Seepage Control Research Articles

The Effect of Shear on the Properties of an Associated Polymer Solution for Oil Displacement.

Polymer flooding is one of the techniques used to enhance oil recovery from depleted hydrocarbon reservoirs. Although this technology is popular for this application, the shearing effect in the injection process causes poor performance, which is an obstacle to meeting the needs of the formation. An experimental evaluation of the rheological properties, viscoelasticity, hydrodynamic size, static adsorption, and seepage characteristics of the associated polymer solution before and after shearing was conducted to determine the influence of shearing on the polymer solution. The results show that the effect of shear on the polymer was irreversible, and the properties of the polymer solution damaged by shear were attenuated. After the critical associating concentration, the associated polymer can recover its solution properties through hydrophobic association, which can improve the shear resistance of the polymer solution and make its own rheological law and reduce the viscoelastic change. Although the hydrodynamic size, viscoelasticity, and adsorption capacity of the polymer solution after shear failure decreased, strong flow resistance during porous media seepage and mobility control was achieved. Improving the shear resistance of the polymer solution by increasing the intermolecular force is proposed to develop new polymer systems for subsequent oil displacement.

Process Water Management and Seepage Control in Tailings Storage Facilities: Engineered Environmental Solutions Applied in Chile and Peru

In the past thirty years many mining projects in Chile and Peru have used: (i) polymeric geomembranes and (ii) design-and-build cutoff trenches, plastic concrete slurry walls, and grout curtain systems to control seepage at tailings storage facilities (TSFs). Geosynthetics are a viable alternative at a TSF dam for clay cores or impermeable materials, mainly because of their marked advantages in cost, installation, and construction time. This article describes the use of geosynthetics liners and cutoff trench–plastic concrete slurry walls–grout curtain systems in TSF dams in Chile and Peru mining, with the objective to decrease seepage to the environment, considering different dam material cases such as: cycloned tailings sand dams, borrow dams, and mine waste rock dams. Finally, this article discusses aspects of geosynthetic technology acceptance in the local regulatory frameworks, lessons learned, and advances. It focuses on the use and implementation of geosynthetics in TSFs in Chile and Peru, which have some of the highest TSF dams in the world, as well as a wet environment, dry environment, extreme topography, and severe seismic conditions. These conditions constitute a challenge for manufacturers, engineers, and contractors, who must achieve optimal technical solutions, while being environmentally aware and economic.

Groundwater flow through fractured rocks and seepage control in geotechnical engineering: Theories and practices

Groundwater flow through fractured rocks has been recognized as an important issue in many geotechnical engineering practices. Several key aspects of fundamental mechanisms, numerical modeling and engineering applications of flow in fractured rocks are discussed. First, the microscopic mechanisms of fluid flow in fractured rocks, especially under the complex conditions of non-Darcian flow, multiphase flow, rock dissolution, and particle transport, have been revealed through a combined effort of visualized experiments and theoretical analysis. Then, laboratory and field methods of characterizing hydraulic properties (e.g. intrinsic permeability, inertial permeability, and unsaturated flow parameters) of fractured rocks in different flow regimes have been proposed. Subsequently, high-performance numerical simulation approaches for large-scale modeling of groundwater flow in fractured rocks and aquifers have been developed. Numerical procedures for optimization design of seepage control systems in various settings have also been proposed. Mechanisms of coupled hydro-mechanical processes and control of flow-induced deformation have been discussed. Finally, three case studies are presented to illustrate the applications of the improved theoretical understanding, characterization methods, modeling approaches, and seepage and deformation control strategies to geotechnical engineering projects.

Geosynthetic liner: A modern solution for a concrete dam constructed from particularly lean roller-compacted concrete

This paper discusses the issue of seepage control in gravity dams made of compacted lean concrete. Several possible design options are outlined. The benefits of using geocomposite impervious blankets are explained. A description of different types of geocomposites is given, including their composition and component parameters. Basic properties of geosynthetics are discussed, along with methods for defining them, such as water permeability, tensile strength, puncture resistance, and ageing. Finally, the main areas for future research are formulated, although it may be helpful to provide more detail on the specific focus of this research.

High-speed train induced vibration measurements in fresh tunnel shotcrete layer

Existing coastal railway track has been undergoing for renovation and improvement work aiming to raise train speed and shorten the travel time between Turku and Helsinki. The track has 16 existing tunnels of which 14 has been renovated between 2019 and 2021. Majority of the tunnels have been reinforced by system and shotcrete and rock bolts. The water seepage control has been solved by using PE sheets with additional 100 mm fibre shotcrete layer as fire protection layer. After the track and tunnel improvements, the track was test driven with two different trains: a high speed SM train unit and a two storey intercity train unit. The speeds used were higher than the current allowed speeds aiming to study the potential to increase the travel speed. One of the most restrictive parameters for the increase is the pressure shock of high speed train entering the tunnel. Too high pressure shock will cause inconvenience for the passengers and can cause damage in tunnel lining structures. Also currently no clear guideline exists what speed limits need to be used for trains entering tunnels with curing shotcrete. To study these matters the test run train units were instrumented including with pressure sensors. The conclusions about the pressure shocks are investigated briefly in the paper.

Efficacy of Pond Ash as a Cover Material in Single and Dual Capillary Barriers

In this paper, numerical study results that highlight the capability of using pond ash as a cover material in covers with capillary barrier effects are succinctly summarized. A model was exclusively developed and calibrated using commercial software SEEP/W for this study. After calibration, the efficiency of pond ash as a coarse-grained layer (CGL), fine-grained layer (FGL), unsaturated drainage layer (UDL), and seepage control layer (SCL) was investigated using various combinations. The CCBE made of pond ash obtained from the output and input points of an ash pond as alternate fine- and coarse-grained layers were observed to perform well. The performance of pond ash as UDL and SCL was also observed to be good. The approach presented in this study is valuable in assessing likely slope failures of coal ash storage facilities that may be triggered by rainfall events. The study aids in significantly reducing rainfall infiltration, improving the overall stability of the slopes, and promoting sustainability by utilising the concept of “waste covering waste”. The approaches used in this study can be extended in the rational design of slopes to address the future challenges anticipated with unprecedent rainfall events and its negative impacts associated with climate change effects.

Simulation of an Ionic Rare Earth Leaching Process Based on the Darcy Law-Chemical Reaction Engineering-Transfer of Dilute Substance Coupling

The basic principle of in situ leaching is chemical mining. The process of in situ leaching is to inject leaching solution into the ore body, and the leaching solution is spread in the pores of the mountain. The process is completed by the coupling action of the liquid seepage field and ion exchange reactions. In the production process, only one injection of liquid can be carried out in a certain stope, so it is impossible to improve the injection process and leaching effect through field practice. By simulating the in situ leaching process of rare earth ions, this paper builds the test stope true three-dimensional numerical model and simulates the leaching process of rare earth ore under the coupling of seepage control, ion exchange, and dilute material transfer in porous media. The migration rule of RE3+ and Mg2+ in stopes was analyzed to evaluate the leaching effect. It is of great significance to increase the recovery rate of rare earth ore.

Evaluation of groundwater flow through a high rockfill dam foundation in karst area in response to reservoir impoundment

Constructing high dams in karst valleys remains a challenging issue as karst conduits provide preferential channels for flow through the foundations. The uncertainty of the karst system drastically increases the risk of leakage and hence the difficulty in seepage control at the foundations. This study examined the transient flow behaviors through a karst foundation on which a rockfill dam with a height of 219 m had been constructed. During reservoir filling, an abnormal pressure rise occurred in the foundation downstream the grout curtains, typically with a magnitude of 53∼69 m higher than the pore pressure head at the neighboring positions. This phenomenon was comprehensively investigated by site characterization, inverse modelling, numerical simulation and cross-correlation analysis, demonstrating that the abnormal pressure rise is locally induced by eroded fault (left bank) or contact zones between karst formations (right bank). These conduits have an effective permeability value one order of magnitude higher than that of the karst formations, which quickly transmit the reservoir pressure pulse across the grout curtains, as evidenced by a higher cross-correlation and a smaller lag between pool level and piezometer measurements. The grout curtains have sufficiently low permeability in limiting the amount of leakage through the foundation, and hence ensure the safety of the reservoir operation in spite of the pressure rise. This study confirms the applicability of the equivalent continuum model in addressing groundwater flow problems in karst formations, as long as the site conditions are properly characterized.

Field-based assessment of the design of lysimeters for landfill final cover seepage control

ABSTRACT Lysimeters are considered the most appropriate instrument for assessing percolations rates through landfill final covers. Their design, however, must take into consideration the unsaturated nature of water seepage, otherwise they may act as a sink or cause flow avoidance. The aim of this study was to investigate whether using a simple approach to lysimeter design produces reliable seepage control data. Two different design methods were compared using a three-year field database of suction and seepage data collected from large-scale lysimeters installed at the St-Nicephore landfill in Canada. The first, or control, whose side walls were as high as the thickness of the cover material, was inspired from lysimeters installed during the Alternative Cover Assessment Program (ACAP; USA). The second lysimeter was designed based on the proposed simple design methodology, which focuses on the unsaturated flow and hydraulic properties of the materials to determine the optimal wall height. Analysis of the database did not show any indication of significant preferential flow, or alteration of the flow regime by the second lysimeter, which collected as much percolation as the control one (less than 5% difference). The linear method has not been tested for extreme climatic conditions and the wall heights calculated using this method may be very high when designed for very fine-grained soil covers.

A Study on the Interaction Behavior between an Earth-Rock Dam and a New-Typed Polymer Anti-Seepage Wall

Polymer anti-seepage wall has been gradually applied in earth-rock dam reinforcement projects as a new seepage control technique. However, due to all-pervasive properties of the new materials and root-like connection between the materials and soils, the interface characteristics between the polymer wall and the earth-rock dam, as well as the interaction behavior of both, are complex and still not clear, which obstruct studying coordination mechanism of dam and wall under earthquake. Therefore, the interface characteristics and interaction behavior of dam and wall were studied in the article. Firstly, the dynamic shear stress-displacement, shear stiffness and damping ratio of the interface between polymer and soil were investigated by ring shear test. In addition, the viscoelastic constitutive model of polymer materials were researched by dynamic mechanical analysis (DMA) test. Based on tests results, a finite element model of earth-rock dam with polymer wall was established, including a non-linear simulation interface element and viscoelastic polymer constitutive model. Next, the validity of the simulation model was verified based on dynamic centrifuge test results. Then, the interaction behavior and seismic response of the dam with polymer wall were explored by using the verified model. The research results provide a scientific basis for the development and application of new-typed polymer anti-seepage wall in reinforcement engineering.

Evaluation of Long-Term Tightness of the Coal Pillar Dam of Underground Reservoir and Protection Countermeasures

The coal mine underground reservoir is an effective facility for mine groundwater utilization in water-deficient and ecologically fragile areas. Usually, the artificial reserved coal pillar is used as the dam of underground reservoir, and little research has been done on its tightness performance. Comsol software is used to simulate the leakage of underground reservoirs in Shendong area, in the western part of China, and the long-term tightness of coal pillar dam under different operation conditions is evaluated. The results show that: (1) When the underground reservoir is not connected with the upper water system, the coal pillar dam has good tightness performance. When they are connected, the leakage of reservoir increased due to the raised water level, and the deeper the burial depth, the greater the leakage amount. (2) When reservoir is pumping and storing water, the leakage is only half of that under constant water pressure storage, indicating that this operation mode is beneficial to the long-term tightness of a coal pillar dam. (3) With the increase of the permeability of a coal pillar dam, the leakage will be aggravated. It is suggested that the permeability of a coal pillar dam should not exceed 1 × 10−15 m2. (4) The tightness of the coal pillar dam damaged by brine immersion is greatly reduced. With only 3 m of soaking damage distance, the total leakage is twice that of the undamaged one. For a coal pillar dam with poor tightness, some protection countermeasures are proposed to reduce the reservoir water level or improve the anti-seepage performance of a coal pillar dam, so as to ensure the long-term tightness of the dam. This research can provide theoretical support and technical guidance for evaluating the seepage stability of a coal pillar dam in an underground reservoir and strengthening its seepage control.

The Factors Affecting Dam Safety and Seepage Control Measures

Dam plays an important role in the development of economy, measurement of flooding, human life and property safety. If dam broken occurs, it could cause massive damage and casualties. Seepage is one of the main problems that influence the dam safety. Therefore, it’s significant to study the dam safety and seepage control measurements. This research focuses on the factors that affecting dam safety and evaluate the seepage fold control methods. Results show that the influence factors of dam safety include geological condition, overtopping, human factors and dam structure. They affect dam safety by causing geological hazards like flood or reducing the dam's ability to withstand these disasters. Seepage prevention and control is effective to alleviate dam safety problems. There are some methods such as concrete impermeable panel, concrete impermeable wall and improvement of dam body. Different measures are applied in different kinds of dam and have specific features.

Analysis of seepage control system improvement in an earthen dam

This paper concerns the adequacy of utilising a chimney drain, horizontal filter and cutoff wall in reducing seepage through an earthen dam. To this end, anti-seepage systems comprising a chimney drain, a horizontal filter and a cutoff wall were investigated. Variations of lengths, angles and locations of these features were studied. The amount of seepage was determined using SEEP/W software. The results indicated that by expanding the vertical chimney drain and the horizontal filter from the embankment toe to half or three-quarters of the downstream slope, the seepage flow from the dam body and its foundation will decrease. On the contrary, when the horizontal filter's length is extended to more than three-quarters of the dam's downstream slope, the amount of seepage flow that may pass through the dam's cross-section rapidly increases. Additionally, it was observed that seepage from the earthen dam and its foundation reduced by increasing the cutoff depth. Finally, with respect to the minimum factor of safety for the downstream slope, obtained using SLOPE/W software, a suitable model for seepage control within the body and foundation of the dam was found to be the hybrid model introduced at the end of this study.

Patterns and driving forces of the agricultural water footprint of Chinese cities

The patterns and determinants of different types of agricultural water footprints in China are poorly understood at the prefecture-city level. In this paper, we evaluate Chinese agricultural water footprints from 2000 to 2017 and analyzed their spatio-temporal characteristics. Our estimation results show that the annual average agricultural water footprint in China was 5.038 × 109 m3, and the proportions of green water, blue water, and gray water were 70%, 9%, and 21%, respectively. In addition, high agricultural water-footprint cities with obvious urban agglomeration effects are mainly located in the Northeast, the Huanghuai River, the Yangtze River Basin, and Northwestern of Xinjiang, while low agricultural water-footprint cities are concentrated in high coastal urbanization-level areas or less developed agricultural areas of the west. We also investigate their determinants using a spatio-temporal fixed-effect model and find that GDP per capita, total investment in fixed assets, the income level of rural residents, the proportion of food grown, spray and drip irrigation technology, low-pressure pipe irrigation technology and seepage control irrigation technology have significant positive impacts on the agricultural water footprint. In contrast, the proportion of secondary and tertiary industries, social retail consumption, urbanization, technology expenditure, and the effective irrigation area proportion have a significant inhibitory effect. The primary determinants of the agricultural water footprint also vary substantially across water footprint categories (green, blue, and gray water footprints) and regions. Our findings imply that the agricultural water footprint should be incorporated into city water resource management and monitoring system.

Conceptual analysis of seepage control for Senggarang Coastal Embankment with chemically-stabilized backfill

One of the common problems of coastal embankments is water seepage. The Senggarang Coastal Embankment (SCE) is examined in the present work, with the objective of proposing the improvement of the earth structure via chemical stabilization. The stabilized soil embankment was simulated and analyzed with PLAXIS 8 to identify a conceptual proposition of solution using a conventional and innovative stabilizer, i.e., lime-ZnO and cement-CSP (cockle shell powder). The base of the embankment was assumed to be bedrock, in order to eliminate the passage of water below the embankment. Stabilization was taken as 100 % for the embankment, i.e., a homogeneous earth structure made entirely of stabilized soil for seepage mitigation. Input parameters for the simulations were acquired from both field samples and past studies. Varying water levels due to tidal effect were applied in the model to determine the changes of pore pressure distribution which could potentially lead to instability of the embankment. As water level increases with the rising tide, total displacement of the original earth embankment was found to increase as the soil weakened, with decreasing effective shear stress. Replacement of the embankment backfill with cement-CSP and lime-ZnO were both observed to significantly reduce the displacements. The use of both stabilizers not only improves the SCE’s engineering performance in terms of reduced water seepage and displacement, accompanied by increased strength, but the ‘green’ nature of the former, as derived from organic waste, also enhances the appeal of the stabilization technique.

Application of Seepage Control Technology in Water Conservancy Project

Application of Seepage Control Technology in Water Conservancy Project

Optimal Design of the Seepage Control for Xianglushan Diversion Tunnel Under High External Water Pressure

Optimal Design of the Seepage Control for Xianglushan Diversion Tunnel Under High External Water Pressure

The investigation of geochemical and geomechanical properties in surface paste disposal by pilot‑scale tests

ABSTRACT Today, seepage control in tailings dams has become an important problem due to the increased production in mining sites. Although very techniques have been developed to solve this problem, research in this field continues. The reason for this is that there is an ongoing search for a one hundred percent successful method to prevent seepage. In this study, the geochemical and geomechanical properties of paste material stored by the surface paste disposal (SPD) method were investigated by pilot field tests. To determine the effects of cement and pozzolanic materials on the geochemical and geomechanical properties of the paste, 2 different pilot-scale storage designs were observed for about 1 year, with no additives (reference) and binder added to some layers (cement and fly ash). Based on the data derived from the former laboratory investigations and with no additives and with a few layers of cement and fly ash, the two different designs were applied on a pilot scale near the existing tailings dam of a currently active mining enterprise. These designs were observed in inland conditions for about 1 year to determine the effects of seasonal changes on the material. The seepage analysis, surface crack densities, microstructural properties, consolidation, and cohesion values of these designs, which are directly exposed to atmospheric effects, were determined during the study period. According to the results obtained, the use of cement improved the volume compressibility coefficient of the material by approximately 25% compared to the reference design. However, the use of fly ash alongside cement improved the volume compressibility coefficient by about 75%. In conclusion, the use of cement made the material more resistant to external factors, and the usability of fly ash, which was used at a 50% replacement ratio with cement to bring down the cost, for long-time storage in the industry was demonstrated within the scope of the study.

Behaviour of loose sand treated using bio-gelation method

Bio-gelation is a new method for improving the hydraulic and mechanical properties of sandy soil through the production of polymeric gel to fill in the pores of the soil. In this paper, a study on the engineering behaviour of loose sand treated using this method is presented. A series of permeability and undrained monotonic and cyclic triaxial tests was carried out on both clean sand and bio-gelled sand. The test results showed that the coefficient of permeability was reduced by three to four orders of magnitude in the bio-gelled sand samples, and the higher the alginate concentration, the lower the permeability. In the monotonic triaxial tests, sand samples that would have liquefied under static conditions manifested strain-hardening behaviour after treatment. The shear strength of the bio-gelled sand also increased, as was indicated by an increase in the slope of the failure line from 1·08 to 1·27. In the cyclic triaxial tests, the number of cycles at failure increased from 183 for clean sand to 485 for bio-gelled sand, and the excess pore water pressure response was also much reduced. The hydrogel produced by the bio-gelation process was stable under both hydrostatic and seepage conditions. The other advantages of the bio-gelation method include: (a) the massive formation of hydrogel can be controlled to be 28 h later after injection; (b) the pH value of the soil fluid can be maintained at neutral; and (c) it is cost-effective for liquefaction or seepage control for sand compared with other conventional methods.

Seepage failure of a foundation pit with confined aquifer layers and its reconstruction

Seepage control is one of the key issues for the design and construction of deep soil excavation projects. A seepage failure occurred around an abandoned pile in a foundation pit with confined aquifer layers, and caused damages to the retaining wall and support system and surrounding environment. The causes of the accident are analyzed, and the reconstruction of the project are introduced. The seepage failure was attributed to the defects in the three-axis mixing piles and the potential weak region created around the abandoned pile. It was finally controlled by filling the whole foundation pit with water. A systematic reinforcement of the foundation pit was carried out. The soil disturbed by the seepage failure was reinforced by two-shot process grouting and sleeve valve pipe grouting. The cast-in-place piles and prestressed assembled steel struts were constructed to strengthen the original retaining wall and support system. An ultra-deep (61.5 m) trench-cutting re-mixing deep wall (TRD) was successfully constructed in complex stratum, and showed good waterproof performance through a pumping test. After the formal dewatering inside the foundation pit by three stages, the project was successfully finished. This study could provide a wealth of experience and guidance for the design and construction of future similar deep excavation projects.