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Thaw-consolidation tests on remoulded clays.
ABSTRACTS
22.
107
M. Livneh, J. Kinsky and D. Zaslavsky. Correlation of suction curves with the plasticity index of soils. J. Materials 5 (1), 209-220 (1970). In order to find a dependence of the suction value pF upon the microstructure of the soil, experiments have been carried out to obtain a correlation between p F and the plastic limit PL and the plasticity index PI. Three groups of soils were tested: clays, loam and sandy loam. First the pF value was determined by two different testing techniques as a function of the moisture content w. Then pF was related to the known values of PL and PI. In the range of 2 to 4.2 pF a linear relation was found between pF and low w. log PL and log PI respectively.
(Geotechnical Abstracts.) 23.
W. F. Mareusoa. The effects of time on the dynamic modulus and damping ratio of clay soils. North Carolina St. University., Raleigh, N.C., U.S.A., D. Thesis (1970), 142 pp. Laboratory tests were used to study the time-dependent characteristics of the dynamic modulus and the damping ratio of two clay soils. Damping was determined using a steady state method and from a method using decay of vibration curves. After completion of primary consolidation, the dynamic response was studied as a function of time for both drained and undrained conditions. The results of these two test conditions were compared and the effects of volume change and effects due to change in soil structure as they apply to the dynamic shear modulus were isolated. Regression analyses were performed on these data and relationships are presented which show the effects of void ratio and time for both materials. This increase was approximately 10 per cent for kaolinite and 40 per cent for bentonite per logarithmic cycle of T-ratio during secondary consolidation for constant effect stress. The damping ratio was shown to decrease approximately 12 per cent for kaolinite and 25 per cent for betonite per logarithmic cycle of T-ratio during secondary consolidation. (Geotechnical Abstracts.)
24.
C. Mesrl. Coefficient of secondary compression. J. Soil Mech. Foundations Divi., ASCE 99 (SMI) 123-137 Proc. Paper 9515 (January, 1973). The mechanism of secondary compression in soils can be described in terms of changes in soil structure. Instant and delayed compression are parts of a continuous process of volume change, and for normally consolidated natural soils, the coefficient of secondary compression and compression index correlate with each other. The composition and physio-chemical-environment determine the compressiblility of the soil. For any given soil the delayed or secondary compression is influenced by such factors as time, consolidation pressure, precomposition, sustained loading, remoulding shear stresses, rate of increase in effective stress, sample thickness and temperature. Of all the factors considered, precompression and sustained loading have the most important influence ort the coefficient of secondary compression. (Author's abstract.)
25. N. R. Morgenstern and L. B. Smith. Thaw-consolidation tests on remoulded clays. Can. Geotech. J. 10 (1), 2 5 4 0 (1973). Controlled thaw-consolidation tests were carried out on three types of remoulded clays. The resulting data showed that the excess pore pressures and the degree of consolidation in a thawing soil depend primarily on the thaw-consolidation ratio. The results obtained demonstrate that the theory adequately represents the soil behaviour. Applications of the theory in practice are indicated. (Authors" abstract.) 26.
A. C. Palmer. Settlement of a pipeline on thawing permafrost. Transp. Engng J. Proc. ASCE 98 (TE3), 477-491 (1972). A buried oil pipeline in permafrost will thaw the frozen soil around it, and will settle as the thawed soil consolidates. Because the amount of ice in the soil varies from point to point along the pipe alignment, the settlement will be uneven, and will induce bending in the pipe. Thaw settlement estimates from single boreholes give no information about the possible magnitude of differential settlements, and instead statistical measures of the intensity of fluctuations in thaw settlement have to be used. Alternative sources of the required data are suggested, and two different ways of estimating the effects on the pipe are described, one way being based on random process theory and the other on statistical simulation. The flexural stiffness of the pipe modifies the settlement, and methods of taking this effect into account are e~plained. (Geotechnical
Abstracts.) 27.
R. S. Saliman. Testing transmission line belled auger footings. ASCE Spec. Conf. Performance of Earth and Earth-Supported Structures 1 (2), 1501-1515 (June, 1972). The soil in which the footings were constructed was classified as silty clay and was placed at
22.
107
M. Livneh, J. Kinsky and D. Zaslavsky. Correlation of suction curves with the plasticity index of soils. J. Materials 5 (1), 209-220 (1970). In order to find a dependence of the suction value pF upon the microstructure of the soil, experiments have been carried out to obtain a correlation between p F and the plastic limit PL and the plasticity index PI. Three groups of soils were tested: clays, loam and sandy loam. First the pF value was determined by two different testing techniques as a function of the moisture content w. Then pF was related to the known values of PL and PI. In the range of 2 to 4.2 pF a linear relation was found between pF and low w. log PL and log PI respectively.
(Geotechnical Abstracts.) 23.
W. F. Mareusoa. The effects of time on the dynamic modulus and damping ratio of clay soils. North Carolina St. University., Raleigh, N.C., U.S.A., D. Thesis (1970), 142 pp. Laboratory tests were used to study the time-dependent characteristics of the dynamic modulus and the damping ratio of two clay soils. Damping was determined using a steady state method and from a method using decay of vibration curves. After completion of primary consolidation, the dynamic response was studied as a function of time for both drained and undrained conditions. The results of these two test conditions were compared and the effects of volume change and effects due to change in soil structure as they apply to the dynamic shear modulus were isolated. Regression analyses were performed on these data and relationships are presented which show the effects of void ratio and time for both materials. This increase was approximately 10 per cent for kaolinite and 40 per cent for bentonite per logarithmic cycle of T-ratio during secondary consolidation for constant effect stress. The damping ratio was shown to decrease approximately 12 per cent for kaolinite and 25 per cent for betonite per logarithmic cycle of T-ratio during secondary consolidation. (Geotechnical Abstracts.)
24.
C. Mesrl. Coefficient of secondary compression. J. Soil Mech. Foundations Divi., ASCE 99 (SMI) 123-137 Proc. Paper 9515 (January, 1973). The mechanism of secondary compression in soils can be described in terms of changes in soil structure. Instant and delayed compression are parts of a continuous process of volume change, and for normally consolidated natural soils, the coefficient of secondary compression and compression index correlate with each other. The composition and physio-chemical-environment determine the compressiblility of the soil. For any given soil the delayed or secondary compression is influenced by such factors as time, consolidation pressure, precomposition, sustained loading, remoulding shear stresses, rate of increase in effective stress, sample thickness and temperature. Of all the factors considered, precompression and sustained loading have the most important influence ort the coefficient of secondary compression. (Author's abstract.)
25. N. R. Morgenstern and L. B. Smith. Thaw-consolidation tests on remoulded clays. Can. Geotech. J. 10 (1), 2 5 4 0 (1973). Controlled thaw-consolidation tests were carried out on three types of remoulded clays. The resulting data showed that the excess pore pressures and the degree of consolidation in a thawing soil depend primarily on the thaw-consolidation ratio. The results obtained demonstrate that the theory adequately represents the soil behaviour. Applications of the theory in practice are indicated. (Authors" abstract.) 26.
A. C. Palmer. Settlement of a pipeline on thawing permafrost. Transp. Engng J. Proc. ASCE 98 (TE3), 477-491 (1972). A buried oil pipeline in permafrost will thaw the frozen soil around it, and will settle as the thawed soil consolidates. Because the amount of ice in the soil varies from point to point along the pipe alignment, the settlement will be uneven, and will induce bending in the pipe. Thaw settlement estimates from single boreholes give no information about the possible magnitude of differential settlements, and instead statistical measures of the intensity of fluctuations in thaw settlement have to be used. Alternative sources of the required data are suggested, and two different ways of estimating the effects on the pipe are described, one way being based on random process theory and the other on statistical simulation. The flexural stiffness of the pipe modifies the settlement, and methods of taking this effect into account are e~plained. (Geotechnical
Abstracts.) 27.
R. S. Saliman. Testing transmission line belled auger footings. ASCE Spec. Conf. Performance of Earth and Earth-Supported Structures 1 (2), 1501-1515 (June, 1972). The soil in which the footings were constructed was classified as silty clay and was placed at