Grout Curtain Research Articles

A Comparative Analysis of Contaminant Migration Models Using Barrier Material Data

Waste containment facilities are often composed of barriers such as liners, grout curtains, and slurry walls. The primary design objective for such systems is to mitigate against the release and transport of contaminants. It is often necessary to quantify barrier effectiveness in order to conduct risk and exposure assessments. The extent to which a barrier material is effective can be assessed using analytical methods, laboratory testing, and field monitoring. Obviously, there is a great deal of time and expense associated with both laboratory and field monitoring, making modeling an attractive first alternative. There are, however, numerous solutions to the well-known advection-dispersion equation that vary in accuracy and applicability, depending on initial and boundary conditions. Moreover, most of the equations formulated for transport through porous media were developed for use in aquifer rather than barrier material. Prudent model selection involves matching the conditions to be analyzed with the appropriate mathematical description.In this article, five transport equations are analyzed and compared with laboratory results and projected field conditions for the migration of Pb2+ through soil-bentonite. After 30 days of continuous source injection, measurable concentrations of lead were only detected in the first 0.5 cm of a column of soil-bentonite. All five solutions predicted approximately the same level of penetration for the column tests; however, significant differences emerged after extrapolation to field conditions. For barrier design purposes, the only equations recommended are Equation 3 (the complete solution from Ogata and Banks [1961]) and Equation 6 (Crank's [1956] solution to Fick's Second Law).

A fluorescent approach to the identification of grout injected into fissures and pore spaces

A new fluorescent approach was developed to visualize grouting processes. The evaluation of the effect of grouting is carried out by methods based mainly on physical measurements such as permeability and porosity characteristics. However, these estimates do not necessarily correlate with practical grouting data. In this paper, the distributions of various grout mixtures containing fluorescent substances were clearly visualized under ultraviolet light, using a borehole television system or a microscope. Since this approach enabled direct observation of grout distribution, it is considered that this approach is useful for analysis of grouting mechanisms, designing grout curtains, etc.

An engineering geological appraisal of the Lakhwar Dam, Garhwal Himalaya, India

A 204 m high solid concrete gravity dam is proposed across the River Yamuna in Garhwal Himalaya, India. It will be located on dolerite rocks which have been intruded into the slates of Chandpur Formation. The present study includes the evaluation of the dam foundation by means of drifts, drill holes, water pressure tests and abutment slope stability studies. The water pressure test indicate the necessity of providing a grout curtain below the dam foundation. The analysis of the dam abutments for stability using the Limit equilibrium method indicates that the right abutment slope is kinematically unstable for plane failure mode. The plane failure analysis of the right abutment slope was carried out by modifying the Hoek and Bray (1981, Rock Slope Engineering, 3rd ed., Institute of Mining and Metallurgy, London) technique of plane failure analysis. The analysis reveals that right abutment slope may become unstable during the stripping operation. Based upon the analysis a safe cut slope design for the abutments have been suggested. Subsurface exploration by means of cross drift and drill holes has indicated a sheared contact of slate and dolerite in the foundation area. To avoid the settlement of the dam along this shear zone precautionary measures are suggested.

NUMERICAL SIMULATION OF GROUTING BY TWO GROUT ANALYSIS METHODS

本論文はグラウチングに対する二つの解析手法, モンテカルロシミュレーションを利用したフラクチャーネットワーク解析 (MSFN) とリアルタイムインバージョン解析 (RTIA) の妥当性を検証する. MSFNは所定の仕様のグラウチングによる改良効果を予測するもので, コンソリデーションとカーテングラウチングのシミュレーションの結果, 1) 注入圧-注入量関係, 2) ルジオン値の低下, 3) グラウト剤の流出, に関して実測データとある程度の一致をみた. RITAは計測された注入圧-注入量関係をもとにグラウト孔近くの水みちとグラウト剤到達距離を逆解析するもので, コンソリデーショングラウチングに対するシミュレーションを行った.

Denmark’s First Metro System

A new mass transit system, the Copenhagen Metro, has been planned to connect the central part of Copenhagen and ∅restad. The contract for the detailed design and construction of the first phase of the Copenhagen Metro was signed in October 1996. The construction of the tunnels and underground stations could affect the stability of buildings and lead to formations of cracks resulting in structural damage unless adequate precautions are taken during the design and execution of the works. The key element in the control of risk of settlement damage is to adopt construction methods that minimise the likelihood of significant ground movement. The requirements led to a design based on tunnelling with earth pressure balance tunnel-boring machines and underground station excavations within retaining walls of secant piles, protected by grout curtains and grout blankets.

The geological problems of the large dams constructed on the Euphrates River (Turkey)

In order to use the energy and irrigation potential of the Euphrates River, a series of dams have been designed (upstream to downstream); Keban, Karakaya, Karababa (Atatürk), Birecik and Karkamis. The first three of these dams have been completed; construction on the Birecik and Karkamis dams is underway. The initial plans involved a 60 m high Gölköy dam, downstream of the Karakaya dam, with the Atatürk dam 60 m lower than it is currently. In the belief that the cost of irrigation by the Atatürk dam's water would be high, the increase of the height of Atatürk dam was preferred to the construction of the Gölköy dam. The Keban dam's basement is formed by karstic rock, named Keban marble. From the author and his colleagues' studies, it has been shown that water would leak from the left side of Keban dam reservoir, forming a spring in the Keban Creek. In order to prevent this water leakage, an intensive grouting programme was applied. In spite of this, when the reservoir was filled, 26–30 m 3/s of water leaked from the Keban Creek. A more recent study on the volume of leakage showed it to be reduced to 7–8 m 3/s, with this amount remaining constant. The Karakaya dam is constructed on metamorphic rocks thus only allowing minimal water leakage. However, on the downstream side of the right slope, the Tillo–Bego–Senketo landslides have been an important risk to the dam. If such landslides cause an artifical lake by blocking the Euphrates River, the Karakaya hydroelectric power station could be flooded. Limestone forms the foundations for the Atatürk dam. On and around the damsite, there is epithermal water (24–26°C) below the aquifer, deeper than 300 m, with the level of the grouting curtain down to 180–200 m. The grouting curtain would not be able to prevent the leakage because the level of karstification extends below the grouting curtain. In February 1993, the total volume of leaking water from the damsite and its vicinity reached 10 m 3/s when the reservoir level was 517 m. When the reservoir is full (542 m), the volume of leaking water is expected to increase. Under the clay core of the dam, extending from the surface to 30–40 m depth, high grouting pressure could not be applied, so water leaked at this part of the grouting curtain and thus the amount of leaked water could not be measured.

The application of rock mass classification systems to underground excavation in weak limestone, Atatürk dam, Turkey

The Atatürk dam was built across the Firat River on clayey limestone. A grout curtain, providing impermeability in the left and right abutments, was done in grouting galleries. The well known rock mass classification systems for tunneling purposes [rock structure rating (RSR), rock mass rating (RMR) and rock mass quality index (Q)] were used to classify the rock mass along these galleries. Based on RSR, RMR and Q values, the rock masses in the galleries have been classified into three different classes. Correlation between the three classification systems is discussed and suggestions are made for using rockbolt, shotcrete with wiremesh and steel ribs for supporting the rock mass.

Remediation and monitoring of a burning coal refuse bank affecting the Southsea Looproad at Brymbo, North Wales

Southsea Looproad at Brymbo suffers large and varied settlements where the highway crosses a smouldering coal refuse bank. A sudden surge in combustion activity during 1991 resulted in considerable subsidence within the carriageway and posed recurring and persistent difficulties for road safety and highway maintenance. Initial investigations involved subsurface temperature measurements to delimit the hot spots and provide a basis for the design of remedial works. The aim of remediation was to extinguish the migrating fire in the outer loop area and to control the burning throughout the remaining areas. The principal strand of the remediation strategy involved excavating the burning coal refuse, cooling, mixing with pulverized fuel ash and compacting. Supplementary containment measures included limestone-filled cut-off trenches, cementitious grout curtains and impervious clay blankets. The works achieved the design objectives, however, small pockets of smouldering material remained within the inner loop. Subsequent monitoring of the site disclosed two markedly different patterns of temperature response on each side of the road. On the outer rim of the looproad temperature trends were steadily downwards in accordance with expectations and indeed reached ambient temperature within about one year. However, on the inside of the looproad seasonal surges in temperature have been recorded during winter months every year since the completion of the remedial works in 1993. The explanation for this unusual pattern of combustion activity is thought to be related to climatic effects and particularly the combined influence of rainfall, atmospheric pressure, air temperature and wind strength and direction. The relative contribution of these factors remains uncertain. Temperature monitoring continues in order to identify the eventual end of combustion activity and determine the appropriate time to complete reinstatement of the carriageway.

Seepage regime in the foundation of the Sayano-Shushenskoe dam during construction and operation

1. A tendency toward an increase of seepage discharges was observed in the dam foundation and bank abutments up to 1996, having reached 549 liters/sec in 1996 versus 240 liter/sec in 1990 and 190 liters/sec expected according to the design. This indicated the development of decompression of the foundation and grout curtain. 2. After repair works with the use of cement grouts at low upper pool levels, positive changes in the seepage regime did not occur: the hydraulic connection between holes along cracks both with and across the flow remains intact; the tendency toward an increase of discharges and heads behind the grout curtain remains. 3. When designating the technology of carrying out the grouting works and materials for subsequent repair operations, it is necessary to take into account the characteristics of the seepage state of the foundation: the amount of opening of the cracks in the foundation, the high seepage velocities, the active reaction to any external actions on the structure, the communication and hydraulic connection between local stretches of the foundation.

Condition of the Sayano-Shushenskoe Dam Foundation in the zone of decompression under the first columns

1. The characteristics of the design of the Sayano-Shushenskoe gravity-arch dam, exacerbated by lagging in the construction of the fourth columns of the structure, predetermined the formation of the decompression zone of the rock foundation under the first two columns with disturbance of the work of the grout curtain in it. 2. To reduce the uplift pressure and seepage discharges in the No. 1 gallery of the dam, it is planned in the near future to inject nontraditional materials into the decompression zone of the foundation which can withstand a high pressure and have good adhesion. The requirements imposed on the properties of the material and grouting technology will be worked out on experimental sections of the dam. 3. On the basis of calculations it is possible to establish the optimal range of the UPL and boundaries of the zones of conducting grouting works to minimize the negative effects of the latter on the stress-strain state of the dam.

Lightweight low profile sound wall panel

Decreased weight, improved sound transmission loss, and maintained sound absorption and durability are all achieved by a highway barrier incorporating a new acoustic barrier panel. The panel remains of the type suitable for being forms, in combinations of multiple panels and multiple, earth-anchored or structure-mounted support posts, into sound barrier walls for use along highways, other rights of way, and the like. The invented acoustic barrier panel comprises a sandwich of slabs. The sandwich comprises a central slab, a first, outer slab sandwich alongside the central slab, and a second, outer slab sandwiched alongside the central slab, opposite the first outer slab. Uniquely, a first grout curtain is interposed between and joins the central slab and the first, outer slab, while a second grout curtain is interposed between and joins the central slab and the second, outer slab. As most preferred, all slabs constitute Durisol™ wood concrete. Welded wire mesh or galvanized welded wire fabric or geotextile fabric or geogrid or other synthetic or metallic reinforcement may reinforce the panels. With panel thicknesses ranging from two and three quarter inches to seven inches, panel weights have been found to be in the range of eighteen to forty pounds per square foot (PSF). At least one known, current highway project specification requires a panel weight of less than twenty PSF and a sound transmission loss of at least twenty-three dB. A prototype panel as invented with a two and three quarter inch thickness has exhibited a weight of nineteen PSF and a sound transmission loss of twenty-eight dB. Sound transmission loss across the panel as invented has been a minimum of twenty-eight dB at all frequencies while loss across past and other panels has been much less.

An Integrated Method of Engineering Geological Mapping for Large Foundation Excavations: The Katse Arch Dam Experience, Lesotho Highlands

A method for mapping the steep foundation excavation of the Katse Arch Dam during construction is presented. The method is practical, adaptable and efficient, and field experience confirms that it overcomes problems often encountered with detailed mapping of large, steeply inclined, geometrically complex, foundation surfaces. The method accommodates on-going mapping activities with the progress of excavation and alleviates the problem of time constraints and limited access often experienced on sites. It involves setting out a 5 m-grid pattern of reference points directly on excavation faces as they become exposed. The reference points are then surveyed and located by elevation and the horizontal coordinate system of the project. Each differently orientated cut-slope surface, called a slope element, is treated as a separate entity. The reference points in an element are projected using the Pythagorean theorem onto a base map in the plane of the element, and the geology is then mapped relative to the plotted reference points providing a view that is always normal to a surface of the element. Mapping in the plane of the element permits accurate and detailed spatial location of discontinuities and lithologies as well as the gathering of appropriate geotechnical data needed for a) slope stability evaluations and support requirements, b) assessments of rock mass conditions for founding, and c) optimum orientation of grout holes. Because of the continually increasing expanse of the foundation excavation towards the river section, each slope element is identified based on its position with respect to the river, the dam center line, and 10 m elevation intervals. Slope elements are further divided into sub-elements in order to facilitate the mapping and tabulation of structural and geotechnical information. Entities of mapping completed in this way are then pieced together to produce composite maps to give the final “as built” record for the foundation excavation. A plan-view projection of prominent geologic data shown on the base maps is ultimately prepared, so that geologic contacts and traces of the major discontinuity sets can be presented on a plan view at a smaller scale. Geologic data presented in this way are very useful for slope and dam stability analyses and for designing optimal orientations for drilling during consolidation and curtain grouting operations.

Seepage and antiseepage measures in foundations of hydraulic structures

1. Rock foundations of dams are inhomogeneous water-bearing systems, seepage in them has a complex and nonuniform character; for substantiating antiseepage measures the seepage model of foundations maximally corresponding to real conditions can be represented in the form of a three-dimensional piecewise-homogeneous model consisting of a number of structurally homogeneous fragments cut by systems of water-conducting fractures (zones) and confining interlayers. 2. The effective thickness of grout curtains on average is equal to 10–12 m, in zones of large-scale fracturing of the rocks — up to 20 m and more; the head gradients in the grout curtains do not exceed 10–18; the effectiveness of grout curtains depends substantially on the permeability of the surrounding rocks, and therefore the role which the grout curtain and drainage play under particular conditions is different. 3. The actual diagrams of uplift pressure in the foundations of many operating structures are below the design and standard ones. Under favorable hydrogeologic conditions a reduction of the heads by the watertight grout curtain and drainage in rock foundations of structures is not difficult and can be provided to values considerably less than the standard ones according to SNiP. A generalized diagram of the seepage heads is recommended for calculating the stability of dams on rock foundations in the presence of a grout curtain and drainage. 4. Watertight curtains made by the diaphragm wall method have a high effectiveness and economy. Their filler should be selected with consideration of the properties of the surrouding soils, SSS, and seepage strength of the foundation and diaphragm wall.

Grout curtain of barrier structures at the Vilyui III hydroelectric station

1. The possibility of creating a grout curtain to a depth of more than 50 m in perennially frozen soils of an argillaceous-carbonate complex with their preliminary electrical thawing was proved for the first time in hydrotechnical construction practice on an experimental field fragment. This achievement made it possible to construct barrier structures on perennially frozen foundation soils having very large settlements and unprovided piping stability after thawing. 2. To provide a stable operating mode of resistance-type electric heaters in rocks saturated with highly mineralized ground waters, it is necessary that the design of the electric heaters minimize leakage currents. If this requirement is not fulfilled, the process of electrical thawing of soils becomes poorly controllable and long, and its economic indices worsen. 3. For an objective evaluation of the degree of corrosiveness of the water-ground system with respect to the grout curtain and also for determining the necessary means of protecting it from corrosion by groundwaters, the development of a special standard is required.

A Simulation Model Solved the Problem of Scheduling Drilling Rigs at Clyde Dam

The Clyde Dam in New Zealand is located in an area more unstable than was thought when it was designed. Therefore, Electricorp has taken additional precautions to ensure the stability of the hillsides surrounding it, constructing an underground grout curtain of 1,362 meters along the Clutha River. A grout curtain is constructed by drilling holes in the rock and injecting concrete into them. With a budget of millions of dollars for hiring drilling rigs, the construction company wanted to minimize the idling time of the drilling rigs and finish the project quickly. We developed a simulation model that enabled it to find an efficient drilling schedule, saving about NZ$580,000 on hiring costs for drilling rigs (seven percent of drilling hours hired) and 10 weeks (about 26 percent of project completion time).

An engineering geological appraisal of the Jamrani Dam Site, across the Gaula river in Kumaun Himalaya, India

A 130-m high dam is under construction across the River Gaula in Outer Kumaun Himalaya, India. It is located on Lower Siwalik rocks consisting of sandstone, siltstone and claystone. The present studies include the evaluation of the dam foundation by water pressure and grouting tests. The water pressure tests indicate the necessity to provide a grout curtain below the dam foundation. The grouting tests indicate that the rocks are amenable to grouting. The analyses of the dam abutments for stability using graphical and vector methods have indicated that the abutments may become unstable during foundation stripping.

SITE CHARACTERIZATION AND CONTAINMENT/REMEDIATION OF ACID MINE DRAINAGE AT AN ABANDONED MINE WASTE DUMP

This paper focuses on the preliminary results of laboratory tests to evaluate a new suspension grout consisting of a mixture of a naturally occurring lignite coal based wax {open_quotes}montan wax{close_quotes}, sodium bentonite {open_quotes}pure gold grout{close_quotes}, and water. The test program assesses the suitability of the grout for creating subsurface containment barriers in coal waste dump sites for acid mine seepage control to surface and ground waters. The laboratory activities evaluated the reduction in permeability that could be achieved in a coal waste dump site under optimum conditions and the compatibility of the grout with representative waste from the test site. Information on geological, geochemical and geophysical about the test site is presented. Laboratory formulation of the grout is complete and simulation of field condition is in progress. Pregrout geophysical surveys for determination of hydrogeologic conditions at the site are also completed. Based on geophysical surveys, a grout curtain is proposed which will consist of two rows of grout placement holes in an array across the seepage area toward Belt Creek in Montana, Post-grout geophysical survey will be carried out immediately after grouting work. Performance of the grout curtain will be monitored by collection of water samples from monitoring wells inmore » the Belt Creek and seepage area.« less

ROADFORD RESERVOIR: DESIGN, CONSTRUCTION AND PERFORMANCE.

Roadford reservoir, the largest in South-West England, forms a major element in the water resources of South West Water Roadford Dam is formed of 1 000 000 m 3 of material, largely rockfill, and has an asphaltic concrete membrane on it upstream face. Extensive ground and material investigations were undertaken in advance of the design of the embankment. The reinforced concrete draw-off tower and the bellmouth overflows were partly constructed by slipform methods. A concrete cut-off located at the upstream toe is extended to a depth of 40m by a grout curtain. Construction began early in 1987 and was substantially complete by October 1989 when reservoir impoundment began.

Grouting through a river : J. A. Morrison, R. J. Switalski, T. R. Scotese & R. J. Essex, Civil Engineering — ASCE, 65(2), 1995, pp 60–63

A regional sewer district in Ohio is implementing a master plan to separate storm and sanitary flows, decommission some old treatment plants and upgrade others. Part of the plan, the West Leg Interceptor, called for a gravity sewer tunnel 4 ft under a sensitive river. Engineers studied cut and cover approaches and decided that because the river is subject to turbulent storm flows, a tunnel boring machine was the better way to construct the 78 inch diameter tunnel. Because of the host rock, Berea sandstone, with its widely spaced bedding planes and near-vertical joints, a grout curtain was placed before tunneling. Engineers first placed a 5 ft concrete cap in the flowing river, then grouted through it. The operation under the river was successful. However, there were excessive inflows at the next stage of the project, and sand and silt got into the boring machine.

95/03285 Smotherfly opencast coal

Kier Mining was awarded the Smotherfly opencast coal contract by British Coal in March 1993 and the project, is recover 1.6 Mt of coal, will be completed in June 1999. Smotherfly is, in geological (being a plunging anticline) and mining terms, a relatively conventional British opencast site. However, it is the environmental challenges which make the project noteworthy. Large areas of industrial dereliction from old ironstone and coal working, a clay pipe works and acid and tar works are being restored and made safe. Work includes the installation of a grout curtain to prevent groundwater contamination of the River Erewash, the containment acid and tar wastes in specially engineered cells and the construction of a water treatment plant on the site. 5 photos.