Seepage Rates Research Articles

Thermo-Hydro-Mechanic-Chemical coupling model for hydrate-bearing sediment within a unified granular thermodynamic theory

The extraction process of methane hydrate involves interactions of multiple fields, phases, and loading stages. By extrapolating deductions from the thermodynamic equation in granular thermodynamic framework and amalgamating with coupled flow theory and linear non-equilibrium theory, a comprehensive Thermo-Hydro-Mechanic-Chemical (THMC) coupling model for hydrate-bearing sediment is established in this study. The mechanical field is established by energy dissipation conservation, the hydraulic field considers the increase in gas and liquid permeability due to temperature gradients, while the thermal field incorporates the rates of seepage, hydrate dissociation, and volumetric strain. Meanwhile, Darcy's law is explained as general deductions from the thermodynamic equation without the need for assumption. The proposed model is applied from the perspective of unit scale and coupling field, and verified with the test data. The modelling results show that the deduced model can capture the strain-softening, dilatancy, and stress paths behavior under various drainage conditions, and the volumetric strain, methane gas production and variations in heat exchange caused by the hydrate dissociation can also be predicted. Furthermore, the mechanical response and dissociation properties of sediment samples with various parameter values are discussed.

Sonlu Farklar Yöntemi Kullanılarak Geçirimsiz Baraj Tabanına Yerleştirilen Palplanş Perdesinin Yerinin Belirlenmesi

In water currents within the ground, a boiling event may occur if the flow direction is opposite to gravity in the outlet area of the flow floor. To prevent a boiling event, the length of the flow path is increased or a weight filter is used in the area where there is a risk of boiling. Increasing the length of the current path is possible by creating an impermeable layer in the upstream (inlet) section of the dam or by making an impermeable sheet pile wall under the dam. The construction of the sheet pile wall under an impervious dam is expensive and difficult. In this study, the sheet pile wall under the dam wall was placed in various positions between upstream region and downstream (outlet) region of the dam, and the value of the dam's seepage rate was analyzed by finite difference method. Vertical seepage rate values and safety numbers against vertical boiling have been found by taking the gradient of the hydraulic head. It has been seen that the sheet pile wall placed in the exit zone of the dam is the solution that minimizes the leakage rate, and, therefore, maximizes the vertical safety number against boiling.

A Model for Calculating the Rate of Seepage and Irrigation Channel Transition Efficiency

A Model for Calculating the Rate of Seepage and Irrigation Channel Transition Efficiency

Influence of a Subsidiary Weir on the Stability of a Main Structure Built on a Finite Stratum

Some dams globally have negatively affected downstream structures. Constructing subsidiary weirs may solve this problem. This novel study focuses on investigating the parameters of seepage beneath the original structure and the proposed subsidiary weir. Conformal mapping and finite element methods are used for the analysis. The proposed subsidiary weir consists of a sloping central apron, flat aprons on both the downstream and upstream ends, and upstream and downstream sheet piles of varying depths. The existing structure also has sheet piles of different depths at its upstream and downstream ends, with an impervious layer situated at a specific depth below both the structures. The study derives equations for the simulation of the upwards pressure on both the structures, seepage rate, and exit gradient along the downstream bed and the filter at an intermediate location. Our own developed software for the analysis and a commercial software for numerical methods named Finite Element Heat Transfer (FEHT)-version-1are used to calculate these parameters. The accuracy of the analytical and numerical methods is verified by comparing the results with experimental data, which demonstrate a good level of agreement. This study also simulates the impacts of various factors, such as sheet pile configurations, the depth of the stratum beneath the structure, the ratio of effective heads, and the length of the intermediate filter.

Stability Analysis of Surrounding Rock in Deep Underground Engineering Under Fluid-solid Interaction

The geological environment of deep rock masses is extreme and complex, characterized by typical deep geological features such as high geostress, high permeation water pressure, and high geotemperature. Geological disasters like water and mud inrush, high-intensity rock bursts, and large-volume collapses occur frequently in engineering construction, presenting more complex mechanisms of disaster than shallower rock masses and severely impacting the construction and operational safety of deep underground projects. Utilizing three-dimensional numerical simulation methods, this study investigated the deformation, stress, and plastic zone characteristics of surrounding rock under multi-field coupling conditions during the construction of deep caverns, revealing the stability influencing factors of deep caverns under multi-field coupling. A funnel-shaped precipitation area forms near the excavation surface of the cavern, gradually expanding as the initial pore water pressure increases. The concentration of seepage vectors in the sidewalls and arch feet continues to increase, with local seepage rates reaching 5.1×10^-6. The cavern's crown and sidewalls are particularly sensitive to changes in pore water pressure, with the maximum tensile stress appearing 1 m and 3 m axially along the sidewalls of the cavern. The plastic zone experiences its greatest increase at a water pressure of 4 MPa.

Earth-fill Dam Seepage Safety Risk Assessment: Randugunting Dam, Blora

Earth-fill dam, the most common dam, is constructed primarily using compacted earth materials from surrounding areas. Despite its simplicity, these dams have higher chances of failures caused by seepage or sliding. Randugunting Dam is an earth-fill dam located in the northern part of Blora, Central Java. This dam was built to accommodate irrigation and domestic needs in Blora, Pati, and Rembang Regencies. This study is conducted to monitor and assess the present Randugunting Dam’s seepage condition using Finite Element Analysis (FEA) and calculate the seepage safety factor. Geological and engineering geological mapping are combined by coring data to understand the rock and soil characteristics of the main dam location. The seepage rate analysis is conducted using Finite Element Analysis on GeoStudio 2021 SEEP/W. The results showed that Randugunting’s main dam and reservoir area primarily comprises calcareous siltstone, carbonaceous sandstone, claystone, and limestone. Weathering rates in this area range from slightly weathered to highly weathered. The seepage rate from FEA ranges from 4.39 - 5.31 litre/s and calculation of safety factor along the Randugunting Main Dam is 4.49. Those values are considered to be safe. Installing blanket type of horizontal drain and seepage berm can act as prevention step in the future.

Fragility Analysis for Water-Retaining Structures Resting on Spatially Random Soil

The maintenance of water-retaining structures involves evaluating their performance against current and future operating water levels. Fragility curves are commonly used for this purpose, as they indicate the conditional probability of failure for various load conditions and accurately characterize a structure’s performance. Monte Carlo simulation (MCS) can be used to determine the fragility curve of water-retaining structures by calculating the probability of failure as the water level changes. However, performing repetitive MCS involves extensive calculations, thus making it inefficient for practical applications. Therefore, it is essential to develop efficient methods that require a minimum number of MCS runs to estimate the fragility curve. This study proposed two methods to estimate the fragility curves of water-retaining structures, thereby allowing for the assessment of failure probabilities related to important quantities such as the steady-state seepage rate, exit gradient, and uplift force, which make them suitable for practical applications. The fragility curves obtained using the proposed methods are valuable for risk assessment, design, and decision-making purposes, as they offer information to evaluate the performance of the water-retaining structure under various water level conditions.

Influences of cement asphalt emulsified mortar construction on track slab geometry status

PurposeThe construction of cement asphalt (CA) emulsified mortar can obviously disturb the slab status after the fine adjustment. To decrease or eliminate the influence of CA mortar grouting on track slab geometry status, the effects of grouting funnel, slab pressing method, mortar expansion ratio, seepage ratio and grouting area on China Railway Track System Type (CRTS I) track slab geometry status were discussed in this paper.Design/methodology/approachCombined with engineering practice, this paper studied the expansion law of filling layer mortar, the liquid level height of the filling funnel, the pressure plate device and the amount of exudation water and systematically analyzed the influence of filling layer mortar construction on the state of track slab. Relevant precautions and countermeasures were put forward.FindingsThe results showed that the track slab floating values of four corners were different with the CA mortar grouting and the track slab corner near CA mortar grouting hole had the maximum floating values. The anti-floating effect of “7” shaped slab pressing device was more efficient than fixed-joint angle iron, and the slab floating value could be further decreased by increasing the amount of “7” shaped slab pressing devices. After CA mortar grouting, the track slab floating pattern had a close correlation with the expansion rate and water seepage rate of CA mortar over time and the expansion and water seepage rate of the mortar were faster when the temperature was high. Furthermore, the use of strip CA mortar filling under the rail bearing platform on both sides could effectively reduce the float under the track slab, and it could also save mortar consumption and reduce costs.Originality/valueThis study plays an important role in controlling the floating values, CA mortar dosage and the building cost of projects by grouting CA mortar at two flanks of filling space. The research results have guiding significance for the design and construction of China's CRTS I, CRTS II and CRTS III track slab.

Settlement, slope stability and seepage analyses By Numerical Modelling Method and their applications in practice

The encountered situations during the design process of a gully erosion control site in Kano State are discussed in this article. The project was to design a rectangular concrete lined drainage channel with short side walls to efficiently convey flood water and prevent embankment erosion. Because of the embankment depth and soil type on the site which are mostly silty/clayey sand, settlement of the huge concrete channel, seepage and the unprotected embankment slope were issues of major concern. Settlement, slope stability and seepage analyses and designs were some of the several activities undertaken for the project. The anticipated total settlement prediction was performed by numerical simulation from which the differential settlement was then calculated. The prediction of the safety factor to determine the stability of the slope was performed by numerical simulation using SLOPE/W. The hydraulic velocity and rate of seepage prediction was performed by numerical modelling using SEEP/W. The use of numerical technique was specifically recommended by the consultants of the funder of the project, the World Bank. It was observed that numerical modelling technique provided accurate results of settlement, factor of safety, hydraulic velocity and rate of seepage and was therefore recommended for both research and practical applications.

Downward seepage effects on flow near a L-shape spur dike and bed morphology

Spur dikes are structures built along riverbanks that serve two purposes: stabilizing the banks and minimizing erosion risk by controlling water flow in the river channel. The current study used L-shaped spur dikes in an alluvial channel to analyze the bed morphology and flow pattern in the spur dikes zone with the influence of no-seepage and two distinct seepage velocities, VS1 = 0.075 mm/s and VS2 = 0.15 mm/s near the channel bed z/h < 0.2. The experimental study was also done to examine and compare the transformation in the local scour depth for the seepage condition. According to the study results, downward seepage movement causes significant modification in the channel's bed elevation and the development of scour depth. Observations indicate that the maximum local scour occurs at the first spur dike's leading edge. Seepage velocity VS1 results in a 16.1% increase in the maximum scour depth compared to the no-seepage scenario. In comparison, seepage velocity VS2 causes an increase of 25.2% in the maximum scour depth. Due to downward seepage, the flow distribution is shifted down near the channel's boundary. With an increase in the seepage rate, the magnitude of velocity, Reynold shear stress, turbulent kinetic energy, and bed shear stress also rise close to the channel's boundary. The current study also examined bursting events near the channel's bed under seepage and no-seepage conditions. These events included outward interaction, inward interaction, ejection, and sweep. Quadrant analysis of velocimeter data revealed that ejection and sweep were the dominant events contributing to the production of Reynolds shear stress in seepage and no-seepage flows. Meanwhile, outward interactions and inward interactions made minor contributions compared to ejection and sweep events to the Reynolds shear stress.

Multi-attribute parameterization modelling to assess response of microtopographic variation to rainfall-seepage coupled erosion

Slope microtopography redistribution caused by the process of surface–subsurface hydrology results in the randomness and nonlinearity of erosion behavior. However, the erosion effects of various microtopographic features under the rainfall-seepage coupled impact remain inadequately explored. In this work, a specialized parameterization framework was employed, coupling numerical attribute, shape, and structure with the spatial pattern of microtopography, specifically to quantify changes in microtopography and to clarify their response mechanisms to rainfall-seepage erosion on purple soil slopes. The continuous rainfall-seepage simulation experiments were conducted on a 15° tilled-slopes differing in microreliefs (conventional tillage, CT; artificial digging, AD; ridge tillage, RT) with constant rainfall intensity of 1.0 mm min−1 coupling three seepage rates of 2, 4 and 8 L/min, respectively. Results revealed that the elevation decay occurred in the stage of transition from sheet erosion to rill erosion for CT, AD and RT slopes, representing a “erosion > deposition” feature. The numeric roughness and multifractal pattern of microtopography showed RT > AD > CT slope during the rainfall-seepage erosion. The spatial change of microtopography was attributed to structural-oriented factors because the nugget ratio with less than 25 % accounted for 73.33 %. Synchronously, the runoff, sediment yields and concentrations increased with the increase of rainfall-seepage intensity. It was found that the response of roughness index on soil erosion was more obvious for smooth surface with relatively contribution rate of 81 %, while the change of microstructure (H) and multifractal shape (ΔD) were more sensitive to erosion process on AD and RT slopes respectively. The results reported in this study have important implications for an in-depth apprehending of microtopography erosion effects in saturation-excess dominated slope cropland.

Post-Earthquake Reconnaissance of a Dam with Stabilizing Fill using Drone Photogrammetry

Post-earthquake reconnaissance is an important process for assessing the safety of massive structures. Dams are critical structures that require evaluation following an earthquake, as dam failure can lead to significant damage to the surrounding area. This paper presents drone (unmanned aerial vehicle) photogrammetry-based reconnaissance of the Angat Dam (Philippines), which has stabilizing fill, following the M 6.1 Luzon earthquake in April 2019. The author presents the results of visual inspection, drone digital mapping, and seismically induced deformation monitoring, as well as a general interpretation of dam safety. Analysis of the instrumentation data did not indicate that any significant changes in crest settlement, piezometric head, or seepage rate resulted from the earthquake. However, seismically induced longitudinal cracking along the dam crest was observed in the drone photogrammetry. The digital surface model, orthoimage, and as-built GIS geometry characterizations generated using the drone photogrammetry facilitated the geospatial analysis of seismic cracking and deformation. It is found that the uplift deformation was caused by counteracting effects between the existing dam body and its stabilizing fill. It is concluded that the results obtained using drone digital mapping are a valuable reference for future deformation monitoring using regular mapping methods in a 3D geospatial digital model.

Theoretical and field investigation into the vacuum formation in the siphon-vacuum drainage system for soft ground improvement

Compared to the traditional drainage consolidation measures for soft ground improvement, the siphon-vacuum drainage method (SVD) offers more advantages, for example, improved drainage efficiency, lower maintenance costs, lower demand for energy and materials, and less environmental impact. Hence, it is expected to be widely applied in soft ground improvement. However, the mechanism of vacuum formation in the system remains unclear. In this study, the vacuum formation mechanism of SVD is investigated based on the theoretical deduction of the variations of the water level and air pressures during the siphon drainage and seepage processes. A theoretical model is developed to describe the vacuum formation, allowing the estimation of the varying air pressure, water level, seepage rate, and discharge rate in the system. Moreover, a field investigation was carried out in Zhoushan, Zhejiang Province, to further validate the correctness of the developed model. This study also provides further insights and suggestions into the field application of SVD for soft ground improvement.

Does the age of ulcerative colitis diagnosis impact outcomes of restorative proctocolectomy?

Ulcerative colitis (UC) can be diagnosed at a variety of different ages. We evaluated if age of ulcerative colitis (UC) diagnosis impacts outcomes of restorative proctocolectomy (RP) with ileal pouch-anal anastomosis (IPAA). A prospectively maintained pouch database (1983-2020) was queried to identify patients undergoing an RP for UC. The cohort was stratified based on bimodal disease presentation into 2 groups: the early adulthood group (19-30years old) and the mid/late adulthood group (40-70years old). Patients' demographics, postoperative complications, functional (stool number, seepage), and quality of life (QoL) rates were compared between the groups. A total of 628 patients with an age range of 19-30years old (18.1 ± 2.2 at the time of diagnosis, 24.2 ± 10.5 at the time of IPAA) and 706 patients with an age range of 40-70years old (45 ± 3.0 at time of diagnosis, 52.3 ± 9.4 at time of IPAA) were identified. Older patients had longer disease duration, higher BMI, lower biologic use, and greater one-/two-staged IPAA, with 20% hand sewn anastomosis and 16.5% of S pouch configuration compared to younger ones. No difference was observed in anastomotic separation, pelvic sepsis, fistulas, or pouch failure in follow-up. Postoperatively, older patients more frequently developed bowel obstructions, strictures, and pouchitis, in addition to higher rates of seepage (p < 0.05). QoL was comparable between groups. While IPAA retention rates are comparable between different age cohorts, older age at diagnosis and IPAA construction is associated with higher rates of pouchitis, bowel obstruction, anastomotic strictures, and worse functional outcome. Quality of life is similar in those who retain their ileal pouch on the long-term.

The influence of drain pipe location and diameter on seepage through an earth dam

Earth dams are built for various reasons these including storage of water, regulation of water flow, prevention of flooding, and the generation of hydroelectric power. The drain pipes within an earth dam, are considered one of the more important control devices used to reduce the effects of problems caused by seepage. As such, the role of drain pipes against seepage problems in an earth dam, has been studied numerically in this investigation. The effects of drain pipe location and their diameters (50, 75, 100, and 150 mm), were examined using different hydraulic heads. The analysis focuses on the characteristics of relative seepage flow, exit gradient, and factor of safety regarding sliding. A range of models of typical earth dams, with and without drain pipes, have been simulated using Geo-Studio software in SEEP/W and SLOPE/W applications, examining more than 200 different cases. By using the data computed from numerical models, new formulas for predicting the seepage parameters and factors of safety were developed in this study by using the multiple non-linear regression (NLR) approaches. The findings show that the presence of a drain pipe reduces seepage flow and the exit gradient, at the same time increasing the factor of safety. Regarding pipe diameter, the rate of seepage and exit gradient decreased while the factor of safety increased as the diameter of the pipe increased. The factor of safety increased by between 11 and 25% when the drain pipe was placed in an optimal position, allowing for a reduction in seepage flow and exit gradient.

Competing impacts of internal pores dissolution and external compression on the permeability evolution during the infiltration of weakly acidic fluids

In the water conservancy and hydropower projects, the infiltration of weakly acidic groundwater has an essential effect on the permeability evolution of sandstones. Previous studies considered that the permeability was only positively proportional to the volume of dissolution pores. This ignored the coupling effects of external compression on internal pores dissolution and inevitably overestimated permeability, which could lead to the misunderstanding of flow mechanisms in actual geotechnical engineering. In this study, a “multi-physical coupling permeability test platform for rocks” was used to conduct the permeation-dissolution experiment on sandstones. Firstly, the evolutions of exudate ion concentration, strain, and seepage rate in sandstone specimens were measured. Secondly, the mechanical degradation of sandstones by chemical dissolution was analyzed through the obtained experimental data. Finally, an improved permeability model was proposed to describe the competing effect of internal pores dissolution and external compression. It was found that (1) Although the water–rock reaction increased the dissolved porosity only by 0.42%, the mechanical properties of the sandstone were significantly weakened; (2) The effect of pores dissolution on permeability enhancement was suppressed by mechanical weakening; (3) The improved permeability model was consistent with the experimental data. This indicated that the improved permeability model could accurately characterize the competing effect between internal pores dissolution and external compression.

Seepage Quantity Analysis Beneath Concrete Dams with Various Sheet Piles using Different Numerical Models

Seepage is a dangerous phenomenon under hydraulic structures and the main cause of failure and damage to dams when neglected and not processed. This study evaluates the numerical effects of the sheet piles' quantity, depth, and spacing beneath a concrete dam with isotropic and homogenous foundations on the seepage rate, pressure head, and exit gradient. The solutions were obtained using SEEP/W code in GeoStudio software 2018 for three configurations using single, double, and triple sheet piles. In addition, SLIDE software 6.02 was examined using single and double sheet piles. Dimensional analysis was applied to draw the dimensionless variables that affect the seepage rate and exit gradient, and all tests were repeated for three different sheet pile depths and distances from the heel of the dam. The findings showed that the seepage rate in all studied configurations reduced when sheet pile depth increased. The position of the sheet pile from the dam's toe significantly decreased the seepage rate in cases using single and double sheet piles, while in cases using three-sheet piles, the position of the middle sheet pile insignificant decreased seepage. It was recognized that when using a single sheet pile, the drop in pressure head increased with depths when the sheet pile was located at the heel and middle of the dam. In addition, in the case of a single sheet pile at the toe or using two and three-sheet piles, the pressure drop decreased as the depths increased. Also, the results showed that the middle sheet pile location in the case of three sheet piles slightly affected pressure reduction. Furthermore, the results showed that using two and three-sheet piles was more effective than using a single one in reducing the exit gradient, while the position of the middle one in the case of using three-sheet piles was insignificant. A nonlinear empirical equation was developed using SPSS 22 program, and the comparison of the seepage rate measured by SEEP/W and SLIDE software versus its quantity calculated from empirical equations showed a good agreement as the determinations (R2) coefficients were equal to 0.9779 and 0.9928, respectively.

Study on heat-exchange efficiency and energy efficiency ratio of a deeply buried pipe energy pile group considering seepage and circulating-medium flow rate

Seepage and circulating-medium flow rate are both primary factors affecting the heat-exchange efficiency and energy efficiency ratio of underground energy structures. In this study, a thermal-seepage coupled model of a deeply buried pipe energy pile group is developed, and the effects of circulating-medium flow rate, seepage velocity, and thermal migration caused by seepage on heat-exchange efficiency and energy efficiency ratio are analyzed. The results show that increasing the circulating-medium flow rate can improve heat-exchange efficiency, but aggravate heat accumulation, resulting in energy efficiency ratio reduction. Seepage can eliminate the heat accumulation as well as improve the heat-exchange efficiency and energy efficiency ratio. The heat accumulated around upstream piles will migrate along the seepage direction, generating thermal disturbance to the downstream piles. An increase in the circulating-medium flow rate of upstream deeply buried pipe energy piles will aggravate thermal disturbance. This phenomenon is slightly retarded if seepage velocity is increased. Additionally, when the circulating-medium flow rate of the deeply buried pipe energy pile group under seepage is within the optimal range, slightly reducing the circulating-medium flow rate of the upstream deeply buried pipe energy piles can reduce thermal disturbance to the downstream piles without affecting the overall heat-exchange efficiency.

Water seepage rate in composted soil

Water infiltration is one important factor for plant growth. Water that cannot seep into the pores of the soil creates a pool of water so that soil permeability is low. From these conditions, it is necessary to conduct research to determine the rate of water seepage in the soil. This study aims to analyze. the rate of water seepage on the ground by utilizing the difference in floating voltage. Based on the difference in floating voltage, two-dimensional modeling of the stress distribution and the distribution of water infiltrate time into the ground using the method of adding water repeatedly. The sample in this study consisted of 2 types of soil, compost and sand. Land with high permeability can increase the rate of infiltration thereby reducing the rate of water. The results of this study concluded that the pore size and particle arrangement greatly affect the rate of water seepage.

Experimental and numerical evaluation of tire rubber powder effectiveness for reducing seepage rate in earth dams

Abstract Tires waste is an undesirable urban industry surplus that has grown worldwide yearly. Because of its seals, this material may be used in earth dams, one option for disposing of this waste. Since this is the main objective of this study, an experiment on a soil sample with various ratios of rubber powder has been conducted to better comprehend the impact of tire rubber powder (TRP) on the seepage rate in earthen dams. This study used physical and numerical models to investigate seepage through earth dams. Analysis indicates that the plotted seepage line in SEEP/W software was comparable to the observed seepage line in the physical model. TRP was tested at concentrations of 15, 30, and 50%. The research demonstrates that there has been a noticeable improvement in reducing the seepage rate through the dam’s body; seepage was decreased by 11.28% when a 15% ratio was adopted, a far smaller impact than the other percentages. The proportion was consequently raised to 30%. The seepage rate was found to be reduced by 35.6%, and TRP with a 50% ratio showed excellent behavior in lowering the water level (phreatic line) from the core point to the downstream face D/S and reducing the seepage rate by 41.5%, producing significantly better results. The findings in SEEP/W software indicate that the relative error in seepage rate varies, averaging 11.8% for the first model, 12.18% for the second, 1.65% for the third, and 7.63% for the fourth. The first and second physical models’ seepage rate (relative inaccuracy) dramatically increased as a result of the presence of piping.