Experimental study on seismic reinforcement of bridge foundation on silty clay landslide with inclined interlayer

A shaking table test for a bridge foundation reinforced by anti-slide piles on a silty clay landslide model with an inclined interlayer was performed.The deformation characteristics of the bridge foundation piles and anti-slide piles were analyzed in different loading conditions.The dynamic response law of a silty clay landslide with an inclined interlayer was summarized.The spacing between the rear anti-slide piles and bridge foundation should be reasonably controlled according to the seismic fortification requirements,to avoid the two peaks in the forced deformation of the bridge foundation piles.The“blocking effect”of the bridge foundation piles reduced the deformation of the forward anti-slide piles.The stress-strain response of silty clay was intensified as the vibration wave field appeared on the slope.Since the vibration intensified,the thrust distribution of the landslide underwent a process of shifting from triangle to inverted trapezoid,the difference in the acceleration response between the bearing platform and silty clay landslide tended to decrease,and the spectrum amplitude near the natural vibration frequency increased.The rear anti-slide piles were able to slow down the shear deformation of the soil in front of the piles and avoid excessive acceleration response of the bridge foundation piles.

Vertical Diffusion Coefficient with Stratification Effect for Silty Sediment Suspension Under Waves

To analyze previous experimental data of suspended sediment concentration for silty sediment with different sediment particle sizes due to waves, a new stratification correction coefficient is presented. The suspended sediment concentration gradient and sediment particle diameter are selected as parameters. Furthermore, a diffusion coefficient model with a stratification effect over the whole water depth for silty sediment suspension under waves is developed. The comparison between the suspended sediment concentration calculated by the presented model and several groups of experimental data shows that the model can reasonably reflect the vertical distribution of silty sediment suspension.The stratification effect calculated by the present model decreases with an increase in the sediment particle diameter,which indicates that the model can be extended to describe the suspended sediment concentration of fine to medium sand when the near-bottom sediment concentration is not very high. Although the original model needs to be iteratively solved, the approximate method without iteration is recommended for applications when the near bottom sediment concentration is between 10 and 20 kg/m~3 due to the small difference between the non-iterative and iterative solution for near bed layer suspended sediment concentration, which plays a major role in sediment transport.

Effects of transient temperature gradient on frost heave of saturated silty clay in an open system

Frost heave in seasonally frozen regions is a one-dimensional process that could severely damage infrastructure subgrades.Stress state,temperature and water migration are important factors for frost heave.This work investigated the effects of soil temperature and volumetric water content on the transient frost heave ratio during the freezing of saturated silty clay in an open system and analyzed the relationships between the transient frost heave ratio and freezing rate and between temperature gradient and frost heave rate.The results show that the frost heave ratio,frost heave rate,and freezing rate are positively correlated with the temperature gradient since the temperature gradient drives the water migration during freezing,indicating the transient temperature gradient could be used to evaluate the frost heave of saturated silty clay.The transient freezing rate and transient frost heave ratio are logarithmically related to the transient frost heave ratio and transient temperature gradient,respectively.The effects of transient temperature gradient on frost heave are the principal mechanism responsible for different frost heave characteristics and uneven frost heave along a subgrade of the same soil type.

Thermomechanical and Hydrous Effect of Heavy Fuel Oil in a Building Material Based on Silty Clayey Soil

This study focuses on the use of heavy fuel oil in construction in Burkina Faso.Mixed with silty and/or clay soil,it is used as a coating to reinforce the walls of raw soil constructions which are very sensitive to water.The interest of this paper is to shed light on the thermomechanical and above all water effects of heavy fuel oil on a sample of silty clayey soil.To achieve this,we used heavy fuel oil added in different proportions to silty clayey soil,to make sample of bricks on which tests were carried out.At the end of the experimental tests carried out on materials made(bricks)with our soil sample,it appears that heavy fuel oil moderately reduces the mechanical resistance of bricks and slightly increases thermal diffusion through them.On the contrary,we note a very good water resistance of the bricks thanks to the heavy fuel oil,in particular their water absorption by capillarity.This confirms that the mixture of heavy fuel oil and a silty-clayey soil used as a coating makes it possible to prevent the infiltration of water into the walls of raw soil constructions.However,its use as a construction material does not guarantee very good mechanical resistance,and slightly increases thermal diffusion.

Failure Envelopes of Wide-Shallow Composite Bucket Foundation for Offshore Wind Turbines in Silty Sand

The wide-shallow composite bucket foundation(WSCBF) is a new type of offshore wind power foundation that can be built on land and rapidly installed offshore, there by effectively reducing the construction time and costs of offshore wind power foundation. In this study, the horizontal bearing capacity is calculated by finite element simulation and compared with test results to verify the validity of results. In this process, the vertical load and bending load are respectively calculated by the finite element simulation. Under the vertical load effect, the bucket foundation and the soil inside are regarded as a whole, and the corresponding buckling failure mode is obtained. The ultimate vertical bearing capacity is calculated using empirical and theoretical formulas; the theoretical formula is also revised by finite element results. Under bending load, the rotational center of the composite bucket foundation(in a region close to the bucket bottom) gradually moves from the left of the central axis(reverse to loading direction) to the nearby compartment boards along the loading direction. The H–M envelope line shows a linear relationship, and it is determined that the vertical and bending ultimate bearing capacities can be improved by an appropriate vertical load.

Studies on batch adsorptive removal of cadmium and nickel from synthetic waste water using silty clay originated from Balochistan-Pakistan

The potentials of silty clay(SC),acquired from Chaman,Balochistan,were investigated as adsorbent for Ni(Ⅱ)and Cd(Ⅱ)removal from contaminated media.The influence of different operating factors like dose,pH,temperature,and time of contact was explored,and optimum values were noted under batch adsorption method.Isothermal study was conducted with varying concentrations of solutions on optimized conditions and different adsorption models i.e.,Langmuir,Freundlich,Temkin and Dubinin-Radushkevich(D-R)isotherm,which were employed to interpret the process.The isothermal data of both Ni(Ⅱ)and Cd(Ⅱ)were well fitted to Langmuir isotherm suggesting the formation of monolayer of metal ions on silty clay.The values of adsorption capacity noted for Ni(Ⅱ)and Cd(Ⅱ)were 3.603 mg·g^-1 and 5.480 mg·g^-1,respectively.Kinetic studies affirmed that pseudo second order(PSO)kinetics was being obeyed by the removal of Ni(Ⅱ)and Cd(Ⅱ).Thermodynamic variables like free energy change(ΔG°),enthalpy change(ΔH°)and entropy change(ΔS°)were calculated.The negative value ofΔG°and the positive values ofΔH°andΔS°unfolded that the removal process of both metal ions of by SC was spontaneous,endothermic and feasible.

Eco friendly adsorbents for removal of phenol from aqueous solution employing nanoparticle zero-valent iron synthesized from modified green tea bio-waste and supported on silty clay

The present research investigated a novel route for the synthesis of nanoparticle zero-valent iron(NZVI)utilizing an aqueous extract of green tea waste as a reductant with ferric chloride.Also,the supported nanoparticle zerovalent iron was synthesized using natural silty clay as a support material(SC-NZVI).The NZVI and SC-NZVI were characterized by infrared spectroscopy(FTIR),scanning electron microscope(SEM),X-ray diffraction(XRD),Brunauer–Emmett–Teller(BET),and zeta potential(ζ).The interpretation of the results demonstrated that the polyphenol and other antioxidants in green tea waste can be used as reduction and capping agents in NZVI synthesis,with silty clay an adequate support.Additionally,the experiments were carried out to explore phenol adsorption by NZVI and SC-NZVI.To determine the optimum conditions,the impact of diverse experimental factors(i.e.,initial pH,adsorbent dose,temperature,and concentration of phenol)was studied.Langmuir,Freundlich,and Tempkin isotherms were used as representatives of adsorption equilibrium.The obtained results indicated that the adsorption processes for both NZVI and SC-NZVI well fitted by the Freundlich isotherm model.The appropriateness of pseudofirstorder and pseudosecondorder kinetics was investigated.The experimental kinetics data were good explained by the second-order model.The thermodynamic parameters(ΔH0,ΔS0,andΔG0)for NZVI and SC-NZVI were determined.The maximum removal rates of phenol at optimum conditions,when adsorbed onto NZVI and SC-NZVI,were found to be 94.8%and 90.1%,respectively.

Frost-heave properties of saturated compacted silty clay under one-side freezing condition

In seasonally frozen regions,the frost-heave properties of soil play a significant role in its upper-structure performance and durability.To investigate the frost-heave behaviors of saturated,compacted silty clay soil widely used as subgrade material,a series of one-side freezing tests was carried out;and the freezing depth and frozen front effected by the compactness,temperature,overburden pressure,and water-supply condition were analyzed and discussed.The results show that the moving speed of the frozen front and growth rate of the frozen depth are positively correlated.The frost heave is maximum in the frost-heave stability condition.The frost ratio of saturated soil is proportional to the water supply and cooling temperature under a one-side freezing condition.The frost ratio of saturated soil is inversely proportional to the initial compactness of the soil specimen and the overburden pressure.

Simulation of Silty Clay Compressibility Parameters Based on Improved BP Neural Network Using Bayesian Regularization

Soil compressibility parameters are important indicators in the geotechnical field and are affected by various factors such as natural conditions and human interference.When the sample size is too large,conventional methods require massive human and financial resources.In order to reasonably simulate the compressibility parameters of the sample,this paper firstly adopts the correlation analysis to select seven influencing factors.Each of the factors has a high correlation with compressibility parameters.Meanwhile,the proportion of the weights of the seven factors in the Bayesian neural network is analyzed based on Garson theory.Secondly,an output model of the compressibility parameters of BR-BP silty clay is established based on Bayesian regularized BP neural network.Finally,the model is used to simulate the measured compressibility parameters.The output results are compared with the measured values and the output results of the traditional LM-BP neural network.The results show that the model is more stable and has stronger nonlinear fitting ability.The output of the model is basically consistent with the actual value.Compared with the traditional LMBP neural network model,its data sensitivity is enhanced,and the accuracy of the output result is significantly improved,the average value of the relative error of the compression coefficient is reduced from 15.54%to 6.15%,and the average value of the relative error of the compression modulus is reduced from 6.07%to 4.62%.The results provide a new technical method for obtaining the compressibility parameters of silty clay in this area,showing good theoretical significance and practical value.

SEDIMENTARY CHARACTERISTICS OF SILTY CLAY FACIES IN THE SOUTH YELLOW SEA SHELF

Grain size analysis, X ray diffraction analysis and biostratigraphy analysis of the structure, composition and formation conditions of the neritic silty clay facies sediments extensively distributed in the central part of the South Yellow Sea showed that the sediments were composed of more than 70% clay, less than 30% silt, had very little or no sand, and were characterized by homogenous texture, soapy feeling, high plasticity, light green gray color and elliptical distribution being about 3 m thick in the center, being thinner towards the margin and finally thinning out. These shelf cyclonic eddy environment sediments formed a sedimentary facies different from that of the sediments in the neighbouring area and revealed the particular sediment dynamic pattern in the environment.

Experimental Investigation of the Response of Monopiles in Silty Seabed to Regular Wave Action

Excessive displacement responses of monopiles affect the serviceability of offshore structures.Related to complicated pile−seabed−wave interactions,the actual behavior of monopiles in silty seabed under periodic wave action remains unclear,and relevant studies in the literature are limited.A series of experiments were conducted in a wave flume containing single piles in silty seabed with relative density of 0.77 subjected to regular waves.Two stages of wave loading were applied successively,accompanied by data recording which included pore water pressure,water surface elevation,pile head displacement,and pile strain.Development of pile-head displacement and pore pressure in silty seabed was the main focus,but the effects of pile diameter,pile type,and pile stiffness were also investigated.The experimental results indicate that,in silty seabed,piles of large diameter or with fins accelerate soil liquefaction,resulting in strengthened soil which allows a higher upper boundary of pore pressure.Using fins at deeper locations led to a quick failure of the piles,but the opposite result was observed with an increase in fin dimensions.Once pile-head displacement entered its rapid development period,the wave load calculated via the pile moment was an overestimation,especially for the piles of large diameter.

Correlation Between Yield Stress of Silty Mud Sediments and Continuous Oscillatory Shearing Properties

Analyzing the rheological properties of silty beds subjected to continuous oscillatory shear loading is crucial for understanding the morphological deformation of the seabed and ensuring safety in geological and marine engineering applications.In this study,the effects of oscillatory shearing properties on the yield stress(S_(u))of silty sediments were quantitatively investigated.The effects of oscillatory shear strength(0-3),water content(26.6%-70.84%),and particle diameter(8.79-50μm)were examined extensively through a series of laboratory tests.The results indicated that the three aforementioned parameters were the major factors that affected the rheological characteristics of silty sediments.Furthermore,their effects could be elucidated using the yield stress of cohesive sediments as the indicator parameter.The ratio of yield stress(S_(u)/S_(u0))varied as the oscillatory shear strength increased up to a critical value,Λ_(cr).S_(u)bsequently,the ratio remained at a constant value.It was deduced that the yield stress decreased with increasing oscillatory shear strength forΛ<Λ_(cr),when the sediments were in a non-equilibrium fluidization stage.WhenΛ>Λ_(cr),the sediments entered an equilibrium fluidization stage,and the yield stress remained almost constant,irrespective of the oscillatory shear strength.Furthermore,during the equilibrium fluidization stage,it was observed that the ratio S_(u)/S_(u0)did not vary with water content but decreased as the particle diameter increased.Finally,based on regression analysis of the experimental data for non-equilibrium and equilibrium fluidization stages,a correlation between yield stress of silty sediments and continuous oscillatory shearing properties was proposed.This correlation can aid in understanding the changes in solid resistance and assessing safety in piling engineering.Furthermore,it can provide a theoretical guidance for reducing soil resistance in marine structures using mechanical vibrations.

A mathematical approach to evaluate maximum frost heave of unsaturated silty clay

Maximum frost heave of unsaturated frost-susceptible soils,in conjunction with a high water table,is an important consideration for the design of foundations in seasonally frozen regions.Therefore,it is necessary to evaluate accurately and efficiently the maximum frost heave for a given soil.For this purpose,a series of one-sided freezing experiments was conducted on unsaturated silty clay in an open system.Multistage cooling of sufficient duration was applied to the soil sample's top,while constant above-zero temperatures were maintained at the bottom.Then,a simple methodology for calculating maximum frost heave at a given cooling temperature was derived utilizing information obtained within the limited time allotted for each stage.On this basis,an empirical equation for defining maximum frost heave as a function of cooling temperature and overburden pressure was determined.Overall,this study provides a simple and practical procedure that is applicable to the evaluation of maximum frost heave of unsaturated frost-susceptible soils.

Investigation on creep behavior of warm frozen silty sand under thermo-mechanical coupling loads

In cold regions,the creep characteristics of warm frozen silty sand have significant effect on the stability of slope and subgrade.To investigate the creep behavior of warm frozen silty sand under thermo-mechanical coupling loads,a series of triaxial creep tests were carried out under different temperatures and stresses.The test results reveal that the creep strains decrease as the consolidation stress increases,and finally tend to be equal under the same loading stress,regardless of whether the stress is isotropic or deviatoric.Additionally,warm frozen silty sand is highly sensitive to temperature,which greatly influences the creep strain both in the consolidation stage and loading stage.Furthermore,based on the creep test phenomena,a new creep model that considers the influence of the stress level,temperature,hardening,and damage effect was established and experimentally validated.Finally,the sensitivity of the model parameters was analyzed,and it was found that the creep curve transitions from the attenuation creep stage to the non-attenuation creep stage as the temperature coefficient and stress coefficient increases.The hardening effect gradually changes to the damage effect as the coupling coefficient of the hardening and damage increases.

Factors Influencing the Soil-Water Characteristics of Unsaturated Tropical Silty Sand

Fine grain soils have a complex engineering behaviour which depends but not limited to moisture content, changes in external pressure and characteristics of the pore medium. Sand often contains a considerable percent of silt which is expected to alter its natural behaviour. This composite matrix is referred to as silty-sand. To understand the behaviour of this matrix under varying moisture conditions, some of the factors influencing the soil-water characteristics of unsaturated silty sands were investigated. Representative samples were collected from a river bank after its index properties were predetermined in the laboratory. The samples were compacted at different moisture conditions and compactive efforts. With the pressure plate extractor device, the Soil-Water Characteristic (SWC) was obtained and SWC Curves plotted. Compaction at greater compactive effort (modified proctor) and optimum moisture content produced the largest air entry value and reduced air voids. The air entry values of the soils obtained ranged from 21 kPa to 57 kPa. Also changes in the shape of the SWCC were consistent with changes in pore size which occur by varying compaction conditions. Result shows that soil structure, compaction water content, compactive effort and percentage of fine particles are factors affecting the Soil-Water Characteristics.

Geotechnical Characterization of Silty Clay Reinforcedwith Jute Cloth as Waster Product

Soil reinforcement is a recent and special field of soil improvement.It covers a range of techniques,which consists of placing inclusions in soil.The most conferences devoted partly or totally the behavior of foundation on reinforced subgrade without regarding the basic characteristics of the reinforced soil.So,the paper presents an experimental investigation into the mechanical and compressibility properties of the reinforced silty clay samples by jute cloth at intermediate depth.The effects of the reinforcement on shear stress and shear failure were studied;also,the presence of the reinforcement on behavior of consolidation process was distinctly described.The laboratory tests were supported by the finite element analysis to identify only the consolidation process and explained the effect of the reinforcement on the effective vertical stress and pore water pressure.The results indicated that the presence of such reinforcement has a considerable effect in increasing the shear strength of the reinforced samples and decreasing the compressibility especially decreasing the soil movement also,relieving both the effective and pore water pressure.

Assessment of Cyclic Resistance Ratio (CRR) in Silty Sands Using Artificial Neural Networks

In this study, a backpropagation neural network algorithm was developed in order to predict the liquefaction cyclic resistance ratio (CRR) of sand-silt mixtures. A database, consisting of sufficient published data of laboratory cyclic triaxial, torsional shear and simple shear tests results, was collected and utilized in the ANN model. Several ANN models were developed with different sets of input parameters in order to determine the model with best performance and preciseness. It has been illustrated that the proposed ANN model can predict the measured CRR of the different data set which was not incorporated in the developing phase of the model with the good degree of accuracy. The subsequent sensitivity analysis was performed to compare the effect of each parameter in the model with the laboratory test results. At the end, the participation or relative importance of each parameter in the ANN model was obtained.

Migration process of ammonium ion in saturated silty sand and sandy loam

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Interaction of the Mining Environment on the Properties of Hydraulic Mortars in Silty Sands in Togo

The objective of this study is to determine the influence of the surrounding soils on the granular properties of the silty sands of Togo and on the resistance of the mortars. Sand compositions are made by substituting silty sands with clay soil, vegetal soil, lateritic soil or fine elements (<0.08 mm) which are the surrounding land polluting the sands in Togo. After identification tests, the mixtures were used to prepare test specimens of mortar which are subjected to bending and compression. It appears that additions of clay and plastic soils (ES = 0, VBM > 0.53 and IP > 19) from 10% to 35% cause drops in resistance of mortars from 7% to 96%;this loss is 8% to 70% for the rates of addition of less clayey soil (ES = 33, VBM = 0.40 and IP = 0) at rates of 10% to 100%. As for fine powdery soils (ES = 56.53 and VBM = 0.25), they have virtually no influence on resistance (loss of less than 3% for rates of 100%). Construction stakeholders thus have a decision-making tool for the choice of silty sand extraction zones according to the surrounding land and the quality of the desired concrete.

Performance of composite foundations with different load transfer platforms and substratum stiffness over silty clay

The semi-rigid pile-supported composite foundation is widely used in highway projects due to its effectiveness in increasing the bearing capacity and stability of foundations.It is crucial to understand the stress distribution across the embankment width and the behaviour of unreinforced foundations.Thus,five centrifuge tests were conducted to examine the bearing and deformation behaviours of NPRS(Non-Connected Piled Raft Systems)and GRPS(GeosyntheticReinforced Pile-Supported systems)with varying substratum stiffness,then a comparative analysis was conducted on embankment settlement,pressures underneath the embankments,and axial forces along the piles.The results indicated that greater substratum stiffness correlates with reduced settlement and deformation at various depths.Deformation occurring 5 meters from the embankment toe includes settlement in NPRS and upward movement in GRPS.The potential sliding surface is primarily located within the embankment in NPRS,whereas it may extend through both the embankment and foundation in GRPS.The pile-soil stress ratio and efficiency in NPRS are higher than in GRPS across the embankment.The axial force borne by end-bearing piles is significantly greater than that by floating piles.As the buried depth increases,the axial force in GRPS initially rises then declines,whereas in NPRS,it remains relatively constant within a certain range before decreasing.This study aids in assessing the applicability of composite foundations in complex railway environments and provides a reference for procedural measures under similar conditions.