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.

scholarly journals Effect of Variable Confining Pressure on Cyclic Triaxial Behavior of K0-consolidated Soft Marine Clay

2018 ◽  
Vol 4 (4) ◽  
pp. 755
Author(s):  
Lei Sun
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Confining Pressure ◽  
Stress Path ◽  
Cyclic Stress ◽  
Marine Clay ◽  
Stress Ratios ◽  
Variable Confining Pressure

The effect of variable confining pressure (VCP) on the cyclic deformation and cyclic pore water pressure in K0-consolidated saturated soft marine clay were investigated with the help of the cyclic stress-controlled advanced dynamic triaxial test in undrained condition. The testing program encompassed three cyclic deviator stress ratios, CSR=0.189, 0.284 and 0.379 and three stress path inclinations ηampl=3,1 and 0.64. All tests with constant confining pressure (CCP) and variable confining pressure (VCP) have identical initial stress and average stress. The results were analyzed in terms of the accumulative normalized excess pore water pressure rqu recorded at the end of each stress cycle and permanent axial strain, as well as resilient modulus. Limited data suggest that these behavior are significantly affected by both of the VCP and CSR. For a given value of VCP, both of the pore water pressure rqu and permanent axial strains are consistently increase with the increasing values of CSR. However, for a given value of CSR, the extent of the influence of VCP and the trend is substantially depend on the CSR.

A Comparative Study of the Response of Double Shearing and Hypoplastic Models

2002 ◽  
Author(s):  
Huaning Zhu ◽  
Morteza M. Mehrabadi ◽  
Mehrdad Massoudi
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Constitutive Relations ◽  
Constitutive Models ◽  
Shear Loading ◽  
Biaxial Compression ◽  
Finite Element Program ◽  
Cyclic Shear ◽  
Hypoplastic Model ◽  
Element Program

The principal objective of this paper is to compare the mechanical response of a double shearing model with that of a hypoplastic model under biaxial compression and under cyclic shear loading. As the origins and nature of these two models are completely different, it is interesting to compare the predictions of these two models. The constitutive relations of the double shearing and the hypoplastic models are implemented in the finite element program ABACUS/Explicit. It is found that the hypoplastic and the double shearing constitutive models both show strong capability in capturing the essential behavior of granular materials. In particular, under the condition of non-cyclic loading, the stress ratio and void ratio predictions of the double shearing and the hypoplastic models are relatively close, while under the condition of cyclic loading, the predictions of these models are quite different. It is important to note that in the double shearing model employed in this comparison the shear rates on the two slip systems are assumed to be equal. Hence, the conclusions derived in this comparison pertain only to this particular double shearing model. Similarly, the hypoplasticity model considered here is that proposed by Wu, et al. [30] and the conclusions reached here pertain only to this particular hypoplasticity model.

Static and cyclic stress distributions in a buckling shear panel

1969 ◽  
Vol 4 (4) ◽  
pp. 278-284 ◽  
Author(s):  
R J Frost ◽  
P P Benham
Keyword(s):  
Stress Ratio ◽  
Cyclic Stress ◽  
Shear Loading ◽  
Stress Conditions ◽  
Accurate Assessment ◽  
Stress Distributions ◽  
Cyclic Shear ◽  
Shear Panel ◽  
Assessment Of Stress ◽  
Static Shear

A panel comprising a thin, square, flat plate of clad copper-aluminium alloy to specification B.S.2L.73, bounded by substantial edge members, was subjected to a range of static shear loadings up to a shear-stress ratio of 3·0. The experimentally determined distributions of strains and stresses within the plate reveal the importance of the stresses due to bending resulting from the formation of diagonal shear buckles. Fair agreement between the results of this study and the work of other investigators was obtained. The work presented is part of an investigation into the fatigue-crack propagation behaviour and residual-strength characteristics of flat panels subjected to shear loading, hence an accurate assessment of stress conditions at least along the two diagonals was required. The strains within the plate when subjected to a range of cyclic shear loadings were determined and a relation between cyclic strains and corresponding static strains was obtained. The use of this relation leads to a simple assessment of stress conditions within the plate due to any magnitude of cyclic shear loading.

scholarly journals Variation in Micro-Pores During Dynamic Consolidation and Compression of Soft Marine Soil

2021 ◽  
Vol 9 (7) ◽  
pp. 750
Author(s):  
Chen-Xiang Dai ◽  
Qiong-Fang Zhang ◽  
Shao-Heng He ◽  
An Zhang ◽  
Hua-Feng Shan ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Pore Structure ◽  
Dynamic Properties ◽  
Confining Pressure ◽  
Cyclic Stress ◽  
Test Results ◽  
Dynamic Consolidation ◽  
Confining Pressures ◽  
Stress Ratios ◽  
Marine Soil

In this study, to explore the microstructure deformation mechanism of marine soft marine soil under cyclic loading, we analyzed the dynamic properties of soft marine soil under cyclic loading via dynamic consolidation compression testing. Then, using Image-Pro Plus (IPP) 6.0 image analysis software, and according to the dynamic consolidation compression test results and the images from a scanning electron microscope (SEM), we determined the weakening effect of soft soils under different consolidation confining pressures, different cyclic stress ratios, and different over-consolidation ratios. After dynamic consolidation and compression, the pore structure of undisturbed soft marine soil tends to compact, the degree of soil particle fragmentation intensifies, small pores increase, large pores decrease, the pores become more regular, and the distribution of pores is directional. Subsequently, for undisturbed soft marine soil, the higher the consolidated confining pressure, cyclic dynamic stress ratio, and over-consolidation ratio, the greater the damage to the pore structure, and the more obvious the structural weakening effect exhibited under cyclic loading.

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.

Correspondence Between Notched and Unnotched Specimen’s Fatigue Data: Fundamental Concept and Formulation of Equivalent Stress Ratio REQ

2005 ◽  
Author(s):  
Hiroshi Matsuno
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Cyclic Loading ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Equivalent Stress ◽  
Cyclic Stress ◽  
Fatigue Data ◽  
Mechanical Models ◽  
Stress Ratios

In the present study, a creative consideration is developed for the problem of the correspondence between notched and unnotched specimen’s fatigue data. The proposed concept is essentially different from that of volumetric damage, and it has the great advantage of being avoidable to encounter the fatally invalid point of the volumetric approach, such as determination of damage-volume sizes. Moreover, the fatigue criteria derived are very easy to be applied to practical notch problems. The approach is developed as follows; (1) A hypothesis of plastic adaptation in a surface layer is proposed and mechanical models reflecting the hypothesis are constructed. (2) From these models, equivalent stress ratios REQ are derived as the new parameter for the correspondence between the cyclic stress conditions of the notched and unnotched specimens. REQ is generalized for proportional multiaxial cyclic loading through the consideration for the case of torsional cyclic loading. Moreover, REQ is derived from the mechanical model for the stress field of the mode I fatigue crack tip. (3) Experimental data on fatigue strength and fatigue crack propagation rates are rearranged on the basis of REQ and are formulated. (4) Practical criteria are proposed for the fatigue strength and the fatigue crack propagation rates.

scholarly journals Experimental study of shear-key equipped pile to grout connection under cyclic loading

2019 ◽  
Vol 92 ◽  
pp. 13005
Author(s):  
Matías Silva ◽  
Orianne Jenck ◽  
Fabrice Emeriault ◽  
Jean Benoit Toni
Keyword(s):  
Cyclic Loading ◽  
Research Work ◽  
Shear Loading ◽  
Technical Solution ◽  
Cyclic Shear ◽  
Constant Stiffness ◽  
In Situ Conditions ◽  
Tidal Turbine ◽  
Number Of Cycles ◽  
Constant Normal Stiffness Conditions

A technical solution for tidal turbine foundation in granite seabed consists of grouted steel piles. The piles would be subjected to cyclic loading due to the severe service conditions. The mechanical behaviour at the interface between the pile and the surrounding media is one of the key points that determine the bearing capacity of the foundation system. Experimental research work has been carried out in the laboratory to study the grouted pile-to-rock connection (GPRC) and focused more precisely on the pile to grout connection when the pile is equipped with shear-keys that enhance the interface capacity. Monotonic and cyclic shear tests were performed using a specific direct shear test device (BCR3D), allowing application of sample confining conditions close to the in-situ conditions, namely constant normal stiffness conditions. Cyclic tests - either under one way or two-way shear loading application - were performed on several samples, under both constant volume and various constant stiffness boundary conditions. This study has shown that the strength of the interface is highly dependent on the combination of mean load, cyclic amplitudes and number of cycles applied to the interface. Cyclic failure was observed with less than 30 cycles for two-way and one-way cyclic loading.

Cyclic loading response of loose air-pluviated Fraser River sand for validation of numerical models simulating centrifuge tests

2005 ◽  
Vol 42 (2) ◽  
pp. 550-561 ◽  
Author(s):  
Dharma Wijewickreme ◽  
Somasundaram Sriskandakumar ◽  
Peter Byrne
Keyword(s):  
Cyclic Loading ◽  
Simple Shear ◽  
Mechanical Response ◽  
Shear Loading ◽  
Shear Stresses ◽  
Fraser River ◽  
River Sand ◽  
Cyclic Shear ◽  
Direct Simple Shear ◽  
Static Shear

Cyclic loading response of loose Fraser River sand was investigated, as input to numerical simulation of centrifuge physical models, using constant-volume direct simple shear tests conducted with and without initial static shear stress condition. Although the observed trends in mechanical response were similar, air-pluviated specimens were more susceptible to liquefaction under cyclic loading than their water-pluviated counterparts. Densification due to increasing confining stress (stress densification) significantly increased the cyclic resistance of loose air-pluviated sand, with strong implications for the interpretation of observations from centrifuge testing. The stress densification effect, however, was not prominent in the case of water-pluviated specimens. The differences arising from the two specimen reconstitution methods can be attributed to the differences in particle structure and highlight the importance of fabric effects in the assessment of the mechanical response of sands. The initial static shear stresses appear to reduce the cyclic shear resistance of loose air-pluviated sand in simple shear loading, in contrast to the increases in resistance reported on the basis of data from triaxial testing. Data from laboratory element tests that closely mimic the soil fabric and loading modes of the centrifuge specimens are essential for meaningful validation of numerical models.Key words: liquefaction of sands, air-pluviation, cyclic loading, direct simple shear testing, specimen preparation, fabric.

Horizontal Connections for Precast Concrete Shear Wall Panels Under Cyclic Shear Loading

PCI Journal ◽  
1996 ◽  
Vol 41 (3) ◽  
pp. 64-80 ◽  
Author(s):  
Khaled A. Soudki ◽  
Jeffrey S. West ◽  
Sami H. Rizkalla ◽  
Bruce Blackett
Keyword(s):  
Precast Concrete ◽  
Shear Wall ◽  
Shear Loading ◽  
Cyclic Shear ◽  
Horizontal Connections ◽  
Wall Panels

TIME TO THE END OF PRIMARY CONSOLIDATION (EOP) OF SOFT CLAYEY SOILS: CONCERNING THE EFFECT OF ATTERBERG’S LIMIT AND CYCLIC LOADING HISTORY

2019 ◽  
Vol 128 (2B) ◽  
pp. 29-41
Author(s):  
Trần Thanh Nhàn
Keyword(s):  
Cyclic Loading ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Clayey Soils ◽  
Loading History ◽  
Cyclic Shear ◽  
Wide Range ◽  
Primary Consolidation ◽  
Time Required

In order to observe the end of primary consolidation (EOP) of cohesive soils with and without subjecting to cyclic loading, reconstituted specimens of clayey soils at various Atterberg’s limits were used for oedometer test at different loading increments and undrained cyclic shear test followed by drainage with various cyclic shear directions and a wide range of shear strain amplitudes. The pore water pressure and settlement of the soils were measured with time and the time to EOP was then determined by different methods. It is shown from observed results that the time to EOP determined by 3-t method agrees well with the time required for full dissipation of the pore water pressure and being considerably larger than those determined by Log Time method. These observations were then further evaluated in connection with effects of the Atterberg’s limit and the cyclic loading history.

Sign in / Sign up

Export Citation Format

Share Document