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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.

In urban areas, vibrations generated by pile driving often affect the neighboring properties vulnerable to ground shaking. These vibrations may cause damage to surrounding structures either by shaking the ground or by causing settlement of the soil beneath foundations in the proximity of pile driving. It is important to distinguish between the conditions under which the vibrations will cause damage and those under which vibrations are tolerable. The numerical studies on the analysis of pile driving have mostly focused on assessing the driving efficiency and the bearing capacity of dynamically loaded piles. A limited number of studies included the study of ground vibrations due to pile driving and its effects on adjacent structures. However, the factors affecting the ground vibrations in soils such as the nonlinear constitutive behavior of soil, soil-pile interaction and penetration depth of the pile have not been clearly identified. The objective of this research is to implement a numerical method to simulate dynamic loading of a single pile, and study the factors influencing the stress wave propagation in the soil surrounding the pile. The thesis is comprised of two main analyses: (1) the static analysis of a pile in which the phenomenon of static consolidation is studied, and (2) the dynamic analysis of a pile in which pile driving and ground vibrations are studied. In the static analysis, the load capacity of a single pile is investigated. The results from the finite element method are compared with widely recognized theoretical methods. The theoretical methods that are used to estimate the end bearing capacities are: (1) General Formula, (2) Vesic's Method, (3) Janbu's Method, (4) Meyerhof's Method, and (5) Coyle & Castello's Method. The estimation of skin friction resistance (shaft capacity) of single piles is performed using the (1) Alpha method, (2) Beta method, and (3) Lambda method. Two numerical applications are performed to predict the load capacity of single piles in normally consolidated clays. It is observed that the model with no slippage at the interface predicts almost twice as much load capacity as the model with interface. In regards with the end bearing capacities, Coyle & Castello's method is found to be most conservative followed by the finite element method, the Janbu's method, the Meyerhof's method, and finally the Vesic's method. In respect to skin friction resistance, the finite element is found to be the most conservative method, followed by the Beta, the Lambda, and the Alpha method. In the dynamic analysis, the amplitudes of ground vibrations are investigated based on the variation of: (1) the soil type, (2) the pile embedment length and (3) the released hammer energy. In the first analysis, five types of soils - loose and dense sands and, soft, medium stiff, and stiff clays - are modeled. The highest vibration amplitude is calculated for the loose sand with a peak particle velocity (PPV) of 10.0 mm/s followed by the dense sand with a PPV of around 4.0 mm/s. Among the clay types, the vibrations are higher for the stiffer clay in the near field, which is 9 m (half a pile length) or less away from the pile. In the second analysis, three different embedment lengths - full, half, and quarter pile length - are modeled. It is found that the quarter embedded piles produce greater vibration amplitudes as compared to the half and fully embedded piles. Larger amplitudes of vibrations are encountered on the ground surface for shorter pile embedment lengths. In the third analysis, three different impact forces consisting of 2,000 kN (F), 6,000 kN (3F) and 10,000 kN (5F) are applied on the pile head. It is concluded that increase in hammer energy causes increase in the peak particle velocities.

[pt] Este estudo objetiva reunir, em uma abordagem qualitativa, o que se conhece sobre as modificações, com o tempo, na capacidade de carga de estacas, fenômenos que, neste tr abalho,chamaremos recuperação e relaxação. A importância destas alterações é significativa: após a execução, as estacas podem manter a capacidade de carga inicial, -recuperar-, aumentando -a de uma porcentagem não previsível, mas que pode chegar a quadruplicá-la, ou -relaxar-, perdendo grande parte de sua resistência (até acima de 50 por cento). O peso econômico do desenvolvimento de tais fenômenos justifica por si a necessidade de melhor compreensão desses processos e, nessa dissertação, passo inicial de um projeto de pesquisa mais amplo na área, foram coletados e grupados resultados e observações sobre o tema. Foram escolhidos e transcritos casos representativos da literatura que contemplam a variedade de comportamentos do solo em função da cravação de estacas. Privilegiou-se as avaliações experimentais nas quais se constatou aumento ou redução da capacidade de carga em estacas cravadas com o decorrer do tempo, ou seja,recuperação e relaxação, respectivamente. Não houve preocupação de restringi -las às mais recentes, uma vez que, mesmo não dispondo do nível do desenvolvimento tecnológico atual, as intuições iniciais não estão muito distantes das propostas e modelos que lhes dão continuidade hoje. Conclui -se ser imprescindível à engenharia de fundações um conhecimento mais profundo que permita melhores e mais seguras previsões do desempenho, ao longo do tempo, de estacas cravadas, especialmente pelos riscos e prejuízos que sua ausência representa. Espera -se que a pequena parcela aqui apresentada, contribuindo para a ampliação da visão global do problema,estimule a adoção de práticas executivas cientificamente éticas. Para tal recomenda -se que, pelo menos, sejam trazidas a público as informações sobre a ocorrência desses fenômenos. / [en] This work is intended to assemble, in the light of a qualitative approach, what is already known about the changes over time in the bearing capacity of piles, setup and relaxation. The importance of such alterations is significant. After the installation process, the piles may keep their initial loading capacity, set it up by increasing it from a non-predictable percentage (which may eventually quadruple) or relax, losing most of its resistance (up to over percent). The cost of such phenomena justifies per se the need of an improved comprehension of such processes, and in the present work, a first step of a broader research project, the results and observations on the subject were collected and assembled. Representative cases found in the literature which contemplate variety in soil behaviour due to the driving of piles were selected and transcribed. Experimental evaluations where a growth or reduction in the bearing capacity of driven piles over time, eg. set-up and relaxation, were given priority. It was not the concern of this work to restrict the set-up and relaxation processes to more recent research because the initial intuitions, though not in charge of the present technological development, were not so distant from the proposals and models which followed. We thus deem as essential to foundation engineering a further insight into the subject, which will permit better and safer anticipations of the behaviour of driven piles over time, in view of the risks and economic losses which may arise from its absence. It is hoped that the present dicussion, by contributing to further a qualitative global view of the matter, may give rise to the adoption of scientifically ethical practices. To such, it is recommended that the information on such phenomena be made public. / [es] Este estudio tiene como objetivo reunir, com um enfoque cualitativo, lo que se conoce sobre las modificaciones en la capacidad de carga de estacas; fenómenos que, en este trabajo, llamaremos recuperación y relajación. La importancia de estas alteraciones es significativa: después de la ejecución, las estacas pueden mantener la capacidad de carga inicial, recuperar, aumentándola en un porcentaje no previsible, que puede llegar a quadruplicarla, o relajar , perdiendo grande parte de su resistencia (hasta más del por ciento). El peso económico del desarrollo de tales fenómenos justifica por sí mismo la necesidad de una mejor comprensión de estos procesos y esta disertación, paso inicial de un proyecto de investigación más amplio, se recolectaron y agruparon resultados y observaciones sobre el tema. Se escogieron y transcribieron los casos representativos de la literatura que contienen la variedad de comportamientos del suelo en función del clavado de estacas. Se privilegiaron las evaluaciones experimentales en las que se constató aumento o redución de la capacidad de carga en estacas clavadas, o sea, recuperación y relajación, respectivamente. No hubo preocupación de restringirlas a las más recientes ya que, incluso cuando no se dispone del nível del desarrollo tecnológico actual, las instituciones iniciales no están muy distantes de las propuestas y los modelos que le dan continuidad hoy. Se concluye que es imprescindible para la ingeniería de fundaciones un conocimiento más profundo que permita mejores y más seguras previsiones del desempeño, a ll largo del tiempo, de estacas clavadas, especialmente por los riesgos y perjuicios que su ausencia representa. Se espera que la pequeña parcela aqui presentada, contribuya a la ampliación de la visión global del problema, estimulando la adopción de prácticas ejecutivas cientificamente éticas. Para tal se recomienda que, por el momento, se hagan públicas las informaciones sobre la existencia de esos fenómenos.

This report has examined the possibilities of stiffening and strengthening a ground stabilization mast, in a way that a small production company can manufacture. The soil stabilization technique in question is Jet-Grouting also called injection drilling, which involves drilling to the desired depth and then letting high-pressure water jets mixed with filling mass to erode the surrounding soil mass and form pillars below the ground surface. The study intends to explore the possibility of placing a simplified model in the simulation program ANSYS that uses the finite element method (FEM) to obtain its results. The product development method described by Karl T. Ulrich and Steven D. Eppinger in the book "Product Design and Development" is then used to produce improvement proposals that will strengthen the mast. The purpose of this study was to identify the strength of a ground stabilization mast and then produce and present an improvement proposal, based on the rotation head that is now mounted on the ground stabilization mast. This rotary head is named "RH24X HP 67 TS" and is produced by Eurodrill, and it generates a maximum torque of 24 kNm. The simulations on the mast with the given torque resulted in the highest stress of 158 MPa to which the mast body was exposed to. With the design that the mast current design, it entails a 2.3 factor of safety, which is considered acceptable since the recommended factor of safety for this type of heavy machine is about 2 (Khan, et al., 2016). When the torque was increased to the limit of the mast, i.e., when the factor of safety is close to 1, it resulted in a maximum torque of 54 kNm. Mounting a rotary head with a torque of 54 kNm is therefore not recommended due to the low safety margin that it would entail. Market research has been done and the proposals presented in this study presents similar manufactures and series as of the current rotary head. The recommended rotary heads come from the Eurodrill X-series and are called "RH32X HP 67 TS" and it produces a maximum torque of 32 kNm, alternatively "RH 4300 HP 48 TSS" which produces a torque of 34 kNm. The improvement proposals presented in this report are developed by evaluating the results of the simulations performed and then identifying the weakest areas. Then, based on the product development method, generate a proposal that can stiffen and strengthen the ground stabilization mast. The improvement proposal on the cradle showed with the rotary head "RH24X HP 67 TS" a 4.8 factor of safety, compared to the current cradle which has a 2.6 factor of safety, it is almost a doubling in strength. A new design of trusses was presented and resulted in a 35% increase in rigidity without the need to add any new material. This means that by re-examining the structure of the truss you can strengthen and possibly check the rigidity of the mast, which among other things leads to better manoeuvrability without any real extra costs being needed. / Denna rapport har undersökt möjligheterna att styva och styrka upp en markstabiliseringsmast på ett sätt som ett mindre produktionsföretag klarar av att tillverka. Markstabiliseringstekniken i fråga är Jet-Grouting även kallad injiceringsborrning, som går ut på att man borrar till önskat djup för att sedan låta högtrycksvattenjetstrålar blandat med fyllnadsmassa erodera den kringliggande jordmassan och bilda pelare under markytan. Studien ämnar utforska möjligheten med att placera en förenklad modell i simuleringsprogrammet ANSYS som använder finit elementmetod (FEM) för att få fram sina resultat. Därefter används produktutvecklingsmetoden som beskrivs av Karl T. Ulrich och Steven D. Eppinger i boken ”Product Design and Development”, för att ta fram förbättringsförslag som ska styrka upp masten.   Studien har haft som syfte att ta reda på hållfastheten hos en markstabiliseringsmast och sedan ta fram och presentera ett förbättringsförslag, utifrån det rotationshuvud som nu är monterat på markstabiliseringsmasten. Detta rotationshuvud har benämningen ”RH24X HP 67 TS” och är producerad av Eurodrill och genererar ett maximalt vridmoment på 24 kNm. Simuleringarna på masten med det givna vridmomentet resulterade i den högsta spänningen på 158 MPa som mastkroppen utsattes för. Med det utförande som masten är idag medför det en 2,3 säkerhetsfaktor, vilket är anses vara acceptabelt eftersom den rekommenderade säkerhetsfaktorn för denna typ av tungmaskin ligger på cirka 2 (Khan, et al., 2016).  När man sedan ökade vridmomentet till mastens bristgräns, det vill säga när säkerhetsfaktorn tangerar 1, resulterade det i ett maximalt vridmoment på 54 kNm. Att montera ett rotationshuvud med ett vridmoment på 54 kNm är därför inte att rekommendera på grund av den låga säkerhetsmarginalen som det skulle innebära. Därför presenteras förslag på rotationshuvuden som masten kan klara av, genom en marknadsundersökning gjord på liknade tillverkare och serier som dagens rotationshuvud. De rotationshuvud som rekommenderas kommer från Eurodrill X-serie och heter ”RH32X HP 67 TS” och den producerar ett maximalt vridmoment på 32 kNm, alternativt ”RH 4300 HP 48 TSS” som producerar ett vridmoment på 34 kNm.  Förbättringsförslagen som presenteras i denna rapport är framtagna genom att utvärdera resultaten av de utförda simuleringarna och sedan identifiera de svagaste områdena. Därefter genereras förslag utifrån produktutvecklingsmetoden som kan styva och stärka upp markstabiliseringsmasten. Förbättringsförslaget på släden visade med rotationshuvudet ”RH24X HP 67 TS” en 4,8 säkerhetsfaktor, jämfört med den nuvarande släden som har en 2,6 säkerhetsfaktor vilket är nästan en fördubbling i hållfasthet. En ny design av fackverk presenterades och resulterade i 35 % ökad styvhet utan att behöva addera något nytt material. Det innebär att man genom att ompröva fackverkets struktur kan stärka och eventuellt kontrollera mastens styvhet, vilket bland annat leder till bättre manövrerbarhet utan några egentliga extra kostnader behövs.

The motivation for this study is to create a scaled laboratory model of a steel construction pile being driven by an impact hammer, which can provide controlled data to aid understanding and development of a structural acoustics numerical model simulating full-scale impact pile driving. The scaled model is approximately thirty times shorter than a typical 30-meter long Cast-in-Shell-Steel (CISS) pile. The relationship between the impact force, structural vibrations, and radiated sound field is analyzed. The time-domain acoustic intensity in the radial direction is found to be predominately negative immediately following excitation by the impact force. Analysis of the radial intensity shows that during the hammer strike, there is a net flow of energy from the structure into the water; however, because the structure and water are acoustically coupled a significant portion of the energy immediately flows back into the cylinder following hammer impact. This fluid-structure interaction results in a highly damped acoustic pulse in the water that propagates to the far field. In addition, the frequency spectra of the impact force, model pile wall acceleration in the radial direction in air and water, and underwater acoustic pressure are analyzed to find transfer functions between these variables. The transfer function between impact force and sound pressure is of particular interest because it can be used to calculate the system response for any other applied hammer force. This transfer function analysis has potential applications in mitigating noise generated by impact pile driving.

The present PhD study, in its first part, uses artificial neural networks (ANNs), an optimization technique called simulated annealing, and statistics to simulate the significant wave height (Hs) and mean zero-up-crossing period ( ) of 3-hourly sea-states of a location in the North East Pacific using a proposed distribution called hepta-parameter spline distribution for the conditional distribution of Hs or given some inputs. Two different seven- network sets of ANNs for the simulation and prediction of Hs and were trained using 20-year observed Hs’s and ’s. The preceding Hs’s and ’s were the most important inputs given to the networks, but the starting day of the simulated period was also necessary. However, the code replaced the day with the corresponding time and the season. The networks were trained by a simulated annealing algorithm and the outputs of the two sets of networks were used for calculating the parameters of the probability density function (pdf) of the proposed hepta-parameter distribution. After the calculation of the seven parameters of the pdf from the network outputs, the Hs and of the future sea-state is predicted by generating random numbers from the corresponding pdf. In another part of the thesis, vertical piles have been studied with the goal of identifying the range of sea-states suitable for the safe pile driving operation. Pile configuration including the non-linear foundation and the gap between the pile and the pile sleeve shims were modeled using the finite elements analysis facilities within ABAQUS. Dynamic analyses of the system for a sea-state characterized by Hs and and modeled as a combination of several wave components were performed. A table of safe and unsafe sea-states was generated by repeating the analysis for various sea-states. If the prediction for a particular sea-state is repeated N times of which n times prove to be safe, then it could be said that the predicted sea-state is safe with the probability of 100(n/N)%. The last part of the thesis deals with the Hs return values. The return value is a widely used measure of wave extremes having an important role in determining the design wave used in the design of maritime structures. In this part, Hs return value was calculated demonstrating another application of the above simulation of future 3-hourly Hs’s. The maxima method for calculating return values was applied in such a way that avoids the conventional need for unrealistic assumptions. The significant wave height return value has also been calculated using the convolution concept from a model presented by Anderson et al. (2001).

Skanska Grundläggning in Region Special wishes to gain an increased understanding of the extent to which it differs in the wear of percussion hammers and pilot drill crowns, depending on which driving medium is used in down-the-hole drilling, as well as logistical and economic aspects depending on the chosen method. Down-the-hole drilling means that the hammer works down in the borehole and forms one of the components at the far end of the drill string together with a drill bit. The blow of the hammer is created by air or water at high pressure. The piling method that is examined is drilled steel pipe piles, which means that a steel pipe pile is driven into the ground in step with the hammer and the drill bit's advancement. Once the desired depth has been reached, the drill string with the drill bit is pulled out of the casing and then the steel pipe pile is filled with concrete. The study aims to examine the products' lifespans and repair intervals from several different perspectives and set them against reality, as well as what the different methods have for differences regarding logistics and establishment. This is to create a basis for future decisions on the most suitable method of down-the-hole drilling. The beginning of the study consisted of qualitative preliminary interviews to identify and create a problem formulation that was dealt with via a literature study, five semi-structured interviews, eleven questionnaires, internal data from drilling protocols and purchasing. The result shows that there is some difference in wear in the hammer depending on whether it is an air or water powered system, the wear appears in different places and can have an impact on the life of the hammer. The wear that occurs most frequently on drill bit is grinding on the buttons. Geotechnical differences for various projects are a significant factor in the service life of the equipment. An air hammer requires that the air constantly being mixed with lubricating oil and that an air compressor consumes more diesel compared to a high-pressure pump for the equivalent water hammer. The handling of water that is flushed out of the borehole is considered a concern. To reduce wear on water hammers and thus fewer replacements and more repairs, a drill bit intended for water powered down-the-hole hammer should be used. DTH-drilling with an air hammer is considered an industry standard and a certain skepticism towards a water powered system may indicate inexperience. / Skanska Grundläggning inom Region Special önskar att få en ökad förståelse hur vida det skiljer sig vid slitage av hammare och pilotborrkrona beroende på vilket drivande medium som nyttjas vid sänkhammarborrning, samt logistiska och ekonomiska aspekter beroende på vald metod. Sänkhammarborrning innebär att hammaren arbetar nere i borrhålet och utgör en av komponenterna längst ut på borrsträngen tillsammans med en borrkrona. Hammarens slag skapas av luft eller vatten i högt tryck. Pålningsmetoden som undersöks är borrade stålrörspålar, det betyder att ett foderrör drivs ned i marken i takt med hammaren och borrkronans framfart. Väl när önskat djup uppnåtts lyfts borrsträngen med hammaren och piloten upp ur foderröret för att sedan fyllas upp med betong. Studien syftar till att undersöka produkternas livslängder och reparationsintervall från flera olika perspektiv och ställa dem emot verkligheten, samt vad dem olika metoderna har för olikheter kring logistik och etablering. Detta är för att skapa underlag för framtida beslut om mest lämplig metod av sänkhammarborrning. Studiens begynnelse bestod av kvalitativa förintervjuer för att identifiera och skapa en problemformulering som avhandlades via en litteraturstudie, fem semistrukturerade intervjuer, elva frågeformulär, interna data från borrningsprotokoll och inköp. Resultatet visar att det förekommer viss skillnad i slitage i hammaren beroende på om det är en luft- eller vattenanläggning, slitaget visar sig på olika ställen och kan ha betydelse för hammarens livslängd. Det slitage som uppträder mest frekvent på piloter är nedslipning av stift. Geotekniska egenskaper för olika projekt utgör en betydande faktor för utrustningens livslängd. En lufthammare är i behov av att luften konstant beblandas smörjolja och att en luftkompressor förbrukar mer diesel jämfört med en högtryckspump för motsvarande vattenhammare. Efterhanteringen av vatten som spolas upp anses vara ett bekymmer. För att minska slitage på vattenhammare och därmed färre byten och mer reparationer bör en pilotborrkrona avsedd för vattendriven sänkhammarborrning nyttjas. Sänkhammarborrning med lufthammare anses som branschstandard och en viss skepticism mot en vattendriven anläggning kan tyda på oerfarenhet.