CIVIL ENGINEERING, SCIENCE AND TECHNOLOGY CHALLENGES: GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING

The book is based on scientific and technological advances in various Geotechnical and Geoenvironmental Engineering areas of Civil Engineering. It nurtures therefore the exchange of discoveries among research workforces worldwide including those focusing on the vast variety of facets of the fundamentals and applications within the Geotechnical and Geoenvironmental Engineering area. To offer novel and rapid developments, this book contains original contributions covering theoretical, physical experimental, and/or field works that incite and promote new understandings while elevating advancement in the Geotechnical and Geoenvironmental Engineering fields. Works in closing the gap between the theories and applications, which are beneficial to both academicians and practicing engineers, are particularly of interest to this book that paves the intellectual route to navigate new areas and frontiers of scholarly studies in Geotechnical and Geoenvironmental Engineering area

Stabilisation of marine clay using polyurethane

The recent need driven by global population growth to build more infrastructures is forcing authorities to build on any soil type available within their vicinity, including weak soils like marine clay (MC). However, due to its poor engineering properties, MC is not suitable for construction purposes. Given this fact, many ground improvement techniques are being employed to improve the properties of MC and to reduce the potential damages caused by it. Although researchers have done a lot to improve the properties of MC using different materials and methods, attention has not been given to the application of polyurethane (PU) to stabilise MC. Therefore, this research focusing on the application of PU for the stabilisation of MC. The MC was characterised by testing its index and engineering properties as well as the geochemistry and microstructure. Correspondingly, PU was characterised by testing its rheological and mechanical properties alongside the microstructural analyses. The effectiveness of PU as a stabiliser was evaluated using unconfined compression tests, consolidated undrained (CU) triaxial tests and one-dimensional consolidation tests to determine the strength and stiffness. Furthermore, x-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDX) were used to discern the roots of improvement in the strength of the MC that was stabilised with PU. PU properties were also improved using reinforcing fillers. Additionally, the bearing capacity of the MC before and after treatment with PU piles was evaluated using physical and numerical models. Finally, the potential for ground contamination resulting from the application of PU to stabilise MC was investigated using toxicity characteristic leaching procedures (TCLP). The results obtained show that PU improved the shear strength and the stiffness parameters of the MC. Neutralising the acidity of MC with NaOH nearly doubled the strength and stiffness of the PU-stabilised MC. The UCS of MC that was treated with PU and NaOH improved significantly. Likewise, the secant stiffness for the CU triaxial test and tangent stiffness for the primary oedometer loading, show improvement compared to the untreated MC sample. Results of the microstructure analyses revealed that no new compounds were formed during the stabilisation of the MC with PU. The improvement in MC strength was due to the densification and coating of MC particles with PU foam. PU improved with SiO2 have superior strength, stiffness and crystallinity compared to the normal PU due to the cross-linking properties of the of SiO2 particles in the chain of PU. The results from the numerical model showed that the bearing capacity of MC that was stabilised with PU piles increases with increase in an improvement area ratio and with a length over height ratio compared to the untreated MC. The TCLP results revealed that the quantity of heavy metals present in PU is far below the regulatory limits. The results further confirmed that PU is odourless, non-corrosive and both non-cyanide and non-sulphide bearing. However, PU is capable of igniting. Overall, the potential application of PU for ground improvement is promising due to its environmental friendliness and high strength

Bearing capacity of clay bed improved by sand compaction piles under caisson loading

Master'sMASTER OF ENGINEERIN

Lunar surface engineering properties experiment definition. Volume 2: Mechanics of rolling sphere-soil slope interaction

The soil deformation mode under the action of a rolling sphere (boulder) was determined, and a theory based on actual soil failure mechanism was developed which provides a remote reconnaissance technique for study of soil conditions using boulder track observations. The failure mechanism was investigated by using models and by testing an instrumented spherical wheel. The wheel was specifically designed to measure contact pressure, but it also provided information on the failure mechanism. Further tests included rolling some 200 spheres down sand slopes. Films were taken of the rolling spheres, and the tracks were measured. Implications of the results and reevaluation of the lunar boulder tracks are discussed

Centrifuge model study on spudcan extraction in soft clay

Ph.DDOCTOR OF PHILOSOPH

SOFT GROUTING FOR SEISMIC ISOLATION: Numerical and Physical modelling

This thesis is a part of a comprehensive research program on the study of an innovative ground treatment approach for the mitigation of the seismic risk of existing structure, by means of the creation of a continuous thin layer of grouted soil at a convenient depth. The motivation of the research was the observation of the damage suffered by the historic buildings under earthquakes. In countries like Italy, with a high seismic hazard and old or very old towns, where many buildings are hundreds of years old, this is one of the most relevant problems for the protection of both population and cultural heritage (Costanzo et al., 2007). Few historic buildings meet current code seismic requirements for life safety, and most have architecturally significant elements that are threatened by future earthquakes. The use of the isolation system conceived for new structure could be in conflict with the respect of the iconic, historical and material integrity of the monuments. The present work provides guidance on the use of the soft barriers to seismic isolate the existing buildings, highlighting pros and cons based on experimental and numerical results

Geotechnical design manual

The South Carolina Department of Transportation Geotechnical Design Manual has been developed to provide uniform practices for the agency's designers to complement the Mission of SCDOT by providing for safe, economical, effective and efficient geotechnical designs

Experimental and Numerical Investigations to Assess the Performance of a Buried Pipe Subjected to Traffic Load / Non-Treated and Cement-Treated Trench

In this research, the performance of buried flexible pipe subjected to traffic load was investigated. First, a numerical parametric study was performed to study the influence of eight factors on pipe-soil behaviour under surface load using ABAQUS. Then, the impact of surface pressure, burial depth, number of cycles and cement stabilization on model response was investigated using laboratory experiments and numerical simulations. Equations were developed using Linear Regression Model and Artificial Neural Network using MATLAB

Mechanical performance and sustainability assessment of reinforced soil walls

Soil reinforced retaining wall structures are materiallymore efficientthan competing construction solutions such as gravity and cantilever walls. Nevertheless, the behaviour and interactions between the com ponent materials are com plex and not fully understood. Current design methods are typically limited to simple cases with respect to material properties, geometry, and boundary conditions. Advanced numerical models using finite element and/or finite difference methods offer the possibilityto extend the understanding ofthese systems and to predictwall performance under operational conditions. In this Thesis, numerical models were developed and shown to give satisfactory predictions ofwall behavior when compared with results of instrumented physical structures. The verified models were useful for sensitivity analyses using a range ofwall geometries and boundaryconditions, material parameters and different constitutive models. As examples ofthe obtained results, the compressibility ofthe precast panel bearing pads significantly modified the axial vertical facing load but has no significant effect on the tension developed in the soil reinforcement layers. Also, the stiffness ofthe foundation soil has greater effect on the tension developed in soil steel reinforcing elements than for polymeric reinforcement layers.lt has been possible to perform sensitivity analysis using parameters that define soil-structure interactions. Such interactions have been analyzed using different commercial software programs and bydefining them with elements from the continuum media using 2D and 3D models. Laboratory reinforcement pullout tests using steelladder and polymeric strips were performed as part of the Thesis. Those parameters that have the greatest influence on soil-reinforcement interaction are identified, quantified, and compared to default-design wlues anda range ofvalues used to calibrate numerical models. From the results of2D and 3D numerical models suitable correlations have been obtained to allow 2D models to be used in plane strain reinforced soil walls with discontinuous soil reinforcement elements in the running walllength ofthese structures. With a proper sustainability assessment it has been possible to make quantitative comparisons between reinforced soil wall structures and other alternativés performing the same function (such as gravity and cantilever walls) construcfed to different heights. Using a modelbased on the multi-attributeutilitytheoryand wlue analysis decision-making, the best solutions with least negative impact were identified in an example set of alternative earth retaining wall options from a sustainable perspective. The results include possible scenarios based on the relative importance ofthe three pillars ofsustainability(i.e., environmental, economic, and sociallfunctional) as judged bydifferentstakeholders. Reinforced soil walls turned outto be the best choice in most cases analyzed, based on a quantitative end score. The models and analysis methodologies developed as part ofthis Thesis work have improved understanding ofthe behavior ofthese structures, and offered possibilities to improve and optimize designs in the future.Els murs de contenció amb sòl reforçat són estructures materialment més eficients que altres solucions constructives alternatives, com ara els murs de gravetat o en voladís. No obstant això, el seu comportament i les interaccions entre els materials que componen aquestes estructures són complexos i no entesos completament. Els mètodes de disseny actuals solen estar limitats a casos senzills respecte a les propietats dels materials, la geometria i les condicions de contorn. Models numèrics avançats utilitzant elements finits i/o diferències finites ofereixen la possibilitat d'ampliar la comprensió d’aquests sistemes estructurals i de predir el comportament de l'estructura en condicions de servei. En aquesta Tesi s'han desenvolupat models numèrics que han demostrat donar prediccions satisfactòries del comportament d’aquest tipus de murs quan es comparen amb resultats obtinguts d'estructures físiques instrumentades. Aquests models verificats han estat útils per a poder fer anàlisis de sensibilitat segons diferents geometries del parament i condicions de contorn, paràmetres dels materials i diferents models constitutius. Com a exemple dels resultats obtinguts, s’ha determinat que la capacitat de compressió de les peces de recolzament dels panells prefabricats modifica de manera significativa la càrrega desenvolupada vertical axial en el parament, però no té un efecte significatiu en la tensió desenvolupada a les capes de reforç del sòl. O també, que la rigidesa del sòl de fonamentació té un efecte més gran sobre la tensió desenvolupada en elements de reforç metàl·lics que en polimèrics. Ha estat possible dur a terme anàlisis de sensibilitat utilitzant els paràmetres que defineixen les interaccions sòl-estructura. Aquestes interaccions han estat analitzades utilitzant diferents programes comercials numèrics i definint-les amb elements del medi continu tant en models 2D com en 3D. Com a part de la Tesi, s'han de dut a terme assaigs de laboratori d'extracció de reforços tipus malla metàl·lica i banda polimèrica. Els paràmetres que tenen una influència principal en la interacció sòl-reforç han sigut identificats, quantificats i comparats tant amb els valors per defecte de disseny com amb valors reportats a la literatura utilitzats per a calibrar models analítics, permetent el calibratge dels models numèrics generats. Dels resultats dels models 2D i 3D s’han obtingut correlacions que permeten concloure que els models 2D en deformació plana són adequats per a representar el funcionament de les estructures de sòl reforçat amb elements de reforç discontinus a la direcció del parament. Mitjançant una avaluació adequada de la sostenibilitat ha estat possible fer comparacions quantitatives entre estructures de sòl reforçat i altres alternatives constructives que compleixen la mateixa funció (com els murs de gravetat o en voladís) construïdes a diferents altures. Mitjançant un model basat en la teoria de la utilitat multiatribut i d’anàlisi de valor per a la presa de decisions, es van identificar els processos més representatius i de major impacte des d’un punt de vista sostenible. Els resultats obtinguts inclouen un ajust basat en possibles escenaris de presa de decisió per la importància relativa dels tres pilars de la sostenibilitat (ambiental, econòmic, i social/funcional). L'alternativa de sòl reforçat va resultar ser la millor, obtenint una puntuació més alta en gran part dels escenaris de presa de decisió considerats. En base a una puntuació quantitativa final, els murs de sòl reforçat van resultar ser la millor opció en la majoria dels casos analitzats. Els models i metodologies d'anàlisi desenvolupades com a part de aquest treball de Tesi han millorat la comprensió del comportament d’aquestes estructures, i ofereixen possibilitats per a millorar i optimitzar els seus dissenys en el futurLos muros de contención con suelo reforzado son estructuras materialmente más eficientes que otras soluciones constructivas alternativas, tales como los muros de gravedad o en voladizo. Sin embargo, su comportamiento y las interacciones entre los materiales que componen estas estructuras son complejos y no completamente comprendidos. Los métodos de diseño actuales suelen estar limitados a casos sencillos con respecto a las propiedades de los materiales, la geometría y las condiciones de contorno. Modelos numéricos avanzados utilizando elementos finitos y/o diferencias finitas ofrecen la posibilidad de ampliar la comprensión de estos sistemas y de predecir el comportamiento de la estructura en condiciones de servicio. En esta Tesis se han desarrollado modelos numéricos que han demostrado dar predicciones satisfactorias del comportamiento de este tipo de muros cuando se comparan con resultados obtenidos de estructuras físicas instrumentadas. Estos modelos verificados han sido útiles para análisis de sensibilidad según diferentes geometrías del paramento y condiciones de contorno, parámetros de los materiales y diferentes modelos constitutivos. Como ejemplo de los resultados obtenidos, la capacidad de compresión de las piezas de apoyo de los paneles prefabricados modifica de manera significativa la carga vertical axial desarrollada en el paramento, pero no tiene un efecto significativo en la tensión desarrollada en las capas de refuerzo del suelo. O también, que la rigidez del suelo de cimentación tiene un mayor efecto sobre la tensión desarrollada en elementos de refuerzo metálicos que en poliméricos. Ha sido posible llevar a cabo análisis de sensibilidad utilizando los parámetros que definen las interacciones suelo-estructura. Tales interacciones han sido analizadas utilizando diferentes programas numéricos comerciales y definiéndolas con elementos del medio continuo tanto en modelos 2D como 3D. Como parte de la Tesis, se han llevado a cabo ensayos de laboratorio de extracción de refuerzos tipo malla metálica y banda polimérica. Los parámetros que tienen una mayor influencia en la interacción suelo-refuerzo han sido identificados, cuantificados y comparados tanto con los valores por defecto de diseño como con valores reportados en la literatura usados para calibrar modelos analíticos, permitiendo la calibración numérica de los modelos generados. De los resultados de los modelos 2D y 3D se han obtenido correlaciones que permiten concluir que los modelos 2D en deformación plana son adecuados para representar el funcionamiento de las estructuras de suelo reforzado con elementos de refuerzo discontinuos en la dirección del paramento. Con una evaluación adecuada sostenibilidad ha sido posible hacer comparaciones cuantitativas entre estructuras de suelo reforzado y otras alternativas constructivas que cumplen la misma función (tales como los muros de gravedad o en voladizo) construidas a diferentes alturas. Mediante un modelo basado en la teoría de la utilidad multiatributo y análisis de valor para la toma de decisiones, se identificaron los procesos más representativos y de mayor impacto desde un punto de vista sostenible. Los resultados obtenidos incluyen un ajuste basado en posibles escenarios de toma de decisión por la importancia relativa de los tres pilares de la sostenibilidad (ambiental, económico, y social/funcional). La alternativa de suelo reforzado resultó ser la mejor, obteniendo una mayor puntuación en gran parte de los escenarios de toma de decisión considerados. En base a una puntuación final cuantitativa, los muros de suelo reforzado resultaron ser la mejor opción en la mayoría de los casos analizados. Los modelos y metodologías de análisis desarrolladas como parte de este trabajo de Tesis han mejorado la comprensión del comportamiento de estas estructuras, y ofrecen posibilidades para mejorar y optimizar sus diseños en el futuroPostprint (published version

2022 geotechnical design manual

The South Carolina Department of Transportation (SCDOT) Geotechnical Design Manual (“Manual”) has been developed to provide uniform design practices for SCDOT and consultant personnel preparing geotechnical reports and contract plans for SCDOT projects. The purpose of this manual is to complement the Mission of SCDOT by providing for safe, economical, effective and efficient geotechnical designs