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The reconstruction of the porous media model is crucial for researching the mesoscopic seepage characteristics of porous concrete. Based on a self-compiled MATLAB program, a porous concrete model was modeled by controlling four parameters (distribution probability, growth probability, probability density, and porosity) with clear physical meanings using a quartet structure generation set (QSGS) along with the lattice Boltzmann method (LBM) to investigate permeability. The rationality of the numerical model was verified through Poiseuille flow theory. The results showed that the QSGS model exhibited varied pore shapes and disordered distributions, resembling real porous concrete. Seepage velocity distribution showed higher values in larger pores, with flow rates reaching up to 0.012 lattice point velocity. The permeability–porosity relationship demonstrated high linearity (the Pearson correlation coefficient is 0.92), consistent with real porous concrete behavior. The integration of QSGS-LBM represents a novel approach, and the research results can provide new ideas and new means for subsequent research on the permeability of porous concrete or similar porous medium materials. [ABSTRACT FROM AUTHOR]

During an oscillation cycle of the mold, the fluid flow, heat transfer, and solidification behavior within the meniscus region control the slag infiltration, lubrication, and formation of oscillation marks, which are of great significance to the smooth running of continuous casting and the surface quality of slab. A comprehensive two-dimensional (2D) transient thermal-fluid model has been developed to study the fluid flow, heat transfer, dynamic shape of steel/slag interface, as well as the growth of shell in the meniscus region during an oscillation cycle. In addition, calculations of slag consumption were performed, and the results were consistent with previous research, thereby the reliability of the model is validated. During an oscillation cycle, the upstroke and downstroke cause the meniscus profile to bulge and collapse, which dominates the increase and decrease of heat flux in the Eulerian reference frame reference frame. However, the variation of heat flux in the Lagrangian reference frame is determined by the instantaneous position. The freezing and overflow behaviors of the meniscus are the primary factors contributing to the formation of oscillation marks, and the final profile of oscillation marks is determined by the two freezing events of the meniscus within an oscillation cycle. The positive slag consumption primarily occurs during the negative strip time (NST), while there is also positive slag consumption during certain periods of positive strip time (PST), which is closer to the motion state of the mold. This research contributes to explaining and understanding the formation mechanism of surface defects and issues of continuous casting strands, aiming to facilitate the improvement of related problems. [ABSTRACT FROM AUTHOR]

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According to statistics, 80% of failed components in mechanical equipment are caused by various types of wear and corrosion. Therefore, in order to reduce material loss, research on wear-resistant materials is urgent. In order to solve the difficulty of directly observing the infiltration process of liquid metal in preform, this study first conducted infiltration experiments on liquid metal in ZTA ceramic particle preform at different pouring temperatures, and then used Fluent software to numerically simulate the infiltration behavior of liquid metal in preform. By changing parameters such as pouring temperature and infiltration pressure, the influence of these parameters on the penetration depth of liquid metal in prefabricated structures was determined. The research results indicate that when the pouring temperatures are 1420 °C, 1570 °C, 1720 °C, and 1870 °C, the infiltration depths are 4 mm, 8 mm, 11 mm, and 15 mm; when the casting infiltration pressures are 7620 Pa, 15,240 Pa, 22,860 Pa, and 30,480 Pa, the infiltration depths are 10 mm, 16 mm, 20 mm, and 22 mm. The simulation results of the pouring temperature on the infiltration depth are basically consistent with the experimental results. [ABSTRACT FROM AUTHOR]

Coalbeds are subject to diverse load conditions stemming from hydraulic fracturing, mining activities, and geological tectonic forces. Understanding how coalbed permeability evolves under various stress conditions—such as effective stress, peak stress, axial deviatoric stress, and stress cycling—is crucial for optimizing coalbed methane flow dynamics. In this study, coal sample permeability evolution was assessed using the steady-state method under various loading paths. The study revealed insights into the impact of irreversible deformation induced by different axial deviatoric stresses on coal permeability. Our results indicate that confining pressure has a greater impact on axial permeability than axial stress does. Initial stress cycles involving confining pressure notably reduce coal permeability, an effect that is less pronounced in subsequent cycles. Different levels of axial deviatoric stress have varied consequences for coal fractures. Specifically, high axial deviatoric stress conditions promote fracture propagation, thereby enhancing coal seam permeability. Conversely, under low axial deviatoric stress, the cyclical application of axial and confining pressures results in coal compaction and fracture closure, leading to a decrease in permeability after unloading. To visualize microcrack development and propagation in coal under differing axial deviatoric stress conditions, we integrated the discrete element method with the Mohr–Coulomb model in a particle flow program. The findings from our triaxial seepage experiments corroborate well with this computational model, providing a robust validation and deeper insight into the observed permeability changes. [ABSTRACT FROM AUTHOR]

Due to their high porosity and permeability characteristics, reservoirs of loose sandstone have great development potential. Under weak dynamic conditions, the vertical migration and mass exchange of oil–water two-phase fluids in loose sandstone reservoirs occur very easily. The phenomenon of vertical seepage flow equilibrium has a significant impact on the distribution of oil–water two-phase fluids in the reservoir. However, existing mainstream numerical simulators cannot accurately describe the phenomenon of vertical migration of oil–water two-phase fluids under weak dynamic conditions. In this study, using 3D printing technology, multiple transparent rock core holders were constructed to conduct experiments on the vertical seepage flow equilibrium time of different viscosities and contents of crude oil under different permeabilities of rock cores. Through the analysis and regression of experimental results, a predictive formula for the vertical seepage flow equilibrium time of loose sandstone reservoirs was established. Based on the time-prediction discriminant formula, a multi-scale numerical simulation method for vertical seepage flow equilibrium was constructed. A comparison between the new method and experimental results showed that the numerical simulation method, considering vertical seepage flow equilibrium, is closer to experimental phenomena than traditional numerical simulation methods. This indicates that the method can more accurately reveal the characteristics and distribution laws of the vertical seepage flow of oil–water two-phase fluids in loose sandstone reservoirs. [ABSTRACT FROM AUTHOR]

Fracture and stress environments significantly affect the flow of coalbed methane. Under stress, fracture deformation and damage occur, which change the original fracture characteristics and lead to changes in gas flow characteristics. The change in gas pressure gradient makes the fluid flow obviously nonlinear. Using linear flow theory to describe the fracture flow leads to a large error in predicting coalbed methane productivity. In this study, seepage tests on fractured coal are carried out under different stresses and gas pressure gradients, the nonlinear flow and changes in related parameters are analyzed, and the applicability of the nonlinear flow equation is evaluated. The resulting seepage of the gas flow in the fracture under stress is obviously nonlinear, which gradually increases with increasing effective stress and gas pressure gradient. When the Forchheimer equation is used to characterize the nonlinear seepage in fractures, the coefficients increase with increasing effective stress. The permeability, nonlinear factor, and critical Reynolds number decrease with increasing effective stress. When the Izbash equation is used for this case, the linear coefficient ranges from 1015 to 1016, and the nonlinear coefficient ranges from 1.064 to 1.795. The coefficients are related to the effective stress through a power function. Both the Forchheimer and Izbash equations can characterize the flow in rough fractures in coal during stress loading. However, the Forchheimer equation better reveals the mechanism of flow transformation from linear to nonlinear in fractures. [ABSTRACT FROM AUTHOR]

Subtle bedrock depressions called gnammas allow the water in ephemeral pools to maintain contact with bare rock, thus serving as natural rock‐weathering experiments. Following filling by precipitation, evaporation is often assumed to be the sole process of water loss from gnammas. We evaluated this assumption by monitoring evolving stable isotope compositions of gnamma waters hosted in granite of Colorado's Front Range. Surprisingly, we found that a significant fraction of the water was lost by seepage through the underlying bedrock. Seepage dominated, with only 10%–20% loss by evaporation. We propose a conceptual model of gnamma formation in which enhanced weathering of the bedrock beneath the gnamma increases the water holding capacity and permeability of the underlying rock that in turn promotes efficient water loss through seepage and further weathering of the surrounding rock. This model has implications for bare‐rock weathering and hence the evolution of landscapes over geologic timescales. Plain Language Summary: Rates and styles of rock weathering influence the evolution of soil, landforms, and climate over geologic timescales. Gnammas are depressions in solid bedrock that periodically fill with rainwater or snowmelt to form ephemeral pools that can provide critical but temporary water sources in arid, bare‐rock surface environments. In contrast to previous assumptions that gnamma water is lost solely by evaporation, our work shows that a significant fraction of the water can be lost by seepage into the underlying rock. These findings suggest a feedback between enhanced seepage into underlying bedrock and enhanced degradation of the surrounding rock that potentially explains the growth and persistence of these unique isolated ecosystems, and informs debates about the role of bare bedrock weathering in landscape evolution. Key Points: Water stable isotopes constrain the hydrologic evolution of gnammasGnammas lose water via seepage through the underlying bedrock, not only by evaporationSeepage may drive a feedback process that enhances bedrock weathering but limits gnamma size evolution [ABSTRACT FROM AUTHOR]

Layered rock slope exists widely. Because of its special slope structure, it is prone to bending deformation and toppling failure, which is a serious threat to engineering construction and safety operation. At present, the research of layered rock slope still has great innovation potential. During the construction of Wudongde Hydropower Station on Jinsha River, safety and stability problems such as slope geological structure development, face rock unloading and relaxation, and even slip and large deformation were encountered. Through field exploration, it is found that the rock and soil stratification of the slope on both sides of Wudongde Hydropower Station is highly obvious. At present, there is a lack of research on-site long-term displacement monitoring of layered rock high-steep slope, especially for layered slope in complex hydrogeology and construction environment. In order to strengthen the research on the deformation and stability of layered rock slope, this paper analyzes the measured displacement data of Wudongde hydropower station slope, and establishes three-dimensional geological finite element model with the help of numerical simulation software. The stability of the slope is calculated by combining the finite difference method and the strength reduction method. Finally, the evolution mechanism of the deformation of the layered rock slope is explained according to the geological structure characteristics. The main conclusions of this paper are as follows: the layered slope in the dam reservoir area is prone to deformation under the combined action of long-term construction disturbance and fissure water seepage, and the construction disturbance has a strong influence on the artificial excavation area below 1070 m, and the maximum rock mass deformation and surface displacement in the artificial excavation area of the slope reach 92.2 mm and 312.5 mm, respectively. However, the influence of construction disturbance on the natural mountain above 1070 m is limited, the valley deformation of the natural mountain on the left bank of the reservoir area is higher than that on the right bank, and the cumulative deformation is still less than 20 mm. The influence of seepage on the displacement of the area with higher elevation at the top of the slope is more obvious, and the influence of excavation and other disturbances on the displacement of the artificial excavation area with lower elevation is more obvious. The deformation of the river valley in the water cushion pond behind the dam increases slowly, and the change trend of the field deformation data is mostly consistent with that of the numerical calculation. The horizontal shrinkage of the mountains on both sides shows a contraction trend on the whole, and the maximum horizontal shrinkage calculated by numerical simulation is close to 20 mm, which is located at the elevation of 990 m. [ABSTRACT FROM AUTHOR]

Introduction: Despite various efforts to reduce nitrogen leaching from agricultural land, the permissible nitrate concentrations in groundwater have often been exceeded in the past. Intensive farming is often seen as the cause of the deterioration in water quality. Therefore, the present lysimeter study aimed to quantify nitrogen (N) leaching at different N fertilization levels for the agricultural land use systems of arable land and grassland to derive suitable management measures for improving groundwater quality. Methods: The effects of three different of mineral fertilization treatments (50%, 100%, and 150%) in arable land and grassland use on four distinct soil types (loamy sand, sand, loam, loess) concerning seepage formation, nitrogen concentrations, nitrogen loads, drymatter yields and nitrogen balances were tested. The study was conducted at the lysimeter facility of the Helmholtz Centre of Environmental Research - UFZ at Falkenberg (northeast Germany). Twenty-four non-weighable lysimeters with a surface area of 1 m² and a depth of 1.25 m were managed as grassland and arable land with three different fertilization treatments since 1985. Results and Discussion: For arable land use, N leaching differed between the studied soil types, with the highest N loads from the sand (36.6 kg ha-1 yr-1) and loamy sand (30.7 kg ha-1 yr-1) and the lowest N loads fromloess (12.1 kg ha-1 yr-1) and loam soil (13.1 kg ha-1 yr-1). In contrast to grassland use, a reduction of N fertilization level by 50 % did not result in reduced N leaching for arable land, whereas a maximal 29% reduced dry matter yields was observed. An increase of N fertilization by 50 % did not cause significant enhanced N leaching at arable land use. Soil-and management-related factors (soil type, texture, soil tillage, crop rotation, and others)mask the effect of increased N fertilization rates in arable land using lysimeters. For arable land use, a reduction of N fertilizer levels as the only measure was insufficient to reduce NO3- leaching, and other strategies besides N fertilization levels are required to improve groundwater quality. Measures should be targeted to reduce N losses by mineralization processes. [ABSTRACT FROM AUTHOR]

Without destroying the structure, the acoustic emission (AE) monitoring technology was used to explore the motion law of gap grading particle media at different flow rates, and to reveal the characteristic law of acoustic emission signals in the process of pore seepage. The analysis was carried out by combining the acoustic emission signal generated by the displacement of the small particle medium during the seepage process with the PIV technique. The results show that; when the number of small-particle media is constant, the experimental group with higher flow velocity has more AE events, that is, the ringing count is larger and the spectrum center of gravity is higher, when the water flow rate is similar, the content of small-particle media in the experiment directly affects the number of AE events. That is, the experimental group with larger sand content has more AE events; in the case of medium with small particles, the larger the water flow rate, the faster the particle movement speed and the greater the initial signal intensity of AE. The above studies show that the acoustic emission detection techn ology can better reflect the movement of granular media in pore seepage, and provide a certain research basis for small particle transport monitoring and dam piping early warning in the process of pore media seepage. [ABSTRACT FROM AUTHOR]

To solve the technical problems of safe and efficient exploitation of coal resources by abandoned oil wells in the Ordos Basin, several characteristics of the coal seam need to be fully explored: petroleum seepage pressure, seepage velocity and seepage range. However, these are difficult to determine in situ, and often numerical models are used. A comprehensive analysis method combining COMSOL Multiphysics numerical software and seepage model is proposed here based on the continuous non-linear theory of seepage flow and the constructed seepage channel model of different pores and fissure coal samples. The characteristic parameters are determined by on-site measurement to verify the accuracy of the proposed analysis method. The results show that the characteristic parameters of each seepage flow studied differ from those measured in the field; however, the difference is small. The seepage pressure in time and space can more accurately describe the changes in the tensile parameters. The spatial dimension seepage pressures forms three-stage distribution along the radial direction. The maximum seepage velocity is about 16 m/month, and the radial seepage range is 221 ∼ 235 m. The comprehensive analysis method based on the new seepage model quantitatively reflects the changes in seepage characteristic parameters and enhances the methods of seepage research. [ABSTRACT FROM AUTHOR]

Tsunamis are a significant coastal hazard that pressurise sediment pore water, which can potentially induce liquefaction, enhance erosion and scour, and undermine the stability of beach sediments supporting natural and built infrastructure in the coastal nearshore environment. Tsunami-induced pressurisation of pore water is attributed to (a) mechanical pressurisation associated with the soil skeleton's tendency to contract or expand around the soil's pore fluid under the changing overlying water weight and (b) seepage of tsunami water into and out of the sand bed. The pore fluid compressibility, which is influenced by air entrainment due to water table fluctuations caused by the tides, can significantly influence development of stabilising and destabilising hydraulic gradients during tsunami runup and drawdown, respectively. Previous work has effectively assumed a constant air content in sand beds and neglected (a) the compression and dissolution of entrained air that influences the pore fluid compressibility and (b) the interaction between saturated sediment underlying sediment with entrained air. By considering the gas kinetics influencing the pore fluid compressibility in a seepage–deformation model, the effect of different pore fluid compressibility assumptions, thickness of sediment with entrained air, initial degree of saturation and tsunami wave properties (height and duration) were studied. The thickness of sediment containing entrained air, the assumed pore fluid compressibility assumption and subtle differences in the initial degree of saturation can significantly influence the predicted maximum depth and duration of tsunami-induced liquefaction. [ABSTRACT FROM AUTHOR]

Tailings from Agnico Eagle's Goldex mine are stored in a tailings pond built in 2007. Used only as a secondary pond since its construction, it will eventually be used as the main facility, which could entail hydrogeological changes in the tailings and surrounding aquifers. To ensure the protection of groundwater during future mine operations, further site characterization and numerical modelling was undertaken to better understand the current hydrogeological system. Detailed new field work was recently completed and a 2D vertical-plane numerical model along the main flow direction of the tailings site was built with the SEEP/W code to simulate the local-scale steady-state flow system. Although piezometric levels were accurately simulated throughout most of the deposition area, the simulated piezometric levels near the dikes were consistently lower than those observed. A sensitivity analysis on hydraulic conductivities and recharge highlighted the importance of relatively lower hydraulic conductivities in maintaining the watertable as high as possible near the dikes, without overflow in the center of the deposition area. This study improved understanding of the hydrogeological behavior of mine tailings at an active site using modelling to better predict the potential impacts on the local groundwater flow system. [ABSTRACT FROM AUTHOR]

An approximate solution that can predict phreatic line through similarity transformation by directly using second-order nonlinear partial differential equations, which is used for one-dimensional unsteady seepage flow analysis is proposed. The proposed approximate solution, derived using similarity transformation, confirms the change of the phreatic line over time in the earthen dam. To evaluate the applicability of the approximate solution, the prediction of the phreatic line using similarity transformation is then compared with that of conventional methods by Kozney, Casagrande, and Schaffernak-Iterson, as well as with numerical and experimental test results. It is noted that the approximate solution can predict the phreatic line reasonably well in homogeneous earthen dams. [ABSTRACT FROM AUTHOR]

Managing the levee system of a river network is an essential aspect to reduce the flood risk and protect communities and urbanised areas. Too many times, the viewpoint of the managing institution in charge of the restoration of river levees is of an emergency type so that the restoration works are conducted only after flood occurrence, without the consideration for a complete and necessary overview of priority criteria at a basin scale. The present work aims to develop a basin-scale methodology to analyse the current state of the Ombrone Pistoiese River (Italy) levees, so as to identify targeted solutions for breakage prevention. By applying a vulnerability index, producing maps of flooded areas and counting the exposed elements induced by levees breaks, this study wants to provide a decision support procedure able to define a priority scale of interventions. [ABSTRACT FROM AUTHOR]

Due to the characteristics of geographical environment and many complicated factors, the seepage properties of calcareous sand are quite different from those of common continental and marine sediments. To investigate the change of permeability coefficient of calcareous sand under external load, a seepage test device equipped with an impact loading system was developed. The effects of particle size distribution, initial relative density and impact load on the permeability of calcareous sand were investigated with this device. The results showed that the larger the curvature coefficient and uniformity coefficient, the smaller the initial relative density lead to the greater the permeability coefficient of calcareous sand and the more obvious the change of permeability coefficient before and after loading. The permeability change of calcareous sand under impact load was greater than that of quartz sand. [ABSTRACT FROM AUTHOR]

The fluid flow in the crack is disturbed by the contact area. The parallel-plate model with a circular cylindrical contact area is regarded as an idealization of the real contact fracture, and a computational fluid dynamics simulation is performed on it to analyze the interaction between the contact area and the flow around it. The size of the contact area controls the disturbance intensity to the flow velocity magnitude and the disturbance range to the velocity direction. Due to the existence of viscosity, the flow near the wall has a larger shear rate. The intermediate transition region is located between the contact area and the fracture lateral wall and does not contain the region with strong viscous friction caused by the wall. The flow velocity magnitude in the intermediate transition zone changes exponentially in space and has a peak value near the contact area. After the flow bypasses the contact area, the inertial effect caused by the increase in flow velocity magnitude in the local flow channel controls the generation and development of the low-velocity region and the asymmetric degree of the velocity direction distribution. Both the mechanical aperture and the inlet flow velocity affect the stress distribution on the surface of the contact area. The occurrence of the nonlinear flow behavior of fracture seepage and nonlinear change trend of logarithmic drag coefficient curve can be predicted with the same critical Reynolds number. These results provide a useful guide for further exploring the local flow and the surface stress distribution of the local interior geometric property in a single rough-walled fracture on the mesoscopic scale. [ABSTRACT FROM AUTHOR]

A clear understanding of the dependence of the heat transfer process on the flow field in three‐dimensional (3D) rough fractures is crucial for many underground projects. In this study, 3D rough rock fractures with heterogeneous apertures and mechanical effects are established. Navier‐Stokes flow and local heat balance theory are used to simulate the seepage‐heat transfer coupling process. Five normal stresses and five flow velocities are set to quantify the influence of aperture variability on the flow field and heat transfer behavior of the fractures. The results show that the change in fracture aperture caused by normal stress is the direct cause of the nonlinear distribution of the flow field and temperature fluctuation. A quantitative parameter of temperature fluctuation degree in the fracture is proposed, which decreases exponentially with increasing fracture aperture and increases with greater flow velocity. An empirical model is established to describe the relationship between the heat transfer coefficient and the ratio of hydraulic aperture to mechanical aperture. The correctness of the model is verified by published seepage‐heat transfer coupling test results. The model is extended to establish the relationship between the heat transfer coefficient and the volume fraction of eddy. It is confirmed that the heat transfer coefficient increases with the augmentation of nonlinear flow, and the reason why the results of evaluating the heat transfer coefficient by roughness alone in related experiments are inconsistent is revealed. The results enhance the understanding of convective heat transfer characteristics in 3D rough rock fractures. [ABSTRACT FROM AUTHOR]

Seepage failure is a common problem in engineering, and the calculation and analysis of critical hydraulic gradient are of great significance for the safety and protection of engineering. Based on the principle of discrete element method and computational fluid dynamics, the fluid–solid coupled models were established to study the critical hydraulic gradient and particle loss rate of granular soils at seepage failure. The evolution of seepage failure was divided into four stages: seepage development stage, local damage stage, volume expansion stage and overall damage stage. The validity of numerical simulation was demonstrated by comparing the critical hydraulic gradient obtained by numerical simulation and by Terzaghi's formula. According to the fabric damage and flow velocity variation of the models at seepage failure, the influences of model size and particle size on the critical hydraulic gradient and particle loss rate were analyzed. The results indicate that critical hydraulic gradient and particle loss rate were not sensitive to changes in model size. A wide particle size distribution range resulted in large critical hydraulic gradient and small particle loss rate at seepage failure. The discrete element numerical simulation can not only be used to determine the critical hydraulic gradient of geotechnical and hydraulic engineering, but also offer a visual portrayal of the evolution of seepage failure, serving as an important complement to comprehend the intricate microscopic mechanisms underlying soil seepage failure. [ABSTRACT FROM AUTHOR]

The local pore water velocity along the preferential flow path signifies the hydraulic parameter responsible for erosion within an earthen dam. This study introduces an empirical approach to ascertain the local pore water velocity within the earth dam's leakage zones by monitoring the travel time of the salt tracer through the corresponding electric potential anomalies in the ground. The alignment of electric potential anomalies with the movement of the salt tracer plume over time was confirmed through experiments on a physical model coupled with numerical simulations. The pore water velocity, calculated based on the location of the maximum electric potential anomaly, demonstrated excellent agreement with the experimental value, with an error of under 6%. For illustrative purposes, a field-scale salt tracer test was conducted at a leaking earthen dam in Vietnam. The tracer breakthrough curve originating from the leakage point revealed that the seepage water's travel time is approximately 40 days. The results of electric potential anomalies over time indicate that the pathway of seepage flow from upstream to the leakage point forms a horizontal V-shape, with the local pore water velocity ranging from 1.7 to 9.9x10-5 m/s. These local pore water velocities are subsequently compared with the critical seepage velocity to assess in-situ information regarding the internal erosion status of the target dam. [ABSTRACT FROM AUTHOR]

The non‐Darcy flow behavior in unfilled and fully filled rough fractures has been investigated thoroughly for decades. Natural fractures usually be partially filled with porous media due to long‐term internal and external dynamic disturbances and water flow erosion. However, how to evaluate the nonlinear seepage characteristics of the partially filled rough fracture (PFRF) is never scrutinized. In the present study, 2D direct numerical simulations are conducted to investigate the non‐Darcy behavior for flow through 6 PFRF models under different filling conditions (i.e., filling degree, roughness, and hydraulic conductivity capability of the filling medium), which included coupling between the free and seepage flow in the unfilled and filled region, respectively. The results show that the critical non‐Darcy factor E = 0.02 can be used to judge the onset of the non‐Darcy regime in PFRF, which is also the critical point of eddy region (ER) volume mutation. The higher the filling degree and the weaker the hydraulic conductivity of the filled medium, the more significant the non‐Darcy behavior. Furthermore, the variation of ER volume can be divided into three stages with the increasing inertia effect, that is, stable stage (E < 0.02), slow nonlinear growth stage (0.02 ≤ E ≤ 0.1), and rapid linear growth stage (E > 0.1). In addition, a new model for quantitatively evaluating the non‐Darcy behavior of PFRF is developed via gene expression programming based on 735 simulation data set, which is further employed to establish the relationship between the friction factor. Plain Language Summary: The nonlinear flow behavior in partially filled rough fractures (PFRF) was investigated by using 2D simulations. The simulation results revealed a critical non‐Darcy factor of 0.02 to determine the onset of non‐Darcy behavior in PFRF. Higher filling degrees and weaker hydraulic conductivity of filling region intensified the non‐Darcy effect. The volume of eddy regions exhibited three stages of variation with increasing inertia effect (i.e., stable stage, slow nonlinear growth stage, and rapid linear growth stage). We developed a new model based on gene expression programming to quantitatively evaluate PFRF's non‐Darcy behavior. This study enhances the understanding of fluid flow in partially filled rough fractures, benefiting for advancing the understanding of nonlinear seepage and solute transport in partially filled rough fractures. Key Points: Critical non‐Darcy factor E = 0.02 can be used to determine the onset of the non‐Darcy regimeVolume evolution of eddy region can be classified into stable, slow nonlinear growth, and rapid linear growth stagesA nonlinear seepage model is developed for partially filled rough fractures [ABSTRACT FROM AUTHOR]

The present study proposes an analytical solution to a linearized Boussinesq equation considering unsteady downslope river stage, spatio-temporal rainfall recharge, and bedrock seepage. This analytical solution alleviates the limitations of the previous studies like varying river boundary, leaky aquifer bed, and non-uniform recharge simultaneously. The time-dependent river stage depicts the seasonal water level variation in the river, whereas the leakage from the confined to the unconfined aquifer or vice versa represents the bedrock seepage. The analytical expression is derived using the separation of variable method along with a variable transformation technique. The proposed solution is validated using nonlinear numerical and linearized analytical solution. The study highlights that the aquifers with higher bedrock conductivity tend to have a higher inflow rate to the aquifer from the river during monsoon season and a higher outflow rate to the river from the aquifer in the lean period. The analysis also illustrates that for a relatively flat catchment area, with the rise of the water level in the river, there is a reverse flow from the river to the aquifer. Further, the stream stage variation rate is found to be pivotal in deciding the duration of flow direction alteration and volume of water released from the aquifer. Furthermore, a sensitivity analysis is performed to assess the influence of flow parameters on the discharge function. The discharge is found to be positively sensitive to hydraulic conductivity, aquifer slope, and recharge. Finally, the residence time distributions corresponding to various bedrock seepage conditions are examined. Results indicate that the residence time for the various conditions tends to exhibit the heavy-tailed distributions. [ABSTRACT FROM AUTHOR]

The study focuses on the changes in seepage and stability of the dam with a clay core constructed with expansive soils. Heave potential of the expansive clay core was also evaluated in the study. Laboratory testing was conducted to evaluate the swelling potential and hydraulic properties for the compacted expansive soils under various dry unit weights and initial water contents. Numerical modeling was conducted to evaluate the changes in seepage flow and slope stability due to the heaving of the expansive clay core for the dam. The findings suggest that to reduce seepage flow, the swelling soil should be compacted to a lower degree of compaction at a moisture content exceeding the optimum moisture content (OMC), which effectively reduces soil swelling and consequently minimizes seepage. Conversely, if stability is the primary concern, the swelling soil should be compacted to a relatively higher degree of compaction at a moisture content lower than the OMC, providing enhanced strength to the dam. In conclusion, the study demonstrates that for expansive soil used in dam cores, the same traditional compaction conditions utilized for seepage and stability in normal clayey soil can be applied. However, it is crucial to consider the specific characteristics of the swelling soil during the compaction process. By implementing suitable compaction techniques based on the desired outcome, seepage control, and dam stability can be effectively managed when utilizing swelling soil in dam construction. The findings offer valuable insights to engineers and practitioners involved in dam design and construction, aiding in informed decision-making and optimal compaction practices when incorporating swelling soils in dam cores. [ABSTRACT FROM AUTHOR]

To study creep failure behaviors of jointed rock mass with seepage pressure as the main damage driving force, creep tests under multi-level loading of seepage pressure were conducted on sandstone with different joint dip angles. In addition, a memory-dependent nonlinear seepage–creep model was established for jointed sandstone. The results show that jointed sandstone experiences three creep stages (initial, steady-state, and accelerated creep stages) in creep tests under multi-level loading paths of seepage pressure. Jointed sandstone with joint dip angles of 30° and 60° undergoes shear failure, while that with the joint dip angle of 45° is subject to tensile–shear failure. Under the same seepage pressure, the sandstone with the joint dip angle of 45° has a greater creep rate in the steady-state creep stage than that with joint dip angles of 30° and 60°. In the volumetric compression stage, the permeability increases at the instant of applying each level of seepage pressure, followed by gradual reduction and stabilization of permeability. In the volumetric dilation stage, the permeability gradually rises. The theory of memory-dependent derivative reflecting the time memory effect was introduced to establish the memory-dependent nonlinear viscoelastic–plastic seepage–creep model for jointed sandstone. The results obtained using the theoretical model conform to the test data. Moreover, the creep failure criterion of the rock was proposed. The creep acceleration starts to increase from 0 and the critical steady state transitions to a non-steady state, suggesting that the rock will soon be damaged. The calculation formula for critical time corresponding to the critical steady state of creep was also deduced. The critical time to onset of creep can serve as an early warning of the creep failure of rocks. [ABSTRACT FROM AUTHOR]

The governing differential equations about the seepage were resolved using the standard numerical. The research location was on the Darbandikhan dam, which is about 230 kilometres northeast of the governorate of Baghdad in the district of Sulaymaniyah on the Diyala River. The Geo-Studio program and its subprogram SEEP/W were used to examine the total water head through the dam and water flux, and exit gradient through the numerical model that represents the dam body to show how seepage affects the dam's stability. To run the dam numerical model, three upstream reservoir water levels at a Minimum water level of 434 m, Normal water level of 472 m, and flood water level of 485 m were selected to represent the model boundary conditions. Maximum total water head through the dam was found when the water level in the reservoir was 485 m while the maximum water flux through the dam was found when the water level in the reservoir was 472 m. It was found the dam safety was ensured for all tested reservoir water levels.

Due to tectonic uplift in the Cenozoic and numerous shelf-wide glaciations during the Quaternary, ∼1–2.5 km of sedimentary overburden has been eroded from the Barents Sea shelf, leading to the exhumation and partial uncapping of hydrocarbon accumulations. Widespread natural gas and oil leakage from the glacially eroded middle-upper Triassic reservoir directly into the water column has been documented at the Sentralbanken high in the northern Norwegian Barents Sea. However, it remains unclear whether the hydrocarbon leakage occurs only from the middle-upper Triassic reservoir units in geological settings exceptionally conducive to hydrocarbon leakage, or if other reservoir formations contributed to the release of hydrocarbons into the water column. It is also not clear whether complete erosion of the caprock is a prerequisite for widespread liberation of natural gas and oil from glacially eroded reservoirs across Arctic continental shelves. Here we analyze multibeam echosounder data covering ∼5,000 km2 and a suite of high-resolution P-cable seismic lines from a range of geological structures across the northern Norwegian Barents Sea. Our analyses reveal that ∼21,700 natural gas seeps originate from exhumed, faulted and variably eroded structural highs bearing a range of Mesozoic reservoir formations. All investigated structural highs fuel seabed methane release hotspots with no exception. Evident from observations of seismic anomalies, fluid accumulations are pervasive in the subsurface and likely to continue fuelling seabed gas seepage into the future. We also document that gas seepage through faults piercing overburden, caprocks and reaching potential reservoir levels is pervasive at all investigated structural highs. On the Storbanken high and the Kong Karl platform, such fault-controlled seepage is more prevalent than seepage from reservoir formations subcropping below the seafloor. Using a simple parametrization approach, we estimate that seeps identified within our multibeam data coverage produce a seabed methane flux of 61 x 107 mol/yr (9,803 ton/yr), which is one to two orders of magnitude higher than other globally known submarine methane seepage provinces. Fluxes of methane from sea water to the air above the thermogenic gas seep provinces in the northern Norwegian Barents Sea remain to be determined.

Dams are mega structures that retain huge volumes of water and their safety is important to national security, economy, and public interest. In this study, the types of regular measurements with their recorded value for Haditha Dam were checked for compliance with the standard international surveillance and monitoring procedures such as the procedures of the International Commission on Large Dams (ICOLD), the United States Bureau of Reclamation (USBR)and other to ensure safe dam operation and to avoid the scenario of the Derna Dam break, in Libya that occurred in September 2023. The result shows that the highest recorded settlement was found at station 41 on the left side of the dam body exceeding the design criteria (219 mm) by about 51 %, the frequency of measurement does not comply with the required international standards. There are 7 cells of pore pressure that exceeded the design criteria and the greatest percentage of exceedance was 21.57 % was found at pore pressure number 995. For piezometer reading, the percentage exceedance was 9.1% and it was found on the left side at piezometers number 58-8. The highest percentage of movement 62 % was found at join meter device number D18. The recorded seepage rate through the dam was found within the permitted limits. The visual inspection followed at Haditha Dam was not according to the standard required inspection.

Introduction. In the current climate change conditions, the protection of irrigation structures, especially dams, is a very important task. Seepage is one of the main causes of dam failure, so it is very important to investigate the seepage regimes and find solutions to prevent dam failures as a result of the seepage processes in earth dams. In this paper, the analysis of the seepage regimes in the body of earth dams is performed by means of mathematical modelling using numerical finite element models. A homogeneous earth dam with an imperfect diaphragm on an impermeable foundation is taken as the object of study. The purpose of the study is to determine the influence of relative parameters: diaphragm height, diaphragm location in the dam body, their number. In addition, the influence of diaphragm parameters on the seepage flow through the dam body and its velocity is analyzed.Materials and methods. The study was carried out with the help of numerical modelling using PLAXIS 2D software. The model of the dam is based on typical design solutions used in practice.Results. The results of the study show that the placement of the diaphragm in the dam body reduces the seepage flow through the dam and the height of the diaphragm is inversely proportional to the seepage rate. The maximum seepage rate was recorded at the upper end of the diaphragm and its magnitude is directly proportional to the height of the diaphragm. When the diaphragm is displaced towards the downstream side, the filtration rate slightly decreases. The value of maximum velocity increases when the diaphragm is displaced towards the downstream end.Conclusions. Dam failure due to seepage can result in serious property damage and loss of life. Implementing methods that reduce seepage discharge and seepage velocities is important to ensure safe dam operating conditions

As a country with a rich cultural and historical heritage, there are many grottoes in China. Unfortunately, many grottoes suffer from fracture seepage due to their age, causing weathering damage that requires prompt attention, detection, and repair to preserve them for future generations. In order to preserve the historical and cultural heritage of Beishan, Chongqing, China, this study illustrates how we assess the fracture seepage system of sandstone grottoes within the Penglaizhen Formation using multiple geophysical survey techniques. They are core data, conventional logging, borehole televiewer, and ground penetrating radar (GPR). Combining these methods, borehole televiewer and core data can improve the accuracy of conventional logging for stratigraphic delineation, as well as aid GPR in finding deep stratigraphic and seepage fractures. This study provides an effective routine to find sandstone grotto fractures and achieves positive results.

In order to reveal the seepage evolution law of high-pressure water injection and improve the effect of water injection and dust suppression in coal, based on triaxial compression and coal mining practices, this paper obtains the matching relationship between coal deformation and pore water pressure through coal-rock permeability test. The user-defined function module is used to compile the relationship into Fluent to simulate the fluid pressure field, velocity field and water distribution in the process of drilling water injection, and analyze the wetting range and seepage velocity in coal around the radial direction of drilling hole under different water injection pressures. The results show that the seepage field pressure increases with the increase of pore water pressure, and the rate of pressure change gradually decreases with the increase of time, and the variation of seepage field velocity shows a similar change law. With the continuous increase of pore water pressure, the porosity of coal increases, and the water content of coal increases gradually, and the distribution range is gradually expanded from around the borehole to both sides. The wetting process around the borehole of coal seam increases rapidly and then decreases slowly to reach a stable state.

Water conservation in arid and semi-arid regions faces significant challenges due to low and irregular rainfall, worsened by climate change, which negatively affects rain-fed crop productivity. Various techniques, including supplemental irrigation using runoff harvesting ponds, aim to address these issues but often suffer from water loss due to infiltration, influenced by the pond liner type. This study uses a factorial analysis to assess the farmers’ perceptions of four pond sealing techniques. Using the Waso-2 method, a survey conducted in 2022 among 41 rainwater harvesting pond owners across three regions of Burkina Faso revealed that farmers prioritized impermeability and ease of maintenance over cost and availability. Concrete, scoring 16/20, was the most preferred, chosen by over 75% of farmers for its durability and resistance to weathering, despite its high cost. Geomembrane, with a score of 12/20, was valued for its waterproofing properties but had durability concerns. Clay, although cheap and available, scored 8/20 due to poor waterproofing on unstable ground. Bitumen, the least favored with a score of 6/20, was hindered by scarcity and lack of familiarity. To enhance supplemental irrigation in Burkina Faso and similar regions, waterproof concrete or durable geomembrane liners are recommended. Further research into improving bitumen and clay liners is also suggested. These findings provide key insights into farmers’ preferences, offering guidance for developing effective water conservation strategies to boost agricultural productivity and address food security challenges in the context of climate change.

The seepage field of a suspended waterproof curtain strip foundation pit in a deep phreatic aquifer is theoretically analyzed, and a calculation method for the foundation pit water inflow and water level outside the curtain is derived. In this paper, it is assumed that the horizontal hydraulic gradient of the seepage field above the aquiclude below the bottom of the waterproof curtain decreases linearly. The separation variable method is used to solve the seepage field in the regular area inside the foundation pit, and the hydraulic head distribution function inside the foundation pit is obtained. According to the hydraulic head distribution function inside the foundation pit, the calculation expression of the water inflow of the foundation pit is further deduced theoretically. On this basis, the improved resistance coefficient method is applied to link the water level outside the pit with the solved hydraulic head inside the pit and solved. In addition, the calculation results presented in this study are compared with the calculation results of the existing model and the measured data of the foundation pit project of Yangwan Station, which proves that the analytical method can effectively meet the requirements of engineering applications.

The increasing demand for natural gas energy will promote unconventional natural gas, such as coal seam gas and shale gas, to play a key role in future energy development. The mechanical properties of coal seams are weaker compared with conventional natural gas reservoirs. The fluid–solid coupling phenomenon exists widely at the pore scale and macro scale of coal seams, and runs through the whole process of coalbed gas exploitation. The objective of this study is to establish a microscale gas–water flow model for coalbed methane considering fluid structure coupling. Frist, this study used scanning electron microscopy (SEM) to obtain microscopic pore images of coal rocks. Then, we constructed a numerical model to simulate the movement of coalbed methane and water within the scale of coal cleats based on the Navier–Stokes equation, phase field method, and solid mechanics theory. Finally, we analyzed the effects of injection pressure and wettability on the microscopic two-phase seepage characteristics and displacement efficiency of coal. Our research shows that when the injection pressure is increased from 60 kPa to 120 kPa, the displacement completion time is shortened from 1.3 × 10−4 s to 7 × 10−5 s, and the time is doubled, resulting in a final gas saturation of 98%. The contact angle increases from 45° to 120°, and the final gas saturation increases from 0.871 to 0.992, an increase of 12.2%. [ABSTRACT FROM AUTHOR]

The soft interlayer and rock structure play a significant role in controlling the deformation of the bedding slope, and it is necessary to consider the phenomenon of the sudden change of local response in these key parts under rainfall conditions, and then to clarify the mechanism of rainfall infiltration and damage mechanism of such slopes. In this paper, a large red-layered flat-dipping bedding landslide was selected as the research object, and numerical calculations based on the Van Genuchten model for saturated–unsaturated flow were performed in order to investigate the hydrological response and distribution patterns of water within the slope during rainfall. Moreover, stability analysis was performed based on the seepage field results and secondary development of FLAC3D, and the landslide evolution process was simulated and reproduced using the constitutive model of double-variables and the strength reduction method (SRM). The results showed that the effects of heavy rainfall on the water distribution and stability of the highway slope are significant, while the effects on the natural slope are not significant. There are three phases of the slope destabilization: flexure and uplift state, deformation exacerbation state and shear failure state. The slope destabilization mechanism is a typical "sliding-bending-shearing" type. The results of the study can provide a theoretical basis for the study of the seepage, stability analysis and destabilization mechanism of bedding slopes. [ABSTRACT FROM AUTHOR]

This paper delves into the Macau landfill's anti-seepage system project quality management, highlighting its environmental significance. We summarize global research and provide an overview of the project, emphasizing the importance of quality control across phases. We focus on monitoring, evaluation, and inspection methods to ensure quality objectives. Our findings contribute to environmental preservation and sustainability. [ABSTRACT FROM AUTHOR]

The investigation of bedform configurations and their migration manifest under varying flow conditions in alluvial channels remains a persistent challenge for engineers and researchers due to the intricate nature and lack of certainty associated with these formations. The study of turbulence characteristics of flow over a dune-shaped bedform can become a foundation for evaluating potential bedform migration and sediment transport behavior in an alluvial stream. Through the present study, effort has been made to demonstrate the variation in turbulent anisotropy associated with the flow over a 2D fixed dune-shaped bedform under the influence of downward seepage. Using an acoustic doppler velocimeter, measurements of flow velocities were taken over several sections of the dune-shaped bedform, in the presence and absence of downward seepage. Flow characteristics at these sections are then compared for both conditions to observe the change in turbulence behavior under the influence of downward seepage. The results reveal that, at the initial sections and lee side sections of the dune, the average contribution of streamwise and spanwise turbulent intensity to turbulent kinetic energy (TKE) along the depth of flow increases by ∼24%–45% and ∼7%–39% for 10% seepage and by ∼26%–63% and ∼25%–45% for 15% seepage, respectively, as compared with the no-seepage condition. The contribution of vertical turbulent intensities to the TKE is negligible as compared with the streamwise and spanwise turbulent intensities. Similarly, the contribution of Reynolds shear stress to TKE increases by ∼2%–30% for 10% seepage and ∼5%–35% for 15% seepage at the initial sections and lee side sections of the dune as compared with the no-seepage condition. The findings from the three anisotropy tensor eigenvalues indicate a significant rise in the strength of turbulent intensities in the streamwise direction with downward seepage primarily in the region near to the bedform surface and at the initial and lee sections of the dune. Analysis of the invariant function and plot of the anisotropic invariant map show that 1D anisotropy prevails in the initial and lee sections of the dune under the action of downward seepage. Downward seepage increases mass and momentum exchange near the bed zone of these sections, causing a significant increase in the contribution and strength of turbulent intensities in the streamwise direction. Additionally, comparative studies employing octant analysis of bursting events under seepage and no-seepage conditions demonstrate that, at the initial and lee side sections of the dune, the probability of occurrences of ejection and sweep events increases with an increase in the seepage percentage. The present investigation can form a basis for understanding the effects of downward seepage on flows over bedforms, which has not been, to our best knowledge, taken into account in the previous literature and may therefore facilitate more accurate prediction of the rate of sediment motion during the migration of bedforms in an alluvial stream. [ABSTRACT FROM AUTHOR]

Improving knowledge of existing levees through investigation and monitoring is an important step in evaluating their safety and that of the surrounding area. Nevertheless, these activities are complex due to the considerable levee length and the high spatial variability of soil composing the body and foundation, especially when paleo-rivers are present. In order to investigate the reliability of new advanced techniques proposed for characterizing the soil stratigraphy and the seepage condition within the levee foundation, a new test site was realized along the Adige River in Bolzano Province (Italy). Here, five boreholes, drilled in a 20-m-side square area straddling the embankment, host four different types of monitoring equipment, among which some are Distributed Fiber Optical Sensors (DFOS), here used for detecting the temperature variations along the well. The present paper focuses on the critical analysis of the preliminary results obtained with DFOS and their comparison with data obtained using traditional pressure and temperature probes. The monitoring data collected in the field during the passage of a flood that occurred on 5th August 2021 are used to better understand the hydraulic behavior and the safety conditions of the levee but also to fully assess the reliability and potential of DFOS. [ABSTRACT FROM AUTHOR]

The overall failure of gas-bearing coal–rock composite is the main cause of composite dynamic disasters. Investigating the mechanical-seepage characteristics of coal–rock specimens is the key to understanding the mechanism and minimizing composite dynamic disasters. In this paper, true triaxial mechanical experiments are designed and conducted under different maximum principal stress-loading rates. The mechanical properties, strength characteristics, and energy responses of samples under different loading rates are studied. A damage constitutive model of coal–rock specimens under different true triaxial loading rates is established; the solving methods for micro strength parameters m and F0 are described. The results show that as maximum principal stress-loading rate increases, the bearing capacity of the sample increases, the deformation parameters gradually increase, the degree of energy change increases, and the deformation failure becomes more severe. The model of gas-bearing coal–rock specimens under different true triaxial loading rates is in agreement with the test curves. Our model can provide useful references for predicting the stability of underground gas-bearing coal–rock. [ABSTRACT FROM AUTHOR]

Currently, the study of karst collapse column water inrush mechanism often ignores the effect of pore structure, and the traditional fractal seepage model ignores the effect of nonlinear seepage velocity field on model permeability. In order to solve this problem, the fractal seepage theory is combined with variable mass seepage theory, and the influence of seepage velocity field on model permeability is considered. The fractal seepage model of the third flow field of the settling column is established and improved, and the influence of different pore structure parameters and nonlinear seepage parameters on the macroscopic seepage of the settling column is analyzed. [ABSTRACT FROM AUTHOR]

Rain-induced shallow failures in expansive soils often occur on gentle slopes with slope ratios of 1:2–1:6, resulting in highly complex stability issuesThis study established an equivalent theoretical model for the swelling behavior of expansive soils based on the similarity theory of temperature and humidity fields. A numerical simulation approach was developed using a model with consistent nodes and the conversion of seepage results and swelling loads, allowing for the decoupling analysis of slope seepage–deformation–stress considering swelling and strength softening. Numerical analyses were conducted on a specific slope profile in a case study, analyzing the distribution and evolution of the slope seepage, deformation, and shear stress. The findings revealed that changes in moisture content at the slope toe have the most significant impact, with infiltration depth and strength attenuation being the largest. Horizontal and vertical deformations were also highly influenced by the reduction of shear strength. The uneven water absorption and swelling of expansive soil slopes resulted in shear stress concentration areas on the slope, leading to local failures near the slope toe and eventual overall instability of the slope. This study provides valuable insights into the complex behavior of shallow failures in expansive soil slopes. [ABSTRACT FROM AUTHOR]