Structural mechanics of clay soils

Zaretskii, Yu. K.; Vyalov, S. S.

doi:10.1007/bf01705105

Cited by 11 publications

(5 citation statements)

References 3 publications

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“…Then, the flow condition under long-term loading (8) where S = σ 1 ll ' + σ 2 mm ' + σ 3 nn ' , , ϕ (t, τ) and c 0 (t, τ) are the time-dependent angle of internal friction and specific cohesion, and l, m, and n, and l ' , m ' , and n ' are the direction cosines of the normal to the site of the limiting equilibrium and slip, respectively.…”

Section: Equation Of Long-term Strengthmentioning

confidence: 99%

“…According to the kinetic theory of soil deformation, as proposed by S. S. Vyalov, Zaretskii, et al [7,8], failure sets in when the extent of damage caused by microcracks attains critical significance in the zone of limiting equilibrium.…”

Section: Equation Of Long-term Strengthmentioning

confidence: 99%

“…Based on results of investigations [3,4,7,8], it is possible to present the next scheme for development of creep deformations and variations in long-term resistance to failure. Two mutually compensating phenomena − hardening, which is caused by the healing of defects and a more dense rearrange- ment of particles, and loosening, which is caused by reorientation of particles, and also the formation and development of micro-and macrocracks (see Fig.…”

Section: Equation Of Long-term Strengthmentioning

confidence: 99%

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Prediction of deformations of foundation beds with a consideration of long-term nonlinear soil deformation

Mirsayapov¹,

Koroleva²

2011

Soil Mech Found Eng

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IntroductionMonitoring of the deformations of buildings under construction indicates significant discrepancies between actual and computed settlements (up to ± 50% and more), which are explained by the conditionality of the computational scheme, errors associated with experimental determination of the deformability characteristics of the soils, and by disregard of the time factor and hardening (aging) of the soils.Development and more precise definition of methods used to calculate deformations are particularly critical for beds composed of clayey soils in which the stress-strain state varies over time, and depends on the loading regime. The deformation and strength of soils depends largely on the load path, initial density and moisture content, and the relationship between the deviator and spherical parts of the stress tensor; this is associated with the effect of constrained dilatancy.In this connection, we investigated the strength and deformation properties of clayey soils under triaxial compression with consideration of the long-term load effect. Instruments and Procedure Used in ExperimentIn the limiting-strength state, a slip (failure) surface is formed at each point (elementary volume) of the soil, and is oriented in a certain manner with respect to the direction of action of principle stresses σ 1 > σ 2 > σ 3 , i.e., a mixed stress-strain state is realized [1].Accordingly, problems arise with selection of the scheme for triaxial-compression tests. First problem: When effects in the form of pressures against the surface of a soil specimen are known, it is necessary to eliminate transfer of the tangential stresses that arise, as a rule, due to friction between the surface of the soil specimen and devices (plates), which transmit a mechanical force onto the specimen. Second problem: Is the plate flexible or rigid? Rigid plates cannot provide for uniformity of applied stresses to the boundaries of a specimen, while flexible plates ensure uniformity of deformations.A computational model of foundation-bed deformation, which is based on the method of layer-by-layer summation with consideration of the components of the deviator S ij and spherical σ ij tensors, and the relationship between which is different at different points of the bed, is presented. Nonlinear dilatational strain of the soil over time is examined with consideration given to the change in degree of consolidation of the bearing layer of soil in the foundation bed owing to dilatancy.

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Section: Equation Of Long-term Strengthmentioning

confidence: 99%

Section: Equation Of Long-term Strengthmentioning

confidence: 99%

Section: Equation Of Long-term Strengthmentioning

confidence: 99%

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Prediction of deformations of foundation beds with a consideration of long-term nonlinear soil deformation

Mirsayapov¹,

Koroleva²

2011

Soil Mech Found Eng

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“…The values of AH* and log A were then plotted against the M and R ratios and are shown in Figures 28 to 32. The possibility of variation in activation energies and proportional ity constants has been noted but not formulated by previous investigators (22,52,95,28,19,63,30,85) due to lack of a diagnostic criteria for structure. Hence a structure function was introduced to the rate process equation without much success.…”

Section: Test Resultsmentioning

confidence: 96%

Clay structure and creep behavior of clays as a rate process

Erol

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“…Since the microcracking caused the plastic strain in brittle rock under compression (Scholz, 1968a) and the arithmetic sum of plastic and viscoplastic strain exhibited positive correlation with the growth of microcracks ( Figure 6.21 and Figure 6.22), it was concluded that the microcracking caused the viscoplastic creep deformation in shale. Zaretskii and Vyalov (1971) experimentally proved that the creep deformation of clay soils depended on stress, time, and density of defects. Similarly, Mallet et al (2015) proposed that the secondary creep in brittle glass depended on temperature, stress, fluid nature, and the initial crack network or crack density.…”

Section: Chapter 7 Discussion and Conclusionmentioning

confidence: 99%

Fundamental Mechanism of Time Dependent Failure in Shale

Gupta¹

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In underground coal mines, mining activity disturbs the natural equilibrium state of in-situ stresses. The induced and in-situ stresses deform the rockmass surrounding the mine openings. Primary roof supports impede the deformation of the rockmass overlying the entries. However, failure can occur in the bolted rockmass, causing fatalities and injuries. The rockmass failure is erratic, and its occurrence often varies from a few days to months and years after the opening of the entry. One of the often-neglected factors in this process is the effect of time on the stability of mine openings, which can often be observed in the propagation of failure in the rockmass. Coalmeasure rocks have exhibited time-dependent strength reduction in laboratory creep tests. However, the exact mechanism responsible for this time-dependent reduction in strength is not clear. Therefore, this thesis investigated the fundamental reason for macroscopic creep deformation in shale through microscopic visualization using an X-ray computed tomography (CT) technique. An approach was formulated based on the following experiments. I would also like to thank the National Institute of Occupational Safety and Health (NIOSH) for providing the necessary funding for this research. I would also like to thank the Office of Graduate Education and Life (OGEL) of WVU which in part supported this research by providing an Outstanding Merit Fellowship for Continuing Doctoral Student. I would also like to thank Dr.

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Structural mechanics of clay soils

Cited by 11 publications

References 3 publications

Prediction of deformations of foundation beds with a consideration of long-term nonlinear soil deformation

Prediction of deformations of foundation beds with a consideration of long-term nonlinear soil deformation

Clay structure and creep behavior of clays as a rate process

Fundamental Mechanism of Time Dependent Failure in Shale

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