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Modern construction sites are associated with high demands on suitable soil conditions, resulting in geotechnical challenges that can be solved using soil stabilisation techniques. The reliability of these techniques is tested using different quality assurance methods. One of the most common ground stabilisation methods is jet injection and installation of jet grouted columns. Quality control (QC) methods are necessary to ensure that the jet grouted columns meet requirements. One critical geometric property to be controlled is the radius. Traditional QC methods are expensive and invasive. An alternative quality assurance method, electrical resistivity tomography (ERT), has been tested as part of this study. The results show that ERT has good potential as a QC method of jet grouted columns. However, the handling of measured ERT data from jet grouted columns need to be improved and handled in a software that takes the cylindrical geometry to account. The installation of the jet grouted columns involves mixing the in-situ soil with cement slurry, which is then injected with a high-pressure jet to create a ground stabilising column. The high-pressure injection can lead to significant variations of radius across column depth. The aim of the thesis is to test how well the quality of the columns are reflected by the measured data and inverted models in the alternative software (AarhusInv)? The ERT method is a geophysical method used to image the subsurface via measuring the subsurface resistivity. By inducing electrical current into the ground and measuring the potential differences the resistivity can be calculated. The method could be used on jet stabilised columns as a QC by measuring the resistivity contrast between the stabilised column and the surrounding soil. The result of this potential QC could indicate the column radius. The data, synthetic ERT data was generated and processed using forward modelling. Different kinds of jet grouted column geometries were simulat, Modern construction sites have high demands on soil conditions, resulting in geotechnical challenges that can be solved using soil stabilisation techniques. The reliability of these techniques is tested using different quality assurance methods. One of the most common ground-stabilizing methods is jet injection. This method involves mixing the in-situ soil with cement slurry, which is then injected with a high-pressure jet to create a ground stabilising column. To ensure that the jet grouted columns meet the designed loads, quality control methods are necessary. One critical geometric property to be controlled in jet grouted columns is the radius, as high-pressure injection can lead to significant variations with depth. The purpose of this study was to test an alternative quality assurance method by using electrical resistivity tomography (ERT). ERT has shown potential as a quality assurance method for jet columns, but the handling of the measured data needed to be improved and handle in a program that takes the cylindrical geometry to account. In this study, synthetic ERT data was generated and processed, simulating different kind of jet grouted columns. In addition, ERT field data from a test site in Moss, Norway was processed. To interpret the measurement results, the “apparent” resistivity was converted into “true” resistivity, by considering the cylindrical geometry. The used inversion program was AarhusInv. The synthetic data series with varying cylindrical geometries were generated using forward modeling to test the program. The synthetic data sets were subjected to different levels of noise, and inversions were performed on the models with and without noise. The inversion of the synthetic and measured data was carried out using two different models: a few-ring model and a multi-ring model. The results from the inversion of the field data were compared with inversions performed on the same data using the programs Res2DInv and pyGIMLi. The conclusion is that t

The Golubac Fortress was built at the very entrance of the Iron Gates gorge, at the point where the Danube is the widest in its course and transitions into the narrow passage of the Carpathian Mountains. The fortress represented an important medieval military border stronghold, strategically constructed due to the military significance of the location. Because of its position, during the 14th and 15th centuries, bordering countries, Hungary and Serbia, and later the Ottoman Empire, fought to conquer the Golubac Fortress in order to gain control and power over the state border. There are no exact records of who and when initially built the Golubac Fortress. The first mention in written sources is from the year 1335, in a Hungarian charter from 1337, which states that the nobleman Nikola Banfi resided in Golubac in 1335. Until the dissolution of the Dušan’s Empire, Golubac Fortress status remains unchanged according to historical sources, and it remains in Hungarian possession. At the beginning of the 21st century, the town of Golubac was in very poor condition, neglected and inaccessible. Reconstruction of the entire Golubac Fortress began in 2011. The reconstruction was officially completed in 2019. However, some minor reconstruction and revitalization work is still ongoing today. The foundation of the Golubac Fortress was adapted to the terrain's configuration and consists of 9 towers connected by the ramparts and the Palace. As part of the restoration efforts, all the towers, ramparts, and the Palace were reconstructed. The paper depicts the reconstruction of the entire Palace, including its foundations and a new roof structure made of glued laminated timber.

Jet grouting is one of the most popular soil improvement techniques, but its design usually involves great uncertainties that can lead to economic cost overruns in construction projects. The high dispersion in the properties of the improved material leads to designers assuming a conservative, arbitrary and unjustified strength, which is even sometimes subjected to the results of the test fields. The present paper presents an approach for prediction of the uniaxial compressive strength (UCS) of jet grouting columns based on the analysis of several machine learning algorithms on a database of 854 results mainly collected from different research papers. The selected machine learning model (extremely randomized trees) relates the soil type and various parameters of the technique to the value of the compressive strength. Despite the complex mechanism that surrounds the jet grouting process, evidenced by the high dispersion and low correlation of the variables studied, the trained model allows to optimally predict the values of compressive strength with a significant improvement with respect to the existing works. Consequently, this work proposes for the first time a reliable and easily applicable approach for estimation of the compressive strength of jet grouting columns.

This master thesis has investigated the performance of a deep excavation with a jet grout bottom plug used to prevent bottom heave and hydraulic uplift failure. The concept of a jet grout plug as a structural and sealing component in a specific case was studied, namely one of the tunnel sections of The West Link tunnel project in Gothenburg. The section was to be built as a cut-and-cover tunnel with the excavation shaft consisting of secant pile walls, struts and a jet grout bottom plug. It is to be established where there are a lot of sensitive buildings and constructions close to the excavation site. This makes it important not to disturb the surroundings during construction with, for example, settlements.The study was carried out by doing a literature study, analytical calculations and numerical simulations in the finite element software PLAXIS 2D. More specifically, the checks evaluated were uplift equilibrium of the jet grout plug and of the whole structure, structural performance of the jet grouted plug and hydraulic conductivity of the jet grouted mass.The results show a design of a jet grout plug that together with the additional structures works sufficiently enough to make a secure construction for a deep excavation below the ground water table. The structural performance of the jet grouted plug to function as a strut level is fulfilled even if the jet grout is not perfectly performed. To work as a sealing component the jet grout column pattern and the centre-to-centre distance between the columns are important factors together with the alignment and diameter of the jet grout columns. To make a completely watertight construction is however almost impossible in this case since the jet grout plug is located at a large depth (around 20 m). To work properly against failure by uplift it does not need to be completely watertight. Instead, the use of relief wells makes sure that the pore water pressure is not larger than the vertical stress from the soil, otherwis

This master thesis has investigated the performance of a deep excavation with a jet grout bottom plug used to prevent bottom heave and hydraulic uplift failure. The concept of a jet grout plug as a structural and sealing component in a specific case was studied, namely one of the tunnel sections of The West Link tunnel project in Gothenburg. The section was to be built as a cut-and-cover tunnel with the excavation shaft consisting of secant pile walls, struts and a jet grout bottom plug. It is to be established where there are a lot of sensitive buildings and constructions close to the excavation site. This makes it important not to disturb the surroundings during construction with, for example, settlements.The study was carried out by doing a literature study, analytical calculations and numerical simulations in the finite element software PLAXIS 2D. More specifically, the checks evaluated were uplift equilibrium of the jet grout plug and of the whole structure, structural performance of the jet grouted plug and hydraulic conductivity of the jet grouted mass.The results show a design of a jet grout plug that together with the additional structures works sufficiently enough to make a secure construction for a deep excavation below the ground water table. The structural performance of the jet grouted plug to function as a strut level is fulfilled even if the jet grout is not perfectly performed. To work as a sealing component the jet grout column pattern and the centre-to-centre distance between the columns are important factors together with the alignment and diameter of the jet grout columns. To make a completely watertight construction is however almost impossible in this case since the jet grout plug is located at a large depth (around 20 m). To work properly against failure by uplift it does not need to be completely watertight. Instead, the use of relief wells makes sure that the pore water pressure is not larger than the vertical stress from the soil, otherwis

With the increased urbanization major cities are facing, expansion of larger facilities and households are inevitable. Expansion means larger areas of the surface needs to be used where the risk of varying subsurface soil properties increases with larger surface areas. This can result in soil properties that might not be stable enough to support these constructions. A potential solution to solve this problem is the soil improvement method of jet grouting. Jet grouting is a versatile soil improvement method used for various geotechnical aspects in construction projects worldwide. By eroding and mix in-situ soil with fluid binders from a high-pressure jet, improved geotechnical properties of the soil body could be achieved. When achieving the desired stability of the column it is crucial that the geometry and homogeneity correlates with the preliminary design standards. Thereby, quality controls are routinely performed on the column however, existing quality controls vary in methodology efficiency as well as the level of accuracy obtained from the controls. The thesis therefore aspired to find and compare an alternative quality control to the existing quality controls based on Electrical Resistivity Tomography (ERT) practice. ERT is a geophysical measuring technique for determining the electric properties of the subsurface. This technique consists of placing electrodes in contact with a specific medium and inject current via the electrodes to create an electric potential field. The electrodes will then measure the potential differences of the potential field which are translated to resistivity properties of the medium. In this thesis a composed cable consisted of electrode cables and temperature sensors were inserted into a freshly produced test column. By injecting current the potential differences in the column and the surrounding soil were measured and the apparent resistivity properties of the underground could be determined. The measurements were performed at dif, Med den ökade urbaniseringen som de flesta städer står inför, är utbyggnad av större anläggningar och hushåll oundviklig. Denna expansion medför ett behov av mer tillgänglig markyta att bygga på, vilket även innebär att platser med varierande markförhållandena behöver utnyttjas. Detta kan resultera i att markegenskaperna inte alltid är passande för stora anläggningar. En lösning till detta problem är att stabilisera marken med den så kallade jetinjekterings-metoden. Jetinjektering är en mångsidig markförbättringsmetod som används för olika geotekniska aspekter i byggprojekt världen över. Genom att erodera marken och blanda cementslurry tillsammans med den befintliga jorden på platsen med hjälp av en högtrycksstråle, bildas en pelare som förbättrar markförhållandet. Vid tillverkningen av en jet-pelare är det viktigt att geometrin och homogeniteten stämmer överens med den förbestämda standarden. Därför genomförs kvalitetskontroller på pelarna för att säkerhetsställa detta. De befintliga kvalitetskontrollerna varierar i metodisk effektivitet samt i nivå av noggrannhet. Syftet med denna rapport är därför att undersöka en alternativ kvalitetskontroll som utförs med hjälp av ERT-mätningar (Electric Resistivity Tomography), samt att jämföra denna metod med de befintliga kvalitetskontrollerna. ERT är en geofysisk undersökningsmetod som mäter de elektriska egenskaperna i marken. Metoden går ut på att placera ut elektroder i kontakt med ett specifikt medium och via dessa elektroder injicera ström som skapar ett elektriskt potentialfält. Elektroderna mäter sedan potentialskillnaden i potentialfältet som omvandlas till resistivitetsegenskaper hos mediet. I detta projekt fördes en kabel med elektroder och temperatursensorer ner i en nyproducerad kolumn. Genom att injicera ström i kolumnen och den omkringliggande jorden, kunde potentialskillnaden i potentialfältet som skapades bestämmas. Denna process gjordes vid flera tillfällen för att kunna studera härdningsprocessen. Med denn, With the increased urbanization major cities are facing, additional structures must be constructed on the ground surface which need sufficient soil strength to be built upon. But with more land used for constructing on, the risk of variable soil conditions increases, and sufficient soil strength becomes more uncertain. One solution to this problem is jet grouting, which is a versatile soil improvement method that radially injects cement slurry in a pre-drilled borehole to erode and mix in-situ soil that forms a stabilized underground column. The most important aspects of achieving desirable properties of the column are the homogeneity of the grout mixture and the diameter of the column, but this can be difficult to inspect without a quality control that intrudes on the surrounding soil. Therefore, can a less intrusive quality control be used for quality assuring jet grouting columns specifically within Electrical Resistivity Tomography (ERT) -practice, and is it comparable with existing quality controls? The underground soil can consist of different layers which inherit certain resistances towards eroding and mixing. This can affect how far the injected grout will penetrate radially into each soil layer, causing the diameter of the column to be varied. Discontinuous column diameter can severely compromise the intended column properties. By routinely performing quality controls on jet grout columns, the column diameter and the homogeneity of the grout mixture can be estimated. However, existing quality controls differ in accuracy and credibility which is why this thesis’ purpose was to investigate if an alternative quality control could be developed using ERT. ERT is a geophysical measuring method that measures the resistivity distribution of the underground by injecting current through electrodes in contact with a material. By applying this method into jet grout columns, the expectation of finding a resistivity contrast between the treated volume and the surrounding

Uno de los grandes retos en el campo de la ingeniería geológica y geotécnica ha sido emplazar obras de ingeniería sobre terrenos que no garantizan la estabilidad de estas. Una posible solución para mejorar las propiedades físicas y mecánicas de estos terrenos es utilizar la técnica de Jet Grouting. Esta técnica implica una perforación inicial a una profundidad predeterminada, seguida de la inyección de un agente cementante mediante un chorro de alta velocidad durante la maniobra de rotación ascendente. Esta corriente erosiona y remodela la matriz del suelo, creando una columna con características mejoradas. Para el diseño de la mayoría de obras mediante esta técnica, la resistencia a la compresión uniaxial es probablemente el parámetro mecánico más importante, pues gobierna la resistencia y la deformabilidad del tratamiento. El propósito general de este trabajo fin de máster, ha sido adquirir un conocimiento profundo sobre la resistencia a la compresión uniaxial que ofrecen las columnas realizadas mediante la técnica del Jet Grouting, especialmente en lo relacionado con su predicción a nivel de diseño. Para lograr este objetivo, se realizó una revisión minuciosa sobre el estado del arte de la técnica y especialmente del parámetro mencionado, seguido de una extensa recopilación de datos que obtuvo 938 registros de resistencia a la compresión, distribuidos por todo el mundo, los cuales fueron recolectados principalmente de publicaciones de revistas científicas. En dicha búsqueda, también fueron recogidos datos relativos a las propiedades del terreno, al agente cementante y a parámetros propios de ejecución de la técnica. Estos datos fueron agrupados por tipo de Jet y textura del suelo; posteriormente, se realizó un estudio estadístico sobre los mismos, que permitió conocer sus características y establecer relaciones entre ellos. Partiendo de los resultados del análisis estadístico de los datos, se han estudiado diversos modelos matemáticos a partir de regresiones no l

Дисертація присвячена обґрунтуванню раціональних технологічних параметрів струменевої цементації в складних геотехнічних умовах. В роботі досліджено та встановлено взаємозв’язки технологічних параметрів струменевої цементації з діаметром ґрунтоцементної колони в різних типах ґрунтів. На основі отриманих експоненціальних залежностей діаметра ґрунтоцементного елементу круглого перерізу від енергії високонапірного струменя цементного розчину розроблено методику розрахунку діаметра струменево-цементаційної колони. В процесі дослідження експериментальним шляхом доведено змінення фізико-механічних властивостей ґрунту, що оточує ґрунтоцементний елемент під час його виконання за струменевою технологією. На підставі математичного моделювання визначено закономірності формування в ґрунтових масивах зон з поліпшеними фізико-механічними параметрами в міжколонному просторі в різних типах ґрунтів. Удосконалено методику комп’ютерного моделювання управління напружено-деформованим станом основи будівлі під час її підсилення струменево-цементаційними елементами з урахуванням складних геотехнічних умов.

Дисертація присвячена обґрунтуванню раціональних технологічних параметрів струменевої цементації в складних геотехнічних умовах. В роботі досліджено та встановлено взаємозв’язки технологічних параметрів струменевої цементації з діаметром ґрунтоцементної колони в різних типах ґрунтів. На основі отриманих експоненціальних залежностей діаметра ґрунтоцементного елементу круглого перерізу від енергії високонапірного струменя цементного розчину розроблено методику розрахунку діаметра струменево-цементаційної колони. В процесі дослідження експериментальним шляхом доведено змінення фізико-механічних властивостей ґрунту, що оточує ґрунтоцементний елемент під час його виконання за струменевою технологією. На підставі математичного моделювання визначено закономірності формування в ґрунтових масивах зон з поліпшеними фізико-механічними параметрами в міжколонному просторі в різних типах ґрунтів. Удосконалено методику комп’ютерного моделювання управління напружено-деформованим станом основи будівлі під час її підсилення струменево-цементаційними елементами з урахуванням складних геотехнічних умов., The dissertation is devoted to substantiation of rational technological parameters of jet grouting in difficult geotechnical conditions. Analysis of previous studies of jet grouting technology has shown that despite the fact that the technology began its development in the 70s of last century, there are still many issues to be explored: the relationship of technological parameters with the characteristics of the soil-cement array, the impact of technological processes on the soil environment, etc. In the course of work the current state of the normative base concerning designing and execution of soil-cement elements on jet technology is analyzed. It is noted that today on the territory of Ukraine there are almost no regulations that determine the procedure for calculation, design and implementation of jet-grouted elements. Based on the experimental data the relationship between the technological parameters of jet grouting and the diameter of the soil-cement column in different types of soils is investigated and established. The experimental data are divided according to the type of soils - incoherent and cohesive: sand and gravel, sandy loam and loam. The dependences of the lifting speed on the diameter of the soil-cement column were obtained, which not only generalize the relationship between the geometric characteristics of the soil-cement column and the technological parameter, but also facilitate the approach to choosing the operating parameters of the drilling tool. The next obtained dependence is the exponential dependence of the jet energy on the obtained column diameter, on the basis of which a method of determining the column diameter depending on soil type, jet pressure, lifting speed of the hydromonitor and cement solution consumption was developed. Comparative calculations were performed on the basis of completed construction projects, which, in turn, made it possible to introduce correction factors for soil conditions in Ukraine. The change of physical, Диссертация посвящена обоснованию рациональных технологических параметров струйной цементации в сложных геотехнических условиях. В работе исследованы и установлены взаимосвязи технологических параметров струйной цементации с диаметром грунтоцементной колонны в различных типах грунтов. На основе полученных экспоненциальных зависимостей диаметра грунтоцементного элемента круглого сечения от энергии высоконапорной струи цементного раствора разработана методика расчета диаметра струйно-цементационной колонны. В процессе исследования экспериментальным путем доказано изменение физико-механических свойств грунтов, окружающих грунтоцементный элемент, во время его выполнения по струйной технологии. На основании математического моделирования определены закономерности формирования в грунтовых массивах зон с улучшенными физико-механическими параметрами в межколонном пространстве в различных типах грунтов. Усовершенствована методика компьютерного моделирования управления напряженно-деформированным состоянием основания здания во время его усиления струйно-цементационными элементами с учетом сложных геотехнических условий.

This article proposed a new method to estimate the diameter of jet grouting columns. The method uses the largest data collection of column diameters measured to date and includes a large amount of new data that fills the existing gap of data for high injection energies. The dataset was analysed using a deep neural network that took into account the problem’s key parameters (i.e. type of soil, soil resistance, type of jet and specific energy in the nozzle). As a result, three different neural networks were selected, one for each type of jet, according to the errors and consistency associated with each. Finally, using the trained networks, a number of design charts were developed to determine the diameter of a jet grouting column as a function of the soil properties and the jet system. These charts allow generating an optimal jet grouting design, improving the prediction of the diameter of jet columns especially in the high energy triple fluid.

This paper describes an approach for predicting the diameter of a jet-grout column using the support vector regression (SVR) technique, which is regarded as a novel learning machine based upon recent advances in statistical theory, in which the combined effects of the construction (construction methods and jetting parameters) and soil properties (soil type and shearing resistance) are considered. Four different kernel functions, namely, a linear kernel function, polynomial kernel function, radial basis kernel function, and sigmoid kernel function, are integrated into the SVR technique. A large amount of field measured data on the diameter of jet-grout column are retrieved from the published literature for training and testing purposes. The results indicate that the SVR technique with a radial basis kernel function provides predictions closest to the measured results, whereas the prepared design charts enable the ability to significantly widen the application of the proposed approach to the areas of ground improvement and environmental protection.

This paper describes an approach for predicting the diameter of a jet-grout column using the support vector regression (SVR) technique, which is regarded as a novel learning machine based upon recent advances in statistical theory, in which the combined effects of the construction (construction methods and jetting parameters) and soil properties (soil type and shearing resistance) are considered. Four different kernel functions, namely, a linear kernel function, polynomial kernel function, radial basis kernel function, and sigmoid kernel function, are integrated into the SVR technique. A large amount of field measured data on the diameter of jet-grout column are retrieved from the published literature for training and testing purposes. The results indicate that the SVR technique with a radial basis kernel function provides predictions closest to the measured results, whereas the prepared design charts enable the ability to significantly widen the application of the proposed approach to the areas of ground improvement and environmental protection.

This article proposed a new method to estimate the diameter of jet grouting columns. The method uses the largest data collection of column diameters measured to date and includes a large amount of new data that fills the existing gap of data for high injection energies. The dataset was analysed using a deep neural network that took into account the problem’s key parameters (i.e. type of soil, soil resistance, type of jet and specific energy in the nozzle). As a result, three different neural networks were selected, one for each type of jet, according to the errors and consistency associated with each. Finally, using the trained networks, a number of design charts were developed to determine the diameter of a jet grouting column as a function of the soil properties and the jet system. These charts allow generating an optimal jet grouting design, improving the prediction of the diameter of jet columns especially in the high energy triple fluid.

This paper presents the structural rehabilitation and stabilization of Tower 11 of Smederevo fortress. The tower is tilted for about 1.8 m towards its outer edge, that is, towards the surrounding vertical walls that it was connected to. As a part of the structural rehabilitation and stabilization of Tower 11, it is planned to improve the soil properties with jet grouting columns and to secure tower’s foundations, as well as to rehabilitate its parts above the ground. After completion of these works, conservation and restoration of the tower can begin.

This paper presents the structural rehabilitation and stabilization of Tower 11 of Smederevo fortress. The tower is tilted for about 1.8 m towards its outer edge, that is, towards the surrounding vertical walls that it was connected to. As a part of the structural rehabilitation and stabilization of Tower 11, it is planned to improve the soil properties with jet grouting columns and to secure tower’s foundations, as well as to rehabilitate its parts above the ground. After completion of these works, conservation and restoration of the tower can begin.

The existence of a layer of hard boulders up to 1 m in size within the soft sediments of the Holocene Llobregat delta in the SW of Barcelona city caused the damage and stoppage of the EPB-type tunnel boring machine that excavated the subway L10 line. This layer constitutes a detrital deposit of exceptionally large grain size developed in the base of the delta. It originated as an alluvial fan in the northern margin of the delta during the last fall of the Mediterranean Sea level, at the end of the Pleistocene period. The subsequent sea level rise (Holocene transgression) caused the flooding of this alluvial fan and the reworking of its materials by sea waves. Thereby a retrogradant boulder beach developed, in which the largest rock fragments of the former alluvial fan remained densely packed. The tunnel boring machine precisely collided with the main boulder concentration area of this ancient beach. The cutter tools and the structure of the cutterhead were seriously affected. The repair tasks required the excavation of a mine in the tunnel face under atmospheric pressure and a sealing and stable environment. To get these conditions a jet grouting block from the surface was performed to consolidate the deltaic sediments around the tunnel face. Additional TAM injections were carried out to improve some deficiencies in the sealing of the block. Subsequently the shield of the tunnel boring machine was embedded into the block and the water table was depressed by pumping wells. After 13 months of complicated works, the tunnel boring machine resumed the excavation encountering further problems. Although the layer of boulders was early identified by the geological and geotechnical studies of the L10 constructive project, its precise geological characteristics and potential adverse influence on tunnelling was then not valued in depth. A better knowledge of the geology of this layer would have been helpful in order to foresee the incident and propose alternatives., Peer Reviewed, Postprint (published version)

The contracts, for part of the Hong Kong rail link, include the excavation of 4 single track tunnels and 18 associated cross passages around 250 m apart. These lie in completely decomposed granite (CDG), moderately decomposed granite (MDG) or a mixture of both. The TBMs selected have a diameter of 9.33 m and use slurry technology. The precast segments for the linings were manufactured with concrete grade C55, traditionally reinforced and sized to provide a ring with an internal diameter of 8.15 m, thickness of 400 mm and a nominal ring length of 1 800 mm. 3D structural models were used to analyse the performance of the segmental lining during cross passage excavations to study the status of loading and restraints of the full rings. Ground treatment was carried out prior to excavation to limit groundwater flow, reduce the seepage pressures into the cross passages, and ensure a stable face. Jet grouting was also used in the CDG. Extensive temporary steel frames were used in places to support the segmental linings during excavation of the cross passages. Monitoring during construction showed that the lining performed better than expected, with deformations from 0 to 5 mm., The contracts, for part of the Hong Kong rail link, include the excavation of 4 single track tunnels and 18 associated cross passages around 250 m apart. These lie in completely decomposed granite (CDG), moderately decomposed granite (MDG) or a mixture of both. The TBMs selected have a diameter of 9.33 m and use slurry technology. The precast segments for the linings were manufactured with concrete grade C55, traditionally reinforced and sized to provide a ring with an internal diameter of 8.15 m, thickness of 400 mm and a nominal ring length of 1 800 mm. 3D structural models were used to analyse the performance of the segmental lining during cross passage excavations to study the status of loading and restraints of the full rings. Ground treatment was carried out prior to excavation to limit groundwater flow, reduce the seepage pressures into the cross passages, and ensure a stable face. Jet grouting was also used in the CDG. Extensive temporary steel frames were used in places to support the segmental linings during excavation of the cross passages. Monitoring during construction showed that the lining performed better than expected, with deformations from 0 to 5 mm.

Research on strengthening the soil with cement and the construction of foundations from soil–cement are conducted by various scientists: Y. L. Vinnikov, N. L. Zotsenko, A. N. Tokin et al. The first experience of using soil–cement in foundation engineering in the USSR belongs to the mid 50 th top 60 th. Using the methods of mixing the local soils with binder made it possible to actually get a new building material. Soil–cement in construction is used to improve the bearing capacity for foundation, reducing the deformability of the weak and the structural — unstable soils, and building foundations. Soil–cement elements are performed by two methods: wet soil–mixing method and dry soil mixing method, the choice of which depends on the soil conditions and specifications of the project. There is a combined method of deep soil mixing, which has the ability to transition between the supplying of the dry binder and injecting the slurry at certain depths. This versatility allows to effectively mixing the layered soils and solves the problem of the presence of local changes in soil moisture sites.For the production of soil–cement various technological devices are used:- jet grouting. To produce soil–cement elements the jet grouting working with the tool for the formation of pile is the jet monitor nozzles from which a jet of water or cement slurry under pressure up to 70 MPa is supplied;- drilling–mixing cementation. The essence of drilling–mixing technology is to produce jet–grouting columns using drilling–mixing instrument consisting of a hollow rod and a special working tool;- jet–grouting mixing cementation. Mechanical mixing with the additional use of the jet energy.Mass soil stabilization is a relatively new method of improving the construction properties of weak soils, which may be performed to a depth of 5 m. The mixing process differs from other methods so that binder material is supplied to the mixer while the mixer is rotating and simultaneously

La subsidencia es un término que hace referencia al hundimiento a largo plazo de la corteza terrestre, ya sea continental o submarina. Este fenómeno se desarrolla en una gran área originando daños en cualquier infraestructura asentada sobre el terreno que se deforma. La construcción de la primera línea del metro de Bogotá beneficiara a la población de la ciudad, sin embargo es de especial cuidado el daño que puede causar a las estructuras superficiales ya que la deformación que se puede presentar en el terreno se transmite a las estructuras afectando la estabilidad de estas.

La subsidencia es un término que hace referencia al hundimiento a largo plazo de la corteza terrestre, ya sea continental o submarina. Este fenómeno se desarrolla en una gran área originando daños en cualquier infraestructura asentada sobre el terreno que se deforma. La construcción de la primera línea del metro de Bogotá beneficiara a la población de la ciudad, sin embargo es de especial cuidado el daño que puede causar a las estructuras superficiales ya que la deformación que se puede presentar en el terreno se transmite a las estructuras afectando la estabilidad de estas.

La subsidencia es un término que hace referencia al hundimiento a largo plazo de la corteza terrestre, ya sea continental o submarina. Este fenómeno se desarrolla en una gran área originando daños en cualquier infraestructura asentada sobre el terreno que se deforma. La construcción de la primera línea del metro de Bogotá beneficiara a la población de la ciudad, sin embargo es de especial cuidado el daño que puede causar a las estructuras superficiales ya que la deformación que se puede presentar en el terreno se transmite a las estructuras afectando la estabilidad de estas.

La subsidencia es un término que hace referencia al hundimiento a largo plazo de la corteza terrestre, ya sea continental o submarina. Este fenómeno se desarrolla en una gran área originando daños en cualquier infraestructura asentada sobre el terreno que se deforma. La construcción de la primera línea del metro de Bogotá beneficiara a la población de la ciudad, sin embargo es de especial cuidado el daño que puede causar a las estructuras superficiales ya que la deformación que se puede presentar en el terreno se transmite a las estructuras afectando la estabilidad de estas.

La subsidencia es un término que hace referencia al hundimiento a largo plazo de la corteza terrestre, ya sea continental o submarina. Este fenómeno se desarrolla en una gran área originando daños en cualquier infraestructura asentada sobre el terreno que se deforma. La construcción de la primera línea del metro de Bogotá beneficiara a la población de la ciudad, sin embargo es de especial cuidado el daño que puede causar a las estructuras superficiales ya que la deformación que se puede presentar en el terreno se transmite a las estructuras afectando la estabilidad de estas.

La subsidencia es un término que hace referencia al hundimiento a largo plazo de la corteza terrestre, ya sea continental o submarina. Este fenómeno se desarrolla en una gran área originando daños en cualquier infraestructura asentada sobre el terreno que se deforma. La construcción de la primera línea del metro de Bogotá beneficiara a la población de la ciudad, sin embargo es de especial cuidado el daño que puede causar a las estructuras superficiales ya que la deformación que se puede presentar en el terreno se transmite a las estructuras afectando la estabilidad de estas.

A framework for the study of the jet-grouting hydration reaction and of the associated thermo-hydro-mechanical and chemical (THMC) interactions with the surrounding soils has been developed. In this work, we summarize the basic formulation that may be used for the simulation of such interactions, including references to the balance equations governing the problem, to the release of heat during the curing of the jet-grouted mass, to the TMC behaviour of such material and to the THM behaviour of the surrounding soil. The approach presented falls within the framework of plasticity for saturated soils, and it has been implemented within a FEM code for the study of the potential effects of the THMC couplings associated to jet-grouting treatments. The results obtained with this program validate it as a proper tool for the systematic analysis of a number of questions of interest in engineering practice, allowing the assessment, among others, of the following issues: magnitude and rate of production of the thermo-plastic settlements caused by the heat release associated to the installation of jet-grouted columns in the soil; effects of the release of the hydration heat on the hydraulic conditions in the surrounding soil; effects of the boundary conditions, the relative position of the jet-grouted zones and its sequence of installation on the rate of increase of the stiffness and strength associated to the curing of the jet-grouted zones; effects of those factors on the impact of the heat release on the surrounding soils., Postprint (published version)

Jet grouting is adopted in different geotechnical conditions to ensure provisional earth retaining and waterproofing functions at the bottom and walls of excavations. Despite careful theoretical models avail-able to predict the mechanical response of these structures, design is often carried out without adequate con-trol, i.e. by assuming ideal effectiveness of ground improvement. On the contrary, adverse effects have been documented by past experiences which can be traced back to erroneous prediction of treatments effects, inac-curate control of the execution or to unexpected responses of the surrounding environment. All these uncertainties, which become particularly critical when excavation is performed in urbanized areas, can be mini-mized by detailed preliminary field trials, accurate controls of the execution of treatments and a prompt monitoring of the surrounding area. The present paper describes this methodology applied to the design and the execution of a massive jet grouting bottom plug forming the base of a large excavation in city environment. The results of preliminary field trials are summarized to directly compare the effectiveness of different injection systems and introduced in statistical design analyses of the jet grouted structure. A detailed investigation of the movements induced at ground level by injections is also reported. To this aim, the evolution of displacements recorded around trial columns and on the area surrounding the excavation is mapped to evaluate the effects of the different adopted injection techniques., Postprint (published version)

The Singapore mass rapid transit project involved the excavation of twin-tube tunnels each 1 000 m long and 6 m in diameter using an open face shield under compressed air through a thick deposit of soft marine clay under a busy road with tall and old buildings alongside. Jet grouting was employed for ground treatment to ensure the integrity of the buildings and involved the pumping cement grout into the ground under a pressure of 20-50 MPa. Under the high pressure the subsoil undergoes deformation and ground surface heave can occur if the sludge is not brought to the surface correctly. The grouting resulted in damage to service utilities along the road and to the surface finish of buildings in the vicinity. A number of methods for controlling heave were employed including the use of different sizes and lengths of casing, drill bits with different configurations and relief holes, increasing the withdrawal rate of the jet grout monitor during grouting, pre-cutting the marine clay and the use of small angle grouting. Stabilisation of the fill layer above the soft marine clay prior to jet grouting and control of sludge density were also carried out. Fast withdrawal rate of the jet grout monitors reduced heave as a smaller quantity of grout was injected, but the withdrawal rate has to be controlled to ensure that the required grouted soil thickness and strength were obtained. Pre-cutting of the marine clay resulted in the creation of voids in the clay which helped to increase the volume and displacement in the soil during grouting, and the sludge was also diluted and sludge flow enhanced. Small angle grouting resulted in easier sludge flow and less heave., The Singapore mass rapid transit project involved the excavation of twin-tube tunnels each 1 000 m long and 6 m in diameter using an open face shield under compressed air through a thick deposit of soft marine clay under a busy road with tall and old buildings alongside. Jet grouting was employed for ground treatment to ensure the integrity of the buildings and involved the pumping cement grout into the ground under a pressure of 20-50 MPa. Under the high pressure the subsoil undergoes deformation and ground surface heave can occur if the sludge is not brought to the surface correctly. The grouting resulted in damage to service utilities along the road and to the surface finish of buildings in the vicinity. A number of methods for controlling heave were employed including the use of different sizes and lengths of casing, drill bits with different configurations and relief holes, increasing the withdrawal rate of the jet grout monitor during grouting, pre-cutting the marine clay and the use of small angle grouting. Stabilisation of the fill layer above the soft marine clay prior to jet grouting and control of sludge density were also carried out. Fast withdrawal rate of the jet grout monitors reduced heave as a smaller quantity of grout was injected, but the withdrawal rate has to be controlled to ensure that the required grouted soil thickness and strength were obtained. Pre-cutting of the marine clay resulted in the creation of voids in the clay which helped to increase the volume and displacement in the soil during grouting, and the sludge was also diluted and sludge flow enhanced. Small angle grouting resulted in easier sludge flow and less heave.

The treatment characteristics, quality control measures and outcomes of two different jet-grout based soil treatments are described in detail. In the first one, a jet-grouted slab was built to limit retaining wall movements in a cut-and-cover tunnel. Quality control relied on borehole core quality assessment and laboratory testing. Core quality was very sensitive to coring practices. The strength and stiffness of the jet-grouted slab were deemed adequate and the structure successfully contributed to minimal wall movements. In the second case, a jet-grouted treatment was designed to provide strengthening and impermeabilization around a tunnel excavated on silty sands below the water table and underneath another tunnel. Control was based on extensive coring, cross-hole seismic surveys and permeability tests. The results were generally favourable and where defects were detected, reparation was undertaken. However, in spite of all those actions, a number of deficiencies escaped detection and only became apparent during the excavation of the tunnel resulting in significant construction problems./ /Les caractéristiques de traitements, les mesures de contrôle de qualité et les résultats de deux différents traitements de sol par jet grouting sont expliqués en détail. Dans l’un d’entre eux, on a construit une plaque par jet grouting pour limiter les mouvements des parois de soutènement d’une tranchée recouverte. Le contrôle de qualité s’appuyait sur l’évaluation de la qualité des carottes de sondage et des tests de laboratoire. La qualité des carottes était très sensible à la méthodologie de forage. La résistance et la rigidité de la plaque par jet grouting ont été considérées adéquates et la structure a contribué avec succès à limiter les mouvements de parois. Dans l’autre cas, un traitement par jet grouting a été conçu pour renforcer et imperméabiliser la zone autour d’un tunnel excavé dans des sables limoneux plus bas que le niveau phréatique et en-dessous d’un autre tunn, Peer Reviewed, Postprint (published version)

The use is discussed of various pre-support techniques in combination with NATM for shallow tunnelling using case studies including tunnels for the Washington metro, USA, the Victoria underground station upgrade and Kings Cross underground station redevelopment in London, UK, the Dulles International Airport busway tunnels in Boston, USA, and the Fort Canning road tunnel in Singapore. In all of the projects tunnelling involved using pre-supports adapted to prevailing ground conditions. Methods included the use of complete ground modification by means of ground freezing in running ground, systematic cementing of generally cohesionless soil by means of jet grouting and the application of steel pipe arches and forepoling elements which were grouted in place. In the case of steel pipe arches the ground must have a certain amount of in situ strength. The pipe arch acts as soil reinforcement, enhances standup time, provides a structural system that longitudinally bridges over the round being excavated and arches radially around the tunnel opening. It limits overbreak and settlements and is a further element of risk control. If the ground conditions are suitable the settlement and risk control properties of grouted steel pipe-arch systems can be achieved at a reasonable cost., The use is discussed of various pre-support techniques in combination with NATM for shallow tunnelling using case studies including tunnels for the Washington metro, USA, the Victoria underground station upgrade and Kings Cross underground station redevelopment in London, UK, the Dulles International Airport busway tunnels in Boston, USA, and the Fort Canning road tunnel in Singapore. In all of the projects tunnelling involved using pre-supports adapted to prevailing ground conditions. Methods included the use of complete ground modification by means of ground freezing in running ground, systematic cementing of generally cohesionless soil by means of jet grouting and the application of steel pipe arches and forepoling elements which were grouted in place. In the case of steel pipe arches the ground must have a certain amount of in situ strength. The pipe arch acts as soil reinforcement, enhances standup time, provides a structural system that longitudinally bridges over the round being excavated and arches radially around the tunnel opening. It limits overbreak and settlements and is a further element of risk control. If the ground conditions are suitable the settlement and risk control properties of grouted steel pipe-arch systems can be achieved at a reasonable cost.

Appropriate seals, portal ground improvement and compatible shaft construction techniques are vital elements for launching and receiving tunnels effectively in urban areas where adjacent property requires protection from excess ground movements. The seals, ground improvement and shaft wall types are discussed that are required to launch or receive tunnel boring machines within wet, permeable ground at the portal zone. The use of probing is considered to verify suitability before the tunnel eye is cut. Methods described include rubber gasket seals, soft eyes, double walls, top hats for reception and portal zone ground improvement including permeation grouting, jet grouting, unreinforced slurry diaphragm wall panels, ground freezing, deep soil mixing, dewatering and over-excavation and backfilling. The launch and reception of pressurised- face TBMs with precast concrete segment linings are also described., Appropriate seals, portal ground improvement and compatible shaft construction techniques are vital elements for launching and receiving tunnels effectively in urban areas where adjacent property requires protection from excess ground movements. The seals, ground improvement and shaft wall types are discussed that are required to launch or receive tunnel boring machines within wet, permeable ground at the portal zone. The use of probing is considered to verify suitability before the tunnel eye is cut. Methods described include rubber gasket seals, soft eyes, double walls, top hats for reception and portal zone ground improvement including permeation grouting, jet grouting, unreinforced slurry diaphragm wall panels, ground freezing, deep soil mixing, dewatering and over-excavation and backfilling. The launch and reception of pressurised- face TBMs with precast concrete segment linings are also described.

The construction is described of the York-Durham sewage system interceptor tunnel project in Richmond Hill, Ontario, Canada. Construction commenced in September 2006 and completion is planned for early summer 2008. Construction methods used were open-cut where the water table lies below the trench invert, tunnelling with a pressurised- face tunnel boring machine (EPB or slurry shield technology) for tunnel sections on 19th Avenue and Leslie Street, and sealed shaft construction. The methods used minimised dewatering and the sealed shafts were constructed with jet grouted break-in and -out blocks so that the EPB mode could be maintained by the tunnel boring machine during shaft entry and exit. Environmental concerns were focused on cold-water fish habitats that either the tunnel passed under or were to be used for discharge of maintenance water. One particular zone involved the crossing of two creeks flowing along either side of Bayview Avenue. The creeks were located in an area of loosely consolidated fill overlying a thin till cap and groundwater was artesian. A compromise was reached involving limited air injection to the ground conditioning equipment, combined with continuous mitigation measures to minimise turbidity from silt carried into the creek by air bubbles., The construction is described of the York-Durham sewage system interceptor tunnel project in Richmond Hill, Ontario, Canada. Construction commenced in September 2006 and completion is planned for early summer 2008. Construction methods used were open-cut where the water table lies below the trench invert, tunnelling with a pressurised- face tunnel boring machine (EPB or slurry shield technology) for tunnel sections on 19th Avenue and Leslie Street, and sealed shaft construction. The methods used minimised dewatering and the sealed shafts were constructed with jet grouted break-in and -out blocks so that the EPB mode could be maintained by the tunnel boring machine during shaft entry and exit. Environmental concerns were focused on cold-water fish habitats that either the tunnel passed under or were to be used for discharge of maintenance water. One particular zone involved the crossing of two creeks flowing along either side of Bayview Avenue. The creeks were located in an area of loosely consolidated fill overlying a thin till cap and groundwater was artesian. A compromise was reached involving limited air injection to the ground conditioning equipment, combined with continuous mitigation measures to minimise turbidity from silt carried into the creek by air bubbles.

The St. Kuzam tunnel on the D8 road in Croatia is a twin-tube road tunnel excavated through flysch and limestone. About 30m of the tunnel caved in whilst excavating from carbonate rock through to non-degraded and weakly-degraded siltstone. For subsequent excavation in this zone jet grouting was used. It has been established by means of boreholes and laboratory testing that jet grouting produced a new, relatively homogenous material with significantly improved properties. Numerical back analysis has also been carried out on the excavation and lining support system based on measurements of ground movement around the underground opening. The results, together with geotechnical measurements and monitoring, have contributed to a better understanding of rock mass behaviour and properties, and can be used in design of the primary support system, to predict progress and to estimate stand-up time of unsupported spans. Using the numerical analysis it was shown that the jet grouting improved the ground stiffness by factors of 4.31 to 5.03., The St. Kuzam tunnel on the D8 road in Croatia is a twin-tube road tunnel excavated through flysch and limestone. About 30m of the tunnel caved in whilst excavating from carbonate rock through to non-degraded and weakly-degraded siltstone. For subsequent excavation in this zone jet grouting was used. It has been established by means of boreholes and laboratory testing that jet grouting produced a new, relatively homogenous material with significantly improved properties. Numerical back analysis has also been carried out on the excavation and lining support system based on measurements of ground movement around the underground opening. The results, together with geotechnical measurements and monitoring, have contributed to a better understanding of rock mass behaviour and properties, and can be used in design of the primary support system, to predict progress and to estimate stand-up time of unsupported spans. Using the numerical analysis it was shown that the jet grouting improved the ground stiffness by factors of 4.31 to 5.03.

Removal of contaminated soil underneath existing structures causes settlement. There is a need for a remediation technology that eliminates this problem. The jet grouting by the triple rod system can be combined with an on site remediation technology (e.g., soil washing). Jet grouting was developed primarily for underpinning and/or excavation support. The benefits of this technology lie in the future reduction of structural settlement, and site access flexibility.

Removal of contaminated soil underneath existing structures causes settlement. There is a need for a remediation technology that eliminates this problem. The jet grouting by the triple rod system can be combined with an on site remediation technology (e.g., soil washing). Jet grouting was developed primarily for underpinning and/or excavation support. The benefits of this technology lie in the future reduction of structural settlement, and site access flexibility.

A review is presented of methods and materials for controlling ground stability and combating instability and collapses in tunnelling. Permeation grouting can be used to aid in the formation of a secure enclosure of frozen ground, and developments in chemical or solution grouts have improved the efficiency of permeation grouting in fine- grained ground or small fissures. Hot bitumen grouting has been used in projects such as the Yung-Chung railway tunnel in Taiwan. Canopies and umbrellas can be used in advance of a soft or mixed ground excavation and jet grouting can be applied for the creation of piles and other reinforcement. Other methods include the use of diaphragm walls and trenching grabs. The former have been used in the underground transport hub which is part of the reconstruction of New York's World Trade Center, and the Amsterdam North-South metro line. The use of cuttable elements for face reinforcement is described, and the development of glass- reinforced plastic elements and fibre-reinforced plastic products is reviewed. Rock bolt systems are discussed, and the use of multiple methods is illustrated with reference to the construction of the Naples Metro Line 1., A review is presented of methods and materials for controlling ground stability and combating instability and collapses in tunnelling. Permeation grouting can be used to aid in the formation of a secure enclosure of frozen ground, and developments in chemical or solution grouts have improved the efficiency of permeation grouting in fine- grained ground or small fissures. Hot bitumen grouting has been used in projects such as the Yung-Chung railway tunnel in Taiwan. Canopies and umbrellas can be used in advance of a soft or mixed ground excavation and jet grouting can be applied for the creation of piles and other reinforcement. Other methods include the use of diaphragm walls and trenching grabs. The former have been used in the underground transport hub which is part of the reconstruction of New York's World Trade Center, and the Amsterdam North-South metro line. The use of cuttable elements for face reinforcement is described, and the development of glass- reinforced plastic elements and fibre-reinforced plastic products is reviewed. Rock bolt systems are discussed, and the use of multiple methods is illustrated with reference to the construction of the Naples Metro Line 1.

Water control in tunnel projects is discussed. Temporary control methods to deal with excess groundwater flows or pressure during construction include the use of shield tunnelling machines, groundwater lowering, ground freezing and compressed air working. Permeation grouting can contribute to long-term water control as well as ground stability during construction. Curtain walling methods such as jet grouting and slurry walls may help reduce water flow and may be incorporated into the final structure. The selection of grouting material is discussed and new technologies described, including the use of bacteria to enhance grout properties. Unlined, hard-rock road tunnels such as the Seymour Capilano water-supply twin tunnel in Vancouver require grouting to reduce inflows, mainly from fracture zones, and insulation boards may be used on road tunnels in northern regions. A heavy-gauge corrugated liner plate was used in the renovated Anton Anderson Memorial Tunnel in Alaska. Developments in concrete formulations are discussed and the use of plastic membranes described, including sprayed membranes., Water control in tunnel projects is discussed. Temporary control methods to deal with excess groundwater flows or pressure during construction include the use of shield tunnelling machines, groundwater lowering, ground freezing and compressed air working. Permeation grouting can contribute to long-term water control as well as ground stability during construction. Curtain walling methods such as jet grouting and slurry walls may help reduce water flow and may be incorporated into the final structure. The selection of grouting material is discussed and new technologies described, including the use of bacteria to enhance grout properties. Unlined, hard-rock road tunnels such as the Seymour Capilano water-supply twin tunnel in Vancouver require grouting to reduce inflows, mainly from fracture zones, and insulation boards may be used on road tunnels in northern regions. A heavy-gauge corrugated liner plate was used in the renovated Anton Anderson Memorial Tunnel in Alaska. Developments in concrete formulations are discussed and the use of plastic membranes described, including sprayed membranes.

Removal of contaminated soil underneath existing structures causes settlement. There is a need for a remediation technology that eliminates this problem. The jet grouting by the triple rod system can be combined with an on site remediation technology (e.g., soil washing). Jet grouting was developed primarily for underpinning and/or excavation support. The benefits of this technology lie in the future reduction of structural settlement, and site access flexibility.

Removal of contaminated soil underneath existing structures causes settlement. There is a need for a remediation technology that eliminates this problem. The jet grouting by the triple rod system can be combined with an on site remediation technology (e.g., soil washing). Jet grouting was developed primarily for underpinning and/or excavation support. The benefits of this technology lie in the future reduction of structural settlement, and site access flexibility.

Removal of contaminated soil underneath existing structures causes settlement. There is a need for a remediation technology that eliminates this problem. The jet grouting by the triple rod system can be combined with an on site remediation technology (e.g., soil washing). Jet grouting was developed primarily for underpinning and/or excavation support. The benefits of this technology lie in the future reduction of structural settlement, and site access flexibility.

Papers are presented in the following sections: European keynote papers (4 papers); British Tunnelling Society (3 papers); Pipejacking innovation (4 papers); Tunnelling case studies (4 papers); Tunnel planning, design and construction processes (4 papers); Tunnelling for utilities I and II (7 papers); Safety and risk management I and II (7 papers); Piling and anchorages - design and performance (3 papers); Pile behaviour, specification and testing (3 papers); Underground space design I and II (6 papers); Box jacking (3 papers); Practical aspects of tunnelling I and II (9 papers); Soil improvement case histories (3 papers); Piling and reinforced wall case histories (3 papers); and Effects of tunnelling (4 papers). There are author and subject indexes, as well as exhibitors' contact details., Papers are presented in the following sections: European keynote papers (4 papers); British Tunnelling Society (3 papers); Pipejacking innovation (4 papers); Tunnelling case studies (4 papers); Tunnel planning, design and construction processes (4 papers); Tunnelling for utilities I and II (7 papers); Safety and risk management I and II (7 papers); Piling and anchorages - design and performance (3 papers); Pile behaviour, specification and testing (3 papers); Underground space design I and II (6 papers); Box jacking (3 papers); Practical aspects of tunnelling I and II (9 papers); Soil improvement case histories (3 papers); Piling and reinforced wall case histories (3 papers); and Effects of tunnelling (4 papers). There are author and subject indexes, as well as exhibitors' contact details.

The project, in Manhattan, New York, involved the excavation and replacement of 750 m of deteriorated invert concrete, 5-7 m below the water table in very permeable ground, while maintaining track service through this section of the subway. The area was dewatered with a single 125 l/s wellpoint system, which was installed from inside the active tunnel structure and configured to coexist with operating trains as well as the construction activities. A thin jet-grouted diaphragm wall was utilised at one end of the site to cut off the flow of the water across a difficult geological interface that was situated immediately below the tunnel invert. The entire 116th Street Station area could then be dewatered completely with wellpoints from outside the excavation., The project, in Manhattan, New York, involved the excavation and replacement of 750 m of deteriorated invert concrete, 5-7 m below the water table in very permeable ground, while maintaining track service through this section of the subway. The area was dewatered with a single 125 l/s wellpoint system, which was installed from inside the active tunnel structure and configured to coexist with operating trains as well as the construction activities. A thin jet-grouted diaphragm wall was utilised at one end of the site to cut off the flow of the water across a difficult geological interface that was situated immediately below the tunnel invert. The entire 116th Street Station area could then be dewatered completely with wellpoints from outside the excavation.

To accommodate double-stack freight through two railway tunnels at the Tilford yard in Atlanta, Georgia, the existing tracks had to be lowered. Removal of the concrete base support would have jeopardised the integrity of the elliptical, horseshoe-shaped tunnels, particularly as the soils beneath part of the tunnel floor included soft, saturated silt overlying rock. Grouted bar anchors combined with a SuperJet soilcrete strut were used to replace the existing support in situ prior to floor lowering. Close co-operation and timely detailed engineering support resulted in a quality project., To accommodate double-stack freight through two railway tunnels at the Tilford yard in Atlanta, Georgia, the existing tracks had to be lowered. Removal of the concrete base support would have jeopardised the integrity of the elliptical, horseshoe-shaped tunnels, particularly as the soils beneath part of the tunnel floor included soft, saturated silt overlying rock. Grouted bar anchors combined with a SuperJet soilcrete strut were used to replace the existing support in situ prior to floor lowering. Close co-operation and timely detailed engineering support resulted in a quality project.

Initially it was planned to route the St Gothard Base Tunnel of the Alptransit project through the Piora syncline, a metamorphic sedimentary formation of sugary or saccharoidal dolomite at high hydrostatic pressure. Detailed site investigations have since realigned the tunnel to avoid the syncline but the potential solutions considered are presented. The techniques used for drilling and cementation under high pressure (up to 20 MPa) in the deep mines of South Africa were investigated. Techniques to cope with cohesionless and alluvial materials include grouting techniques, high pressure jetting or jet grouting, and slurry trenching. Cement diffusion with low-density slurries and possibly microfine cement or crystallisation grouting should stabilise the dolomite in order to allow effective core drilling and define the critical zones. An appendix outlines cover grouting., Initially it was planned to route the St Gothard Base Tunnel of the Alptransit project through the Piora syncline, a metamorphic sedimentary formation of sugary or saccharoidal dolomite at high hydrostatic pressure. Detailed site investigations have since realigned the tunnel to avoid the syncline but the potential solutions considered are presented. The techniques used for drilling and cementation under high pressure (up to 20 MPa) in the deep mines of South Africa were investigated. Techniques to cope with cohesionless and alluvial materials include grouting techniques, high pressure jetting or jet grouting, and slurry trenching. Cement diffusion with low-density slurries and possibly microfine cement or crystallisation grouting should stabilise the dolomite in order to allow effective core drilling and define the critical zones. An appendix outlines cover grouting.

SuperJet grouting uses opposing injection nozzles, sheathed by compressed air, to create columns of soil-based concrete up to 5 m in diameter. Holes are drilled to the required depth and a mixture of air and cement slurry injected at high velocity in step increments, with the drill rods slowly rotating. The method has been successfully used for a cut-and-cover highway tunnel in New Jersey and has many potential applications for soft ground tunnelling and microtunnelling., SuperJet grouting uses opposing injection nozzles, sheathed by compressed air, to create columns of soil-based concrete up to 5 m in diameter. Holes are drilled to the required depth and a mixture of air and cement slurry injected at high velocity in step increments, with the drill rods slowly rotating. The method has been successfully used for a cut-and-cover highway tunnel in New Jersey and has many potential applications for soft ground tunnelling and microtunnelling.

The research projects in this cluster, from the European Commission Industrial and Materials Technologies Programme (BRITE-EURAM III), cover an extremely wide range of activities but all aim to encourage and promote the developments urgently needed to meet future requirements, by creating awareness, exchanging ideas, disseminating and applying results, and defining and pursuing the most urgent needs in new fields. The following reports are presented: Improvement of the capabilities of cutting tools and cutting systems for hard-rock conditions (ICACUTROC), by Akerman J., Gerer R., Lammer E. and Siebenhofer G., p.99-114; OSIS - tools for fire simulation in underground, by Sence M.O. and Reichenauer X. , p.115-127; Smart tunnel boring machine, by Deguine M., de Broissia M. et al., p.129-159, 78 refs.; Computer-integrated road construction, by Carrel A. et al., p.161-176, 5 refs.; Marine pollution in the Black Sea due to mining activities - risk assessment, development of preventive and remedial action, by Paspaliaris I., Komnitsas K., Lazar I., Groudev S., Cambridge M. and Hallett C., p.177-189, 6 refs.; Innovative industrial technologies for the rehabilitation of land contaminated from polymetallic sulphide mining and processing operations (ROLCOSMOS), by Paspaliaris I. et al., p.191-215, 42 refs.; Navigational jet grouting (NAVIJET), by Evers G., Puller D.J., Douglas G., Geropp B., Petit E. and Hassen F.H., p.217-223; Electrical disintegration of rock (paper not included); Modelling, prediction and prevention of the impact of mine effluents on river water quality using artificial neural networks (RIVERMOD), by Durucan S., Korre A. and Imrie C., p.227-244, 7 refs.; and Rehabilitation and revegetation of mining waste-dumps by the use of industrial and domestic sewage sludges from waste-water purification plants, by Repmann F., p.245-254, 1 ref. Reference is made to wastes at Navodari, Vromos Bay, Lavrion and Monte Vecchio., The research projects in this cluster, from the European Commission Industrial and Materials Technologies Programme (BRITE-EURAM III), cover an extremely wide range of activities but all aim to encourage and promote the developments urgently needed to meet future requirements, by creating awareness, exchanging ideas, disseminating and applying results, and defining and pursuing the most urgent needs in new fields. The following reports are presented: Improvement of the capabilities of cutting tools and cutting systems for hard-rock conditions (ICACUTROC), by Akerman J., Gerer R., Lammer E. and Siebenhofer G., p.99-114; OSIS - tools for fire simulation in underground, by Sence M.O. and Reichenauer X. , p.115-127; Smart tunnel boring machine, by Deguine M., de Broissia M. et al., p.129-159, 78 refs.; Computer-integrated road construction, by Carrel A. et al., p.161-176, 5 refs.; Marine pollution in the Black Sea due to mining activities - risk assessment, development of preventive and remedial action, by Paspaliaris I., Komnitsas K., Lazar I., Groudev S., Cambridge M. and Hallett C., p.177-189, 6 refs.; Innovative industrial technologies for the rehabilitation of land contaminated from polymetallic sulphide mining and processing operations (ROLCOSMOS), by Paspaliaris I. et al., p.191-215, 42 refs.; Navigational jet grouting (NAVIJET), by Evers G., Puller D.J., Douglas G., Geropp B., Petit E. and Hassen F.H., p.217-223; Electrical disintegration of rock (paper not included); Modelling, prediction and prevention of the impact of mine effluents on river water quality using artificial neural networks (RIVERMOD), by Durucan S., Korre A. and Imrie C., p.227-244, 7 refs.; and Rehabilitation and revegetation of mining waste-dumps by the use of industrial and domestic sewage sludges from waste-water purification plants, by Repmann F., p.245-254, 1 ref. Reference is made to wastes at Navodari, Vromos Bay, Lavrion and Monte Vecchio.

The volume is intended as a reference book for students, engineers, consultants and contractors, covering the principles of grout mix design, rheology and strength, theoretical and experimental developments, grouting plants and their specifications, geological investigations, field drilling techniques, compaction grouting, and monitoring of grouting, along with case studies on the grouting of dams, tunnels and other structures. The principles of grouting are demonstrated mainly through examples derived from field studies. The second edition includes new chapters on jet grouting and on the performance of new microfine grouts, while the essence of the old chapter on rheology has been included in the chapters on cement-based coarse grouts and chemical-based fine grouts. A list of about 540 references is provided., The volume is intended as a reference book for students, engineers, consultants and contractors, covering the principles of grout mix design, rheology and strength, theoretical and experimental developments, grouting plants and their specifications, geological investigations, field drilling techniques, compaction grouting, and monitoring of grouting, along with case studies on the grouting of dams, tunnels and other structures. The principles of grouting are demonstrated mainly through examples derived from field studies. The second edition includes new chapters on jet grouting and on the performance of new microfine grouts, while the essence of the old chapter on rheology has been included in the chapters on cement-based coarse grouts and chemical-based fine grouts. A list of about 540 references is provided.

Microtunnelling was specified for 3 400 feet of 24 inch pipeline to be installed through estuarine soil deposits (the soft and weak San Francisco Bay Mud) and alluvium beneath downtown Martinez, in California. Directional drilling was specified for 900 feet of 8 inch diameter pipeline in four separate segments to be drilled through bedrock within narrow utility easements between houses. Significant aspects of the microtunnelling included the choice of pipe under railway tracks and at other locations, shaft location and drive length, ground treatment by jet grouting in soil volumes potentially affected by a planned new railway track, special lightweight backfilling of manholes and shafts, jacking forces, bearing capacity of the Bay Mud for the microtunnelling TBM, slurry loss to soil and hydrofracturing, and shaft construction and support. The main concern in directional drilling was to keep the drill in as consistent a subsurface material as possible, and drilling from a pit was utilised. In order to keep the hole as clean as possible, double reaming was specified., Microtunnelling was specified for 3 400 feet of 24 inch pipeline to be installed through estuarine soil deposits (the soft and weak San Francisco Bay Mud) and alluvium beneath downtown Martinez, in California. Directional drilling was specified for 900 feet of 8 inch diameter pipeline in four separate segments to be drilled through bedrock within narrow utility easements between houses. Significant aspects of the microtunnelling included the choice of pipe under railway tracks and at other locations, shaft location and drive length, ground treatment by jet grouting in soil volumes potentially affected by a planned new railway track, special lightweight backfilling of manholes and shafts, jacking forces, bearing capacity of the Bay Mud for the microtunnelling TBM, slurry loss to soil and hydrofracturing, and shaft construction and support. The main concern in directional drilling was to keep the drill in as consistent a subsurface material as possible, and drilling from a pit was utilised. In order to keep the hole as clean as possible, double reaming was specified.

The Central Artery/Tunnel highway project in Boston, Massachusetts, has featured a number of ground improvement techniques. The present paper describes the use of deep soil mixing and jet grouting as applied extensively on several of the project contracts. In one of these, at Bird Island Flats, deep soil mixing was used to form buttresses to hold back an excavation support wall that had experienced large deformations during excavation. The success of this in resisting further lateral movements allowed more complex applications to be employed subsequently elsewhere. In all, over 600 000 m3 of soil cement are being formed by deep mixing and jet grouting for a variety of applications, the principal of which is the resisting of unbalanced lateral loads on tunnel structures along the Fort Point Channel. In the North Station area, a proposed mined tunnel option, which was not chosen for construction, incorporated an interesting and innovative means of improving ground stability prior to tunnelling: a cement bentonite wall formed by jet grouting in conjunction with passive construction dewatering., The Central Artery/Tunnel highway project in Boston, Massachusetts, has featured a number of ground improvement techniques. The present paper describes the use of deep soil mixing and jet grouting as applied extensively on several of the project contracts. In one of these, at Bird Island Flats, deep soil mixing was used to form buttresses to hold back an excavation support wall that had experienced large deformations during excavation. The success of this in resisting further lateral movements allowed more complex applications to be employed subsequently elsewhere. In all, over 600 000 m3 of soil cement are being formed by deep mixing and jet grouting for a variety of applications, the principal of which is the resisting of unbalanced lateral loads on tunnel structures along the Fort Point Channel. In the North Station area, a proposed mined tunnel option, which was not chosen for construction, incorporated an interesting and innovative means of improving ground stability prior to tunnelling: a cement bentonite wall formed by jet grouting in conjunction with passive construction dewatering.