higher deformations, differences are lessened, and effects may be masked in soils with a sandy skeleton or a high plasticity. There is a bibliography of 33 items. Chief interest will be for researchers. (Appl. Mech. Rev., 1970.)
41.
E. D'Appalonia. Dynamic loadings. J. Soil Mech. Fndns Div. ASCE, 96, SM1, Proc. Paper 7010, 49-72 (Jan. 1970). Criteria for placing and improving soil sustaining dynamic loadings are presented for building and machinery foundations and for earth embankments. These criteria are compared and their limitations in practice without consideration of the response of the soil and structure to dynamic loadings are illustrated. Vibratory-induced settlement of footings supported on granular soils depends on the dynamic stresses and accelerations. For accelerations less than lg, for most practical cases, accelerations per se do not cause sand densification. Rather, accelerations produce inertia stresses whose continued repetition results in orientation of sand grains and settlement. Confining pressure, density, grain size, dynamic stress, its magnitude and repetition, etc., influence liquefaction of granular soils. These factors are considered in appropriate design criteria for foundations. Analytical procedures developed by Seed, Ambraseys and Sarma, and Newmark for stability and deformations of earth dams in seismic regions are presented. (Author's summary.)
42.
D. d. D'Appolonia and T. W. Lambe. Method for predicting initial settlement. J. Soil Mech. Fndns Div. ASCE, 96, SM2, Proc. Paper 7167, 523-544 (Mar. 1970). A method of analysis is developed for predicting initial settlement, i.e., settlement due to strains which occur within soil that remains at constant volume. The method employs finite element analysis and includes the following effects: (1) stress and displacement boundary conditions; (2) soil nonlinearity, nonhomogeneity, and anistropy; and (3) initial gravity stress in the soil. An example problem is used as a vehicle for qualitatively indicating the importance of initial anisotropic gravity stresses and undrained strength anisotropy with rotation of principal planes to settlement prediction and actual settlement behavior. Also considered is the sensitivity of load-deformation predictions to uncertainties in soil modulus and shear strength. The load-settlement behavior of a footing on clay strongly depends on the stress-strain modulus and the initial state of stress in the soil. The soil modulus in laboratory tests is subject to major uncertainties. (Authors' summary.)
43.
G. A. DegraL Some results of the investigation of stresses in soil. 5 pp. (2 June 1969). The increase of operating speed of agricultural machines and tools very urgently requires studying the process and the influence, taking place in soil, as the object of cultivation. For investigation of stress fields, the principles of propagation, magnitudes of failure stresses, limits of speed of agricultural machines, the author conducted special experiments for two and three-edged wedges at the Department of machine-tractor park utilization. Strain gage dynamometers were used in these tests. (U.S. Gov. Res. Dev. Rep., 25.10.69, PB-185497T.)
ABSTRACTS
39.
J. L. Bogdanoff, F. Kozin and L. J. Cote. Atlas of off-road ground roughness p.s.d.'s and report on data acquisition technique. 292 pp. (Sept. 1966). Power spectral densities, in one (line) and two (area) dimensions, are presented for off-road ground in eleven sites in the United States. Methods of acquiring, recording, and processing the data are described in detail. (U.S. Gov. Res. Dep. Rep., 10.8.69, AD-802503.)
40.
M. Bouche. Physical and mechanical properties of fine compacted soils. Annls. Inst. Tech. Batiment Tray. Publ., 20, 240, 1705-1727 (Dec. 1967). Following a general review of the physicochemical viewpoint of the microscopic behaviour of soils, author discusses several aspects of the behaviour of compacted soils, relating them to the state of a dispersed soil (inter-particle forces repel) or flocculated soil (forces attract). This is done by discussing 24 sets of graphs, many taken from the work of Seed and Chan, with extensions showing results with an Orly mud. Attention is focused on the influence of structure, which is shown to depend on the w/c of compaction and method (static, vibratory, impact or kneading), and on wetting. Swelling shearing and rigidity are examined. On the dry side of optimum (flocculated soil), or with increased energy of compaction, swelling pressures and rigidity are often higher. Likewise, statically and kneaded compacted soils may have equal early rigidities if compacted dry, but static compaction may give greater rigidity when compacted wet. A drooping characteristic against dry density was noted for low deformations when compacted wet. At higher deformations, differences are lessened, and effects may be masked in soils with a sandy skeleton or a high plasticity. There is a bibliography of 33 items. Chief interest will be for researchers. (Appl. Mech. Rev., 1970.)
41.
E. D'Appalonia. Dynamic loadings. J. Soil Mech. Fndns Div. ASCE, 96, SM1, Proc. Paper 7010, 49-72 (Jan. 1970). Criteria for placing and improving soil sustaining dynamic loadings are presented for building and machinery foundations and for earth embankments. These criteria are compared and their limitations in practice without consideration of the response of the soil and structure to dynamic loadings are illustrated. Vibratory-induced settlement of footings supported on granular soils depends on the dynamic stresses and accelerations. For accelerations less than lg, for most practical cases, accelerations per se do not cause sand densification. Rather, accelerations produce inertia stresses whose continued repetition results in orientation of sand grains and settlement. Confining pressure, density, grain size, dynamic stress, its magnitude and repetition, etc., influence liquefaction of granular soils. These factors are considered in appropriate design criteria for foundations. Analytical procedures developed by Seed, Ambraseys and Sarma, and Newmark for stability and deformations of earth dams in seismic regions are presented. (Author's summary.)
42.
D. d. D'Appolonia and T. W. Lambe. Method for predicting initial settlement. J. Soil Mech. Fndns Div. ASCE, 96, SM2, Proc. Paper 7167, 523-544 (Mar. 1970). A method of analysis is developed for predicting initial settlement, i.e., settlement due to strains which occur within soil that remains at constant volume. The method employs finite element analysis and includes the following effects: (1) stress and displacement boundary conditions; (2) soil nonlinearity, nonhomogeneity, and anistropy; and (3) initial gravity stress in the soil. An example problem is used as a vehicle for qualitatively indicating the importance of initial anisotropic gravity stresses and undrained strength anisotropy with rotation of principal planes to settlement prediction and actual settlement behavior. Also considered is the sensitivity of load-deformation predictions to uncertainties in soil modulus and shear strength. The load-settlement behavior of a footing on clay strongly depends on the stress-strain modulus and the initial state of stress in the soil. The soil modulus in laboratory tests is subject to major uncertainties. (Authors' summary.)
43.
G. A. DegraL Some results of the investigation of stresses in soil. 5 pp. (2 June 1969). The increase of operating speed of agricultural machines and tools very urgently requires studying the process and the influence, taking place in soil, as the object of cultivation. For investigation of stress fields, the principles of propagation, magnitudes of failure stresses, limits of speed of agricultural machines, the author conducted special experiments for two and three-edged wedges at the Department of machine-tractor park utilization. Strain gage dynamometers were used in these tests. (U.S. Gov. Res. Dev. Rep., 25.10.69, PB-185497T.)