PERFORMANCE OF TWO TIEBACK WALLS AND ROCK ANCHORS IN A SHALE STRATUM

Tieback walls are typically design based on predetermined pressure distribution; however, these pressures were proposed based on performance of excavations. For retaining walls used in slope remediation, the application of these pressures might not be adequate; the construction procedure; therefore, a different response of the wall is expected. This document, presents the performance of two tieback walls installed in a shale stratum. Monitored responses is correlated with construction activities; these activates implied excavation and backfilling in both of the tieback walls. In addition, this research shows a numerical procedure to evaluate the anchor capacity based on the t- z approach. Finally, this study introduces an empirical method to estimate lateral wall deformation profiles and internal bending moments along a retaining wall installed in a clay stratum

Stability, Erosion, and Morphology Considerations for Sustainable Slope Design

The construction of more natural and sustainable earth slopes requires the consideration of erosion and runoff characteristics as an integral part of the design. These effects not only result in high costs for removal of sediment, but also a profound damage to the ecosystem. In this dissertation, innovative techniques are developed such that more natural appearing slopes can be designed to minimize sediment delivery, while meeting mechanical equilibrium requirements. This was accomplished by: a) examining the fundamental failure modes of slopes built with minimum compaction (FRA) to enhance quick establishment of forest, b) investigating the geomechanical and erosion stability of concave slopes, and c) developing design equations for a new type of inclined-face retaining structure, the Piling Framed Retaining Wall (PFRW), which in the limit is a confined slope. The analysis of several potential failures via Limit Equilibrium (LEM) and Finite Element (FEM) suggested that the governing failure of FRA slopes is shallow and well represented by infinite slope conditions, and laboratory and field data suggests that seasonal increase of stability due to matric suction is possible, while instability may occur under local seismicity. The investigation of the mechanical and erosion stability of concave slopes began with a mathematical definition of critical concave slopes at limiting equilibrium. Based on this, a mechanism to design concave slopes for a selected Factor of Safety (FS) was proposed. Results indicated that concave slopes can yield 15-40% less sediment than planar slopes of equal FS, and the stability is not compromised by errors in the construction. Concave slopes satisfying mechanical equilibrium are not necessarily in erosion equilibrium as observed in many natural landscapes. It was shown that when these two equilibrium conditions are met, the slopes become sustainable and a set of equations describing sustainable concave slopes was proposed. Finally, rational design equations for the innovative PFRW were developed based on numerous FEM analyses for different soil and geometry conditions. The equations provided a good prediction of the soil stresses measured on a PFRW built in Knoxville, TN

The Evolution of Geotechnical Earthquake Engineering Practice in North America: 1954-1994

This paper traces the evolution of geotechnical earthquake engineering practice in North America from 1954 to 1994. The development of the state-of-the-art has been shaped strongly by four areas of practice: assessment of seismic hazard, estimation of liquefaction potential, seismic response analysis of earth structures and seismic safety evaluation and remediation of existing dams with potentially liquefiable zones. Evolution of practice in each of these areas will be traced and the current state-of-the-art evaluated. Present capabilities in practice will be illustrated by examples from the areas of seismic response of dams, liquefaction potential and seismic safety evaluation and remediation of potentially liquefiable embankment dams

Advances in Geotechnical Earthquake Engineering

This book sheds lights on recent advances in Geotechnical Earthquake Engineering with special emphasis on soil liquefaction, soil-structure interaction, seismic safety of dams and underground monuments, mitigation strategies against landslide and fire whirlwind resulting from earthquakes and vibration of a layered rotating plant and Bryan's effect. The book contains sixteen chapters covering several interesting research topics written by researchers and experts from several countries. The research reported in this book is useful to graduate students and researchers working in the fields of structural and earthquake engineering. The book will also be of considerable help to civil engineers working on construction and repair of engineering structures, such as buildings, roads, dams and monuments

Influence of concrete material time-dependency and temperature on the performance of a cofferdam structure braced with reinforced concrete ring beams

The lateral load resisting system of tall buildings is often made of reinforced concrete shear walls that are constructed using a cofferdam structure. The term cofferdam, often used in offshore applications, is employed in this research as a temporary watertight structure made of steel sheet piles and internally braced with steel or reinforced concrete ring beams to retain the surrounding soil. The soil removal inside of the cofferdam, necessary to install the foundations of the concrete core in rock or competent soil, is typically performed following a bottom-up excavation sequence. The performance of these type of systems in urban environments is critical as excessive excavation-induced ground movements can lead to significant damage of adjacent infrastructure. In this research, concrete material time-dependent and temperature-dependent effects of shrinkage, creep, and aging of concrete ring beam bracings are shown to have contributed to the lateral deformations of an urban cofferdam built for a structure that was projected as the tallest building in America. It is shown that because of the very low stiffness of perimeter steel sheet piles, the performance of these cofferdams is highly influenced by the quality control and adequate curing of the concrete material of the ring beams used as the internal lateral bracing system of the cofferdam. It is also shown with actual performance data how the sequence and timing of cycles of excavation and lateral bracing highly impacted the performance. The concrete material time-dependent effects presented in this research have not been incorporated as an integral part of the analysis and design of these temporary structures in urban environments and ignoring these effects conceal the fundamental reason for the resulting lateral deformations of these structures.Resumen: Los sistemas de contención para cargas laterales de edificios altos son comúnmente hechos con muros de concreto construidos a partir de ataguías. Las ataguías son normalmente usadas para aplicaciones costeras, la empleada en esta investigación fue usada como una estructura temporal impermeable construida con tablestacas de acero y arriostrada internamente por anillos de acero o concreto reforzado para soportar el suelo alrededor. El proceso de excavación dentro de la ataguía necesario para instalar las fundaciones del núcleo rígido de concreto en roca o suelo competente, es típicamente realizado a partir de una excavación descendente-ascendente. El desempeño de este tipo de estructura en un ambiente urbano es crítico, pues movimientos del suelo alrededor inducidos por la excavación pueden llevar a daños significativos en estructuras cercanas. En esta investigación se muestran como los efectos en el tiempo y de la temperatura del concreto: contracción, repteo y madurez han contribuido a deformaciones laterales en una ataguía urbana construida para el edificio proyectado como el más alto de América. Se muestra como por la baja rigidez del tablestacado perimetral de acero, las deformaciones de la ataguía son altamente dependientes del control de calidad y del curado del concreto reforzado empleado para el arrostramiento interno con anillos perimetrales. También se presenta con instrumentación de campo como la secuencia constructiva y los tiempos de los ciclos de excavación impactaron altamente el desempeño de la estructura. Los efectos del concreto, dependientes del tiempo y la temperatura que son tratados en esta investigación no son tenidos en cuenta de forma integral en los análisis y durante la etapa de diseño, ignorar estos efectos es la principal razón de las deformaciones laterales resultantes de estas estructuras.Maestrí

Influence of concrete material time-dependency and temperature on the performance of a cofferdam structure braced with reinforced concrete ring beams

The lateral load resisting system of tall buildings is often made of reinforced concrete shear walls that are constructed using a cofferdam structure. The term cofferdam, often used in offshore applications, is employed in this research as a temporary watertight structure made of steel sheet piles and internally braced with steel or reinforced concrete ring beams to retain the surrounding soil. The soil removal inside of the cofferdam, necessary to install the foundations of the concrete core in rock or competent soil, is typically performed following a bottom-up excavation sequence. The performance of these type of systems in urban environments is critical as excessive excavation-induced ground movements can lead to significant damage of adjacent infrastructure. In this research, concrete material time-dependent and temperature-dependent effects of shrinkage, creep, and aging of concrete ring beam bracings are shown to have contributed to the lateral deformations of an urban cofferdam built for a structure that was projected as the tallest building in America. It is shown that because of the very low stiffness of perimeter steel sheet piles, the performance of these cofferdams is highly influenced by the quality control and adequate curing of the concrete material of the ring beams used as the internal lateral bracing system of the cofferdam. It is also shown with actual performance data how the sequence and timing of cycles of excavation and lateral bracing highly impacted the performance. The concrete material time-dependent effects presented in this research have not been incorporated as an integral part of the analysis and design of these temporary structures in urban environments and ignoring these effects conceal the fundamental reason for the resulting lateral deformations of these structures.Resumen: Los sistemas de contención para cargas laterales de edificios altos son comúnmente hechos con muros de concreto construidos a partir de ataguías. Las ataguías son normalmente usadas para aplicaciones costeras, la empleada en esta investigación fue usada como una estructura temporal impermeable construida con tablestacas de acero y arriostrada internamente por anillos de acero o concreto reforzado para soportar el suelo alrededor. El proceso de excavación dentro de la ataguía necesario para instalar las fundaciones del núcleo rígido de concreto en roca o suelo competente, es típicamente realizado a partir de una excavación descendente-ascendente. El desempeño de este tipo de estructura en un ambiente urbano es crítico, pues movimientos del suelo alrededor inducidos por la excavación pueden llevar a daños significativos en estructuras cercanas. En esta investigación se muestran como los efectos en el tiempo y de la temperatura del concreto: contracción, repteo y madurez han contribuido a deformaciones laterales en una ataguía urbana construida para el edificio proyectado como el más alto de América. Se muestra como por la baja rigidez del tablestacado perimetral de acero, las deformaciones de la ataguía son altamente dependientes del control de calidad y del curado del concreto reforzado empleado para el arrostramiento interno con anillos perimetrales. También se presenta con instrumentación de campo como la secuencia constructiva y los tiempos de los ciclos de excavación impactaron altamente el desempeño de la estructura. Los efectos del concreto, dependientes del tiempo y la temperatura que son tratados en esta investigación no son tenidos en cuenta de forma integral en los análisis y durante la etapa de diseño, ignorar estos efectos es la principal razón de las deformaciones laterales resultantes de estas estructuras.Maestrí

Geotechnical Engineering for the Preservation of Monuments and Historic Sites III

The conservation of monuments and historic sites is one of the most challenging problems facing modern civilization. It involves, in inextricable patterns, factors belonging to different fields (cultural, humanistic, social, technical, economical, administrative) and the requirements of safety and use appear to be (or often are) in conflict with the respect of the integrity of the monuments. The complexity of the topic is such that a shared framework of reference is still lacking among art historians, architects, structural and geotechnical engineers. The complexity of the subject is such that a shared frame of reference is still lacking among art historians, architects, architectural and geotechnical engineers. And while there are exemplary cases of an integral approach to each building element with its static and architectural function, as a material witness to the culture and construction techniques of the original historical period, there are still examples of uncritical reliance on modern technology leading to the substitution from earlier structures to new ones, preserving only the iconic look of the original monument. Geotechnical Engineering for the Preservation of Monuments and Historic Sites III collects the contributions to the eponymous 3rd International ISSMGE TC301 Symposium (Naples, Italy, 22-24 June 2022). The papers cover a wide range of topics, which include: 　 - Principles of conservation, maintenance strategies, case histories - The knowledge: investigations and monitoring - Seismic risk, site effects, soil structure interaction - Effects of urban development and tunnelling on built heritage - Preservation of diffuse heritage: soil instability, subsidence, environmental damages The present volume aims at geotechnical engineers and academics involved in the preservation of monuments and historic sites worldwide

Ground compaction due to vibrodriving of piles

Civil engineering construction frequently requires the use of piles to carry structural loads to stronger ground strata or to control lateral ground movements. A variety of techniques are available to install piles into the ground. Of central interest to this research is the vibratory hammer, or vibrodriver, which is the preferred method used to drive piles into granular soils. .The installation of sheet and bearing piles by vibrodriver causes periodic vibration in the adjacent ground which is severe very close to the piles, but attenuates with distance. A potential consequential effect of the vibrations that are caused by vibrodriving is ground compaction, which may be observed as differential surface settlement. It is desirable that vibration induced ground compaction settlement should be estimated for contracts where loose to medium-dense granular soils occur, especially when buildings on shallow foundations or poorly bedded service pipes are adjacent. It is unlikely that a simple in-situ soils test will allow accurate, specific estimates, but rather that a range of vibratory tests should be performed which can then be used as a knowledge base. Settlement trends and associated parameters can then be identified which will allow the prediction of settlement with reference to the in-situ soil and the ground vibration data. This argument forms the basis of the laboratory test programme. A range of granular soils were studied using an adapted 150mm Rowe cell (a hydraulic oedometer). Use of the Rowe cell enabled samples to experience compaction under effective stress conditions that are appropriate for equivalent soils in the field. The complete cell was mounted on an electromagnetic shaker and after static consolidation, the samples were vibrated under maintained hydraulic load, at frequencies and accelerations that are appropriate for soils adjacent to vibrodrivers. Change in sample height was recorded for controlled vertical (and horizontal) vibrations, typically in the range of 0.lg to 5.0g at 25Hz and 40Hz. Soils were tested under a range of effective stresses and moisture content. The results of the laboratory programme and subsequent data analysis are presented in tables and diagrams. Expressions that describe a good relationship between acceleration, soil type, relative density and static load allow upperbound estimates of vibratory settlements to be made for accelerations of up to 6.0g. An additional expression is presented that accounts for the influence of moisture content, ground vibration frequency and vibration duration. Summary tables are presented that define categories of vibration induced ground compaction settlement based on settlement potential, risk and severity. The use of the settlement equations and the influence of various parameters are demonstrated for a range of example applications, hi addition, data is abstracted from case studies found in the literature and sites that were visited during the research. The abstracted data are then used to perform settlement estimates which are compared to the reported examples. Good correlation between observed and calculated settlement is demonstrated in many cases. However, in some instances, it appears that ground settlements were exacerbated by at least one additional mechanism, such as cumulative pore water pressure increase, or lateral movement of sheet piles, in addition, extraction of piles by vibrodriver appears to contribute significantly to the reported cases of ground settlement

Centrifuge Modeling of Dense Granular Columns in Layered Liquefiable Soils with Varying Stratigraphy and Overlying Structures

Soil liquefaction and ground failure have been a major source of damage to slopes, embankments, and structures during previous earthquakes. The risk of liquefaction and associated ground deformations can be reduced by various forms of improvement, including the granular column technique. Granular columns are known to be cost effective and environmentally friendly, and they have been in use since the 1970’s to mitigate the liquefaction hazard. Granular columns mitigate the consequences of soil liquefaction through a combination of: 1) installation-induced ground densification, 2) increase in lateral effective stresses in the surrounding soil, 3) increase in shear stiffness, and 4) enhanced drainage. These mechanisms aim to reduce the liquefaction potential of the improved soil or the resulting deformations. However, the independent influence and contribution of these mitigation mechanisms (in particular shear stiffness and drainage) on excess pore pressures, accelerations, and lateral and vertical deformations experienced in level and gently sloped sites are not sufficiently understood to facilitate their reliable performance-based design. In addition, the net influence of granular columns on competing mechanisms leading to lateral and vertical deformations with or without a structure is uncertain and requires further investigation, particularly in the presence of stratigraphic variations and layering expected in natural deposits.In this dissertation, centrifuge experimental results are presented to investigate the influence of dense granular columns and their properties on the performance of layered liquefiable deposits with stratigraphic variations with and without a structure. The first set of experiments enabled investigation of granular columns in level sites with uniformly layered liquefiable deposits as well as gently sloping sites with a slight variation in the thickness of the liquefiable layer. No structure was present in these tests. The spacing and drainage capacity of columns were varied. In the second set of experiments, the same granular columns were evaluated in non-uniform liquefiable deposits with a gentle surface slope and a level surface. The presence of a shallow-founded structure and its seismic interaction with soil was also evaluated in terms of the performance of the soil-mitigation-foundation-structure system.The experiments showed that granular columns can be effective in reducing the lateral and vertical deformations in gently sloped sites only if closely spaced (area replacement ratios exceeding about 20%) and able to enhance drainage. Hence, it is critical in such conditions to avoid clogging in subsequent events. Test results also showed that a slight variation in the liquefiable layer thickness can produce large permanent lateral ground deformations, even in the absence of a surface slope or a structure, which could damage utilities and lifelines. Use of granular columns below the foundation could effectively reduce the magnitude of void redistribution and shear strain localization underneath the sand-silt interface, hence reducing net settlements, rotations, and lateral displacements. However, granular columns could transfer greater accelerations to and seismic deformations in the superstructure, depending on the amplitude and frequency content of the motion in relation to the structure’s modal frequencies. This dissertation provides a comprehensive experimental database that aims to improve our fundamental understanding of deformations in layered liquefiable deposits of varying stratigraphy, when unmitigated and when mitigated with granular columns. Overall, the results point to the importance of considering even slight variations in surface slope, liquefiable layer thickness, as well as seismic soil-foundation-structure interaction when designing mitigation strategies in the context of system performance. However, additional physical and numerical modeling with a rang

Technology and Management for Sustainable Buildings and Infrastructures

A total of 30 articles have been published in this special issue, and it consists of 27 research papers, 2 technical notes, and 1 review paper. A total of 104 authors from 9 countries including Korea, Spain, Taiwan, USA, Finland, China, Slovenia, the Netherlands, and Germany participated in writing and submitting very excellent papers that were finally published after the review process had been conducted according to very strict standards. Among the published papers, 13 papers directly addressed words such as sustainable, life cycle assessment (LCA) and CO2, and 17 papers indirectly dealt with energy and CO2 reduction effects. Among the published papers, there are 6 papers dealing with construction technology, but a majority, 24 papers deal with management techniques. The authors of the published papers used various analysis techniques to obtain the suggested solutions for each topic. Listed by key techniques, various techniques such as Analytic Hierarchy Process (AHP), the Taguchi method, machine learning including Artificial Neural Networks (ANNs), Life Cycle Assessment (LCA), regression analysis, Strength–Weakness–Opportunity–Threat (SWOT), system dynamics, simulation and modeling, Building Information Model (BIM) with schedule, and graph and data analysis after experiments and observations are identified