scholarly journals Effective stress response of clay to undrained cyclic loading

1994 ◽  
Vol 31 (5) ◽  
pp. 714-727 ◽  
Author(s):  
M. Zergoun ◽  
Y.P. Vaid
Keyword(s):  
Stress Response ◽  
Cyclic Loading ◽  
Effective Stress ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Initial Direction ◽  
Marine Clay ◽  
Test Characteristic ◽  
Characteristic Behaviour ◽  
Effective Stress Ratio

The effective stress response of a natural marine clay to slow undrained symmetrical cyclic reversal in shear stress is presented. The effects of cyclic principal stress difference amplitude, cyclic principal effective stress ratio amplitude, initial direction of loading, and step increase in cyclic stress level on the clay stress–strain response are studied under stress conditions of the triaxial test. Characteristic behaviour patterns are identified in terms of effective stresses. Key words : clay, cyclic loading, effective stress, hysteretic work, loading direction, step loading.

scholarly journals Experimental and Estimation Studies of Resilient Modulus of Marine Coral Sand under Cyclic Loading

2020 ◽  
Vol 8 (4) ◽  
pp. 287 ◽  
Author(s):  
Shao-Heng He ◽  
Qiong-Fang Zhang ◽  
Zhi Ding ◽  
Tang-Dai Xia ◽  
Xiao-Lu Gan
Keyword(s):  
Cyclic Loading ◽  
South China Sea ◽  
Effective Stress ◽  
South China ◽  
Stress Ratio ◽  
Resilient Modulus ◽  
Cyclic Stress ◽  
Marine Transportation ◽  
Cyclic Stress Ratio ◽  
Coral Sand

Coral sand is an important filler resource that can solve the shortage of terrestrial fillers in coastal areas. Recently, the foundations of many infrastructures in the South China Sea have been built with coral sand as fillers, which have been subjected to wave and traffic cyclic loads. Resilient modulus (Mr) is an important design parameter in marine engineering, but there are few studies on the resilient modulus response of coral sand under cyclic loading. A series of drained cyclic triaxial tests were carried out to investigate the effects of the initial mean effective stress (p0) and cyclic stress ratio (ζ) on the resilient modulus response of the coral sand from the South China Sea. The change of fractal dimension (αc) can reflect the rule of particle breakage evolution. The αc of coral sand shows a tendency of almost maintaining stable and then increasing rapidly with the increase of mean effective stress p0 under each cyclic stress ratio ζ. There is a threshold of p0, when the p0 exceeds this threshold, αc will increase significantly with the increase of p0. The increase of p0 has a beneficial effect on the improvement of the Mr, while the increase of ζ has both beneficial and detrimental effects on the improvement of the Mr. A new prediction model of the Mr considering particle breakage was established, which can better predict the Mr of coral sand in the whole stress interval. The research results can provide guidance for the design of marine transportation infrastructures, which can promote the development of marine transportation industry and energy utilization.

Experimental assessment of the response of sands under shear–volume coupled deformation

2008 ◽  
Vol 45 (9) ◽  
pp. 1310-1323 ◽  
Author(s):  
S. Sivathayalan ◽  
P. Logeswaran
Keyword(s):  
Shear Strength ◽  
Boundary Conditions ◽  
Pore Pressure ◽  
Effective Stress ◽  
Strain Path ◽  
Stress Ratio ◽  
Volumetric Strain ◽  
Strain Paths ◽  
Pressure Boundary Conditions ◽  
Effective Stress Ratio

An experimental study of the behaviour of an alluvial sand under different strain increment paths representing shear–volume coupled deformation is presented. Both pore pressure and pore volume change simultaneously in these tests. Linear strain paths with different levels of limiting volumetric strain and nonlinear strain paths that simulate different pore pressure boundary conditions were applied to the soil specimen in the laboratory. The strain paths imposed included both expansive and contractive volumetric deformation. Nonuniform excess pore pressures generated during earthquakes (on account of the heterogeneity in natural soils) often lead to such deformation in situ following the end of strong shaking. The shear strength of the soil could decrease significantly when the pore pressure boundary conditions result in volume inflow that leads to a considerable reduction of the effective confining stress. The rate of volume inflow plays a significant role on the resulting stress–strain and pore pressure responses. Both the peak and the minimum shear strength mobilized during the test were significantly dependent on the strain path. The effective stress ratio at the instant of peak pore pressure is independent of the strain path followed, and it is equal to the effective stress ratio noted at the instant of phase transformation in undrained tests.

Effective Stress Ratio of Triangular Pattern Perforated Plates

2008 ◽  
Author(s):  
Naoto Kasahara ◽  
Hideki Takasho ◽  
Nobuchika Kawasaki ◽  
Masanori Ando
Keyword(s):  
Effective Stress ◽  
Material Properties ◽  
Constitutive Equations ◽  
Stress Ratio ◽  
Equivalent Material ◽  
Solid Materials ◽  
Perforated Plates ◽  
Non Linear ◽  
Effective Stress Ratio ◽  
Equivalent Material Properties

Tubesheet structures utilized in heat exchangers have complex perforated portions. For realistic design analysis, axisymmetric models with equivalent solid materials of perforated plate are conventionally adopted to simplify perforated area (figure1). Sec.III Appendix A-8000 (ASME 2004) provides elastic equivalent solid materials for flat tubesheets. Plastic properties were studied by Porowski et al. (1974), Gorden et al. (2002) and so on. Elevated temperature design of tubesheets requires plastic and creep properties in addition. The purpose of this study is to develop a general determination method of non-linear equivalent material properties for perforated plates and to confirm their applicability to both flat and spherical tubesheets. Main loadings of tubesheets in fast reactor heat exchanges are inner pressure and thermal stress at transient operations. Under above conditions, average stress of perforated area becomes approximately equi-biaxial. Therefore, average inelastic behaviors of various perforated plates subjected to equi-biaxial field were investigated by inelastic finite element method. Though above investigations, Authors clarified that perforated plates have their own effective stress ratio (ESR). ESR is a function of geometry and is independent from their materials. ESR can determine non-linear equivalent material properties of perforated plates for any kind of constitutive equations of base metals. For simplified inelastic analysis of perforated plates, the brief equations were proposed to determine equivalent plastic and creep material properties for perforated plates. It is considered that physical meaning of ESR is an effective stress ratio between perforated plates and equivalent solid plates. ESR is a function of geometry and is independent from constitutive equations. ESR can determine non-linear equivalent material properties for perforated plates from any kind of constitutive equations of base materials. Assumptions in ESR are von Mises’s equivalent stress-strain relationship and equi-biaxial loadings. Applicability of ESR was investigated through finite element analyses of various flat and spherical tubesheets.

Strain degradation of saturated clay under cyclic loading

2001 ◽  
Vol 38 (1) ◽  
pp. 208-212 ◽  
Author(s):  
Jian Zhou ◽  
Xiaonan Gong
Keyword(s):  
Mathematical Model ◽  
Cyclic Loading ◽  
Stress Ratio ◽  
Axial Strain ◽  
Influence Factors ◽  
Cyclic Stress ◽  
Point Of View ◽  
Triaxial Tests ◽  
Cyclic Stress Ratio ◽  
Saturated Clay

Soil degradation is studied from the point of view of cyclic axial strain through stress-controlled triaxial tests on Hangzhou normally consolidated clay. Different influence factors on strain, such as cyclic stress ratio, overconsolidation ratio, and frequency, are studied. Degradation index is redefined according to the tests. A mathematical model for strain degradation is presented and verified.Key words: cyclic loading, saturated clay, strain degradation, mathematical model.

Behaviour of Marine Clay Under Wave Type of Cyclic Loading

2003 ◽  
Author(s):  
S. Narasimha Rao ◽  
G. Gerald Moses
Keyword(s):  
Cyclic Loading ◽  
Deformation Behaviour ◽  
Cyclic Stress ◽  
Shear Loading ◽  
Load Level ◽  
Marine Clay ◽  
Cyclic Shear ◽  
Coastal Marine ◽  
Storm Wave ◽  
Stress Ratios

This paper presents the results of two series of cyclic triaxial shear tests carried out under both uniform and Varied cyclic shear loading and these bring out the influence of load cycles on strain and undrained strength of a cemented marine clay from East coast of India. The undrained shear strength and deformation behaviour of Indian coastal marine clay have been established through a detailed shear testing carried out. In order to estimate the effect brought in by varied cyclic loading, it becomes necessary to conduct reference standard tests under uniform cyclic loading at various cyclic stress ratios (CSR) on identical soil specimens and these stress levels are chosen in such a way that there is no failure taking place during testing. In field situations, storm wave loading is considered to be irregular cyclic loading in which there is a continuous variation in the load level from one cycle to the other. The results obtained from tests under uniform cyclic loading are compared with the results obtained from tests under varied cyclic loading.

In situ evaluation of K0 in eastern Canada clays

1995 ◽  
Vol 32 (4) ◽  
pp. 677-688 ◽  
Author(s):  
K.K. Hamouche ◽  
S. Leroueil ◽  
M. Roy ◽  
A.J. Lutenegger
Keyword(s):  
Hydraulic Fracturing ◽  
Effective Stress ◽  
Stress Ratio ◽  
Large Range ◽  
Horizontal Stress ◽  
In Situ Tests ◽  
Eastern Canada ◽  
Testing Program ◽  
Effective Stress Ratio

An approximate value of the horizontal effective stress in an overconsolidated clay deposit is often determined from an estimate of the effective stress ratio, K0, using the equation [Formula: see text]. It is also generally considered that the α parameter is approximately equal to sin [Formula: see text]. For evaluating K0 in sensitive clays of eastern Canada, a testing program has been initiated on three different sites representing a large range of overconsolidation ratios. Three different in situ devices were used: the Cambridge self-boring pressuremeter, the flat dilatometer, and hydraulic fracturing. The results show that the different techniques give essentially the same K0 values. They also give K0 values larger than those expected, with an α parameter typically between 0.75 and 1.15. Key words : clay, dilatometer, horizontal stress, hydraulic fracturing, in situ tests, self-boring pressuremeter.

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