This study tested the electrical conductivity and pressure sensitivity of lime⁃improved silty sand reinforced with Carbon Fiber Powder(CFP)as the conductive medium.The influence of CFP dosage,moisture content and curi...This study tested the electrical conductivity and pressure sensitivity of lime⁃improved silty sand reinforced with Carbon Fiber Powder(CFP)as the conductive medium.The influence of CFP dosage,moisture content and curing duration on the unconfined compressive strength,initial resistivity and pressure sensitivity of the improved soil was systematically analysed.The results showed that the unconfined compressive strength varied non⁃monotonically with increasing CFP dosage,reaching a peak at a dosage of 1.6%.Furthermore,the initial resistivity showed slight variations under different moisture conditions but eventually converged towards the conductive percolation threshold at a dosage of 2.4%.It is worth noting that CFP reinforced lime⁃improved silty sand(CRLS)exhibit a clear dynamic synchronization of strain with stress and resistivity rate of variation.The pressure sensitivity was optimized with CFP dosages ranging from 1.6%to 2.0%.Both insufficient and excessive dosages had a negative impact on pressure sensitivity.It is important to consider the weakening effect of high moisture content on the pressure sensitivity of the specimens in practical applications.展开更多
In order to explore the mechanical properties and microstructure changes of frozen saline silty clay in the Hexi region of Gansu Province,triaxial compression tests and scanning electron microscopy(SEM)analysis experi...In order to explore the mechanical properties and microstructure changes of frozen saline silty clay in the Hexi region of Gansu Province,triaxial compression tests and scanning electron microscopy(SEM)analysis experiment were conducted to explore the effects of moisture content,confining pressure,and temperature on the stress-strain characteristics and failure modes of frozen soil,as well as the changes in the internal microstructure of the sample.The experimental results show that the strength of frozen sulfate saline soil first increases and then decreases with the increase of moisture content,and the maximum strength corresponds to a moisture content of 15%.The changes in confining pressure and strength have the same trend.The lower the temperature,the greater the strength of the sample.During the entire loading process,the specimens undergo a gradual transition from volume shrinkage to volume expansion.Due to the strain harden behavior of the stress-strain curve throughout the entire loading process,the failure mode of the specimens is plastic failure.The internal microstructure of the sample gradually transitions from point-point contact and edge-point contact before shearing to edge-surface contact and edge-edge contact after shearing,and the pore size inside the sample increases after shearing,with a loose arrangement of the particle skeleton.The above research conclusions can lay a certain theoretical foun-dation for the engineering design and construction of sulfate saline soil in cold and arid areas.展开更多
The soil construction materials cured with biopolymers are gradually being recognized and widely used in engineering areas,such as roadbeds or foundation fills.The strength of biopolymer-solidified soils(BSS)is easily...The soil construction materials cured with biopolymers are gradually being recognized and widely used in engineering areas,such as roadbeds or foundation fills.The strength of biopolymer-solidified soils(BSS)is easily influenced by the change of internal residual moisture content(RMC),however,the quantitative relationship between them remains unclear.Xanthan gum,as a representative of biopolymer,was used in this study to enhance the mechanical properties of silty sand dredged from the Yellow River under different initial water contents and curing temperatures.The unconfined compressive strength(UCS),curing time,water stability and microscopic properties of BSS were investigated via a series of indoor experiments.Results show that the proposed method for quantitatively evaluating the BSS strength using different RMC values was found to be workable compared to that of the traditional cement-treated method under different curing ages.The curing time required for BSS to reach a certain target strength,i.e.2900 kPa,is reduced to 9.3 h at a higher curing temperature of 90℃.Moreover,BSS exhibits the“self-healing”properties of strength recovery after re-temperature drying,with a strength recovery ratio above 45%.The control raw soil samples completely disintegrate in water within 10 s,and even lower xanthan gum biopolymer dosages,such as 0.5%,improved stability in water by reducing permeability by sealing the internal voids of the soil.SEM results indicate that the initial water content and curing temperature mainly affect the distribution of effective xanthan gum linkages,and thus significantly improve the strength and water stability of BSS.展开更多
Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This...Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.展开更多
The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process,leading to the failure of roadbed structures.Commonly used methods for improving silty soils in engin...The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process,leading to the failure of roadbed structures.Commonly used methods for improving silty soils in engineering often yield unsatisfactory economic and ecological outcomes.As an environment-friendly soil improvement material,Xanthan gum has broad application prospects and is therefore considered a solidifying agent for enhancing silty soil properties in the Yellow River Basin.In this study,a series of tests is conducted using a scanning electron microscope and a dynamic triaxial testing apparatus to investigate the microstructure and dynamic deformation characteristics of unsaturated silty soil with varying xanthan gum contents during the wetting process.The results show that xanthan gum effectively fills voids between soil particles and adheres to their surfaces,forming fibrous and network structures.This modification enhances the inherent properties of the silty soil and significantly improves its stability under dynamic loading.Specifically,with increasing xanthan gum content,the dynamic shear modulus increases while the damping ratio decreases.During the wetting process,as suction decreases,the dynamic shear modulus decreases while the damping ratio increases.Xanthan gum reduces the sensitivity of the dynamic deformation characteristics of the treated silty soil to changes in suction levels.Finally,based on the modified Hardin-Drnevich hyperbolic model,a predictive model for the dynamic shear modulus and damping ratio of treated silty soil is proposed,considering the xanthan gum content.These research findings provide a theoretical basis for the construction and maintenance of water conservancy,slope stabilization,and roadbed projects in the Yellow River Basin.展开更多
Landslides frequently occurred in Jurassic red strata in the Three Gorges Reservoir(TGR)region in China.The Jurassic strata consist of low mechanical strength and poor permeability of weak silty mudstone layer,which m...Landslides frequently occurred in Jurassic red strata in the Three Gorges Reservoir(TGR)region in China.The Jurassic strata consist of low mechanical strength and poor permeability of weak silty mudstone layer,which may cause slope instability during rainfall.In order to understand the strength behavior of Jurassic silty mudstone shear zone,the so-called Shizibao landslide located in Guojiaba Town,Zigui County,Three Gorges Reservoir(TGR)in China is selected as a case study.The shear strength of the silty mudstone shear zone is strongly influenced by both the water content and the normal stress.Therefore,a series of drained ring shear tests were carried out by varying the water contents(7%,12%,17%,and 20%,respectively)and normal stresses(200,300,400,and 500 kPa,respectively).The result revealed that the residual friction coefficient and residual friction angle were power function relationships with water content and normal stress.The peak cohesion of the silty mudstone slip zone increased with water content to a certain limit,above which the cohesion decreased.In contrast,the residual cohesion showed the opposite trend,indicating the cohesion recovery above a certain limit of water content.However,both the peak and residual friction angle of the silty mudstone slip zone were observed to decrease steadily with increased water content.Furthermore,the macroscopic morphological features of the shear surface showed that the sliding failure was developed under high normal stress at low water content,while discontinuous sliding surface and soil extrusion were occurred when the water content increased to a saturated degree.The localized liquefaction developed by excess pore water pressure reduced the frictional force within the shear zone.Finally,the combined effects of the slope excavation and precipitation ultimately lead to the failure of the silty mudstone slope;however,continuous rainfall is the main factor triggering sliding.展开更多
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 dis...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.展开更多
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 ...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.展开更多
To investigate the influence of confining pressures and temperatures on the seepage characteristics of fractured rocks, seepage tests were conducted on a fractured silty mudstone using a self-developed experimental sy...To investigate the influence of confining pressures and temperatures on the seepage characteristics of fractured rocks, seepage tests were conducted on a fractured silty mudstone using a self-developed experimental system, and the effects of different factors on coefficient of permeability were discussed. The results showed that the increasing confining pressure will gradually decrease the coefficient of permeability, and this process is divided into two stages: 1) the fast decrease stage, which corresponds to a confining pressure less than 30 kPa, and 2) the slow decrease stage, which corresponds to a confining pressure larger than 30 kPa. Unlike confining pressure, an increase in temperature will increase the coefficient of permeability. It is noted that fracture surface roughness will also affect the variation of coefficient of permeability to a certain extent. Among the three examined factors, the effect of confining pressure increases is dominant on fracture permeability coefficient. The relationship between the confining pressure and coefficient of permeability can be quantified by an exponential function.展开更多
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 cos...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.展开更多
In this paper, flume experiments are focused on sediment transport inside and outside the surf zone. According to the energy dissipation balance principle of sediment-laden flow and the similarity between energy dissi...In this paper, flume experiments are focused on sediment transport inside and outside the surf zone. According to the energy dissipation balance principle of sediment-laden flow and the similarity between energy dissipation of spilling breaking wave and hydraulic jump, formulas are proposed to predict time averaged suspended sediment concentration under both non-breaking and breaking waves. Assuming that the sediment diffusion coefficient, which is related with energy dissipation, is proportional to water depth, formulas are proposed to predict close-to-bed suspended sediment concentration and vertical distribution of suspended sediment under spilling breaking waves, and the prediction shows a good agreement with the measurement.展开更多
The objective of this study is to develop an analytical methodology to evaluate the effectiveness of vibro stone column (S.C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and miti...The objective of this study is to develop an analytical methodology to evaluate the effectiveness of vibro stone column (S.C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and mitigate liquefaction in saturated sands and non-plastic silty soils. It includes the following: (i) develop numerical models to simulate and analyze soil densitication during S.C. installation and D.C. process, and (ii) identify parameters controlling post-improvement soil density in both cases, and (iii) develop design guidelines for densification of silty soils using the above techniques. An analytical procedure was developed and used to simulate soil response during S.C. and D.C. installations, and the results were compared with available case history data. Important construction design parameters and soil properties that affect the effectiveness of these techniques, and construction design choices suitable for sands and non-plastic silty soils were identified. The methodology is expected to advance the use of S.C. and D.C. in silty soils reducing the reliance on expensive field trials as a design tool. The ultimate outcome of this research will be design charts and design guidelines for using composite stone columns and composite dynamic compaction techniques in liquefaction mitigation of saturated silty soils.展开更多
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...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.展开更多
Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering.Basalt fiber is a new kind of environment-friendly and highperfo...Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering.Basalt fiber is a new kind of environment-friendly and highperformance soil reinforcement material,and the mechanical properties of basalt fiber-reinforced soil have become a hot research topic.In this paper,we conducted monotonic triaxial and cyclic triaxial tests,and analyzed the influence of the fiber content,moisture content,and confining pressure on the shear characteristics,dynamic modulus,and damping ratio of basalt fiber-reinforced silty clay.The results illustrate that basalt fiber can enhance the shear strength of silty clay by increasing its cohesion.We find that the shear strength of reinforced silty clay reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%(optimum moisture content).Similarly,we also find that the dynamic modulus that corresponds to the same strain first increases then decreases with increasing fiber content and moisture content and reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%.The dynamic modulus is positively correlated with the confining pressure.However,the change in the damping ratio with fiber content,moisture content,and confining pressure is opposite to that of the dynamic modulus.It can be concluded that the optimum content of basalt fiber for use in silty clay is 0.2%.After our experiments,we used scanning electron microscope(SEM)to observe the microstructure of specimens with different fiber contents,and our results show that the gripping effect and binding effect are the main mechanisms of fiber reinforcement.展开更多
Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the norm...Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the normal operation of railway lines. This study is to obtain the influencing rules of freeze-thaw on the dynamic properties （dynamic strain, confining pressure and compactness） of silty sand. Based on an amount of inner tests, the dynamic modulus and damping ratio properties of silty soil subjected to repeated freeze-thaw cycles were deeply researched and analyzed. The results are as follows： At the same dynamic strain, the relationship of dynamic stress and freeze-thaw cycles presents negative cor- relation, and the relationship of dynamic stress, confining pressure and compactness present positive correlation. The dynamic modulus double decreases while the damping ratio double increases with incremental increase in dynamic strain. The dynamic modulus sharply decreases while the damping ratio increases with incremental increase in freeze-thaw cycles, and then the changes level off after six freeze-thaw cycles. The dynamic modulus increases while the damping ratio decreases as the confining pressure and compactness increase at the same strain level.展开更多
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 nanopartic...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.展开更多
A number of studies focus on the pore-water pressure in seabed under thewaves and seabed instability induced by liquefaction, but rarely on the wave pressureof liquefied soil. In this paper, flume tests were performed...A number of studies focus on the pore-water pressure in seabed under thewaves and seabed instability induced by liquefaction, but rarely on the wave pressureof liquefied soil. In this paper, flume tests were performed at varying wave heightsunder both conditions of liquefied and stable seabed. The total pressures equal to soilpressures and pore water pressures were measured and analyzed at each depth. Theresults showed that the liquefied seabed had little difference from the stable seabed onthe peak pressures. However, the pressure amplitude of the liquefied soil increased byseveral to 10 times and decreased faster with increasing soil depths, compared with thestable soil. According to the experiments and further analysis, an empirical equationbetween pressure amplitude of the liquefied soil and wave parameters was put forwardunder the flume test. The results provide a valuable reference for engineeringapplications.展开更多
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,temperatur...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.展开更多
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...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.展开更多
Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankme...Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.展开更多
基金Sponsored by Jilin Provincial Department of Education Scientific Research Project(Grant Nos.JJKH20190875KJ,JJKH20230348KJ).
文摘This study tested the electrical conductivity and pressure sensitivity of lime⁃improved silty sand reinforced with Carbon Fiber Powder(CFP)as the conductive medium.The influence of CFP dosage,moisture content and curing duration on the unconfined compressive strength,initial resistivity and pressure sensitivity of the improved soil was systematically analysed.The results showed that the unconfined compressive strength varied non⁃monotonically with increasing CFP dosage,reaching a peak at a dosage of 1.6%.Furthermore,the initial resistivity showed slight variations under different moisture conditions but eventually converged towards the conductive percolation threshold at a dosage of 2.4%.It is worth noting that CFP reinforced lime⁃improved silty sand(CRLS)exhibit a clear dynamic synchronization of strain with stress and resistivity rate of variation.The pressure sensitivity was optimized with CFP dosages ranging from 1.6%to 2.0%.Both insufficient and excessive dosages had a negative impact on pressure sensitivity.It is important to consider the weakening effect of high moisture content on the pressure sensitivity of the specimens in practical applications.
基金supported by the National Natural Science Foun-dation of China(12362032)the Key Research and Development Pro-gram of Gansu Province-Social Development(23YFFA0063).
文摘In order to explore the mechanical properties and microstructure changes of frozen saline silty clay in the Hexi region of Gansu Province,triaxial compression tests and scanning electron microscopy(SEM)analysis experiment were conducted to explore the effects of moisture content,confining pressure,and temperature on the stress-strain characteristics and failure modes of frozen soil,as well as the changes in the internal microstructure of the sample.The experimental results show that the strength of frozen sulfate saline soil first increases and then decreases with the increase of moisture content,and the maximum strength corresponds to a moisture content of 15%.The changes in confining pressure and strength have the same trend.The lower the temperature,the greater the strength of the sample.During the entire loading process,the specimens undergo a gradual transition from volume shrinkage to volume expansion.Due to the strain harden behavior of the stress-strain curve throughout the entire loading process,the failure mode of the specimens is plastic failure.The internal microstructure of the sample gradually transitions from point-point contact and edge-point contact before shearing to edge-surface contact and edge-edge contact after shearing,and the pore size inside the sample increases after shearing,with a loose arrangement of the particle skeleton.The above research conclusions can lay a certain theoretical foun-dation for the engineering design and construction of sulfate saline soil in cold and arid areas.
基金support provided by the Major science and technology program of Inner Mongolia,China(Grant No.2021ZD0007)National Natural Science Foundation of China(Grant Nos.51979267 and 52074143).
文摘The soil construction materials cured with biopolymers are gradually being recognized and widely used in engineering areas,such as roadbeds or foundation fills.The strength of biopolymer-solidified soils(BSS)is easily influenced by the change of internal residual moisture content(RMC),however,the quantitative relationship between them remains unclear.Xanthan gum,as a representative of biopolymer,was used in this study to enhance the mechanical properties of silty sand dredged from the Yellow River under different initial water contents and curing temperatures.The unconfined compressive strength(UCS),curing time,water stability and microscopic properties of BSS were investigated via a series of indoor experiments.Results show that the proposed method for quantitatively evaluating the BSS strength using different RMC values was found to be workable compared to that of the traditional cement-treated method under different curing ages.The curing time required for BSS to reach a certain target strength,i.e.2900 kPa,is reduced to 9.3 h at a higher curing temperature of 90℃.Moreover,BSS exhibits the“self-healing”properties of strength recovery after re-temperature drying,with a strength recovery ratio above 45%.The control raw soil samples completely disintegrate in water within 10 s,and even lower xanthan gum biopolymer dosages,such as 0.5%,improved stability in water by reducing permeability by sealing the internal voids of the soil.SEM results indicate that the initial water content and curing temperature mainly affect the distribution of effective xanthan gum linkages,and thus significantly improve the strength and water stability of BSS.
基金the financial support by the National Natural Science Foundation of China(Grant No.52108397)“Xiaohe”Science and Technology Talent Special Project(Grant No.2024 TJ-X06)Water Resources Science and Technology Project of Hunan Province(Grant No.XSKJ2023059-41).
文摘Cracking affected by wetting-drying cycles is a major cause of shallow failure of soft rock slopes.Knowledge of rock tensile properties and cracking behaviors helps better assess the stability of soft rock slopes.This study aims to examine the cracking behaviors and tensile strength of silty mudstone under wetting-drying cycles.The wetting-drying cycle and Brazilian splitting tests were performed on silty mudstone considering various cycle number and amplitude.The cracking behaviors of wetting-drying cycles were analyzed by digital image correlation,three-dimensional(3D)scanning technology,and scanning electron microscopy.The results reveal a spiral-like pattern of crack ratio escalation in silty mudstone,with a higher crack ratio observed during drying than wetting.Tensile strength and fracture energy correlate negatively with cycle number or amplitude,with cycle number exerting a more pronounced effect.The variance of the maximum principal strain reflects stages of initial deformation,linear deformation,strain localization,and stable deformation.The formation of strain localization zones reveals the physical process of crack propagation.Crack tip opening displacement progresses through stages of slow growth,exponential growth,and linear growth,delineating the process from crack initiation to stable extension.Failure modes of silty mudstone primarily involve tensile and tensile-shear failure,influenced by the geometric parameters of cracks induced by wetting-drying cycles.Fracture surface roughness and fractal dimension increase with cycle number due to mineral dissolution,physical erosion,and nondirectional crack propagation.Hydration-swelling and dehydration-shrinkage of clay minerals,along with absorption-drying cracking,initiate and merge cracks,leading to degradation of the rock mechanical properties.The findings could provide insights for mitigating shallow cracking of soft rock slopes under wetting-drying cycles.
基金supported by the Postgraduate Education Reform and Quality Improvement Project of Henan Province,China(Grant No.YJS2023AL004)the Graduate Innovation Project of North China University of Water Resources and Electric Power(Grant No.NCWUYC-202315069)the China National Scholarship Fund organized by the China Scholarship Council(Grant No.202208410337).
文摘The deformation characteristics of silty soils under vibrational loads can easily change due to the wetting process,leading to the failure of roadbed structures.Commonly used methods for improving silty soils in engineering often yield unsatisfactory economic and ecological outcomes.As an environment-friendly soil improvement material,Xanthan gum has broad application prospects and is therefore considered a solidifying agent for enhancing silty soil properties in the Yellow River Basin.In this study,a series of tests is conducted using a scanning electron microscope and a dynamic triaxial testing apparatus to investigate the microstructure and dynamic deformation characteristics of unsaturated silty soil with varying xanthan gum contents during the wetting process.The results show that xanthan gum effectively fills voids between soil particles and adheres to their surfaces,forming fibrous and network structures.This modification enhances the inherent properties of the silty soil and significantly improves its stability under dynamic loading.Specifically,with increasing xanthan gum content,the dynamic shear modulus increases while the damping ratio decreases.During the wetting process,as suction decreases,the dynamic shear modulus decreases while the damping ratio increases.Xanthan gum reduces the sensitivity of the dynamic deformation characteristics of the treated silty soil to changes in suction levels.Finally,based on the modified Hardin-Drnevich hyperbolic model,a predictive model for the dynamic shear modulus and damping ratio of treated silty soil is proposed,considering the xanthan gum content.These research findings provide a theoretical basis for the construction and maintenance of water conservancy,slope stabilization,and roadbed projects in the Yellow River Basin.
基金funded by the National Science Foundation of China(CN)(Nos.42090054,41922055,41931295)the Key Research and Development Program of Hubei Province of China(No.2020BCB079)。
文摘Landslides frequently occurred in Jurassic red strata in the Three Gorges Reservoir(TGR)region in China.The Jurassic strata consist of low mechanical strength and poor permeability of weak silty mudstone layer,which may cause slope instability during rainfall.In order to understand the strength behavior of Jurassic silty mudstone shear zone,the so-called Shizibao landslide located in Guojiaba Town,Zigui County,Three Gorges Reservoir(TGR)in China is selected as a case study.The shear strength of the silty mudstone shear zone is strongly influenced by both the water content and the normal stress.Therefore,a series of drained ring shear tests were carried out by varying the water contents(7%,12%,17%,and 20%,respectively)and normal stresses(200,300,400,and 500 kPa,respectively).The result revealed that the residual friction coefficient and residual friction angle were power function relationships with water content and normal stress.The peak cohesion of the silty mudstone slip zone increased with water content to a certain limit,above which the cohesion decreased.In contrast,the residual cohesion showed the opposite trend,indicating the cohesion recovery above a certain limit of water content.However,both the peak and residual friction angle of the silty mudstone slip zone were observed to decrease steadily with increased water content.Furthermore,the macroscopic morphological features of the shear surface showed that the sliding failure was developed under high normal stress at low water content,while discontinuous sliding surface and soil extrusion were occurred when the water content increased to a saturated degree.The localized liquefaction developed by excess pore water pressure reduced the frictional force within the shear zone.Finally,the combined effects of the slope excavation and precipitation ultimately lead to the failure of the silty mudstone slope;however,continuous rainfall is the main factor triggering sliding.
基金financially supported by the National Natural Science Foundation of China(Nos.51878577 and 52378463)the Natural Science Foundation of Shandong Provincial,China(No.ZR2022ME042)the School-Enterprise Cooperation Program of China Railway 14th Bureau Group Co.(QTHT-HGLCHSD-00052)。
文摘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.
基金Sichuan Science and Technology Program under Grant No.2023NSFSC0894Major Project of the Science and Technology Research and Development Program of the Ministry of Railways of China under Grant No.Z2012-061。
文摘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.
基金Projects(51838001, 51878070, 51908073, 51908069) supported by the National Natural Science Foundation of ChinaProject(2019SK2171) supported by the Key Research and Development Program of Hunan Province, China+2 种基金Project(kq1905043) supported by the Training Program for Excellent Young Innovators of Changsha, ChinaProject(2019IC04) supported by Double First-class Scientific Research International Cooperation Expansion Project of Changsha University of Science & Technology, ChinaProject(CX20200811) supported by Postgraduate Research and Innovation Key Project of Hunan Province, China。
文摘To investigate the influence of confining pressures and temperatures on the seepage characteristics of fractured rocks, seepage tests were conducted on a fractured silty mudstone using a self-developed experimental system, and the effects of different factors on coefficient of permeability were discussed. The results showed that the increasing confining pressure will gradually decrease the coefficient of permeability, and this process is divided into two stages: 1) the fast decrease stage, which corresponds to a confining pressure less than 30 kPa, and 2) the slow decrease stage, which corresponds to a confining pressure larger than 30 kPa. Unlike confining pressure, an increase in temperature will increase the coefficient of permeability. It is noted that fracture surface roughness will also affect the variation of coefficient of permeability to a certain extent. Among the three examined factors, the effect of confining pressure increases is dominant on fracture permeability coefficient. The relationship between the confining pressure and coefficient of permeability can be quantified by an exponential function.
基金supported by the National Natural Science Foundation of China (No.51379142 and No.51679163)Innovation Method Fund of China (No.2016IM030100)the Tianjin Municipal Natural Science Foundation (No.17JCYBJC22000)
文摘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.
基金supported by special fund for important and large scientific and technical projects from the Ministry of Communications (Grant No. 201132874660)funds from Nanjing Hydraulic Research Institute (Grant No. Y210001)
文摘In this paper, flume experiments are focused on sediment transport inside and outside the surf zone. According to the energy dissipation balance principle of sediment-laden flow and the similarity between energy dissipation of spilling breaking wave and hydraulic jump, formulas are proposed to predict time averaged suspended sediment concentration under both non-breaking and breaking waves. Assuming that the sediment diffusion coefficient, which is related with energy dissipation, is proportional to water depth, formulas are proposed to predict close-to-bed suspended sediment concentration and vertical distribution of suspended sediment under spilling breaking waves, and the prediction shows a good agreement with the measurement.
基金Federal Highway Administration(FHWA)Under Grant No.DTFH61-98-C-0094
文摘The objective of this study is to develop an analytical methodology to evaluate the effectiveness of vibro stone column (S.C.) and dynamic compaction (D.C.) techniques supplemented with wick drains to densify and mitigate liquefaction in saturated sands and non-plastic silty soils. It includes the following: (i) develop numerical models to simulate and analyze soil densitication during S.C. installation and D.C. process, and (ii) identify parameters controlling post-improvement soil density in both cases, and (iii) develop design guidelines for densification of silty soils using the above techniques. An analytical procedure was developed and used to simulate soil response during S.C. and D.C. installations, and the results were compared with available case history data. Important construction design parameters and soil properties that affect the effectiveness of these techniques, and construction design choices suitable for sands and non-plastic silty soils were identified. The methodology is expected to advance the use of S.C. and D.C. in silty soils reducing the reliance on expensive field trials as a design tool. The ultimate outcome of this research will be design charts and design guidelines for using composite stone columns and composite dynamic compaction techniques in liquefaction mitigation of saturated silty soils.
基金financially supported by NSFC—Shandong Joint Fund Project (Grant No. U1906231)。
文摘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.
基金Project(51978674) supported by the National Natural Science Foundation of ChinaProject(2017G008-A) supported by the China Railway Corporation Science and the Technology Development Project。
文摘Fiber reinforcement technology can significantly improve the mechanical properties of soil and has been increasingly applied in geotechnical engineering.Basalt fiber is a new kind of environment-friendly and highperformance soil reinforcement material,and the mechanical properties of basalt fiber-reinforced soil have become a hot research topic.In this paper,we conducted monotonic triaxial and cyclic triaxial tests,and analyzed the influence of the fiber content,moisture content,and confining pressure on the shear characteristics,dynamic modulus,and damping ratio of basalt fiber-reinforced silty clay.The results illustrate that basalt fiber can enhance the shear strength of silty clay by increasing its cohesion.We find that the shear strength of reinforced silty clay reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%(optimum moisture content).Similarly,we also find that the dynamic modulus that corresponds to the same strain first increases then decreases with increasing fiber content and moisture content and reaches its maximum when the fiber content is approximately 0.2%and the moisture content is 18.5%.The dynamic modulus is positively correlated with the confining pressure.However,the change in the damping ratio with fiber content,moisture content,and confining pressure is opposite to that of the dynamic modulus.It can be concluded that the optimum content of basalt fiber for use in silty clay is 0.2%.After our experiments,we used scanning electron microscope(SEM)to observe the microstructure of specimens with different fiber contents,and our results show that the gripping effect and binding effect are the main mechanisms of fiber reinforcement.
基金funded by the National Key Basic Research Development Plan of China (Grant No. 2012CB026104)the National Natural Science Foundation (NSFC) of China (Grant Nos.51208320 and 51171281)
文摘Under repeated freezing and thawing in deep seasonal frozen regions, the stability and strength of the soil are imposed in the form of large uneven settlement, instability and strength reduction, which affect the normal operation of railway lines. This study is to obtain the influencing rules of freeze-thaw on the dynamic properties （dynamic strain, confining pressure and compactness） of silty sand. Based on an amount of inner tests, the dynamic modulus and damping ratio properties of silty soil subjected to repeated freeze-thaw cycles were deeply researched and analyzed. The results are as follows： At the same dynamic strain, the relationship of dynamic stress and freeze-thaw cycles presents negative cor- relation, and the relationship of dynamic stress, confining pressure and compactness present positive correlation. The dynamic modulus double decreases while the damping ratio double increases with incremental increase in dynamic strain. The dynamic modulus sharply decreases while the damping ratio increases with incremental increase in freeze-thaw cycles, and then the changes level off after six freeze-thaw cycles. The dynamic modulus increases while the damping ratio decreases as the confining pressure and compactness increase at the same strain level.
文摘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.
基金supported by National Natural Science Foundation of China (Grant No.41576039)the Scientific Research Projects of Marine Public Welfare Industry (Grant No.201305026)
文摘A number of studies focus on the pore-water pressure in seabed under thewaves and seabed instability induced by liquefaction, but rarely on the wave pressureof liquefied soil. In this paper, flume tests were performed at varying wave heightsunder both conditions of liquefied and stable seabed. The total pressures equal to soilpressures and pore water pressures were measured and analyzed at each depth. Theresults showed that the liquefied seabed had little difference from the stable seabed onthe peak pressures. However, the pressure amplitude of the liquefied soil increased byseveral to 10 times and decreased faster with increasing soil depths, compared with thestable soil. According to the experiments and further analysis, an empirical equationbetween pressure amplitude of the liquefied soil and wave parameters was put forwardunder the flume test. The results provide a valuable reference for engineeringapplications.
文摘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.
基金supported by the National Key Basic Research Development Plan (2012CB026104)the National Natural Science Foundation of China (Nos. 51408163 and 51578200)+1 种基金the Natural Science Foundation of Heilongjiang Province (No. ZD201218)the Research Foundation of Fuzhou University (510406)
文摘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.
基金Project(2010G003-F)supported by Technological Research and Development Programs of the Ministry of Railways,China
文摘Based on back analysis of lateral displacements measured in situ by using the analytical solution, a useful method for estimating stress concentration ratio of geosynthetic-reinforced and pile-supported(GRPS) embankments was proposed. In order to validate the proposed method, a full-scale high-speed railway embankment(HSRE) with four instrumented subsections over medium compressibility silty clay was constructed in three stages. The soil profile, construction procedure and monitoring of settlements and lateral displacements of the four test sections were described. The field deformation analysis results show that 1) the combined reinforcement of CFG piles and geosynthetic layer perform well in terms of reducing lateral displacements; 2) the development of lateral displacements lags behind the increase of fill load, which can be attributed to the vertical load transfer mechanism of the pile foundation; and 3) pile length has a dominant effect on the stress distribution proportion between piles and surrounding soils. The comparison between predicted and experimental results suggests that the proposed analytical solution and the back analysis-based method are capable of reasonably estimating the lateral deformation and the stress concentration ratio, respectively, if the appropriate soil elastic modulus is chosen.
