Fine Sand Research Articles

Morphometric Changes between Peroba and Redonda Beaches, Icapuí-Ceará Region, Brazil, Applying High Resolution Remotely Piloted Aircraft Images from 2020 to 2021

Beaches are regions of the coastal zone where the effects of interaction between marine, terrestrial and atmospheric ecosystems are often seen. Natural and anthropic agents act together in coastal processes, which may result in erosion or accretion. If the erosion is intense and continuous, it will represent a severe problem, especially in densely occupied and economically significant beaches, such as the beaches of Peroba and Redonda that have registered erosive events. Thus, this work aimed to analyze the variation of the coastline and the volume of beach sediments through a historical series of one year employing a remotely piloted aircraft, conjugated with the analysis of sediments collected in fields. At Peroba beach, the shoreline was stable, having varied by about 0,87 m/year, and the volume indicated a positive sediment balance of about 18.815 m3. At Redonda beach, the coastline degraded by about 1,27 m/year. The volume indicated a negative sediment balance of -1.230 m3. The beaches were mainly characterized by sediments of very fine and fine sand fractions. The volume variation indicated similar trends to the shoreline, with more significant deposition in the west and erosion in the east.

Experimental Investigation on Reinforcement Application of Newly Permeable Polymers in Dam Engineering with Fine Sand Layers

The grinding reinforcement of fine sand layers is a difficult problem in dam engineering construction. As a new type of grouting material, permeable polymer with excellent impermeability and high strength is widely used in dam engineering. In this paper, a series of compressive tests were designed considering different grouting pressures, curing days, moisture content, and porosity of fine sand. The influence of grouting parameters and sand layer conditions on the strength of fine sand layers reinforced by permeable polymers was analyzed. SEM and XDR tests were conducted to analyze the microscopic characteristics of the grouting stone. The functional calculation model of the strength and the influencing factors was established to explore the main factors influencing grouting stones. The compressive strength of grouted stones increases rapidly from the 7th to the 14th day, reaching about 96% of the maximum strength. The degree of influence of different factors is grouting pressure > moisture content > porosity. The compressive strength of the grouted stones increases with the increase of grouting pressure and the number of curing days. The compressive strength decreases with the sand layer’s increasing moisture content and porosity.

Neohypoplasticity Revisited

AbstractThis paper presents further improvements to the neohypoplasticity (NHP), a constitutive model for sand, which overcomes some shortcomings of widely used hypoplastic models. The novelties presented in this paper includes a new description of the additional dilatancy due to the structural variable and the introduction of a new state variable, denoted as , to consider the small strain stiffness in case of a 1D loading reversal. They remove shortcomings of earlier versions of NHP. The new formulations are presented and the performance of NHP is validated with experimental data from Karlsruhe fine sand. Both monotonic and cyclic tests are simulated under drained and undrained conditions. The results demonstrate that the NHP accurately reproduces the observed behaviour in monotonic and cyclic experiments.

Estimation of the variability of sand deposits in chosen communities in parts of Niger delta, Southern-Nigeria using geophysical techniques

Fine and coarse typical sand are among the most vital raw materials in building construction. A lot of drilling has been done without appropriate subsurface information resulting to a waste of resources and time. Geophysical methods give information on subsurface lithologies to locate areas with huge success. Thus, a geophysical investigation of subsurface deposits was carried out in this research to ascertain the quantity of fine/Coarse sand or areas with viable fine/Coarse sand utilizing Schlumberger configuration, Dipole–Dipole (2D) and well logging in parts of Okpe and Ughelli North LGA of Delta State, Nigeria, before extraction (dredging) for the benefit of exploitation and development. This was done by assessing the geo-electric formation of fine/coarse sand in the studied areas concerning their depths and thicknesses. Seven Vertical Electrical Sounding (VES) were obtained with the application of Schlumberger array, seven 2D and three well logging to estimate the viability of sand deposits in the study areas. These techniques have the efficacy of detecting near-bed formation with vital resolution. The data obtained from the field were illustrated by partial curve matching coupled with computer iteration using the WIN RESIST and Dipro Software to obtain sounding curves which revealed four to six layers. The layers consist of topsoil, lateritic clay and clayey sand, fine sand deposit, medium to coarse grain sand and coarse sand. For Agbarho, thicknesses of fine/coarse sand in the VES stations ranges from 18.0 to 55.6 m with resistivity varying from 223.7 to 572.9 Ωm, Osubi Fine/Coarse sand thickness ranges from 13.5 to 59.9 m with resistivity values within 211.9–891.0 Ωm and Oha town locations have fine/coarse sand thickness varied from 46.6 to 83.7 m with resistivity interval computed between 145.9 Ω-m and 466.4 Ω-m. Thus, the best VES stations that are more viable for sand mining are VES 1, 5 and 7 which contain relatively huge viable sand deposits in the study areas to a depth above 80 m.

The Cracking and Tensile-Load-Bearing Behaviour of Concrete Reinforced with Sanded Carbon Grids

This article presents the cracking and load-bearing behaviour of carbon-reinforced prismatic concrete tensile specimens. Grids with different geometries and impregnations were used as carbon reinforcement. In addition, the roving surfaces were partially coated with a fine sand to improve the bond between concrete and reinforcement. The article shows the influence of the different parameters on the developing cracks with respect to their width and spacing from each other. The material properties and tensile strengths of carbon concrete are also presented. These can be used for calculations. A fine-grained, commercially available shotcrete was used for the investigations. Based on the tests and results described in this article, an influence of the sanded carbon grids on the crack properties (crack widths, crack spacing) could be shown in comparison to unsanded carbon grids.

Soil Fractions Affect on Soil Organic Carbon Stock in the Coastal Land of Aceh Utara Regency, Indonesia

Background: Soil organic carbon stocks (SOCs) play a critical role in supporting soil quality and ecosystem functions. Information on SOCs content in coastal lands is scanty and the types of clay minerals and soil fraction size that affect SOCs are still debated. We evaluated the SOCs content and identified the mineral type and soil fraction affecting the SOCs on coastal land. Methods: Soil samples were collected from each layer of nine different soil profiles in three subdistricts: Seunuddon (SD), Lapang (LP) and Dewantara (DT) in Aceh Utara Regency of Indonesia. The soil profiles were taken from different distances (300, 900 and 1500 m from the shoreline-d.f.s). Result: The results revealed that SOCs possessed by each soil layer of coastal land in Aceh Utara varied between 0.64 to 43.45 MgC ha-1. The highest to lowest average total of SOCs content for the location is SD greater than DT greater than LP, while for the position, the distance to the shoreline is 900 m greater than 1500 m greater than 300 m. Clay minerals such as labradorite, smectite, vermiculite and chlorite positively increase the SOCs content. Very fine sand is a size of the soil fraction that affects the increase in the levels of SOCs in coastal land.

Development of data-driven models for the optimal design of multilayer sand filters for on-site treatment of greywater

Greywater, with limited content of pathogens, makes up more than half of the produced wastewater in urban areas. Given the high cost of wastewater management and treatment, it causes sense to collect greywater separately at the source and employ an on-site treatment system to increase opportunities for on-site water reuse. For this purpose, this paper aims to propose a multilayer granular filter as an inexpensive and simple on-site treatment method for greywater reuse. Furthermore, as determining the optimal structure of multilayer filters is a serious challenge, a simulation-optimization model is developed for determining the best filter configuration. An Artificial Neural Network (ANN) is trained based on experimental results to simulate the filter performance with different combinations of layers and the Genetic Algorithm (GA) is used to find the optimal thickness of different layers based on ANN simulation results. The proposed filter in this paper for greywater treatment consists of silica sand (in three different gradings) and activated carbon (with fixed grading) and treatment measures for evaluation of filter performance are considered as Chemical Oxygen Demand (COD) and Electrical Conductivity (EC). Due to difficulties in collecting, transferring, and storing the real greywater, synthetic greywater was used in this study. 49 experiments with different combinations of filter media thicknesses were performed and the performance of the filter was analyzed. Generally, three-layer filters perform better in COD and EC reduction, however, the average COD and EC elimination equals 36.3% and 15.1%, respectively, which indicates more efficiency of filter in COD reduction in comparison with EC. Based on the optimization-simulation model and experimental results, a filter consisting of 33 cm of fine sand, 20 cm of activated carbon, and 7 cm of medium sand results in the maximum efficiency and can reduce the COD and EC of greywater by 72% and 30%, simultaneously. According to the optimization outputs, the ideal filter can treat greywater up to having EC of 1000 μS/cm and COD of 321 mg/L, which is generally suitable for irrigation purposes.

Experimental Investigation of the Effect of Microsilica on the Uniaxial Compressive Strength and Rupture Strain of Fine Sand

In many areas, natural soil does not have necessary resistance, some additives such as cement and microsilica are added to increase their resistance. In this research, the effect of microsilica on the strength and physical characteristics of fine sand stabilized with cement in sand samples containing cement and microsilica will be discussed. For this purpose, samples of fine sand with three different ratios of cement (2, 4, and 6 percent of soil weight) and four different ratios of microsilica (0, 0.5, 1, and 1.5 percent of soil weight) were mixed with optimal moisture, after Two curing periods of 1 and 7 days were subjected to compression and uniaxial compressive strength tests. The results of the experiments indicate that with the increase in the amount of cement and microsilica, the optimum moisture content in the density increases, the specific weight of the mixture of sand, cement and microsilica increases by adding these materials up to a certain amount, but after that it begins to decrease. . With increasing processing time, uniaxial compressive strength and rupture strain both increase. With a curing time of 1 day, for a fixed cement ratio, the compressive strength of sand-cement increases with the increase of microsilica up to about 20% of the cement weight, but after that, the resistance ratio decreases.
 With a curing time of 7 days for a constant cement ratio, the compressive strength increases with the increase of microsilica. It is also observed that in both curing times for different cement ratios, with the increase in the amount of microsilica, the relative deformation of the fracture increases.

Comparison and analysis of four advanced bounding surface models

The accuracy of the constitutive model affects the precision of the finite element analysis. Four advanced sand constitutive models—the DM04 model, the SANISAND-MS model with memory surface (MS), the SANISAND-Sf model with semi-fluidized state (Sf), and the SANISAND-MSf model with both memory surface and semi-fluidized state—are examined in this article based on a comparison of simulation and experiment results of element tests. First, four constitutive models are implemented in OpenSees, and the constitutive models are calibrated based on the cyclic loading experiments of Karlsruhe fine sand. After that, the advantages and disadvantages of four constitutive models under different test conditions are analyzed. Finally, the finite element model of the LEAP-UCD-2017 (Liquefaction Experiments and Analysis Project, University of California Davis, 2017) centrifuge test is established to evaluate the performance of the four constitutive models for solving boundary value problems. It is found that the SANISAND-MSf model can well reproduce the undrained cyclic properties.

Mechanical Review of Fine Sand-Clay Varians


 
 
 
 Clay in nature consist of a mixture of grains and minerals with or without the content of organic matter. The variation in the size of clay grains and the proportion of their distribution is a very useful indicator for knowing soil behavior. Testing the combination of fine sand - clay (FSC) using clay from Kulim Pekanbaru and fine sand from Teratak Buluh Riau. Variants of the percentage of FSC are carried out with the types of tests carried out are Standard Proctor Test, Unconfined Compressive strength test, Direct Shear Test and sieve analysis test and hydrometer. Increasing the percentage of clay in the FSC variant, increases the liquid limit, increasses the plastic limit and increases the plasticity index. Increases optimum moisture content, decreases maximum dry density and increases soil friction angle and decreases compressive strength
 
 
 

Field demonstration of in-situ microemulsion flushing for enhanced remediation of multiple chlorinated solvents contaminated aquifer

The remediation of in-situ microemulsion flushing for multiple chlorinated solvents contaminated groundwater is challenging, because different chlorinated solvent has major influence on microemulsion formation and solubilization behaviors. This work was conducted to evaluate the remediation effectiveness for various chlorinated solvents contaminated site and monitor the disturbance of groundwater during in-situ microemulsion flushing process. Groundwater at this site was contaminated with chlorobenzene (MCB), chloroaniline and nitrochlorobenzene. The medium layer was mainly composed of fine and silty sand, with average hydraulic conductivity of 4.97 m/d. Results of this field-scale test indicated in-situ microemulsion flushing successfully enhanced the apparent solubility of various chlorinated solvents. Post-flushing concentration of various chlorinated solvents were 1.33–71.6-fold the concentration of pre-flushing values at 10 sampling locations within the test zone. This field was flushed with 16.8 m3 microemulsion, removing approximately 18.49 kg chlorinated solvents. Besides, a trend in the desorption order of various chlorinated solvents was observed. The least hydrophobic pollutant was flushed first, followed by contaminants of increasing hydrophobicity. In addition, during remediation process, the indexes of groundwater fluctuated insignificantly, indicating the reagent had little disturbance to aquifer. This field work demonstrated the feasibility of in-situ microemulsion enhanced remediation via increasing apparent solubility of multiple chlorinated solvents.

Granulometry, carbonate and glauconite content as stratigraphic tools to distinguish the Kiel Member and lower Antwerpen Member (Berchem Formation) in the City of Antwerp area (Belgium)

Granulometric, carbonate and glauconite analyses were performed on samples of the Kiel and Antwerpen members (Berchem Formation) in temporary exposures and boreholes in the area of the City of Antwerp. Since the upper part of the Antwerpen Member is only locally preserved from post-depositional erosion, this study focuses on the much more frequently sampled lower part of the Antwerpen Member. The granulometric results show that the Kiel Member and lower part of the Antwerpen Member are both dominated by the fine sand fraction, with an overall finer grain size for the lower Antwerpen Member compared to the Kiel Member. The Kiel Member is relatively enriched in the fine and medium sand fractions, whereas the lower Antwerpen Member is relatively enriched in the very fine sand to silt fraction. Both members show a similar, low clay content. Measurements of clay content are higher in boreholes (on average 3.9–5.2%) than in temporary exposures (less than 1%), which might be explained by the crushing of the glauconite into the clay fraction during drilling. In borehole samples, especially those analysed by sieving, the Antwerpen Member often shows a higher amount of coarse grains than the Kiel Member, which represent shell fragments present in the Antwerpen Member and nearly absent in the Kiel Member. Like the amounts of shells, also the measured carbonate content—measured outside the shell beds—is lower for the Kiel Member than for the lower Antwerpen Member (3% vs 4.2%). The average glauconite content—based on the >63 µm fraction—displays similar, strong fluctuations between 35% and 60% for both members. On top of these fluctuations, a general downward decrease in glauconite content is noticed in the Kiel Member.

Seed settling and trapping during submerged secondary dispersal: Implications for saltmarsh recruitment and restoration

Given the decline of global salt marshes, there is a pressing need to pinpoint the key processes that limit and facilitate seed-based pioneer recruitment. Secondary seed dispersal, in the form of short-distance submerged movement, is a prerequisite for initiating pioneer establishment in adjacent tidal flats but has not been fully appreciated and understood. In this study, using a settling tube and race-track flume, seeds of four global occurring saltmarsh species were studied in terms of their settlement speed and trapping opportunity to understand how seed traits and physical settings affect submerged dispersal behavior and thus seed-based saltmarsh recruitment. Present study led to the following novel insights: 1) Seeds have density-dependent settling speeds, which are comparable to that of fine sand, but much faster than that of very fine sand and silt. Since the latter is the type of sediment commonly found in many estuaries worldwide (such as the Scheldt), seeds will typically settle faster than local sediments. A sufficiently long hydrodynamic-calm period allows slowly settling sediment to bury settled seeds, otherwise, seeds will remain uncovered if the period is short. 2) Seed trapping ratio increased linearly with surface roughness (a proxy for local topographic complexity), but this effect becomes smaller with increasing hydrodynamic intensity. Seed drag coefficient was identified as the key biotic factor contributing to interspecies variability in trapping ratio. Overall, present results suggest that submerged seed dispersal may form a primary bottleneck for salt marsh recruitment by limiting seed availability via two mechanisms: i) reduced chance of seed burial through asynchronous settling of seeds and sediment particles; ii) reduced probability of seed trapping due to encountering smooth tidal flat surfaces. This study provide mechanistic and data basis for the targeted application of biophysical models in predicting outcomes of saltmarsh recruitment and long-term maintenance, thereby informing seed-based conservation and restoration.

Seabed characterization of the Trindade island shelf, Brazil

This paper presents the first mapping of bedform morphological features on the Trindade Island shelf, with the goal of identifying and defining them.By using a side scan sonar, collecting seabed samples, and taking submarine photographs, five different morphological types were identified on this shelf: an erosive type: (i) characterized by the dispersion of rocks and rock blocks; and four depositional types: (ii) one formed by calcareous algal reefs, (iii) one composed by rhodoliths, (iv) one formed by medium sands with large symmetrical wave ripples, (v) and the last one formed by fine sands with asymmetrical wave ripples. The main result is a morphological map of the Trindade Island shelf, which shows the occurrence of these five seabed units.To further understand the sedimentological factors that affect the island shelf, we also examined the sediments that were collected for this study. Our results show that the amount of carbonate-formed grains on the collected sand sediments is higher than the amount of grains formed by the volcanoclastic ones, generated by the disaggregation of the main building on Trindade Island. The sediments formed by bioclastic grains are more frequently found in the coarser fractions than in the finer fractions when compared to lithic ones.

Waste Reduction in Industry: A Study on Using Fine Green Foundry Sand Waste in Foamed Concrete Production

The reuse of waste in construction has been an alternative to minimize the environmental impact and transform waste into raw material. The present study evaluated the replacement of natural sand by fine green foundry sand waste in the manufacture of foam concrete. Different levels of substitution were tested, as well as the amount of foam and the type of curing. The results indicated that the compressive strength ranged from 4.0 to 12.6 MPa, with mixtures with 20% foam and 50% fine green foundry sand waste (FGFSW) presenting results close to 6 MPa. The cementitious matrices presented uniform and distributed pores for mixtures with 20% foam in all levels of FGFSW substitution. The dry and saturated densities varied from 946 to 1743 kg/m³ and from 1244 to 1881 kg/m³, respectively. Thermal conductivity results ranged from 0.28 to 0.53 W/m.K and water absorption ranged from 4.5% to 38.2%. In summary, the study showed that it is possible to use the FGFSW for the manufacture of foamed cellular concrete with technical effectiveness.

Study on Spatiotemporal Transport Characteristics of Soil Moisture in Layered Heterogeneous Vadose Zone Based on HYDRAS-3D

The heterogeneity of layered soils affects the transport processes of water in the vadose zone. However, the mechanism of soil moisture transport in the vadose zone under heterogeneous media conditions, especially the three-dimensional transport mechanism, is a frontier problem to be studied. In order to reveal the law of soil water transport in the vadose zone under heterogeneous media, this paper constructs a three-dimensional model of water transport using HYDRAS-3D (V 2.x) software through in situ tests of water transport in 3 × 3 × 4 m sample and verifies and analyzes the model. The vertical distribution and variability of soil water content and the temporal and spatial rules of soil water transversal transport at the soil–layer interface were analyzed. The results indicate that after adjusting the parameters in the HYDRAS-3D model using measured values, the simulation results are reasonable, and the model has high reliability. To represent the water content variability characteristics of the test tube profile, water movement in the vadose zone was classified as follows: (I) steady period (April–September, less affected by rainfall), (II) slow change period (January–March), and (III) rainfall rapid change period (June, when the impact of rainfall on the test cylinder was greater). The two largest values of the soil water potential variation gradient, 19.9 and 17.8 cm/d, were observed in the silty clay layer of the test cylinder, and the influence of evaporation and infiltration in the silty clay layer was most notable at the interface. The lateral transport of soil water at the interface was influenced to a certain degree by the layered heterogeneity, wherein the fine sand layer exhibited the most pronounced impact. This was followed by silt and silty clay layers, with the silt layer showing the lowest degree of influence. The research results can provide scientific reference for the rational planning of water resources in the Yinchuan Plain.

Analysis of the influence of excess cement paste content on the compression strength of UHPC

This research aimed to propose a rational method for dosing ultra-high performance concretes based on the association of three approaches: the definition of the ideal silica content, the use of the minimum paste volume, and the incorporation of fine basalt artificial sand. Through the combination of experimental methods and granular packing models, a robust experimental program consisting of eight steps was developed, aiming to obtain different compositions of ultra-high performance concretes, with self-compacting characteristics and compressive strength greater than 150 MPa at 28 days, after heat water treatment at 90°C. In addition, the influence of silica content, additional paste volume, different types of cure, test ages, and the addition of metallic fibers on the fluidity and strength of the composites were evaluated. Through the proposed method, the average strength of 186 MPa was achieved in the mix containing the minimum volume of paste, 484 kg∕m³ of cement, and 25% silica fume. The results obtained indicate that the proposed method tends to have the best proportion among the component materials, giving rise to traits that fit the international parameters that define the UHPC, but with reduced paste volumes and consumption of binders lower than those identified in the related literature. Through a rational, economic, and sustainable approach, which aims to optimize the use of higher-cost materials and minimize the use of scarce natural resources, the method contributes positively to the technological development of the sector.

Enhancing Biocrust Development and Plant Growth through Inoculation of Desiccation-Tolerant Cyanobacteria in Different Textured Soils.

In recent years, there has been a burgeoning interest in the utilization of cyanobacteria for the purpose of land rehabilitation via enhancements in soil fertility, prevent erosion, and counter desertification. This study evaluated the ability of Nostoc calcicola BOT1, Scytonema sp. BOT2, and their consortia to form biocrusts on the substrate of coarse sand, fine sand, and loamy soil. A nutrient- and water-deficient substrate was inoculated with cyanobacteria to facilitate biocrust formation and evaluate their impact on agriculture. Cyanobacteria inoculation resulted in significant improvements in soil fertility, especially in coarse and fine sand, which initially had the lowest fertility. The findings of this investigation underscore that the consortium of cyanobacteria exhibited greater efficacy than individual strains in enhancing soil fertility and stimulating plant growth. The loamy soil treated with the consortium had the highest plant growth across all soil types, in contrast to the individual strains. The consortium of cyanobacteria showed promising results in promoting biocrust formation and fostering rice seedling growth in fine sand. This study provides empirical evidence supporting the potential utility of cyanobacterial consortia as a valuable tool for the rehabilitation of degraded land. Furthermore, the results indicate that cyanobacterial species can persist in soil environments even following prolonged periods of desiccation.

Simulation of complex triaxial tests with HySand, a new multisurface constitutive model in the hyperplastic framework

Offshore wind has a key role to play in the energy transition. The majority of offshore wind turbines (OWTs) are bottom-founded with monopiles [1]. Monopiles account for up to 35% of the installation cost of the OWT [2, 3]. Optimising the design of monopiles can thus lead to significant savings and increased competitiveness of OWTs in the energy market.
 The PISA project [4] has led to the optimisation of the design under monotonic lateral loading of monopiles founded in sands, clays, and layered profiles [5 ,6, 7]. Because of this optimisation, along with the increasing size of OWTs, and the deeper waters where they are installed, design under cyclic loading is becoming crucial. There are, however, significant shortcomings in current design methods to predict the effects of cyclic loading on a monopile: accumulated rotation, changes in stiffness, energy dissipation and strength.
 The PICASO project, a joint research project between the University of Oxford and Ørsted, seeks to develop a new design method for monopiles under cyclic loading in sands and clays. Similarly to PISA [8,9], this design method will use the finite element method to simulate the behaviour of monopiles. For PICASO, such simulation requires constitutive models able to capture the behaviour of soil under cyclic loading. However, available advanced constitutive models for sand face severe limitations [10, 11] and are not satisfactory for the simulation of cyclic loading.
 HySand [12, 13], a family of models developed in the hyperplastic framework, fills this gap. HySand_base is a 14 parameter multisurface plasticity model with non-linear elasticity, shear plasticity and hardening, and two plastic volumetric mechanisms resulting in non-associative plasticity: one dilation mechanism which value depends on the evolving density and anisotropy of the sample, and one density dependent consolidation mechanism.
 This document presents comparisons between the database on Karlsruhe fine sand by Wichtmann [14] and results of simulations with HySand_base. The focus will be on complex tests that other models fail to simulate adequately, such as undrained strain-controlled cyclic tests. Data and simulation with HySand_base of such test on medium dense sand are presented in Figure 1.
 HySand_base performs well across densities and types of triaxial tests. This gives confidence in its existing three-dimensional implementation in finite element codes, and demonstrates its value to future design processes.

Evolution characteristics of mid‐channel bars with a typical high/low bank structure in the Middle Yangtze River

AbstractAdjustments in mid‐channel bars (MCBs) often influence the stability of channel regime and the safety of river navigation in anabranching reaches. This study aims to investigate the evolution characteristics of the low and high parts of MCBs (L‐MCBs and H‐MCBs) in the Middle Yangtze River (MYR) and reveal the main factors influencing the deformation of these two components. Results show that the total exposed area of L‐MCBs decreased from 305 to 288 km2 in 2003–2019, whereas the H‐MCBs remained relatively stable. Taking the Nanyang bar with a typical high/low bank structure as an example, the deformation of the L‐MCB mainly occurred in the head zone, while the deformation of the H‐MCB was characterised by bank retreat in the tail zone and floodplain deposition on the top of the H‐MCB. In terms of influencing factors, the impacts of the altered flow–sediment conditions and the MCB's properties (soil composition and morphology characteristics) on the Nanyang bar deformation were investigated. On the one hand, the reduction in sediment concentration was the most direct factor causing the shrinkage of L‐MCBs, and the decrease in flood occurrence frequency made the deformation of H‐MCB less significant. On the other hand, the soil composition of the L‐MCB primarily consisted of fine sand with weak erosion resistance, while the large content of cohesive sediment made the H‐MCB difficult to be eroded by overbank flows; moreover, the riverbank of the H‐MCB in the bar‐tail zone was much steeper than that in the bar‐head zone, causing the deformation of the high part to mainly occur in the tail zone. Furthermore, the deformation of the high part was simulated using a bank erosion model at section scale, and the calculated safety factors of riverbank at a typical cross‐section show that the riverbank of the H‐MCB was the most unstable during the receding period.