scholarly journals Continuum-Based Approach to Model Particulate Soil–Water Interaction: Model Validation and Insight into Internal Erosion

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 785
Author(s):  
Ahmed Ibrahim ◽  
Mohamed Meguid
Keyword(s):  
Experimental Data ◽  
Soil Water ◽  
Pore Water Pressure ◽  
Fluid Model ◽  
Water Pressure ◽  
Interaction Model ◽  
Internal Erosion ◽  
Wide Range ◽  
Particulate Soil ◽  
Soil And Water

Resolving the interaction between soil and water is critical to understanding a wide range of geotechnical applications. In cases when hydrodynamic forces are dominant and soil fluidization is expected, it is necessary to account for the microscale interactions between soil and water. Some of the existing models such as coupled Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) can capture microscale interactions quite accurately. However, it is often computationally expensive and cannot be easily applied at a scale that would aid the design process. Contrastingly, continuum-based models such as the Two-Fluid Model (TFM) can be a computationally feasible and scalable alternative. In this study, we explored the potential of the TFM to simulate granular soil–water interactions. The model was validated by simulating the internal fluidization of a sand bed due to an upward water jet. Analogous to leakage from a pressurized pipe, the simulation was compared with the available experimental data to evaluate the model performance. The numerical results showed decent agreement with the experimental data in terms of excess pore water pressure, fluidization patterns, and physical deformations in violent flow regimes. Moreover, detailed soil characteristics such as particle size distribution could be implemented, which was previously considered a shortcoming of the model. Overall, the model’s performance indicates that TFM is a viable tool for the simulation of particulate soil–water mixtures.

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.

scholarly journals Stability Improvement Method for Embankment Dam with Respect to Conduit Cracks

2022 ◽  
Vol 12 (2) ◽  
pp. 567
Author(s):  
Young-Hak Lee ◽  
Jung-Hyun Ryu ◽  
Joon Heo ◽  
Jae-Woong Shim ◽  
Dal-Won Lee
Keyword(s):  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Internal Erosion ◽  
Scale Model ◽  
Seepage Analysis ◽  
Large Scale Model ◽  
Proposed Model ◽  
Improvement Method

In recent years, as the number of reservoir embankments constructed has increased, embankment failures due to cracks in aging conduits have also increased. In this study, a crack in a conduit was modeled based on the current conduit design model, and the risk of internal erosion was analyzed using a large-scale model test and three-dimensional deformation–seepage analysis. The results show that when cracks existed in the conduit, soil erosion and cavitation occurred near the crack area, which made the conduit extremely vulnerable to internal erosion. Herein, a model is proposed that can reduce internal erosion by applying a layer of sand and geotextiles on the upper part of the conduit located close to the downstream slope. In the proposed model, only partial erosion occurred inside the conduit, and no cavitation appeared near the crack in the conduit. The results suggest that internal erosion can be suppressed when the water pressure acting intensively on the crack in the conduit is dispersed by the drainage layer. To validate these results, the pore water pressure, seepage line, and hydraulic gradient were investigated to confirm the erosion phenomenon and reinforcement effect.

Soil-water characteristics of compacted sandy and cemented soils with and without vegetation

2015 ◽  
Vol 52 (9) ◽  
pp. 1331-1344 ◽  
Author(s):  
W.M. Yan ◽  
Guanghui Zhang
Keyword(s):  
Soil Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rapid Development ◽  
Characteristic Curve ◽  
Degree Of Saturation ◽  
Material Density ◽  
Water Characteristics ◽  
Field And Laboratory Conditions ◽  
Humidity Monitoring

Experiments were undertaken to study the soil-water characteristics of compacted sandy soil (SS) and cemented soil (CS) in field and laboratory conditions. The influence of vegetation and material density on the development of negative pore-water pressure (PWP) and degree of saturation (Sr) in the studied materials was investigated. The field planting experiments demonstrated a promising survival rate of Schefflera heptaphylla in both types of material, while the (SS) promoted better growth of the seedlings than the cemented one. In the field study, PWP and Sr of the compacted SS responded noticeably and promptly to natural drying–wetting cycles. However, the responses in the CS were relatively mild. When subjected to the same drying–wetting cycles, PWP responded more slowly and to a smaller magnitude compared with that of the uncemented counterpart. In addition, Sr changed little in CS. An increase in the density of the SS promoted rapid development of negative PWP, while an opposite trend was observed for CS. Attempts have been made to explain the observations from the perspectives of material permeability and change in water content during a drying period in both soil types. Furthermore, in SS, the development of PWP (with a measurement limit of −90 kPa) was minimally affected by the presence of vegetation, while vegetation noticeably helped the development of negative PWP in CS. Bounds of the soil-water characteristic curve (SWCCs) of the studied materials were presented based on estimates from the drying and wetting scanning curves derived from the field monitoring. A corresponding laboratory study was carried out in an environmental chamber with controllable temperature and humidity. Monitoring results from the laboratory agreed qualitatively with those obtained from the field.

scholarly journals Mechanical response and pore pressure generation in granular filters subjected to uniaxial cyclic loading

2018 ◽  
Vol 55 (12) ◽  
pp. 1756-1768
Author(s):  
Jahanzaib Israr ◽  
Buddhima Indraratna
Keyword(s):  
Cyclic Loading ◽  
Pore Pressure ◽  
Pore Water ◽  
Mechanical Response ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Internal Erosion ◽  
Excess Pore Water Pressure ◽  
Excess Pore

This paper presents results from a series of piping tests carried out on a selected range of granular filters under static and cyclic loading conditions. The mechanical response of filters subjected to cyclic loading could be characterized in three distinct phases; namely, (I) pre-shakedown, (II) post-shakedown, and (III) post-critical (i.e., the occurrence of internal erosion). All the permanent geomechanical changes such, as erosion, permeability variations, and axial strain developments, took place during phases I and III, while the specimen response remained purely elastic during phase II. The post-critical occurrence of erosion incurred significant settlement that may not be tolerable for high-speed railway substructures. The analysis revealed that a cyclic load would induce excess pore-water pressure, which, in corroboration with steady seepage forces and agitation due to dynamic loading, could then cause internal erosion of fines from the specimens. The resulting excess pore pressure is a direct function of the axial strain due to cyclic densification, as well as the loading frequency and reduction in permeability. A model based on strain energy is proposed to quantify the excess pore-water pressure, and subsequently validated using current and existing test results from published studies.

scholarly journals Predicting the Performance of Highway Embankment Slopes

2019 ◽  
Vol 271 ◽  
pp. 02007
Author(s):  
Navid H. Jafari ◽  
Anand Puppala ◽  
Burak Boluk ◽  
Jack A. Cadigan ◽  
Sayantan Chakraborty ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
High Plasticity ◽  
Soil Water Retention ◽  
Ring Shear ◽  
Wide Range ◽  
Van Genuchten Model ◽  
Ring Shear Tests ◽  
Highway Embankments ◽  
Marginal Condition

Resilience of transportation infrastructure, such as highway embankments, is critical to avoiding commuter delays and costly repairs. The majority of highway embankments in Louisiana and Texas are in marginal condition because the high-plasticity clays that are used during construction will moisten with time to significantly lower strengths. The ring shear tests demonstrate that the Gamez and Stark [1] empirical correlations are applicable to Texas and Louisiana soils. The soil water retention curves at each site were fitted to the Van Genuchten model [2]. For example, the air entry values vary from 0.013 to 0.053 kPa-1 in Louisiana and from 0.008 to 0.01 kPa-1 in Texas. The implications of this wide range of air entry values is that the matric suction pressure required to saturate and desaturate controls the pore-water pressure build-up during a rainfall event.

scholarly journals Influence of initial fines content on fabric of soils subjected to internal erosion

2016 ◽  
Vol 53 (2) ◽  
pp. 299-313 ◽  
Author(s):  
Mao Ouyang ◽  
Akihiro Takahashi
Keyword(s):  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Internal Erosion ◽  
Experimental Investigations ◽  
Compression Tests ◽  
Fines Content ◽  
Instability Zone ◽  
Before And After ◽  
Undrained Behavior

Seepage-induced internal erosion often happens in earth structures. This paper presents experimental investigations on the influence of initial fines content on fabric of soils subjected to internal erosion. The tested materials were the binary mixtures of silica No. 3 and silica No. 8, which correspond to the coarse and fine fractions, respectively. One group of specimens was prepared with initial fines contents of 0, 15%, 25%, and 35% by weight. The undrained monotonic compression tests were performed on this group to examine the influence of fines content on the undrained behavior. The other group was prepared with initial fines contents of 15%, 25%, and 35% by weight, on which the seepage tests and subsequent undrained compression tests were carried out to demonstrate the mechanical influence of the internal erosion. The undrained behavior of the first group of specimens reveals that the presence of fines would decrease the peak and residual strengths. A comparison between the undrained behavior of soils with erosion and that of soils without erosion shows that the soils become less contractive after the internal erosion. When the axial strain is less than 0.4%, the undrained secant stiffness of soils with erosion is larger than that without erosion at the same axial strain. Meanwhile, the undrained peak strength and residual strength are larger for soils with erosion than that for soils without erosion. The less amount of excess pore-water pressure is generated during the undrained compression for the eroded soils comparing to those of the uneroded soils. Furthermore, the eroded soils show a wider instability zone than that of the uneroded soils, which suggests that the instability zone be enlarged by the internal erosion. Besides, one-dimensional upward seepage tests were performed to investigate the change of fabric of the mixed sand with 15%, 25%, and 35% fines contents due to internal erosion. The recorded microscopic images of soils before and after erosion reveal that the fabric is altered by the internal erosion.

Research on Application of Seismic Piezocone Penetration Tests in Pile Foundation

2011 ◽  
Vol 368-373 ◽  
pp. 2722-2730
Author(s):  
Quan Cao ◽  
Hong Chen ◽  
Fa Bo Chen
Keyword(s):  
Bearing Capacity ◽  
Pile Foundation ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Single Pile ◽  
In Situ Tests ◽  
Stress Theory ◽  
Theoretical Relationship ◽  
Wide Range ◽  
Penetration Tests

According to the characteristics of installation about the penetrometer of seismic piezocone penetration tests (SCPTu) and the pile, a theoretical relationship between ultimate bearing capacity of single pile, time-effect of shaft bearing capacity of single pile, excess pore water pressure around the pile during pile driven and the data measured from SCPTu is developed based on the cavity expanded theory, the Terzaghi one-dimensional consolidation theory and effective stress theory. The result of field test in KunShan and the calculated result which used the theoretical relationship mentioned above are compared. The results indicate that the analytical solutions agree well with the in-situ tests, which show that the application of seismic piezocone penetration tests have wide range in the pile foundation.

A unified approach to densification and liquefaction of cohesionless sand in cyclic shearing

1979 ◽  
Vol 16 (4) ◽  
pp. 659-678 ◽  
Author(s):  
S. Nemat-Nasser ◽  
A. Shokooh
Keyword(s):  
Experimental Data ◽  
Void Ratio ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Unified Theory ◽  
Saturated Sand ◽  
Unified Approach ◽  
Homogeneous Sample ◽  
Excess Pore Water Pressure ◽  
Excess Pore

When submitted to cyclic shearing, loose dry sand densifies, and undrained saturated sand may liquefy. Based on energy considerations, a unified theory for densification and liquefaction of a homogeneous sample of cohesionless sand is proposed. It is observed that these phenomena involve rearrangement of grains in microscale, requiring an expenditure of a certain amount of energy, which increases as the void ratio approaches its minimum value and decreases as the excess pore water pressure increases. On the basis of rough estimates, explicit relations are developed for both the densification and liquefaction phenomena, and the results are applied to predict relevant available experimental data.

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