In a homogeneous earth fill dam, an initial process of internal erosion was observed near the base of the downstream slope, which is one of the main dam failure causes in the world. This problem was adequately solved, and research was started aiming to find the causes of the detected anomaly. The history of the structure was investigated, field testing results were analyzed and undisturbed samples were collected in different regions of the dam. Characterization tests, saturated permeability coefficients tests under different effective stresses and flow directions, and Filter Papel tests were run. Results were incorporated into computational models to investigate the behavior of hydraulic gradients and the height of the exit point of the phreatic line defined on the basis of monitored piezometers installed at the site. The software Plaxis LE was used in this study. It was evaluated whether the adoption of unsaturated parameters or 3D analysis would promote any change in the flow pattern in the studied structure, which did not occur. It was also considered whether the soil-atmosphere interaction could generate critical hydraulic gradients through rainfall and evaporation cycles, but there were no critical results either. Finally, it is concluded that effects of natural vegetation previously found in Dam X may have led to the observed internal erosion process. These somewhat unusual findings are relevant for improving the understanding of vegetation impacts on earth dam safety and can help guide future monitoring and, particularly, maintenance practices to prevent similar issues in other similar earth fill dams.

Landslide dams are naturally formed dams with loose structures and poor stability. Whether and how landslide dams break after formation is directly affected by the upstream inflow conditions. In this study, different erosion patterns of landslide dam were achieved by controlling the water level through inflow conditions. Failure processes and characteristics of landslide dams with different erosion patterns were investigated by a series of physical model tests. The tested results showed that the failure process of landslide dam undergoing coupled erosion with seepage and overtopping included piping, slope erosion, settlement, breach evolution, large-scale scouring and formation of armor layer. With the increase in seepage duration before overtopping, the slope scouring and internal erosion were more serious. Headward erosion in coupled erosion occurred earlier and had a faster maximum erosion rate than that of rapid overtopping. When a landslide dam has been subjected to serious piping before overtopping, the peak discharge would increase, the emerging time of the flood peak would be early and the breaching duration would be short compared with that of rapid overtopping and failure triggered by seepage, respectively. The coupled erosion resulted in the smallest volume ratio of residual dam, the largest volume ratio of downstream alluvium and the longest transport distance. Failure processes and characteristic of landslide dams were influenced by seepage erosion that would alter the internal stress conditions and cause migration of fine particles to result in soil deformation. The results indicate that the coupled erosion is more harmful and is not conducive to risk assessment and timely rescue.

In the Interreg-funded Polder2C’s project, large-scale overflow experiments were conducted from 2020 to 2022 on levee slopes along the Scheldt River in Belgium and the Netherlands. These tests assessed surface erosion resistance under varied conditions, including levee sections containing animal-induced damages. Electrical Resistivity Tomography (ERT) was employed as a non-invasive monitoring tool to observe subsurface changes, particularly those linked to erosion-prone animal burrows. A unique system configuration enabled detailed imaging of the levee’s internal dynamics during overflow testing. Post-processed ERT data effectively captured subsurface changes during these events, including water infiltration into existing burrows, cavity formation and collapse, and the interconnection of subsurface voids. The study demonstrates ERT’s ability to identify critical subsurface features, with low resistivity zones indicating water-saturated areas and high resistivity zones marking air-filled voids. Time-lapse ERT imaging successfully captured dynamic resistivity shifts, correlating with key processes like soil displacement around burrows. Despite potential limitations, such as environmental noise and the influence of synthetic road plates used as protective coverings, ERT proved effective in detecting internal erosion patterns and pre-existing structural weaknesses. The results indicate that ERT offers a feasible, scalable approach, also for real-time levee monitoring in overflow scenarios, enhancing its applicability for validation of erosion models. Future studies should investigate the effect of cumulative damage during overflow testing and optimize forms of data presentation to improve interpretability, ultimately refining ERT’s potential as a reliable tool for predicting levee vulnerabilities.

Earth dams on complex geology without proper foundation treatment often face the risk of seepage problems. Sufficient installation and interpretation of field instruments are essential for monitoring dam behavior. Three indicators are introduced for assessment of seepage behavior: time lag (TL), pore pressure ratio (PR), and trigger water level (HW). The normalized TL reflects the washing out and plugging of rock cracks, as well as the progression of internal erosion. The foundation of the studied dam consisted of foliated rocks that were highly fractured, with the axis of the foliations aligned almost in the upstream-downstream direction, with a possible low-stress zone on the syncline axis. The existing crack easily opened in the concave section of the syncline when the reservoir had risen to a certain elevation, resulting in increased permeability and a higher flow to the downstream area, known as “hydraulic fracturing” (HF). The piezometer TL clearly indicated a shorter response time as the operating period progressed. The study dam showed the possibility of HF in the foundation, as observed during 2003–2024. The progression of HF was also confirmed by the increase in PR levels toward downstream. This revealed that the ongoing progression of HF had occurred at sta.2+700, which agreed well with the location of the slip zone that had occurred in 1993. HWwas activated by the reservoir water level response also decreasing with time from 2003 to 2024, confirming that water infiltration through the rock crack progressed with time. These three indicators could act as good warning indices for seepage problems. This compiled knowledge could be transformed into a flowchart to identify the possible risks of hydraulic fracturing in the dam. If the three indices all showed the same trend, the potential for hydraulic fracturing and internal erosion would be very high. Doi: 10.28991/CEJ-2025-011-03-019 Full Text: PDF

Research of erosion and buckling of pipe bends under gas-solid two-phase flow

To study the internal wall particle erosion corrosion behavior of domestic and imported nuclear power plant condenser titanium welded tubes, the paper dynamically simulated the cooling water system of a steam turbine condenser and subjected domestic and imported titanium welded tubes to artificially configured water quality and flow velocity. The experimental results of erosion corrosion showed that the domestic titanium welded tubes had excellent corrosion resistance in seawater, with a corrosion rate of only 0.001 to 0.002mm/a. By observing the changes in the weld seam and original titanium inner surface of the tubes before and after erosion using a scanning electron microscope, no obvious erosion marks were found on the surface, indicating that domestic titanium welded tubes can match the corrosion resistance of imported titanium welded tubes.

Effect of internal erosion on the hydraulic behavior of gap-graded coarse-fine mixtures: Experimental and mathematical investigations

Mechanisms and characteristics of sand seepage deformation under groundwater level fluctuation scenarios

Prediction of hydraulic gradient for backward erosion piping in river levees considering flow regime and pipe geometry

Characterizing the onset and development of internal erosion in gap-graded soils under complex stress states

ABSTRACTDuring the Covid‐19 crisis, there was a process of renovation of social dialogue that led to social pacts in Europe and, especially, in Spain. Following the neo‐corporatist literature, our argument is that these pacts have been based on the exceptional circumstances of social, political and economic factors that have led to concertation (as a process) rather than to a modification of the existing corporatist foundations. To understand the relevant features, we analyse the changes in the industrial relations system brought about by the labour reforms implemented during the Great Recession. Using data from the Collective Bargaining Agreement Statistics, we propose that the governance (coverage, dominance and control) of collective bargaining depended on a set of institutional practices that have been internally eroded. In conclusion, the effects of social dialogue are transitory, and further transformations would be necessary to achieve a permanent change that restores collective bargaining equilibrium.

This paper the flexural and compressive strengths of the reactive powder concrete (RPC) with steel scoria and quartz sand containing NaCl are investigated. Moreover, the RPC’s mass, the chloride ion permeability and the carbonation depth (Dc) are determined. The mass ratios of steel scoria and the NaCl are 0%~20% and 0%~0.25% by mass of binder materials and the quartz sand respectively. The RPC specimens are exposed to the NaCl erosion environment. The scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD) spectrum are acquired for analyzing the mechanism of RPC’s performance. Results show that the flexural strength, the compressive strengths, the mass and the dynamic modulus of elasticity (RDME) of RPC decrease in the form of cubic function with the mass ratio of NaCl. When the mass ratio of steel scoria is 10%, the mechanical strengths and the RDME are the highest. The RPC’s flexural strength, the compressive strength and the RDME decrease by rates of 4.94%~42.28%, 5.11%~48.65% and 8.72%~226.1% after NaCl erosion. Meanwhile, the corresponding mass loss rate, the chloride ion permeability, the Dc are increased by rates of 1.32%~27.63%. RPC with 10% steel scoria shows the lowest performance degradation. The SEM-EDS results show that the pores and cracks inner RPC and the Cl and Ca elements are increased by the NaCl. The Fe and Ca elements are increased by the added steel scoria. The addition of steel scoria exhibit decreasing effect and the added NaCl shows increasing effect on the Ca (OH)2 crystals respectively.

Unified assessment of mass loss behaviors in soluble, biodegradable, and internally erodible geomaterials

The focus in the present study is on the quantification soil erodibility properties (representing an erosion threshold (such as the critical shear stress) and a resistance property (e.g., the soil erosion coefficient)). These are necessary for an adequate assessment of soil erosion mechanisms affecting earth-made hydraulic structures (e.g., dams, dykes and levees). The paper gives a quantitative statistical analysis of the aforementioned soil erodibility parameters. To do so, a wide range of experimental tests, used for the study of internal erosion (hole erosion test (HET) and slot erosion test (SET)) and surface erosion (jet erosion test (JET), flume test (FT), erosion function apparatus (EFA), and rotating cylinder test (RCT)), were examined. A dataset of previously published experimental data was collected, harmonized, structured, treated, and used in a multicriteria analysis. The outcomes of the study provide a better understanding of the limitations and ambiguity in the assessment soil erodibility properties, highlight the differences among tests and between processes, and assess their inter-useability. Correlations between the erodibility properties themselves and between each of them and an in-study-defined midrange soil texture diameters were evaluated at specific level of erosion process, erosion test, and/or soil texture. Furthermore, a set of new empirical formulas has been proposed linking soil erodibility properties to themselves or each erodibility properties to the midrange soil texture diameter. A set of reference values and ranges and trends for the studied erodibility properties, useful for design or risk assessment purposes or for evaluating the quality of experimental data, are derived.

IntroductionThis study investigates the backward erosion piping mechanism and its dependency on model size through both experiments and numerical simulations. The objective is to understand how different model dimensions affect the hydraulic gradients and piping behavior in dike systems.MethodsNumerical simulations were performed using the finite element method (FEM), where the dike foundation was modeled in 3D and seepage flow was simulated under various hydraulic gradients. Physical experiments were also conducted using small-scale dike models to verify the numerical results and study the effects of model size.Results and DiscussionThe results show that in dikes without blanket layers, hydraulic gradients increase steadily as the piping channel develops, leading to upstream erosion and failure. In contrast, dikes with a blanket layer exhibit a stabilizing effect: the hydraulic gradient initially decreases before increasing, leading to a self-healing phenomenon that halts further channel progression. The study further reveals that the size effect—indicated by hydraulic gradients—diminishes with larger model dimensions and becomes negligible beyond a certain threshold. Additionally, the interaction between model width and depth significantly influences the progression of piping. These findings offer valuable insights for designing more resilient dike systems and improving flood protection strategies.

Early recognition of leakage flows within embankment dams, which may lead to internal erosion or deterioration, is a challenge to dam safety, particularly where the flow of water and its impacts do not appear on the surface. Recent research suggests that there is a critical seepage velocity at which soil particles will begin to move. Ground temperature measurements within a dam and its foundations can locate any leakage flow and provide a realistic estimate of the seepage velocities. Continuous monitoring of the temperatures can quickly identify any significant increases in the velocity, and provide early warning of potential disaster, thus allowing sufficient time for remedial action to be taken.

Impact of Geometric, Mechanical, and Hydraulic Factors on Internal Erosion in Embankment Dams

Abstract One of the main causes of failures in earth dams and embankments is internal erosion. This process initiates when seepage forces exceed the internal frictional resistance within soils. This paper investigates the effect of physical properties of soils that control failure due to internal erosion of soils such as plastic limit, cohesion and initial dry density. Three types of clayey soils with different properties were used in this research. Specimens were prepared to perform direct shear test and hole erosion test at different initial dry densities to find cohesion and internal erosion characteristics of soils. An effort was made to identify the relationship between engineering properties and internal erosion parameters of soil like critical shear stress and erosion rate index. Results show that increase in initial dry density and liquid limit of soil makes them less susceptible to erosion and increase the critical shear value. Moreover, equations were developed to predict both erosion rate index and critical shear based on the initial physical properties of the soils. The findings of this research will contribute in selecting the soils for dams and embankments and predict their behavior from proposed equations using simple geotechnical properties.

This study aims to explore the evolution laws of particle migration and the force chain networks during the process of levee piping erosion. The stability of the dam body under different working conditions of particle friction coefficient, fine content, and hydraulic gradient is analyzed. Sphericity is applied to characterize the shape of nonspherical particles, and the drag model is corrected. The applicability of the nonspherical particle resistance model is analyzed. The applicability of the corrected drag model is verified by combining indoor hydrostatic sedimentation tests and numerical simulations. A numerical model of nonspherical particle piping erosion is established by using the coupled DEM‐CFD analysis platform. Using the corrected resistance model, permeability simulations are conducted for different working conditions. The particle migration laws are explored in terms of particle loss, flow field distribution, and porosity. Information such as the number of contact forces, distribution direction, and fine material stress‐bearing ratio is statistically analyzed from the mesoscopic scale, revealing the influence of force chain network evolution on seepage stability. This study reveals the mechanism of levee piping erosion and has important guiding significance and practical application value for filler design and levee erosion protection.

ABSTRACT One of the most important causes of the failure of a clay core rockfill dam (CCRD) is seepage failure caused by defects inside the clay core (e.g. a high permeability zone, HPZ for short). This study conducted a seepage stability analysis of the Pubugou CCRD with an HPZ, considering the uncertainty of dam parameters, including hydraulic conductivities, water level, and height of the HPZ. The reliability analysis methodology, both with and without the monitoring information, was first introduced. By inputting multi-source monitoring data, the probabilities of both the seepage failure and the dam parameters can be updated. The results show that the large monitoring values on 1 December 2010 have incurred an increase in the failure probability from 3.28 × 10−5 to 8.47 × 10−5, which was mainly caused by the increase of the hydraulic conductivity of the clay core (k 1). The failure probability then decreased from 8.47 × 10−5 to 7.46 × 10−6 when smaller monitoring values on 6 September 2011 were input. The maximum probability interval of the k 1 decreased from greater than 1.48 × 10−7 to between 4.18 × 10−8 and 7.86 × 10−8 due to long-term consolidation. However, the hydraulic conductivity of HPZ (k 2) slightly increased because of possible internal erosion caused by long-time seepage in HPZ.