Revealing the evolution of micropore structure in industrial by-product solidified sludge is essential for elucidating strength development mechanisms and promoting the engineering utilization of industrial wastes. In this study, a series of tests, including unconfined compressive strength (UCS), low-field nuclear magnetic resonance, direct shear, and scanning electron microscopy coupled with energy-dispersive spectroscopy, were conducted on granulated blast furnace slag–carbide slag–titanium gypsum (GCT)-solidified sludge (GSDS) and cement-solidified sludge (CSDS). The results demonstrate that GSDS exhibits significantly superior compressive strength, deformation resistance, and pore-filling capacity compared with CSDS. With increasing curing age, both materials show logarithmic increases in UCS and mesopore volume fraction, accompanied by power-law decreases in total pore volume and the most probable pore size. On this basis, quantitative relationships between micropore characteristics and macroscopic mechanical properties are established for both solidified sludges. Microscopic analyses reveal that strength development in GSDS is primarily attributed to the formation of abundant C-(A)-S-H gels and expansive ettringite crystals, which effectively cement soil particles and refine interparticle pores. The synergistic solidification mechanism of GCT, involving ion exchange, cementitious bonding, and pore filling, promotes particle aggregation, enhances interparticle bonding, and refines pore structure, thereby markedly improving structural integrity and macroscopic strength in GSDS.

Variations in environmental humidity induce changes in the moisture content of rockfill materials, thereby influencing their creep behavior. In core rockfill dams, reservoir impoundment alters the environmental humidity conditions of the upstream rockfill materials, which often induces nonuniform creep deformation between the upstream and downstream zones. Excessive nonuniform creep deformation may lead to structural damage of the dam during its subsequent operation. This study presents an in-depth analysis of the impact of nonuniform creep deformation following reservoir impoundment on the long-term safety of an asphalt-concrete core dam exhibiting pre-existing crest cracks. To this end, a classical empirical creep model was modified to incorporate the humidity-dependent creep behavior of rockfill materials and subsequently integrated into a finite-element program for numerical analysis. Model parameters used in the modified creep model were identified using on-site monitoring data through the backpropagation-particle swarm optimization inversion method. The good agreement between the calculated results and existing monitoring data indicates the validity of the proposed numerical simulation scheme. Based on the simulation results, a thorough discussion is presented to clarify the causes of crest cracking and evaluate the safety of the dam. Stress analysis of the core crest pavement reveals that differential saturation levels on either side of the core wall induce tensile stresses in the pavement, which lead to cracking. Further stress analysis of the core wall suggests a low probability of cracking or hydraulic fracturing. Meanwhile, predictive deformation analyses indicate that creep deformation is expected to stabilize approximately 4 years after impoundment.

Crushed-compacted solidified sludge (CCSS) is a novel fill material produced by first chemically solidifying dredged sludge to a target strength, followed by crushing and compaction. A systematic investigation into the wet-dry durability of CCSS and the corresponding mitigation strategies is of great significance for its engineering application. In this study, CCSS specimens solidified with an industrial by-product-based curing agent (GCP, composing ground-granulated blast-furnace slag, calcium carbide slag, and phosphogypsum), as well as GCP combined with waste pulp fibers (WPF), were subjected to cyclic wetting and drying tests, with ordinary Portland cement (OPC)-solidified CCSS serving as a comparison. Variations in macroscopic appearance, mass and volume, unconfined compressive strength (UCS), splitting tensile strength (STS), deformation modulus (E50), and fracture energy (W), along with microstructural evolution characterized by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and low-field nuclear magnetic resonance (LF NMR), were analyzed to elucidate the degradation behavior of GCP-CCSS and the reinforcing mechanisms of WPF under wet-dry cycling. Results showed that GCP-CCSS exhibited lower mass and volume losses than OPC-CCSS under wet-dry cycling, and these losses were further mitigated by the incorporation of WPF. Throughout the cycling process, the UCS, E50, STS, and W of GCP-CCSS remained obviously higher than those of OPC-CCSS, while both mechanical stability and fracture energy were effectively enhanced by fiber reinforcement. Microstructural analyses revealed that GCP-CCSS initially contained abundant C-(A)-S-H gel and ettringite (AFt), which partially dissolved and disintegrated after 10 cycles, resulting in pore structure coarsening. In contrast, the incorporation of WPF effectively delayed microcrack initiation and propagation by enveloping soil aggregates and redistributing stress through interfacial friction among fibers, soil particles, and hydration products, thereby mitigating the detrimental effects of wet-dry deterioration.

To address the inadequate bearing capacity of crane operation platforms in wind farms constructed on soft ground and to promote the resource utilization of industrial by-products, this study employed ground granulated blast-furnace slag (GGBS), carbide slag (CS), and phosphogypsum (PG) to reinforce in-situ muddy soil, forming a solidified crust over soft ground (SCSG). The bearing behavior and environmental characteristics of the SCSG were comprehensively investigated. First, response surface methodology was adopted to determine the optimal mix proportion of GGBS, CS, and PG for the in-situ muddy soil, designated as GCP. Subsequently, a series of field plate loading tests, pH measurements, heavy metal leaching tests, and analyses of hydration products and microstructural morphology, were performed on both GCP-SCSG (GCP dosage of 70 140 kg·m−3 with treatment depths of 1.5 3.0 m) and ordinary Portland cement (OPC)-SCSG (OPC dosage of 100 kg·m−3 with a treatment depth of 2.0 m). The characteristic bearing capacity, deformation modulus, and stress diffusion angle of GCP-SCSG were comparatively evaluated against those of OPC-SCSG, while its environmental compatibility was assessed based on pH variation and the leaching concentrations of Cr, As, Ni, Cu, Zn, and Pb. Furthermore, the mechanisms of ground reinforcement and heavy metal stabilization by GCP and OPC were compared and discussed. The findings are expected to provide valuable references and practical insights for the effective utilization of industrial by-products in soft ground solidification.

Organic matters lead to high water content of river sludge and difficulty in its deep dewatering. Flocculationprecipitation is considered as an efficient and low-cost dewatering technology. Flocculants play a key role in the dewatering process. This study employed anionic polyacrylamide (APAM) and lime as flocculant and conditioner for flocculation-precipitation dewatering treatment for river sludge with different organic matter content. Combination of response surface methodology (RSM) with CRITIC weighting method was used to determine the optimum flocculant and conditioner dosage, organic matter content. The results showed that the increase of organic matter content reduced the flocculation-precipitation effect of river sludge. APAM significantly enhanced particle size of the sludge and improved the flocculation efficiency. Lime effectively destroyed extracellular polymeric substances (EPS) and promoted the dewatering efficiency by providing Ca2+and adjusting pH, significantly reducing the absolute Zeta potential of the sludge and reducing turbidity of the supernatant by 9.36 times. The combined utilization of APAM and lime obtained higher dewatering efficiency than that using single APAM or lime. The optimum conditions were organic matter content of 4.92 %, APAM of 0.34 g/L, lime of 3.65 g/L). Turbidity of the supernatant, capillary water absorption time (CST) and median particle size (Dx(50)) of the sludge reached 2.77 NTU, 80.47 s, and 271.46 mu m, respectively. This study can provide valuable guidelines for flocculation-precipitation dewatering treatment of river sludge in real projects.

Sediment is a core part of lake ecosystems, and its organic matter (OM) content is a key indicator of lake ecological health and regional carbon cycling. OM provides nutrients for phytoplankton and algae in water, thereby influencing the degree of lake eutrophication. However, excessively high OM content may trigger water eutrophication, alter sediment’s physical and chemical properties, and ultimately threaten the stability and health of ecosystems. This study innovatively selected Poyang Lake, Taihu Lake, Qinghai Lake, and Hulun Lake from China’s four major geographical regions to systematically investigate sediments’ OM content, sources, and distribution characteristics at different times. The results showed that the organic matter content of sediments in lakes from different regions varied significantly and was influenced by multiple factors, such as watershed characteristics, eutrophication levels, human activities, and climate change. Poyang Lake and Taihu Lake, characterized by high levels of agricultural activities and urbanization within their basins, exhibit significant fluctuations in organic matter content, with total organic carbon (TOC) levels ranging from 0.35% to 2.9% and 0.7% to 2.4%, respectively. In contrast, Qinghai Lake and Hulun Lake, influenced by natural conditions and ecological policies, show relatively stable TOC levels, ranging from 1.3% to 2.75% and 1.25% to 3.58%, respectively. By analyzing sediments’ OM content and combining methods such as organic carbon, nitrogen isotopes, and organic C/N ratios, it is possible to effectively assess the ecological health of lakes, provide critical data support for pollution control, and play a significant role in carbon cycle management.

Ground granulated blast furnace slag (GGBS), calcium carbide slag (CS), and phosphogypsum (PG) were combined in a mass ratio of 60:30:10 (abbreviated as GCP) to solidify dredged sludge (DS) with high water content. The long-term strength characteristics of solidified DS under varying curing agent dosage and initial water contents, as well as its durability under complex environmental conditions, were investigated via a series of mechanical and microstructural tests. The superior performance of GCP-solidified DS (SDS-G) in terms of strength and durability was demonstrated in comparison to solidified DS using ordinary Portland cement (SDS-O). The results indicated that the unconfined compressive strength (UCS) of SDS-G was approximately 3.0-4.5 times greater than that of SDS-O at the same dosage and curing ages, exhibiting a consistent increase in strength even beyond 28 days of curing. Additionally, the strength and deformation modulus (E50) of SDS-G increased initially and then decreased during wet-dry cycles, with reductions in mass, volume, and strength significantly were smaller than those observed in SDS-O. Furthermore, the reductions in UCS and E50 induced by freeze-thaw cycles were considerably smaller for SDS-G than for SDS-O, with strength losses of 50.7% and 88.3%, respectively, after 13 freeze-thaw cycles. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses revealed that the enhancements observed in SDS-G were attributed to the formation of ettringite (AFt), which effectively fills larger pores between agglomerated soil particles, thereby creating a denser and more stable microstructure in conjunction with hydrated calcium aluminosilicate (C-(A)-S-H) gels.

Application of solidified river sludge for ecological slope protection is important way for recycling river sludge. Evaluation on their environmental characteristics under nature conditions is an essential work, which may be significantly affected by rainfall. This study aimed to study the environmental characteristics of in-situ solidified river sludge used as matrix of ecological slope protection under natural rainfall conditions. Impact of traditional cement (CC) and composite solidifiers (GCP) on the solidification effect of pollutants solidifying agents and the environmental characteristics of the solidified river sludge were also discussed. The results indicated that rainfall led to the formation of pore structures in the solidified sludge, causing the leaching of contaminants such as nitrogen, phosphorus, and heavy metals. Simultaneously, rainfall reduced the HA/FA ratio in the CC and GCP solidified sludge by 37.78 % and 34.25 %, respectively, affecting its aggregation stability, fertilizer-holding capacity, and growth of dogtooth grass. The total leaching amounts of total phosphorus (TP), total nitrogen (TN), and total organic carbon (TOC) from GCP solidified sludge were 9.05, 98.32, and 539.49 mg/kg, respectively. Its accumulated leaching amounts of heavy metals (Cr, Ni, Cu, Zn, As, Pb) were lower than that from CC solidified sludge. After rainfall, GCP solidified sludge produced more calcium silicate hydrate gel (C-SH) and ettringite (AFt) to fill pore structures, which effectively enhanced its structure stability. Furthermore, the dogtooth grass growing on GCP solidified sludge exhibited higher photosynthetic (7.1 x10- 4 mg/g of chlorophyll (a+b) content) and growth capacity than that on CC solidified sludge (3.7 x10- 4 mg/g). The number of beneficial microorganisms such as Bradyrhizobium, Rhodobacter, and Gemmatimonas in GCP solidified sludge increased after rainfall. Thus, GCP solidified sludge exhibited stronger tolerance to rainfall and higher ecological friendliness than CC solidified sludge. The findings of this study provide reference for recycling solidified river sludge in ecological slope protection.

River sludge usually contains a high content of organic matter, leading to its low strength or difficult solidification in its solidification/stabilization (S/S) treatment projects. This study selected river sludge with medium and high content of organic matter for the S/S treatment using modified curing agent (GCP) and cement (P.O). Effects of humus and curing agent on the S/S process of river sludge were investigated via analyzing physical properties, changes in organic matter, microstructure, and mineral compositions of the solidified sludge. The results showed that the increase rate of compressive strength of the solidified sludge was influenced by the content of organic matter and composition of the curing agent. The presence of humus inhibited the hydration reaction and reduced the increase rate of compressive strength of solidified sludge. Slag and phosphogypsum in GCP promoted the hydration reaction, significantly enhancing the compressive strength of the solidified sludge to 2242.24 KPa. The water content of the solidified sludge was influenced by the environmental conditions and curing agent, which could reflect the level of hydration reaction in the solidified sludge. The pH of the solidified sludge was directly affected by the humus in the sludge, with a decreasing trend during the S/S process. Decomposition of the humus in the sludge released H+, which reacted with OH− produced by the hydration reaction via neutralization reaction. The pH of the solidified sludge was lowered, and the hydration reaction was inhibited, hindering the decrease in the water content of the solidified sludge. Therefore, the hydration reaction has an antagonistic effect on the decomposition of the humus. Microstructure analysis (SEM) confirmed that GCP could effectively solidify the organic-rich river sludge. This study provides a theoretical basis for the S/S treatment of organic-rich river sludge.

The concrete face rockfill dam is widely used in the construction of pumped storage power stations. Significant daily water level fluctuations in pumped storage power stations result in slow-rate cyclic loading effects on the rockfill materials behind the slab, leading to particle breakage and accumulation of deformation. The purpose of this study is to explore the impact of slow-rate cyclic loading on the crushing behavior of individual rockfill grains at the particle scale. First, a serious of single-particle crushing tests were conducted to investigate the impacts of particle size, cyclic loading times and cyclic loading amplitude on particle crushing. The load–displacement curves and fragmentation patterns under different test conditions were further discussed. Additionally, the test results were analyzed using the Weibull statistical method, and the variations in Weibull characteristic strength under different test conditions were explored. Finally, a single-particle crushing model was proposed to reflect the size-dependent and cyclic loading-related characteristics of particle Weibull characteristic crushing strength. In the newly proposed model, the concept of fatigue-crack propagation was applied to tackle the strength degradation of rockfill grains under slow-rate cyclic loading effects, and the Weibull statistics was adopted to consider the influence of the random defects on the scale effect of crushing strength. The robust performance of the newly proposed model was verified by comparing the predicted results with statistical Weibull characteristic strength, with the coefficient of determination exceeding 0.92. This work provides a particle-scale perspective on the degradation behavior of rockfill under slow cyclic loading, while the research findings establish a connection between grain-scale phenomena and continuum-scale processes in rockfill materials under such conditions.

Although dredged sludge after solidification generally meets engineering strength requirements, it often exhibits brittle failure and inadequate crack resistance, limiting its performance under complex loading conditions involving deformation and stability challenges. To enhance tensile properties and reduce the environmental impact of conventional cement-based binders, polypropylene fibers (PF) were incorporated into dredged sludge solidified with an industrial by-product-based curing agent (GCP), comprising ground granulated blast furnace slag (GGBS), carbide slag (CS), and phosphogypsum (PG). A series of direct tensile and unconfined compressive strength (UCS) tests were conducted to investigate the effect of fiber content on tensile properties of solidified sludge, explore correlations between tensile and compressive behaviors, and comprehensively assess the mitigation of brittleness due to fiber addition. Furthermore, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed to elucidate the underlying toughening mechanisms. Results indicate that tensile strength peaks at a fiber content of 6 %o by mass and exhibits logarithmic growth with curing age and exponential growth with GCP content under varying fiber contents. Moreover, fiber incorporation effectively enhances ductility and toughness while mitigating brittle failure characteristic. At 6 %o fiber content, toughness improves by 160 %- 340 %, and brittleness decreases by 39 %- 50 % compared to solidified sludge without fiber incorporation. Additionally, strong linear correlations exist between direct tensile strength and UCS, and between compressive and tensile toughness, with direct tensile strength approximately 11.5 % of UCS. Hydration products generated through the synergistic reactions among GGBS, CS, and PG significantly reduce interparticle pores, strengthen interparticle bonding, and markedly increase interfacial friction between fibers and soil particles through cementation and filling effects, forming an integrated soil particle-hydration product-fiber composite structure. Under tensile loading, interconnected fibers facilitate stress redistribution, delay crack initiation and propagation, thus enhancing tensile strength and ductility of solidified sludge below the critical fiber content. Moreover, the fiber bridging effect maintains substantial residual load-bearing capacity after fracture, thereby improving toughness and reducing brittleness.

A large amount of dredged sludge is annually generated in rivers, and their suitable treatment or recycling utilization is significant for reducing their potential pollution to the surrounding environment. Rapid dewatering is a crucial step of their treatment and resource utilization. This study used a flocculation, filter-pressing, and electro-osmosis coupled process to dewater river sludge with high water content. The dewatering performance by using inorganic flocculants (polyaluminum ferric chloride, PAFC), organic flocculants (anionic polyacrylamide, APAM), and their compounded flocculants was compared to explore the impact of their compounding on the dewatering performance. Water content and sedimentation volume of the river sludge after flocculation and sedimentation treatment were not significantly different among the addition of single APAM, PAFC, and their compounded flocculants. However, addition of the compounded flocculants (the mass dosage of PAFC+APAM was 0.03%+0.13%) obtained a higher dewatering volume and lower energy consumption in the subsequent filter-pressing and electro-osmotic dewatering processes. Compared with addition of single PAFC and APAM, the dewatering efficiency of filter-pressing treatment with addition of the compounded flocculants was enhanced by 17.38% and 21.00%, respectively. The dewatering efficiency of electro-osmotic treatment was increased by 12.25% and 9.90%, respectively. In addition, the energy consumption of electro-osmotic treatment was reduced by 29.11% and 33.42%, respectively. The characterization results indicate that the larger particle and pore size, the looser structure, and the more inside micropores of the sludge flocs were observed after flocculation treatment by adding the compound flocculants. These changes in properties resulted in better dewatering performance of the sludge in filter-pressing and electro-osmotic. The economic analysis reveals that addition of the compound flocculants during the three-stage dewatering process achieved a lower cost than that with addition of single flocculants. This study can provide valuable references for the selection of flocculants in real dewatering projects of river sludge.

Application of solidified dredged sludge for constructing ecological slope protection represents a vital strategy for sustainable utilization of river sludge. Evaluating the environmental characteristics of solidified river sludge under prolonged exposure to natural conditions is essential for assessing its ecological safety and practical applicability. In this study, conventional cement (CC) and a novel composite solidifying agent (GCP) were employed to stabilize river sludge. Impact of natural rainfall erosion on the physicochemical properties and environmental characteristics of the solidified sludge was examined. Particular focus was placed on the release patterns of water pollutants, including nitrogen, phosphorus, and heavy metals from both types of solidified sludge under natural rainfall exposure. The results showed that rainfall erosion reduced the strength and pH of the solidified sludge, affected the immobilization effect of heavy metals, nitrogen, phosphorus, and promoted their release. Compared with CC, GCP exhibited better immobilization effects on pollutants and a stronger buffering capacity against rainfall erosion. The compressive strength of the GCP solidified sludge (GCPSS) after rainfall erosion was 1.35 times greater than that of the CC solidified sludge (CCSS). The concentrations of total phosphorous and nitrogen in the GCPSS decreased significantly under the action of multiple rainfall events. Cynodon dactylon cultivated on the GCPSS demonstrated superior growth performance, accompanied by greater microbial diversity and abundance. Notably, the populations of Pseudolabrys, Gaiella, and Bacillus were enriched, contributing positively to soil stability. In contrast, the microbial community in the CCSS exhibited no significant variation. These findings are important for assessing the feasibility and environmental safety of utilizing solidified river sludge in the construction of ecological slope protection.

Dewatering treatment is the primary step for treatment and recycling of river sludge. This study employed a flocculation-electroosmosis coupled process for dewatering treatment on river sludge. Impact of organic matter content in the sludge on the dewatering process was explored. Addition of cationic polyacrylamide (CPAM) significantly enhanced the dewatering performance of the combined treatment, especially for the sludge with medium organic matter content (SMOC). The lowest moisture contents of SMOC and the sludge with high organic matter content (SHOC) achieved 49.64 % and 58.45 % with 1.0 and 2.5 g/L of CPAM, respectively. Protein-like substances in SHOC could prevent destabilization and flocculation of the sludge through electrostatic repulsion due to its highly negative charge density of surface, maintaining a stable hydrated colloid structure to prevent water release. Thus, flocculation dewatering of SHOC required a higher CPAM dosage. SMOC after CPAM flocculation treatment more easily formed larger sludge flocs (399.53-665.79 mu m), more and larger pores due to the bridging effect of CPAM, providing abundant internal hydrophobic channels for electroosmotic dewatering. Energy consumption of the electroosmotic process achieved a low level (0.08-0.13 kWh/kg removed water). The results can provide valuable insights for dewatering treatment of river sludge with different organic matter content.

A large amount of sediment is dredged from surface water bodies such as rivers, lakes, and oceans every year around the world. It should be further disposed of or recycled. Dewatering is an essential step before the treatment and recycling of dredged sediment. At present, flocculation is one of the most used techniques for dewatering of dredged sediment. This article provides a comprehensive review on the status of dewatering of dredged sediment in water bodies by flocculation processes, with emphasis on the self-flocculation process of dredged sediment and the effects of adding different flocculants. The important influencing factors for the self-flocculation process of dredged sediment were summarized, and the corresponding mechanisms were discussed. The mainly used flocculants for the flocculation process and their influencing mechanisms for the properties of the flocs were also reviewed. In addition, the effect of the flocculants on the migration of contaminants in dredged sediment was assessed. This review can provide reference and guidance for future studies and the real projects on dewatering of dredged sediment by flocculation processes.

Rainfall-induced landslides are common natural hazards, particularly in cases involving unsaturated soils. Slope instability issues may arise due to extreme climate events, while, creep effects can also contribute to landslide problems. In this study, a modified ViscoElastic-ViscoPlastic constitutive model is developed to more accurately characterise the mechanical properties of unsaturated loess, considering stress-level dependency of stiffness and creep properties. In addition, to better characterise the collapsibility of loess, the relationship between strengths and matric suction has been introduced. The infiltration process of an unsaturated porous medium is illustrated by the Van Genuchten model and the generalized Darcy’s law. Additionally, the atmospheric boundary condition is incorporated in the numerical simulations, considering factors such as runoff generation and various climate events.In the context of slope stability analysis, a numerical approach has been developed to determine the safety factor of the slopes, by using displacement changes as the key assessment criterion. A good agreement between numerical and analytical results has been observed, verifying the proposed approach to determining safety factor. Finally, in parametric analyses, the effects of creep and matric suction on safety factor have been identified. Slope stability of unsaturated loess slopes subjected to different rainfall intensities and rainfall durations has been studied. The maximum depth of the sliding part increases obviously when considering the contribution of creep deformations, which is crucial in analysing slope stability.

堆石料的压实密度是反映其工程力学特性的重要指标.提出了一种基于降维映射的颗粒堆积算法,仅有一个模型参数即可在给定堆石料级配的情况下实时预测当前级配下的最大干密度.与试验结果对比发现,该算法能够较好预测给定的连续、间断级配堆石料最大干密度,为堆石料级配的高效优化设计提供了新思路.采用该算法模拟了堆石料细料截断和缩尺对堆石料压实密度的影响,结果表明:本算法可以较好地根据缩尺后的结果预测原型级配的堆石料压实密度,但堆石料压实密度的缩尺效应预测存在细料截断误差,误差与细料含量呈正相关;堆石料缩尺后粗料部分骨架的孔隙尺寸降低,有降低压实密度的趋势,而缩尺时增加的细料含量对密度的影响并无统一的规律,而是与粗料和细料的具体粒径分布相关.

This paper presents a finite element analysis for the behavior of the Lianghekou high earth-core rockfill dam, which was just completed in construction in China. An elastoplastic constitutive model that can account for the degradation of rockfills due to particle breakage (hhu-SH-breakage model) was applied to simulate the mechanical behavior of the rockfills. The earth-core wall was analyzed by using the modified Cam-clay model combined with the Biot's consolidation theory. Numerical results are in good agreement with in-situ measurements during construction, indicating the reasonability of the numerical analysis. Based on the breakage-packing concept, which is able to extract the breakage-induced deformation from the total deformation, numerical analysis showed that the breakage-induced settlement for the extra high rockfill dam is not negligible. Inspired by the sensitivity analysis using the hhu-SH-breakage model, engineering advices were proposed to reduce the settlement of high rockfill dams.

In this paper, a new cross-scale finite element method is developed to study the mechanical response of concretefaced rockfill dams, in which an arbitrary-node hexahedron element is used to deal with the mesh transition between the concrete slab and dam body. By using the proposed method, the mesh sizes of concrete slab and rockfill may be very different. Moreover, since the cross-scale method doesn't change the finite element calculation framework, the proposed method is easy to use. In the simulated CFRD, the mechanical behavior of the concrete slab is described by an elastic-plastic constitutive model, and a nonlinear elastic model is applied to the rockfill materials. The computational accuracy and performance of the proposed method are analyzed. The numerical results and analysis provides an effective approach to study the local behavior of concrete face slabs.

Soilbags are expandable three-dimensional geosynthetic bags made from high-density polyethylene or polypropylene. This study conducted a series of plate load tests to explore the bearing capacity of soft foundations reinforced by soilbags filled with solid wastes based on an onshore wind farm project in China. The effect of contained material on the bearing capacity of the soilbag-reinforced foundation was investigated during the field tests. The experimental studies indicated that soilbag reinforcement with reused solid wastes could substantially improve the bearing capacity of soft foundations under vertical loading conditions. Solid wastes like excavated soil or brick slag residues were found to be suitable as contained material, and the soilbags with plain soil mixed with brick slag had higher bearing capacity than those with pure plain soil. The earth pressure analysis indicated that stress diffusion occurred through the soilbag layers to reduce the load transferred to the underlying soft soil. The stress diffusion angle of soilbag reinforcement obtained from the tests was approximately 38°. In addition, combining soilbag reinforcement with bottom sludge permeable treatment was an effective foundation reinforcement method, which required fewer soilbag layers due to its relatively high permeability. Furthermore, soilbags are considered sustainable construction materials with advantages such as high construction efficiency, low cost, easy reclamation and environmental friendliness while making full use of local solid wastes.