scholarly journals A MODEL FOR UNDRAINED CYCLIC SHEAR DEFORMATION BASED ON THE EFFECTIVE STRESS PATH AND THE ACCUMULATIVE SHEAR WORK

2008 ◽  
Vol 64 (1) ◽  
pp. 157-174
Author(s):  
Akira SAKAI
Keyword(s):  
Shear Deformation ◽  
Effective Stress ◽  
Stress Path ◽  
Cyclic Shear ◽  
Effective Stress Path

Effective stress paths and yielding in soft clays below embankments

1985 ◽  
Vol 22 (3) ◽  
pp. 357-374 ◽  
Author(s):  
D. J. Folkes ◽  
J. H. A. Crooks
Keyword(s):  
Pore Water ◽  
Effective Stress ◽  
Strain Softening ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soft Clay ◽  
Stress Path ◽  
Excess Pore Water Pressure ◽  
Soft Clays ◽  
Effective Stress Path

Current methods of predicting the response of soft clays to surface loading are often unsuccessful because the assumed constitutive relationships, including effective stress path behaviour, are incorrect. In particular, the transition from small-strain to large-strain behaviour (i.e. yielding) is frequently not taken into account. Recent laboratory testing has demonstrated that the behaviour of soft clays is largely controlled by yielding. The locus of effective stress states causing yield is known as the yield envelope (YE).The effective stress paths (ESP's) in soft clay foundations below the centre of six fills were determined from computed total stresses and measured pore-water pressures. Yield behaviour is clearly indicated by ESP shapes. The yield envelopes inferred from analyses of field data are similar to those obtained from laboratory testing. Effective stress path shapes vary widely, depending on a variety of factors, including imposed stress level, rate of construction, and boundary drainage conditions. This finding contradicts an earlier conclusion that soft clay behaviour can be characterized by a single ESP. Because of the wide range of possible ESP shapes, the parameters [Formula: see text] does not provide an adequate basis for determining the effective stress state in a soft clay.The ESP/YE analyses indicate that yield can occur either during loading or during excess pore-water pressure dissipation following completion of loading. Yield of sensitive soils during loading is usually followed by strain softening. However, in some soils, dilatant behaviour appears to occur. Yield during dissipation of excess pore-water pressure is characterized by a dramatic change in cv and increased compressibility. Key words: soft clay, yield, effective stress paths, field behaviour, strain softening, rate of consolidation.

An embankment failure on soft fissured clay

1986 ◽  
Vol 23 (4) ◽  
pp. 528-540 ◽  
Author(s):  
J. H. A. Crooks ◽  
K. Been ◽  
B. W. Mickleborough ◽  
J. P. Dean
Keyword(s):  
Effective Stress ◽  
Soft Clay ◽  
Monitoring Program ◽  
Stress Path ◽  
Performance Criterion ◽  
The North ◽  
Empirical Performance ◽  
Average Shear ◽  
Translational Mode ◽  
Effective Stress Path

Construction at the Genesee Power Project near Edmonton required 13 m high approach fills on soft clay for a roadway overpass structure. During construction, the north approach fill failed at a height of about 12 m. An investigation of the failure was carried out and a monitoring program instigated for further fill construction and piling for the overpass structure.The in situ mass strength of the soft clay was found to be controlled by defects such as slickensides rather than the intact strength. A translational mode of failure is considered most likely to have occurred, with computations based on c′ = 0 and [Formula: see text] determined from normally consolidated samples yielding the appropriate factors of safety to account for the failure. "Tearing" of the fill and overconsolidated crust due to the translational failure mechanism, with associated reduced average shear strengths, also occurred.Monitoring data for construction after the failure are presented and discussed. The effective stress path/yield envelope approach was used to assess the data. An empirical performance criterion for the site was developed for the overpass structure based on the observed deformation rates and computed factors of safety. Key words: embankment, stability, clay, failure, translational failure, effective stress path, fissured.

scholarly journals Experimental Study on Undrained Shear Properties of Saline Soil under Freeze-Thaw Cycles

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Shukai Cheng ◽  
Qing Wang ◽  
Jiaqi Wang ◽  
Yan Han
Keyword(s):  
Pore Water ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Stress Path ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Effective Stress Path ◽  
Strain Relationship

The freeze-thaw cycle is an important external factor affecting the hydromechanical characteristics of saline soil in cold regions. Due to the presence of water and salt, it has a greater impact on stability. The construction of various projects, such as ditch fills and road subgrades, has mostly used disturbed soils. Therefore, this article takes remolded saline soil in Qian’an, Jilin Province, China, as the research object to evaluate the action of freeze-thaw cycles on the critical state line, effective stress path, pore water pressure-strain relationship, stress-strain relationship, shear strength index, and other mechanical properties via a freeze-thaw cycle test and a consolidated undrained triaxial shear test (CU). The experimental results show that regardless of whether the soil specimen undergoes a freeze-thaw cycle, its stress-strain relationship shows characteristics of strain hardening, while, as the number of freeze-thaw cycles increases, the shear strength gradually decreases. As both the confining pressure and number of freeze-thaw cycles increase, the pore water pressure increases, as does the pore water pressure coefficient in shear failure. Under the action of freeze-thaw cycles, on the p ′ − q plane of the stress space, the effective stress path gradually moves to the lower left side. Both the effective stress path and the pore water pressure characteristics indicate that the degree of consolidation of the soil specimens continuously decreases as the number of freeze-thaw cycles increases. The position of the critical state line gradually lowers, and the critical state stress ratio decreases. The effective stress strength index can more accurately reflect the comprehensive influence of freeze-thaw cycles and confining pressure on the mechanical characteristics of soils than the total stress strength index. Logistic functions can be used to fit and predict the degradation law of the internal friction angle and cohesion.

PLASTIC POTENTIAL AND EFFECTIVE STRESS PATH IN ONE DIMENSIONAL CONSOLIDATION

2015 ◽  
Vol 71 (2) ◽  
pp. 119-124
Author(s):  
Koichi IINUMA ◽  
Yoshihito IMAI ◽  
Masaru AKAISHI ◽  
Motohiro SUGIYAMA
Keyword(s):  
Effective Stress ◽  
Stress Path ◽  
One Dimensional ◽  
Plastic Potential ◽  
Effective Stress Path

Rheological Behavior of Semisolid Al-6.5wt%Si Alloy under Cyclic Shear Deformation

2011 ◽  
Vol 306-307 ◽  
pp. 104-107
Author(s):  
Hong Chao Luo ◽  
Jun Mei Yang ◽  
Li Yuan Sun ◽  
Li Ping Ju
Keyword(s):  
Experimental Data ◽  
Shear Rate ◽  
Hysteresis Loop ◽  
Shear Deformation ◽  
Rheological Behavior ◽  
Qualitative Agreement ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Cyclic Shear ◽  
The Difference

In the present work, the MCF model for semisolid metal slurries (SSMS) is applied to investigate the thixotropy of the Al-6.5wt%Si alloy under cyclic shear deformation. The study shows that the semisolid Al-6.5wt%Si alloy has the behavior of thixotropy. The area of the hysteresis loop increases with decreasing the up-time, the initial shear rate and increasing resting time, solid volume fraction and maximum shear rate, respectively. These results have qualitative agreement with the experimental data. The origin of the hysteresis loop is atrributed to the difference between the deagglomeration rate and the agglomeration rate.

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