Article
Engineering, Geological
Md Mizanur Rahman, Yannis F. Dafalias
Summary: This study discusses the effects of fabric anisotropy and fines content on the mechanical behavior of sands, and develops the Anisotropic Critical State Theory and Equivalent Granular State Theory for clean sands. By combining these two theories, a constitutive model is proposed to simultaneously consider the effects of fabric anisotropy and fines content on the undrained response of sands.
Article
Engineering, Geological
Q. X. Wu, J. J. Zheng, Z. X. Yang
Summary: This study presents a convenient and efficient DEM sample preparation procedure to generate three-dimensional specimens with different intensities of initial fabric anisotropy. The initial fabric can be altered by changing the bedding plane angle α of the soil deposition relative to the horizontal plane. A range of α values was considered, from -90 to 90 degrees. Undrained rotational shear tests were conducted on these initially anisotropic samples using a novel discrete element approach. The simulation results provide new insights into the strain evolution patterns and fabric evolutions of initially anisotropic samples under undrained rotational shear.
Article
Engineering, Geological
Zhiwei Gao, Dechun Lu, Yue Hou, Xin Li
Summary: Sand liquefaction under static and dynamic loading can lead to the failure of crucial infrastructure, such as embankments, slopes, and bridges. It can also cause submarine landslides and tsunamis. The internal soil structure's fabric anisotropy, including particle orientation, force network, and void space, plays a significant role in sand liquefaction. We propose a constitutive model that considers the effect of anisotropy on sand liquefaction and validate it with extensive test results on Toyoura sand. The model also investigates the response of sand ground under earthquake loading, demonstrating that sand with horizontal bedding plane has the highest resistance to liquefaction.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2023)
Article
Engineering, Geological
Lin Zhou, Jian-Feng Chen, Xiao-Ying Zhuang
Summary: A series of monotonic and multidirectional cyclic simple shear tests were conducted on reconstituted fiber-reinforced calcareous sand specimens. The results showed that the inclusion of fibers and increasing fiber contents can improve the liquefaction resistance of calcareous sand under cyclic loading. A linear relationship was found between the normalized liquefaction resistance of reinforced sand and the number of cycles for triggering liquefaction. A pore pressure prediction model considering the effect of fiber contents was proposed.
Article
Engineering, Geological
Quoc T. Phan, Ha H. Bui, Giang D. Nguyen, Abdelmalek Bouazza
Summary: This study demonstrates that the rolling resistance of silty sand significantly influences its critical state, peak state, and zero-dilatancy state, and the rolling resistance of fine particles can reduce the liquefaction susceptibility of the sand.
Article
Engineering, Geological
Amirreza Fotovvat, Abouzar Sadrekarimi, Michael Etezad
Summary: The drained instability of two gold mine tailings under lateral stress relief is investigated in this study. It was observed that specimens consolidated to the same void ratio and initial stress ratio undergo instability at similar stress ratios or friction angles in both CDS and undrained shear tests. This suggests that the instability characteristic of tailings prone to stress relief can be predicted using undrained triaxial tests on anisotropically consolidated specimens.
Article
Engineering, Geological
W. Rong, J. S. McCartney
Summary: This study investigated the volumetric changes of unsaturated sand specimens during undrained cyclic shear tests, revealing a nonlinear relationship between volumetric contraction and degree of saturation. The largest contraction occurred at a saturation degree of 0.4, coinciding with the largest decrease in mean effective stress. The sand specimens followed a wetting-path scanning curve during shearing, with small changes in matric suction.
JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING
(2021)
Article
Computer Science, Interdisciplinary Applications
An Zhang, Mingjing Jiang, Dong Wang
Summary: To understand the effects of fabric anisotropy on cyclic liquefaction of sands, undrained cyclic triaxial tests on vertical and horizontal specimens were simulated using the discrete element method. The simulation accurately depicted the anisotropic cyclic responses observed in experiments, showing that the vertical specimen is more susceptible to liquefaction than the horizontal specimen under symmetrical cyclic loading conditions. The study investigated various fabric parameters at the particle scale to gain insights into the macro response and applied anisotropic critical state theory to explore the relationship between macro-mechanical behavior and fabric evolution.
COMPUTERS AND GEOTECHNICS
(2023)
Article
Engineering, Geological
Xiaoli Xie, Bin Ye, Teng Zhao, Xiaoqing Feng, Feng Zhang
Summary: Prior earthquakes have significant impacts on the liquefaction resistance of sandy soils. Non-liquefying loading can either increase or decrease the liquefaction resistance, depending on the cyclic stress ratio and excess pore pressure ratio. Specimens previously loaded under larger cyclic stress ratios exhibited lower liquefaction resistance after reconsolidation, while those reconsolidated from smaller cyclic stress ratios showed higher liquefaction resistance. Sand liquefaction resistance is correlated with initial anisotropic degree and mechanical average coordination number.
SOIL DYNAMICS AND EARTHQUAKE ENGINEERING
(2022)
Article
Engineering, Geological
Haohua Chen, Pin-Qiang Mo
Summary: This paper proposes a rigorous undrained solution for cylindrical cavity expansion problems in K0-consolidated clays, adopting a simple non-associated and anisotropic model, SANICLAY. The solution considers non-associativity, K0-consolidation, and stress-induced anisotropy, and can be validated against the modified Cam-clay solution. The effects of overconsolidation ratio on cavity pressure curves, stress distributions, evolutions of anisotropic parameters, and stress paths are investigated. The proposed solution serves as a benchmark for extensions of analytical solutions, numerical simulations, and backcalculations of geotechnical problems.
JOURNAL OF ROCK MECHANICS AND GEOTECHNICAL ENGINEERING
(2022)
Article
Geochemistry & Geophysics
Baojian Li, Panpan Guo, Gaoyun Zhou, Zhe Wang, Gang Lei, Xiaonan Gong
Summary: Through undrained cyclic triaxial tests, it was found that calcareous sand with different relative densities have varying cyclic responses under static shear stress. Dense sand has greater cyclic resistance than loose sand, but the initial static stress affects the cyclic resistance differently for the two types of sand. Dense sand dissipates energy more quickly, while loose sand reaches the lowest cyclic resistance at a static shear stress of 0.12.
Article
Engineering, Mechanical
Kristian Krabbenhoft
Summary: The new total stress failure criterion takes into account both isotropic and anisotropic soils under undrained conditions, and has been validated with reported data from various types of tests.
JOURNAL OF ENGINEERING MECHANICS
(2021)
Article
Engineering, Geological
Yuxuan Wen, Yida Zhang
Summary: This study introduces the concept of critical fabric surface (CFS) and establishes a single CFS spanning across a wide range of coordination numbers. This provides a new perspective to interpret and model the mechanics of granular soils in both pre- and post-liquefied regimes.
Article
Engineering, Geological
Q. X. Wu, Z. X. Yang
Summary: The undrained response of sand under principal stress rotation (PSR) has been studied using the discrete element method, providing insights into the fabric evolution and macroscopic mechanical behavior of granular materials under rotational shear.
JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING
(2022)
Article
Engineering, Geological
D. Liao, Z. X. Yang
Summary: The unified hypoplastic model incorporates anisotropic critical state theory to describe the fabric effect in sand under both monotonic and cyclic loading conditions, successfully simulating the anisotropic behavior of sand using a single set of parameters.
Article
Engineering, Geological
Jinquan Shi, Wim Haegeman, Veerle Cnudde
Summary: This study investigates the stiffness anisotropy of calcareous sand and Mol silica sand through triaxial tests, finding that calcareous sands show elastic homogeneous continuum behavior at small strains. Air pluviation samples of calcareous sand display notably higher anisotropic ratios, while samples prepared by moist tamping and dry funnel deposition methods exhibit less pronounced stiffness anisotropy. The lower sphericity and smaller particle sizes of calcareous sands are attributed to the higher anisotropic ratios observed in this study.
Article
Engineering, Ocean
Jinquan Shi, Wim Haegeman, Arjen Mascini, Veerle Cnudde
Summary: The study investigates the behavior of sandy soil in laboratory tests with different sedimentation techniques using calcareous sand from the Persian Gulf reclamation site. X-ray tomography is used to examine the microstructure of the sand samples, showing distinct differences in sample uniformity and spatial fabric anisotropy based on the preparation method. The sample density, affected by boundary effects, varies along the sample height, and the spatial consistency of fabric anisotropy is proven except for samples prepared by water pluviation method.
MARINE GEORESOURCES & GEOTECHNOLOGY
(2021)