The research was led by Jianwei Zhang, Weitao Wu, and Ge Hou of the School of Water Conservancy at North China University of Water Resources and Electric Power in Zhengzhou, together with Jinlin Huang of the Guangdong Research Institute of Water Resources and Hydropower in Guangzhou and Biao Jia of the Inner Mongolia Water Conservancy Science Research Institute in Hohhot. Their starting point was the structural character of embankments, the earthen barriers that form the backbone of many reservoirs. Rather than relying on a single measurement, the team constructed a comprehensive evaluation index system that captures three distinct streams of evidence: continuous monitoring data from instruments, the findings of on-site inspections, and review indicators drawn from formal safety assessments.

Once the indicators were defined, the researchers confronted a classic dilemma in multi-criteria evaluation: how much should each factor count? Subjective weighting methods, which rely on expert opinion, capture engineering experience but can introduce personal bias. Objective weighting methods, which are derived mathematically from the data itself, avoid bias but may ignore knowledge that experienced inspectors bring. The team calculated weights separately using both approaches and then fused them through an improved game theory framework built on the idea of minimizing the overall loss of information. In game theory terms, the subjective and objective weight vectors are treated as players whose combined outcome should preserve as much information as possible from both sources, yielding fusion weights that neither approach could achieve alone.

With the weights settled, the model had to handle the deep uncertainty that pervades dam monitoring. Instrument readings drift, inspection findings are qualitative, and the boundary between safe and unsafe is fuzzy rather than sharp. To convert between these qualitative judgments and quantitative numbers, the researchers employed forward and reverse cloud generators, the computational engines of the cloud model, a cognitive framework first proposed by Li Deyi and colleagues in 2009. A forward cloud generator transforms linguistic concepts, such as a rating of normal or abnormal, into populations of cloud droplets, which are random numerical realizations that scatter around the concept according to defined statistical properties. A reverse cloud generator performs the opposite conversion, distilling raw data back into the numerical characteristics of a concept.

The cloud model’s dependence on randomly generated cloud droplets introduces its own subtle error: the number of droplets used in a calculation changes the resulting membership degrees. The team tackled this by developing a calculation method based on membership degree that quantifies the error generated by different numbers of cloud droplets, allowing a reasonable optimization of the droplet count. This optimization matters because too few droplets produce unstable, noisy results, while too many waste computational effort without meaningfully improving accuracy. By calibrating the droplet number against the error it induces, the model achieves a balance that keeps its verdicts both stable and efficient.

To demonstrate the framework, the researchers applied it to the embankment of the Helong Reservoir in Guangzhou City, in China’s Guangdong Province. The model’s output is expressed as a membership degree, a measure of how strongly the embankment’s overall condition belongs to each safety grade. The result showed that the membership degree of the Helong Reservoir to the normal category reached 62.9 percent, a clear indication that the structure was operating in a satisfactory state. Crucially, this verdict was consistent with the evaluation results of other established models and with the actual current situation of the reservoir, confirming the validity and reasonableness of the new method.

The agreement between the game theory-cloud model and alternative evaluation approaches is more than a technical footnote. Dam safety evaluation models are needed to accurately identify the safety status of dams precisely because failure can have a significant impact on the lives and health of people downstream. Statistical analyses of dam failures in China, cited in the study’s bibliography, underline how monitoring data, inspection records, and formal review indicators each tell part of the story, and how a comprehensive model that weighs all three can catch deterioration before it becomes an emergency. The new framework provides a reference for the comprehensive evaluation of embankment safety that other agencies can adapt to their own structures.

Behind the mathematics lies a broader movement in dam engineering toward data-driven health diagnosis. Recent studies have explored multi-source monitoring information fusion based on Wasserstein distance, anomaly identification for tailings dams, deep learning methods for dam behavior after extreme loads, and even digital twins that mirror a dam’s condition in real time. The cloud model has already been applied to dam safety monitoring, water cycle health assessment, and risk evaluation of dam-break environmental impacts. What distinguishes the new contribution is the systematic way it merges subjective and objective weighting through improved game theory while simultaneously taming the randomness inherent in cloud-based reasoning, two improvements that address the main sources of error in prior cloud-model evaluations.

The practical implications reach far beyond one reservoir in Guangdong. Embankments and earthen dams number in the tens of thousands worldwide, many of them aging structures whose instrument networks are sparse and whose inspection regimes depend on human judgment. A model that can quantitatively reconcile expert opinion with measured data, and that can express its conclusion as a graded membership rather than a binary pass or fail, gives operators a richer picture of margin and risk. The 62.9 percent membership in the normal category for Helong Reservoir illustrates the granularity available: instead of a single label, managers see how strongly the evidence supports each safety state, which can guide the intensity of future monitoring and inspection.

The research was supported by the National Natural Science Foundation of China, the Science and Technology Innovation Program from Water Resources of Guangdong Province, and the Guangdong Provincial Water Conservancy and Hydropower Technology Center. As climate change intensifies floods and raises the stakes for water infrastructure, tools that turn uncertain evidence into clear safety verdicts are likely to attract growing attention from engineers and regulators alike. The improved game theory-cloud model joins a rapidly expanding toolkit for keeping the world’s aging embankments under quantitative watch, and its validation at Helong Reservoir suggests the approach is ready to be tested on structures whose safety is far less certain.

Subject of Research: Comprehensive Evaluation of Embankment Safety Based on Improved Game Theory-Cloud Model

Article Title: Comprehensive Evaluation of Embankment Safety Based on Improved Game Theory-Cloud Model

Article References: Zhang, J., Wu, W., Hou, G., Huang, J., & Jia, B. (2026). Comprehensive Evaluation of Embankment Safety Based on Improved Game Theory-Cloud Model. Water Resources Management, 40(14), Article 540. https://doi.org/10.1007/s11269-026-04907-6

Image Credits: AI Generated

DOI: 10.1007/s11269-026-04907-6

Keywords: Comprehensive, Evaluation, Embankment, Safety, Based, Improved, Game, Theory-Cloud, Model, scientific research

The team’s starting material was dredged sludge from Nanjing, in China’s Jiangsu Province, a silty clay with a water content of 33 percent, a liquid limit of 35.3 percent and a plasticity index of 16.6. Classified as silty clay because of its 73 percent silt fraction, the soil in its natural state has a loose microstructure and poor mechanical strength, making it unsuitable for load-bearing embankment fill without treatment. Compaction testing showed the soil reaches its maximum dry density at a water content of 14 percent, a figure the researchers used to design their mixtures.

Rather than relying on Portland cement, whose production accounts for a substantial share of global carbon dioxide emissions, the researchers turned to two abundant industrial by-products. Fly ash, captured from coal combustion flue gases, is rich in silica and alumina, while granulated blast furnace slag from ironmaking contributes abundant calcium. Both materials pose disposal problems of their own; uncontrolled fly ash can generate airborne dust and contaminate water. Under alkaline activation with sodium hydroxide and sodium silicate, however, these wastes dissolve and recombine into powerful cementitious gels, turning a liability into a resource.

To find the best formulation, the team ran an orthogonal test program examining four variables: the fly ash to slag ratio, the sodium hydroxide to sodium silicate ratio, the total alkali content and the water to solid ratio. Variance analysis revealed that the fly ash to slag ratio exerted the strongest influence on compressive strength, followed by alkali content, water to solid ratio and finally the activator balance. The optimal recipe emerged as an equal 5:5 blend of fly ash and slag, a sodium hydroxide to sodium silicate ratio of 1:7, an alkali content of 10 percent by mass of the binder, and a water to solid ratio of 0.35. The researchers attributed the strength gains to abundant calcium aluminate crystals that fill pores when the activator chemistry is properly balanced, while too much or too little water either leaves binder unreacted or dilutes the activator concentration.

With the optimal binder in hand, the team blended it into the dredged soil at doses ranging from 2 to 10 percent by mass and cured the compacted cylindrical specimens for 28 days under standard laboratory conditions of 20 degrees Celsius and 95 percent humidity, deliberately avoiding the high-temperature curing that pure fly ash geopolymers typically require. The results showed a clear threshold effect. Below about 4 percent binder content, the newly formed gel mainly repairs the cohesive soil structure disturbed by mixing, so properties improve only modestly. Above that threshold, enough gel is produced to bond soil particles into a genuinely new, stable skeleton, and performance climbs steeply. Compared with untreated soil, the 10 percent mixture delivered a 110 percent gain in compressive strength, a 106 percent increase in toughness index, a 243 percent boost in tensile strength and an 85 percent improvement in the water stability coefficient.

That last metric matters enormously for embankments, which must survive rainfall and saturation. The researchers saturated specimens after 21 days of curing and compared their strength with samples kept dry. Stress-strain curves showed the stabilized soil fails in a softening, plastic manner rather than shattering brittlely, absorbing energy before gradually losing load capacity. The toughness index, calculated as the area under the stress-strain curve up to peak strain, quantified this resistance to brittle fracture and rose steadily with binder dose.

Head-to-head against a conventional 4 percent cement-stabilized control, the picture was nuanced. At equal 4 percent dosage, the alkali-activated material lagged behind cement, with compressive strength, tensile strength and water stability reduced by 44, 53 and 21 percent respectively, because cement’s higher calcium content generates more calcium silicate hydrate gel. But at 10 percent dosage, the waste-based binder overtook cement on every measure, edging ahead by 4 percent in compression, 13 percent in tension and 14 percent in water stability. The trade-off is more binder, but one made entirely from wastes that would otherwise be landfilled.

The environmental accounting is where the new binder truly shines. Using life cycle assessment aligned with ISO 14040, the team quantified global warming potential, acidification, eutrophication, photochemical ozone creation and resource consumption for stabilizing one tonne of soil. The 4 percent alkali-activated mixture cut global warming potential by 99 percent relative to cement treatment, from 71.6 kilograms to 0.363 kilograms of carbon dioxide equivalent, while acidification, eutrophication and photochemical oxidation potentials fell by 100, 99 and 91 percent and resource consumption dropped 98 percent. Even the 10 percent mixture, using twice the binder mass, reduced global warming potential by 99 percent and resource consumption by 95 percent compared with the cement control.

To understand why the material performs so well, the researchers deployed an arsenal of microscopic techniques: X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy with energy dispersive spectroscopy, and nuclear magnetic resonance. Electron images revealed that untreated soil consists of blocky, flaky and flocculated particle aggregates riddled with voids, while the 10 percent mixture forms a dense fabric of flocculent gel bonding particles into lumpy aggregates. Image analysis showed porosity falling by 25 percent at 4 percent binder and 70 percent at 10 percent. Nuclear magnetic resonance confirmed that large pores declined by 75 percent and small pores by 28 percent at the highest dose, indicating the gel primarily bridges particles and eliminates large voids while also filling finer ones. Notably, no spherical fly ash particles survived, evidence that the ash dissolved and reacted almost completely.

The spectroscopic data converged on a clear chemical mechanism. Elemental analysis detected oxygen, sodium, aluminum, silicon and calcium, with sodium, calcium and aluminum to silicon ratios rising sharply with binder dose. Under the alkaline conditions created by sodium hydroxide and sodium silicate, Ca-O, Na-O, Al-O and Si-O bonds break, releasing calcium ions, sodium ions, aluminate and silicate species that then geopolymerize. Slag-derived calcium forms calcium silicate hydrate and calcium aluminosilicate hydrate gels, while fly ash contributes to sodium aluminosilicate hydrate, the signature N-A-S-H gel of alkali-activated systems. X-ray diffraction identified these new gel phases alongside the soil’s native quartz, illite and kaolinite; infrared spectra showed strengthened Si-O and Al-O absorption bands; and thermal analysis recorded additional mass losses from gel decomposition and bound water, cross-validating the mechanism. The gels weld soil particles into a stable skeleton and fill pores, explaining the dramatic mechanical and durability gains. The authors note that future work must test the material against sulfate attack, high temperatures and freeze-thaw cycling, but the study establishes that two of the world’s most troublesome industrial wastes can jointly convert dredged mud into a durable, genuinely low-carbon construction material.

Subject of Research: Alkali-activated fly ash and blast furnace slag stabilization of dredged waste soil for sustainable embankment construction

Article Title: Applicability and chemical mechanism of alkali-activated fly ash and blast furnace slag stabilized soil for sustainable embankment

Article References: Zhang, C., Wang, W., Zhu, Z., Li, N., Jang, P., & Ma, B. (2026). Applicability and chemical mechanism of alkali-activated fly ash and blast furnace slag stabilized soil for sustainable embankment. Case Studies in Construction Materials, 25, Article e06619. https://doi.org/10.1016/j.cscm.2026.e06619

Image Credits: AI Generated

DOI: 10.1016/j.cscm.2026.e06619

Keywords: alkali-activated materials, fly ash, blast furnace slag, soil stabilization, embankment, geopolymer, dredged sludge, low-carbon construction, life cycle assessment, N-A-S-H gel, C-A-S-H gel, waste recycling

The PCCS system, short for precast concrete piles reinforced by cemented soil, marries two established ground-improvement techniques. A deep-mixing column, created by blending cement into soft soil in place, forms a stiff outer sleeve. Into that sleeve, engineers insert a slender precast concrete pile that acts as a rigid inner core. The two components work in complementary fashion: the concrete core supplies axial stiffness and bearing capacity, while the cemented-soil column enlarges the effective diameter of the pile, expands the contact area with the surrounding ground, and improves lateral confinement and interfacial bonding. Depending on whether the inner core is shorter, equal to, or longer than the outer column, the system is classified as short-core, equal-core, or long-core. For deep and thick soft-soil deposits—the kind encountered along the Beijing–Shanghai corridor—only the long-core variant makes sense, because the extended concrete core can reach down toward a competent bearing stratum that a shallow cemented column alone could never touch.

The field test section sits between chainages K950+054 and K950+158 of the expressway expansion. The original design called for conventional precast concrete piles of 28 to 35 meters, but the project team adopted the PCCS alternative for its combination of high bearing capacity and cost savings. Each PCCS unit consisted of a 32-meter-long, 0.4-meter-diameter precast concrete core of C60-grade concrete topped with a 1.6-meter square pile cap, surrounded by a 12-meter-long, 0.8-meter-diameter cemented-soil outer core. The piles were arranged in a square grid at 3.5-meter center-to-center spacing, and a 0.3-meter gravel cushion laced with a geocell—a honeycomb-like polymer reinforcement—was laid over the pile heads to distribute load and limit differential movement at the ground surface.

To dissect the load-transfer mechanics, the research team built two fully coupled fluid–solid numerical models in ABAQUS: a full half-width cross-section of the embankment and an idealized unit cell centered on a single pile. The deep saturated soft soil was represented with the modified Cam-Clay constitutive model, its compression and swelling indices calibrated against laboratory consolidation and triaxial tests, while the embankment fill, cushion, and cemented soil used the Mohr-Coulomb elastoplastic model. A bond–slip friction model captured the interface between the concrete core and its cemented sleeve, with a bond strength of 200 kilopascals and a tangential friction coefficient of 0.65 drawn from prior experimental work. Mesh sensitivity checks confirmed that predictions of settlement and pile–soil stress ratio changed by less than 2 percent between medium and fine meshes, giving the team confidence in the computational framework.

Validation against field instrumentation proved convincing. At 320 days after construction, measured pile-top stress fell between the two models, with the unit model deviating by at most 12 percent from observations, and normalized settlement profiles along the embankment height agreed within 4.2 percent. The simulations revealed a clear temporal choreography: during embankment filling, both pile and soil stresses climbed steadily, but once construction ended their paths diverged. The pile-top stress kept rising as the soft ground consolidated and drained, while the stress in the surrounding soil peaked and then gradually declined—signature behavior of soil arching, the process by which load sheds from yielding soil onto stiffer inclusions through intergranular shear. In the final stabilized state, the surrounding soil carried only about 33 kilopascals, roughly 55 percent of the embankment’s average applied pressure, while the pile top reached 266.2 kilopascals, yielding a pile–soil stress ratio of 8.1. In load-sharing terms, the PCCS carried 68 percent of the total embankment weight and the soil just 32 percent.

Settlement performance was equally impressive. Immediately after filling, the pile and the adjacent soil had settled 6.9 and 22.5 millimeters respectively; as consolidation proceeded, the soil continued to compress, stabilizing after 204 days at a final measured settlement of 47.5 millimeters. The pile top, by contrast, essentially stopped moving about 86 days after construction, finishing at just 15.2 millimeters. The growing gap between pile and soil settlement—eventually stabilizing at 31.3 millimeters after 264 days—is precisely what drives soil arching above the pile caps. Numerical stress contours captured the result vividly: as the embankment rose, principal stress concentrated above the pile tops in a distinctive mushroom-shaped pattern, and stress vectors tilted outward to form a coherent arch. Once the arch was fully developed, the upper embankment fill became nearly differential-settlement-free, meaning the pavement above rode on a smoothly supported platform despite the uneven foundation below.

The study quantified this arching with a critical height of approximately 1.15 times the net pile spacing—the distance between pile-cap edges. Below that plane, differential settlement and stress redistribution are concentrated; above it, settlement curves converge and the embankment behaves as a uniform body. The analysis also distinguished between an inner arch, spanning adjacent piles, and a higher outer arch spanning the diagonals of the pile grid. At an embankment height of 5 meters, the outer arch reached a maximum of 1.55 times the net spacing above the embankment base, reflecting the wider diagonal pile spacing. The horizontal earth pressure coefficient, a direct measure of arching intensity, stayed near the at-rest value through most of the embankment height but surged near the base, where at 5 meters of fill it reached values 3.2 and 2.3 times those measured under 3-meter and 4-meter embankments respectively.

Parametric sweeps explored how the embankment fill’s own properties modulate the arch. Increasing the fill’s elastic modulus modestly reduced peak stress and displacement—each 10-megapascal increment trimmed normalized stress by roughly 4 to 5 percent and displacement by about 3 percent. Cohesion proved more influential: every 5-kilopascal gain cut maximum normalized displacement by 7 to 11 percent, indicating that a more cohesive fill helps the arch develop and hold its shape. The internal friction angle, surprisingly, mattered little, with stress and displacement fluctuating within 3 percent for each 5-degree change. The geocell embedded in the cushion added its own membrane effect, deforming symmetrically along the embankment axis and developing peak tensile force near the shoulder pile, where it helped distribute lateral load and maintain stability at the slope.

Horizontal ground movements told a consistent story. Displacements decreased with depth but showed a localized bulge between 4 and 12 meters during the first 120 days after construction, and intensified from the surface down to 16 meters as time passed. At the slope toe, the computed maximum horizontal displacement was 4.4 millimeters at the end of construction against 2.5 millimeters measured in the field; by 365 days the computed value reached 14.9 millimeters, exceeding the field measurement by only 15.5 percent. Axial-force profiles along the pile depth revealed a neutral point at 16 meters for the central pile, below which negative skin friction gave way to positive resistance, while piles beneath the slope, carrying less overburden, showed neutral points at 9.0 and 4.0 meters for their inner and outer cores respectively.

The authors are candid about the model’s limits: pile installation disturbance, long-term creep of the soft clay, cemented-soil degradation, and progressive interface damage were not explicitly simulated, and these simplifications likely explain why measured soil settlement slightly exceeded predictions. Still, the agreement achieved across stress, settlement, and displacement metrics demonstrates that the long-core PCCS is a genuinely effective answer to deep soft-soil embankments—delivering rigid-pile settlement control at a fraction of the cost of conventional piling, and giving engineers a quantified, field-validated framework for designing the next generation of highways across the world’s soft deltaic plains.

Subject of Research: Load transfer mechanism and settlement performance of long-core PCCS composite foundations supporting embankments over deep soft soil

Article Title: Load transfer mechanism and performance evaluation of the PCCS composite foundation with long-core under embankment load

Article References: Zhang, C., Zhang, D., Liu, S., Wang, Z., Liu, L., & Zhu, M. (2026). Load transfer mechanism and performance evaluation of the PCCS composite foundation with long-core under embankment load. Case Studies in Construction Materials, 25, Article e06506. https://doi.org/10.1016/j.cscm.2026.e06506

Image Credits: AI Generated

DOI: 10.1016/j.cscm.2026.e06506

Keywords: PCCS composite foundation, precast concrete pile, cemented soil, soil arching, embankment, soft soil, pile-soil stress ratio, settlement control, geocell reinforcement, modified Cam-Clay model, Beijing-Shanghai Expressway, ground improvement