Saturated Sandy Soil Research Articles

Effect of Excess Pore Pressure on Earthquake‐Induced Displacement of Partially Saturated Sandy Soil Slopes: Flexible Sliding Block Analysis

Effect of Excess Pore Pressure on Earthquake‐Induced Displacement of Partially Saturated Sandy Soil Slopes: Flexible Sliding Block Analysis

Predicting strain energy causing soil liquefaction

Liquefaction, which typically occurs in saturated sandy soil deposits, is one of the destructive phenomena that can occur during an earthquake. When the soil reaches liquefied state, it loses a significant amount of resistance and stiffness, which often results in widespread catastrophic damages. Therefore, accurate evaluating the potential of soil liquefaction occurrence is of great importance in earthquake geotechnical designs in regions prone to this phenomenon. The strain energy-based approach is a novel robustness technique to evaluate liquefaction potential. In the current research, 165 laboratory data sets from cyclic experiments were collected and analyzed. A predictive model using gene expression programming (GEP) was proposed to assess strain energy needed for occurrence of soil liquefaction. Assessing physical behavior of developed GEP-based model was conducted through sensitivity analysis. Performance of GEP-based was validated by comparing with a series of centrifuge experiments and cyclic triaxial tests results. Subsequently, after experimental verification of numerical modeling, the strain energy required for soil liquefaction under cyclic loading at different conditions were numerically evaluated and compared with the strain energy calculated by proposed model. Finally, the developed GEP-based model was compared with established strain energy-based relationships. The results indicated high precision of proposed GEP-based model in determination of strain energy required for soil liquefaction triggering.

Dynamic responses of large-diameter variable-section group-piles subjected to shaking-table tests with varying scour depths

Scouring leads to soil loss around piles, which, in turn, changes the ground-vibration characteristics and influences the seismic performance of bridges. In this study, the Xiang’an Bridge was used as a reference for constructing a large shaking-table test model to investigate the dynamic characteristics of the pore-pressure ratio of saturated sandy soils, accelerations, and bending moments of the piles, as well as the horizontal displacements of the pile-top at scouring depths of 10, 20, and 32 cm, with ground-vibration intensities ranging from 0.10-0.45 g. The results indicated that as the scour depth increased, the pile acceleration of the group piles increased and changed abruptly at the variable cross-section and soil-stratum interface. The peak values of the horizontal displacement of the pile-top and bending moment of the pile exhibited an increasing trend. As the ground-shaking intensity increased, the pore-pressure ratio of the saturated sandy soil, pile acceleration of the group piles, horizontal displacement of the pile-top, and bending moment of the pile body gradually increased, whereas the base frequency of the pile foundation gradually decreased. This study can serve as a reference for the seismic design and reinforcement of scour bridges in areas prone to seismic activity.

Unraveling the competitive transport of metformin and erythromycin in saturated sandy soil: Experimental investigation, modeling insights and implications on SDGs

The presence of metformin (MTN) and erythromycin (ETM) in groundwater is a growing global concern due to their persistence and toxicity. This study addresses a critical gap in understanding the fate and transport of these pharmaceutical and personal care products in saturated sandy soil columns at environmentally relevant concentrations, an underexplored area. The results show that MTN, due to its high mobility, appeared earlier in the soil column with a recovery rate exceeding 90 % and an adsorption coefficient (Kd) of 1.063 Lkg−1. In contrast, ETM, with a higher Kd value of 5.426 Lkg−1, exhibited delayed breakthrough and recovery of less than 15 %, indicating stronger adsorption potential. Desorption studies indicated a greater risk of MTN leaching into groundwater, while ETM remained strongly adsorbed to soil particles. Despite the limited organic matter content in sandy soil, a significant amount of ETM was adsorbed, suggesting sands' high adsorption capacity and potential for natural remediation. This research fills a knowledge gap regarding the adsorption capacity of sandy soils at environmentally relevant concentrations, providing essential insights for environmental risk assessments and groundwater contamination mitigation strategies, directly supporting Sustainable Development Goals 3 (Health and Well-being), 6 (Clean Water and Sanitation), and 14 (Life Below Water).

Enhancing sand liquefaction resistance through microbial-induced partial saturation: An experimental study

The liquefaction potential of saturated sand can be significantly reduced by inducing partial saturation in the soil. Conventional soil liquefaction mitigation methods, namely soil densification, drainage, cementing, and groundwater lowering, pose environmental concerns and are challenging to apply to pre-existing structures. However, the microbially induced partial saturation (MIPS) method is emerging as a novel and eco-friendly approach to mitigate liquefaction. The MIPS method involves microbial denitrification, which produces nitrogen gas and results in a desaturating effect in the saturated soil. The current study conducted a series of stress-controlled undrained cyclic triaxial tests on saturated sandy soil and microbially-desaturated sandy soil under different relative densities and loading conditions. In addition, the study systematically analyzed the effects of temperature and pH on bacterial activity and the denitrification process. Batch experiments were conducted to establish a relationship between the initial nitrate concentration in the bacterial media and the resulting desaturation.Comprehensive analyses of cyclic resistance curves were performed to gain a thorough understanding. Additionally, the study conducts detailed analyses of the accumulation of excess pore pressure and the resulting axial strains and deformation patterns in both treated and untreated sand. This study demonstrates that the MIPS treatment considerably enhances the liquefaction resistance of treated sand.

Effects of Muddy Water Infiltration on the Hydraulic Conductivity of Soils

Despite the high sand content of Yellow River water in arid Northwest China, locals in the region opt to use muddy water to meet the demand for agricultural irrigation. Muddy water irrigation is a complex process and is still poorly understood. In this study, six sets of saturated soil column infiltration tests were designed, considering soil texture (silt loam, sandy loam, and sand) and muddy water sand content (3%, 6%, 9%, and 12%) as the influencing factors, with two sets of validation tests. Change in hydraulic conductivity (Kh), the average change rate of hydraulic conductivity (ΔK), and cumulative infiltration volume (I) were experimentally studied in the context of muddy water infiltration to respectively establish the separate functional models and developed to fit their relationship with time. The study results indicated that the hydraulic conductivity (Kh) decreased with increasing muddy water infiltration time. For silt loam and sandy loam, Kh stabilized at 0.0030 and 0.0109 cm/min, respectively, after 70 min of infiltration. In contrast, Kh in the saturated sandy soil column significantly declined throughout the muddy water infiltration, showing a 90.84% reduction after 90 min compared to the saturated hydraulic conductivity of the sandy soil. As the sand content of the muddy water increased from 3% to 12%, Kh decreased by 83.99%, 90.90%, 91.92%, and 92.21% for 3%, 6%, 9%, and 12% sand content, respectively, in the saturated sandy soil columns at the end of the infiltration period. The I values were 21.20, 9.29, 7.90, and 6.25 cm for 3%, 6%, 9%, and 12% sand content, respectively. The ΔK values were 0.0037, 0.0041, 0.0043, and 0.0044 cm/min2 for the respective sand contents, at an infiltration time of 80 min. The validation test demonstrated that the segmented function model accurately emulated the changes in hydraulic conductivity of sandy soil textures throughout the infiltration period. Results from this study provide a significant basis for understanding the mechanisms to hinder muddy water infiltration and to efficiently utilize muddy water for irrigation.

Implementation of temporal moments to elucidate the reactive transport of metformin and erythromycin in the saturated porous media.

This study investigates the fate and transport dynamics of metformin (MTN) and erythromycin (ETM), both classified as pharmaceutical and personal care products (PPCPs), in a saturated sandy soil column using temporal moment analysis (TMA). The key flow and transport parameters, including Darcy velocity, longitudinal dispersivity, adsorption, and degradation coefficients, were analyzed. The results reveal that MTN, a highly mobile contaminant, is eliminatedfrom the column in approximately 40days, while ETM shows significant adsorption due to its hydrophobic and adsorptive nature. Darcy velocity significantly affects PPCP transport; a one-order magnitude change alters contaminant mass recovery at the column outlet by 88% for MTN and 39-fold for ETM. Longitudinal dispersivity has minimal impacton the transport of PPCPs. However adsorption primarily governs the fateofPPCPs with high adsorption coefficients (Kd), and degradation rates control the fateoflow-sorbing PPCPs. A one-order magnitude change in Kd results in a 55% change in the zeroth temporal moment (ZTM) of MTN and a 30-fold change in the case of ETM. Additionally, a one-order magnitude change in the degradation coefficient leads to a 60% variation in MTN's ZTM and a 5% variation in ETM's ZTM. Thus, TMA is a valuable tool for understanding PPCP dynamics in subsurface environments, providing critical insights for managing their increasing concentrations.

Study of The Axial and Lateral Bearing Capacity of Bored Piles Affected by Liquefaction

Abstract Liquefaction can lead to structural failure as it reduces the bearing capacity of building foundations. This phenomenon occurs in saturated sandy soils where pore water pressure increases, significantly decreasing effective soil stress. Evaluating the axial and lateral bearing capacity of bored piles affected by liquefaction is crucial to ensure the stability and performance of foundation systems. This study focuses on assessing the capabilities of bored piles in the Governor’s Office of Sulawesi Barat Province, which are influenced by liquefaction phenomena. The empirical approach applied the O’Neill and Reese 1989 method, while the numerical approach used RS Pile. The calculation results revealed decreased axial bearing capacity under liquefaction conditions. In non-liquefaction, PC.4 can withstand up to 24946 kN, with displacements of 0.94 cm (x), 0.39 cm (y), and 1.12 cm in settlement. In liquefaction, it decreases to 2876.78 kN, with displacements of 1.32 cm (x), 0.86 cm (y), and 1.68 cm in settlement. In non-liquefaction, PC.3 can withstand up to 17407.93 kN with displacements of 0.02 cm (x), 0.04 cm (y), and 0.06 cm in settlement. In liquefaction, it decreases to 1713.05 kN, with displacements of 0.02 cm (x), 0.05 cm (y), and 0.07 cm in settlement.

An uncoupled approach for estimating seismic-induced pore water pressures in liquefiable sandy soils

Proper evaluation of seismic-induced excess pore water pressures in saturated sandy soils is still an open issue, which can be tackled with fully coupled to uncoupled approaches. The former are more accurate but computationally onerous, while the latter require seismic demand and pore pressure build-up to be computed in two successive steps, typically employing simple constitutive assumptions.Starting from the work by Seed et al. (1975), this paper presents a novel uncoupled procedure to compute excess water pressures developing in a 1D soil column under partially drained conditions, when subjected to horizontal seismic excitations. Fundamental modifications are introduced to account for: non-uniform distribution of equivalent loading cycles; soil stiffness degradation; and modification of the frequency content of ground motion due to pore pressure build-up.The approach was implemented in Matlab via the Finite Difference Method and validated against both fully-coupled Finite Element analyses and one centrifuge test. An extensive parametric study was also performed for a two-layer soil column, by varying the thickness and hydraulic conductivity of the shallow layer, as well as the seismic input. The good agreement with both numerical and experimental data demonstrates that key features of liquefaction are well-captured by the proposed uncoupled approach.

Effect of salt types on salt precipitation and water transport in saline sandy soil

AbstractSalt precipitation on the surface of porous media significantly affects water transport processes. Most studies on salt precipitation mainly focused on single salts, but in nature, salt precipitation usually occurs as mixtures. Consequently, information on the crystallization of salt mixtures and its effect on water transport remains scarce. This study investigated the precipitation of mixtures (the mass ratios of NaCl:Na2SO4 were 3:7, 5:5, and 7:3, respectively) of NaCl (typical efflorescence) and Na2SO4 (typical subflorescence) in the initially saturated sandy soil columns and its effect on evaporation and compared it with the cases of the two salts individually. The results showed that salt mixtures exhibited a mixed pattern of crystals including both efflorescence and subflorescence, and the efflorescence showed granular aggregation, unlike the mono‐salts. The crystallization coverage of the salt mixtures was smaller than that of NaCl mono‐salt; high (7:3) and low (5:5 and 3:7) proportions of NaCl led to larger and smaller crystallization coverage than that of Na2SO4 mono‐salt, respectively. While the salt mixtures had less crystallization coverage than the mono‐salts, they showed lower evaporation because the salt mixtures formed a denser crystallization structure of efflorescence‐subflorescence‐soil layer, this crystallization structure exhibited greater inhibition of water vapour diffusion, thus reducing evaporation. In addition, the crystallization of the salt mixtures with higher NaCl proportion afforded greater resistance of evaporation. The mixed crystallization pattern formed by the salt mixtures significantly enhances the crystallization resistance to evaporation.

Studying Effect of Saturation Degree on the Bearing Capacity and Failure Mechanism of Sandy Soils

In this research, an experimental method was employed on samples of sandy soils from the Tartous and Palmyra regions. The objective was to investigate the impact of saturation degree on the bearing capacity of partially saturated sandy soil and the associated failure mechanism. To achieve the aim of the research, a series of tests were conducted to determine the basic physical properties of the soils. Additionally, a series of laboratory loading tests were conducted for a footing model atop sandy soil under various saturation degrees. Matric suction was measured, and soil water characteristic curves were determined using the filter paper technique. The results were subjected to analysis and discussion, and the experimental work demonstrated that saturation degree had a clear effect on the bearing capacity. It was observed that the bearing capacity of partially saturated soil is higher than that of fully saturated soil. The values of the increase were found to range between 2.3 and 9.7 times the bearing capacity in the fully saturated state. An empirical relationship was proposed to simulate the bearing capacity of partially saturated sandy soil based on the experimental results. Furthermore, the results indicated that the saturation degree exerted a discernible influence on the failure mechanism. In particular, a failure mode associated with dense soils was discerned in medium-dense soils at specific degrees of saturation for the tested soils.

Investigation of sand liquefaction potential in cyclic triaxial test and some premilinary research results in Vietnam

In the world, cyclic triaxial tests are widely used to evaluate the liquefaction potential of soil and determine the cyclic parameters for seismic design. However, the application of cyclic trixial test for evaluation of soil liquefaction is still limited in Vietnam. This paper introduced the cyclic triaxial apparatus, method and testing procedure to access the liquefaction potential of sand under cyclic loading. The research on some saturated sandy soils with high fine-grained content in Vietnam showed that the research results of soil liquefaction potential is reliable. In which, the liquefaction characteristics of sand are evaluated based on the changes of stress, strain and pore water pressure according to the cyclic cycles, thereby determining the liquefaction point and liquefaction boundary for fine sandy soils at different density levels.

Using microdialysis with a deuterium oxide tracer to estimate water exchange, water content and active surface area of the probe

Microdialysis is a useful tool for measuring in situ fluxes of soil compounds with minimal disturbance of soil structure and function. Fluxes of sampled compounds are commonly calculated per unit of membrane surface area, assuming that the entire membrane surface is capable of exchange – which is unlikely given varying soil moisture and the occlusion of membrane pores by the soil solid phase. We present a method to quantify the degree of connectivity of the microdialysis probe membrane to the surrounding soil by means of water exchange between a microdialysis perfusate and soil solution using deuterium (2H2O; equilibrated to DHO) as an internal standard. We applied the method to a range of probe membrane surface areas and soil moisture conditions to generate empirical models that estimate membrane surface area active in exchange. Our results suggest that even in a saturated sandy soil, active membrane surface areas reach only 40.3% of the probe surface area, perhaps due to occlusion by soil particles. However, when accounting for volumetric water content of the soil, active surface areas approached 80–90% of the area likely in contact with water, indicating that sampling efficiency of water-filled pores may still be high, particularly at slow flow rates. Furthermore, our method enables assessment of local soil water content around the probe. Models estimating soil water content were applied to field measurements of DHO exchange in three soil horizons (Organic, B1, B2) at two boreal sites, and in situ estimates were similar to those from conventional soil moisture methods when models were calibrated with the same soil type. We present DHO exchange as a powerful method for improving microdialysis flux interpretations in future studies, and for exploring small-scale water variability in relatively undisturbed soils.

Revealing the infiltration process and retention mechanisms of surface applied free DNA tracer through soil under flood irrigation

It has been recently demonstrated that free DNA tracers have the potential in tracing water flow and contaminant transport through the vadose zone. However, whether the free DNA tracer can be used in flood irrigation area to track water flow and solute/contaminant transport is still unclear. To reveal the infiltration process and retention mechanisms of surface applied free DNA tracer through soil under flood irrigation, we tested the fate and transport behavior of surface applied free DNA tracers through packed saturated sandy soil columns with a 10 cm water head mimicking flood irrigation. From the experimental breakthrough curves and by fitting a two-site kinetic sorption model (R2 = 0.83–0.91 and NSE = 0.79–0.89), adsorption/desorption rates could be obtained and tracer retention profiles could be simulated. Together these results revealed that 1) the adsorption of free DNA was dominantly to clay particles in the soil, which took up 1.96 % by volume, but took up >97.5 % by surface area and densely cover the surface of sand particles; and 2) at a pore water pH of 8.0, excluding the 4.9 % passing through and 3.1 % degradation amount, the main retention mechanisms in the experimental soil were ligand exchange (42.0 %), Van der Waals interactions (mainly hydrogen bonds), electrostatic forces and straining (together 44.7 %), and cation bridge (5.3 %). To our knowledge, this study is the first to quantify the contribution of each of the main retention mechanisms of free synthetic DNA tracers passing through soil. Our findings could facilitate the application of free DNA tracer to trace vadose zone water flow and solute/contaminant transport under flood irrigation and other infiltration conditions.

Investigation of the effects of cyclic lateral load characteristics on monopiles in saturated sandy soils using hypoplastic material model

AbstractOffshore wind turbines play a critical role as a renewable energy source and are experiencing continuous growth in usage. Both the design and implementation phases of constructing these structures present difficulties. It is crucial to ensure these structures are built to resist such conditions, assuring their durability, as they are exposed to lateral external influences such as wind and wave loads. This study investigated how monopile foundations behave in saturated sandy soil under cyclic loading. Pore water pressure accumulations in saturated sandy soil, monopile head lateral displacements, and vertical settlements around the monopile are investigated using the hypoplastic material model and two‐phase element with the ANSYS finite element program. Analyses conducted in this study demonstrated that lateral cyclic loads could cause excessive pore water pressure accumulations around the monopile, leading to displacements in the monopile head and soil settlements around it, highlighting the importance of carefully considering loading characteristics during the design process to provide the security and longevity of offshore wind turbines.

Prediction of yield shear strength of saturated sandy soils using artificial neural networks

ABSTRACT The undrained shear strength of sandy soils during flow failures and liquefaction is a critical metric in the analysis of undrained stability. In our study, the numerical technique known as Artificial Neural Network (ANN) is used for simulating the triaxial stress–strain relationship of sandy soils. This paper aims to predict the undrained shear strength of saturated sandy soil. The proposed program requires simple laboratory soil data to proceed. They are median grain diameter (D50), fines content percentage (FC%), void ratios and relative density. In addition, the stress data of undrained loading such as effective vertical stress (σ’1) and effective horizontal stress (σ’3) are needed. Then, using the program, the deviator stress at yield (qu yield) and, consequently, the yield shear strength of sandy soil (Su (yield)) can be determined. A database of experimental undrained triaxial of saturated sandy soils was collected from the literature and prepared to be the inputs of the network. Two artificial neural networks have been built. By comparing the effectiveness of the two networks, the Back Propagation Neural Network (PBNN) approved higher results and more accuracy than the General Regression Neural Network (GRNN). The computer program, yield shear strength prediction application, written in visual basic, has been developed by the author. For model validation, seven case studies (seven patterns of the production set), which were not seen by the network previously, were presented to the application and the results are compared to the actual output. The produced yield shear strength is very close to the actual strength.

Improvement of liquefaction potential in saturated sandy soil by CKD and bentonite

AbstractDue to the increase in earthquake activity in Iraq and Middle East during the last two decades, the study and understanding of probable destructive action and the best method to mitigate this effect became more important. So, many improvements and mitigation methods can be used. In this study, the use of permeation grout technique was adopted to prevent the existing soil condition in urban area by using cement kiln dust and bentonite clay. The tests were executed by using 1 g shaking table apparatus to simulate a sinusoidal motion (vibration) at specified different frequencies. The liquefaction phenomena were observed for loose saturated sand at 60 s, 25 s, and 10 s for 0.5 Hz, 0.75 Hz, and 1 Hz, respectively. After mitigation process, the soil liquefaction did not occur until 100 s, 60 s, and 30 s, for the same mentioned frequencies. Besides, the use of cement kiln dust decreases the liquefaction potential and increase the factor of safety.

Experimental investigation of factors affecting the characterisation of soil strength properties using a Bevameter in-situ plate sinkage and shear test apparatus

The Bekker-Wong soil-wheel interaction model has been widely adopted in the terramechanics field. This model requires the soil to be characterised using a Bevameter, which entails performing in situ plate sinkage and shear stress tests. Bevameter soil characterisation is not a standardised test procedure, and the test setup may influence the identified soil model parameters. This study investigates the influence of the following five factors for partially saturated sandy soil: I) soil preparation method on pressure-sinkage, II) soil preparation method on shear stress, III) torsional vs. translational shear mechanism, IV) shear contact area, and V) the influence of shear velocity. The results indicate that the influence of soil preparation on pressure-sinkage response is substantial, exhibiting an order-of-magnitude difference. The influence of soil preparation on shear tests is notable, but less significant. The shear mechanism, shear contact area and shear velocity exhibited a maximum absolute shear stress difference of 18%, 20% and 10%, respectively. Moreover, depending on the test setup configuration and data processing decisions, the estimated internal soil friction angles ranged from 16.5 to 37.5° for the same soil. The findings are expected to have significant implications for the prediction of vehicle drawbar pull using the Bekker-Wong model.

Energyand vapour transfer in evaporation processes over saturated bare soil and water surface‐lysimeter studies

AbstractPotential evaporation (PE) is a significant input in many hydrological models for the estimation of actual evaporation. Evaporation from water (PEw) is generally considered equivalent to evaporation from saturated bare soils (PEs). The influences of the underlying surface on PE as well as the energy and vapour transfer in potential evaporation processes over different surfaces are rarely discussed. In this research, lysimeter experiments were set up to measure the diurnal cycles of evaporation from two saturated sandy soils and water at a high temporal resolution in the Guanzhong Basin, China. Evaporation from Class A Pan, meteorological variables and temperatures were also measured during the experiment. Observation results show that PEsis ~12% higher than PEwon a yearly scale. There were also some clear differences in diurnal and seasonal PE dynamics between saturated bare soils and water. In summer, PEsis higher than PEwat day but smaller at night, with the peak value of PEwlagging ~4 h behind PEs. These observed PE dynamics and energy transfer processes can be quantitative explained on the basis of a full analysis of the energy balance equation. A comprehensive description of the flux transfer processes showed that these differences in PE are governed by differences in available energy (including albedo and thermal properties) between soils and water. Moreover, the observed differences in PE and vapour transfer processes were reproduced and described by improving the vapour diffusion equation, with considering the influence of different surfaces and boundary layer thicknesses. It is found that dynamics in PE were mainly characterised by surface temperature, which further determined the vapour gradients between the evaporation surface and air flow. The results suggested that differences between PEsand PEwcannot be neglected in hydrological applications. This study can act as both an experimental and theoretical reference for estimating potential evaporation rates.

Liquefaction triggering of non-saturated sandy soils

In saturated sandy soils liquefaction triggering is generally well-identified according to stress or strain criteria. On the contrary, the attainment of liquefaction in non-saturated sandy soils is still a cause of discussion in the scientific community. Even if the liquefaction resistance of non-saturated soils is higher than that of saturated ones, these soils may liquefy, as well. The increasing interest for cyclically mechanical behaviour of non-saturated sandy soils is due to the fact that desaturation or induced partial saturation can be used as useful mitigation techniques against soil liquefaction. Therefore, it is important to define, as accurately as possible, the attainment of liquefaction, on which depends the estimation of liquefaction resistance. The relevance of the apparent viscosity as a physically based parameter for the correct identification of the liquefaction triggering for fully saturated soils has been already demonstrated. In this paper, the viscous triggering approach has been used for non-saturated soils, processing some cyclic triaxial tests carried out on different sandy soils. The results confirm the reliability of the apparent viscosity as a liquefaction triggering parameter, showing a tight correlation with the strain liquefaction triggering criterion. Therefore, strain criterion should be preferred in non-saturated sandy soils.