Vibration compaction is the most effective way of compacting coarse-grained materials. The effects of vibration frequency and amplitude on the compaction density of different backfill materials (No. 4 natural sand, No. 24 stone sand and No. 5, No. 8, No. 43 aggregates), were studied in this research. The test materials were characterized based on the particle sizes and morphology parameters using digital image analysis technique. Small-scale laboratory compaction tests were carried out with variable frequency and amplitude of vibrations using vibratory hammer and vibratory table. The results show an increase in density with the increase in amplitude and frequency of vibration. However, the increase in density with the increase in amplitude of vibration is more pronounced for the coarse aggregates than for the sands. A comparison of the maximum dry densities of different test materials shows that the dry densities obtained after compaction using the vibratory hammer are greater than those obtained after compaction using the vibratory table at the highest amplitude and frequency of vibration available in both equipment. Large-scale vibratory roller compaction tests were performed in the field for No. 30 backfill soil to observe the effect of vibration frequency and number of passes on the compaction density. Accelerometer sensors were attached to the roller drum (Caterpillar, model CS56B) to measure the frequency of vibration for the two different vibration settings available to the roller. For this roller and soil tested, the results show that the higher vibration setting is more effective. Direct shear tests and direct interface shear tests were performed to study the impact of particle characteristics of the coarse-grained backfill materials on interface shear resistance. A unique relationship was found between the normalized surface roughness and the ratio of critical-state interface friction angle between sand-gravel mixture with steel to the internal critical-state friction angle of the sand-gravel mixture.

Urban construction sites require strict control of their environmental impact, which, for vibratory sheet pile driving, can include damage to nearby structures due to ground vibrations. However, the lack of knowledge concerning the generation of soil vibrations makes the prediction of ground vibration levels difficult. This MSc. thesis in particular, focuses on a crucial link in the vibration transfer chain: the sheet pile – soil interface, which is also one of the least documented. The aim of this thesis is first, to carry out a full-scale field test consisting in the monitoring of sheet pile and ground vibrations during sheet pile vibratory driving. And second, to analyze a selected portion of the collected data with focus on the sheet pile – soil vibration transfer. Both aspects of the thesis work aim, more generally, to contribute to the understanding of ground vibration generation under vibratory sheet pile driving. The full-scale field study was performed in Solna in May 2013. It consisted in the vibratory driving of seven sheet piles, out of which three were fitted with accelerometers. During the driving, ground vibrations were measured by accelerometers, the closest ones placed only 0.5 m from the sheet pile line. The design and installation of the soil instrumentation was innovative in as much as accelerometers were not only set on the ground surface but also at three different depths (~ 3 m, 5 m and 6 m). The analysis presented in this thesis is primarily a comparison between sheet pile vibrations and ground vibrations measured 0.5 m from the sheet pile line. The principal aspects considered in the comparison are: the influence of penetration through different soil layers, the sheet pile – soil vibration transfer efficiency, the frequency content of sheet pile and soil vibrations, and differences between toe- and shaft-generated vibrations. The main conclusions from this study are:  Most of the vibration loss occurs in the near field: 90-99% of the sheet pile vibration magnitude was dispersed within 0.5 m from the driven sheet pile. Moreover, the sheet pile – soil vibration transfer efficiency was reduced for higher sheet pile acceleration levels and higher frequencies.  The soil characteristics strongly influence the sheet pile vibration levels. A clear distinction could be made between "smooth" and "hard" driving, the latter being associated with an impact situation at the sheet pile toe.  The focus of ground vibration studies should not only be the vertical vibrations. Indeed, the ground vibrations’ horizontal component was found to be of the same or even higher magnitude than the vertical component.

Applicering av överlast på kalkcementförstärkta jordar är ofta förekommande idag, forskning indikerar dock på att överlasten här, inte ger samma effekt som på oförstärkta jordar. Med grund i uppmätta värden i fält, visas i denna rapport, sättningsdifferenser mellan att använda överlast jämfört med att endast applicera brukslast. Resultat av analyserna visar på sättningsbeteende observerat i fält. Om erforderlig liggtid för brukslast finns, uppstår endast små sättningsdifferenser mellan att använda överlast eller inte. Genom att utföra sensitivitetsanalys i FEM- programvaran PLAXIS studeras kryputvecklingen i den förstärkta jorden. Effekten av att applicera en överlast visas för krypsättningar över lång tid. Inget resultat från de numeriska FEM- analyserna visade att märkbart gynnsam effekt uppstår på grund av överlastens applicering, med avseende på krypsättningar. De numeriska analyserna utförs i 2 och 3 dimensioner för att belysa effekt av förenkling av ett lastfall som inte uppfyller krav för oförstärkta jordar i plant töjningstillstånd. Utöver detta ges efter en litteraturstudie, förslag på hur vissa indataparametrar kan utvärderas från empiriska relationer. Indataparametrar som ligger till grund för analyserna är utvärderade från sonderingsresultat i kombination med värden från laborationsförsök och empiriska data.

Geotechnical engineering is strongly associated with large uncertainties. Exploring a medium (soil) that is almost entirely and completely hidden from us is no easy task. Investigations can be made only at discrete points, and the majority of a specific soil volume is never tested. All soils experience inherent spatial variability, which contributes to some uncertainty in the design process of a geotechnical structure. Furthermore, uncertainties also arise during testing and when design properties are inferred from these tests. To master the art of making decisions in the presence of uncertainties, probabilistic description of soil properties and reliability-based design play vital roles. Historically, the observational method (sometimes referred to as the “learn-as-you-go-approach”), sprung from ideas by Karl Terzaghi and later formulated by Ralph Peck, has been used in projects where the uncertainties are large and difficult to assess. The design approach is still highly suitable for numerous situations and is defined in Eurocode 7 for geotechnical design. In paper I, the Eurocode definition of the observational method is discussed. This paper concluded that further work in the probabilistic description of soil properties is highly needed, and, by extension, reliability-based design should be used in conjunction with the observational method. Although great progress has been made in the field of reliability-based design during the past decade, few geotechnical engineers are familiar with probabilistic approaches to design. In papers II and III, aspects of probabilistic descriptions of soil properties and reliability-based design are discussed. The connection between performing qualitative investigations and potential design savings is discussed in paper III. In the paper, uncertainties are assessed for two sets of investigations, one consisting of more qualitative investigations and hence with less uncertainty. A simplified Bayesian updating technique, referred to as “the multivariate approach”, is used to cross-validate data to reduce the evaluated total uncertainty. Furthermore, reliability-based design was used to compare the two sets of investigations with the calculated penetration depth for a sheet-pile wall. The study is a great example of how a small amount of both time and money (in the pre-investigation phase) can potentially lead to greater savings in the final design. / <p>QC 20160201</p> / TRUST, Transparent Underground Structures

An essential demand in any underground facility is to seal it against the water ingress to reduce the time and cost of the construction and the corresponding environmental hazards. To achieve this, obtaining sufficient grout spread is of great importance. Among the grouts, cement grouts with lower costs and environmental issues have been more reliable, whereas their main problem is filtration that restricts the grout spread. Several investigations have been therefore aimed to develop instruments to measure the grout penetrability as a fundamental means to improve the grout spread. Due to the difference in assumptions, limitations, and test conditions, and the deficiency in design their results are occasionally in contradiction. The question here is how to measure the grout penetrability more realistic? To answer this, two of the most frequently used instruments, Filter pump and Penetrability meter, were adjusted to approach the test conditions in Short slot. The results were discussed with respect to the origins of contradictions to better evaluate the reliability and functionality of the instruments. Among the influencing parameters on grout spread, applied pressure is a key element. The stepwise pressure increment is the method currently used to improve the grout spread in rock. Application of dynamic grouting has been studied as a solution to improve the grout spread for almost three decades. Despite some promising results, the method has not been yet industrialized due to the limited efficiency and issues in the type and frequency of the applied pressure, and the geometry of the test equipment. Therefore, finding a more efficient alternative of the applied pressure was the second goal of this study. A pneumatic pressure control system was consequently employed to examine the efficiency of the method in Short slot. The results conclusively revealed the effectiveness of the method and provided a strong basis for further development of the dynamic grouting. / Ett viktigt krav när man bygger under mark är att konstruktionen blir tillräckligt tät, så att inläckage av grundvatten minimeras. Detta minskar både projektkostnaden och eventuell miljöpåverkan. För att skapa en tät konstruktion måste injekteringsbruket spridas tillräckligt i bergmassan. Kemiska injekteringsmedel har ofta bättre spridning i bergmassan än cementbaserade bruk, men cementbaserade bruk är både billigare och ger mindre miljöpåverkan. Det finns dock en del problem med cementbaserade bruk, nämligen att cementpartiklarna filtreras och att brukets reologiska egenskaper begränsar brukets utbredning. Ett antal studier har därför utförts för att studera dessa egenskaper hos cementbaserade bruk och utveckla metoder och instrument för att mäta brukets inträngningsförmåga. Detta i syfte att förbättra brukets utbredning. Dagens metoder och instrument ger nämligen ibland motsägelsefulla resultat på grund av de olika antaganden, begränsningar och förutsättningar som används i de olika testerna. Huvudfrågan är alltså hur man kan mäta brukets inträngningsförmåga på ett mer realistiskt sätt. För att undersöka detta modifierades två vanliga mätinstrument – filterpumpen och filterpressen – för att passa förhållandena i testanordningen Short slot. Resultaten diskuterades med avseende på olika typer av skillnader mellan metoderna i syfte att utröna dels vad som påverkar inträngningsförmågan, dels instrumentens tillförlitlighet och funktionalitet. Bland de parametrar som påverkar brukets spridning i bergmassan har injekteringstrycket en central roll. I dagsläget används stegvis tryckökning för att förbättra brukets spridning i sprickigt, hårt berg. Hur man kan använda dynamisk injektering för att förbättra brukets spridning har dock undersökts under snart tre decennier. Trots lovande resultat av denna metod ännu inte börjat användas i praktiken. Ett problem är svårigheten att ta försök på labb till fältmässiga förhållanden. Ett exempel är att man använde ett tryck som varierade med hög frekvens i en spricka som modellerades med två parallella skivor utan förträngningar, vilket är mycket annorlunda jämförelse med en riktig bergspricka. I modellen blir nämligen brukets spridning starkt beroende av brukets reologiska egenskaper, medan det snarare är filtrering som är problemet i en naturlig spricka på grund av förträngningarna. Dessutom fokuserade tidigare studier endast på sprickor med en sprickvidd större än 100 μm, trots att god spridning av bruket även i de smala sprickorna med mindre än 70 μm bredd är mycket viktigt när det är höga krav på anläggningens täthet. Ett annat mål med denna licentiatuppsats var därför att hitta nya sätt att förbättra brukets spridning i berget. Därför övervakades trycket med ett pneumatiskt kontrollsystem vid tester i Short slot för att studera hur effektiv denna metod är under mer realistiska förhållanden med förträngningar på mindre än 70 μm. Resultaten visade att metoden är effektiv, vilket utgör en bra bas för att fortsätta utveckla dynamisk injektering. / <p>QC 20160413</p>

Det finns en innovativ, grön grundläggningsteknik kallad energigrundläggning. Principen är att integrera redan erforderliga, strukturella element såsom pålar med en värmeväxlare i syfte att utvinna energi. Tekniken har funnits sedan tidigt 80-tal men har knappt används i Norden. Tekniken visar på stor potential då man kan uppnå synergi genom utvinning av värme under vinterhalvåret och kyla under sommarhalvåret. I detta arbete redogörs för grundläggande principer och mekanismer bakom energigrundläggning samt en omfattande litteraturstudie av vad som tidigare har studerats inom området. Det finns få exempel i litteraturen på problematiken med förändrade geotekniska egenskaper hos jorden på grund av energiutvinningen och än färre exempel på knäckningsproblematiken hos slagna, slanka stålrörspålar. Tyngdpunkten i arbetet har varit just denna förändring av de geotekniska egenskaperna, främst skjuvhållfastheten och hur denna förändring påverkar pålens bärförmåga. På grund av saknad av originell data har flera antaganden och erfarenheter tagits från Tidfors (1987) som undersökte förändringar hos olika lerors geotekniska egenskaper då de utsattes för olika temperaturdifferenser. I arbetet har två konsekvenser av användning av energipålning studerats i en fallstudie, nämligen temperaturinducerad rörelse av pålen och försämrad bärförmåga med avseende på knäckning. Fallstudien är ett nyligen färdigställt projekt i Jyväskylä, Finland där en kommersiell byggnad grundlagts på energipålar. De temperaturinducerade rörelserna hos pålen har undersökts analytiskt genom beräkning med gällande förutsättningar i Jyväskylä. De axiella lasterna som uppkommer i studien visar inte de storlekar som krävs för att innebära ett strukturellt problem. Dock visar fenomenet på ett reellt problem som måste tas i beaktning. Det är även svårt att modellera problemet då det är svårt att avgöra vilken slags inspänning pålen har. Knäckningsproblematiken studerades även den analytiskt genom beräkning. En typ-påle dimensionerades enligt gällande normer med en gradvis försämrad och förbättrad skjuvhållfasthet. Förändringen av skjuvhållfastheten byggde på antaganden baserade på resultaten presenterade av Tidfors (1987). Den försämrade skjuvhållfastheten innebär självfallet försämrad bärförmåga. Brottmoden knäckning blev dimensionerande vid en 50 % försämring av skjuvhållfastheten. Användandet av energigrundläggning medför förändringar av jordens geotekniska egenskaper och innebär att ett behov av att kvantifiera dessa förändringar uppstår. Vidare måste konsekvenserna av användande integreras i dimensioneringsprocessen så att framtida ekonomiskt gångbart användande är möjligt. På så sätt kan tekniken växa och infria sin stora potential. / There is an innovative, green foundation technique called energy foundation. The principle is to integrate already required structural elements such as piles with a heat exchanger to extract energy. The technology has been around since the early 1980’s but has hardly been used in the Nordic countries. The technique shows great potential as one can achieve synergy by extracting heating in wintertime and cooling in the summertime. This thesis presents the basic principles and mechanisms of energy foundation and an extensive literature review of what has been previously studied in the area. There are few examples in the literature on the problems associated with the changes of geotechnical properties due to energy extraction. Even fewer examples of the buckling problem of driven, slender steel pile. The focus of this thesis has been this change of the geotechnical properties, mainly the shear strength and how this change affects the pile bearing capacity. Because of a lack of original data, several assumptions and experiences has been derived from Tidfors (1987). She subjected different clays to different temperatures and investigated the changes in the various clays’s geotechnical properties. In the thesis has two consequences of the use of energy piles been studied in a case study. The two consequences are temperature-induced motion of the pile and buckling problems due to loss of shear strength of the soil. The case study is a recently completed project in Jyväskylä, Finland, where a commercial building’s foundation has been laid on energy piles. The temperature-induced motion of the pile has been investigated analytically by calculation given the conditions in Jyväskylä. The axial loads arising in the pile did not show the sizes needed to represent a structural problem. However, the phenomenon presents a real problem that must be taken into consideration. It is also difficult to model the problem as it is difficult to determine what kind of restraint the pile got. The buckling problem was also studied analytically by calculation. A typical pile was designed according to current standards with a gradual deterioration and improved of the soils shear strength. The change in the shear strength was based on assumptions corresponding to the results presented by Tidfors (1987). The deterioration of the shear strength did obviously reduce the pile’s carrying capacity. Failure by bucklingmode came into play at a reduction of the shear capacity of 50 %. The use of energy foundation results in changes of the soil’s geotechnical properties and creates a need to quantify these changes. Furthermore must the consequences by using energy foundation be integrated into the design process so that in the future economically viable usage is possible. By doing so the technology can grow and fulfil its great potential.

<p>Most of the attention to the seismic performance of tunnels has been devoted to shear waves propagating in a direction perpendicular to the tunnel axis, with motion perpendicular to the tunnel axis, causing the so-called “ovaling or racking response”. Body waves, however, can travel through the ground and intersect the tunnel at different angles, thus inducing a complex seismic response that requires a comprehensive understanding of all modes of deformation. This study provides analytical solutions to capture the behavior of the liner and the surrounding ground, for a deep circular tunnel subjected to body waves, for all five possible modes of deformation: (i) axial compression-extension; (ii) transverse compression-extension; (iii) ovaling; (iv) axial shear; and (v) axial bending or snaking. The main assumptions used to derive the analytical solutions include: (i) the tunnel is deep and very long and has a circular cross section; (ii) the ground and the support are homogeneous and isotropic, and their response remains elastic; (iii) the interface between the ground and the liner is either no-slip or full-slip; (iv) the pseudo-static approach, i.e. inertia forces can be neglected, is acceptable to estimate seismic deformations; (v) for the transverse compression-extension and ovaling deformation modes, plane strain conditions in the direction of the tunnel axis apply at any cross section; and (vi) for the axial compression-extension and axial bending deformation modes, the wavelength of the seismic motions is much larger than the tunnel radius. Two and three-dimensional numerical simulations with the finite element codes ABAQUS, for static drained/undrained loading and dynamic drained loading conditions, and MIDAS GTS NX, for dynamic undrained loading conditions, are carried out to validate the analytical solutions and further investigate the seismic response of the tunnel. All the comparison results show good agreement between the analytical and numerical solutions.</p> <p>Dynamic amplification effects on the tunnel cross section are studied for the axial compression-extension, transverse compression-extension, and axial bending deformation modes, through a set of dynamic time-history models where the input frequency of the far-field seismic motion is changed. The results reveal the limits of the analytical solutions, in the form of minimum wavelength-to-tunnel diameter (/D) ratios such that the errors are less than twenty percent, including: (i) 25 (drained) and 20 (undrained) for axial compression-extension; (ii) 25 (drained) and 12.5 (undrained) for transverse compression- extension; and (iii) 7.5 (unsupported tunnel), 7.5 (supported tunnel with no-slip interface), and 12.5 (supported tunnel with full-slip interface) for axial bending or snaking. These ratios are also the limits of applicability of quasi-static (instead of dynamic) numerical simulations to estimate the seismic behavior of the liner and the surrounding ground.</p>

Rock masses may present remarked geostatic stress anisotropy and anisotropic material properties; thus, the tunnel alignment with the geostatic principal stress directions and with the axes of material anisotropy is unlikely. Nevertheless, tunnel design often neglects those misalignments and; yet, the misalignment effects were unknown. In this doctoral research, tunnels under complex anisotropic conditions were modelled analytically and numerically with 3D nonlinear Finite Element Method (FEM). When the tunnel misaligns with the geostatic principal stress directions, anti-symmetric axial displacements and shear stresses are induced around the tunnel. Analytical solutions for misaligned shallow and deep tunnels in isotropic elastic ground are provided. The analytical solutions were validated with 3D FEM analyses. Near the face, the anti-symmetric axial displacements are partially constrained by the tunnel face, producing asymmetric radial displacements and stresses. The asymmetric radial displacements at the face can be divided into a rigid body displacement of the tunnel cross-section and anti-symmetric radial displacements. Those asymmetries may affect the rock-support interaction and the plastic zone developed around the tunnel. In anisotropic rock masses, the tunnel misalignment with the axes of material anisotropy also produces anti-symmetric axial displacements and stresses around the tunnel. It occurs because when the tunnel is not aligned with the principal material directions, the in-plane stresses are coupled with the axial displacements (i.e. the compliance matrix is fully populated). Thus, tunnels in anisotropic rock mass not aligned with the geostatic principal stresses and with the axes of material anisotropy are substantially more complex than tunnels not aligned with the principal stress directions in isotropic rock mass. An analytical solution for misaligned tunnels in anisotropic rock mass is provided. It was observed that the relative orientation of the geostatic principal stresses with respect to the axes of material anisotropy plays an important role. The axial displacements produced by far-field axial shear stresses and by the rock mass anisotropy may compensate each other; thus, axial and radial displacements around the tunnel are reduced. On the other hand, those anti-symmetric axial displacements may be amplified; thus, the ground deformations are increased. Asymmetric radial and axial deformations, and asymmetric spalling of the tunnel walls are commonly observed on tunnels in anisotropic rock masses. The tunnel misalignment with the geostatic principal stress directions and with the axes of material anisotropy could be associated with those phenomena that, so far, are not well comprehended

Med den nuvarande situationen med ökade oroligheter i Europa, bristande elproduktion och en utveckling mot mer elektrifierade samhällen så har ett behov för hållbara energikällor uppstått. Många länder har börjat satsa på små modulära reaktorer (SMR) istället för storskaliga kärnkraftverk då de kan serietillverkas och är enkla att bygga vilket gör dem kostnadseffektiva. Denna studie fokuserade på var den mest optimala placeringen av SMR är inom elområde 4 om man bortser från 17 kap 6a§ miljöbalken. Elområde 4 valdes då det är det elområdet som producerar allra minst och har störst underskott av el. Detta gjordes med hjälp av en multikriterieanalys (MKA) och en efterföljande känslighetsanalys med totalt sex restriktionskriterier och nio faktorer med anvisningar hämtade från svensk lagstiftning, tidigare studier och internationella atomenergiorganet (IAEA). För att bedöma placeringen genomfördes en viktsättning med hjälp av intervjuer och enkäter med fyra olika personer med olika expertisområden inom kärnkraft. För att relatera faktorernas vikter till varandra användes Analytisk Hierarki process (AHP)-metoden vid skapandet av den genomsnittliga viktsättningen. En MKA-karta gjordes för att ta reda på vart den mest optimala platsen är utifrån den genomsnittliga viktsättningen samt en egen karta för de olika experternas egna viktsättningar. Det följdes upp av en känslighetsanalys med en faktor i taget (OAT) metoden och genom att eliminera en faktor i taget för att avgöra ifall den mest optimala platsen ändras och procentuellt hur mycket som arean ändras mellan de olika modellerna. Resultatet visar att den mest optimala platsen att placera en SMR är runtom Barsebäck, där det har stått ett storskaligt kärnkraftverk sedan tidigare. Man kan dra slutsatsen att känslighetsanalysen är robust och att den inte påverkas mycket av förändringar. / With the current situation of increased tension in Europe, inadequate electricity production, and a move towards more electrified societies, there has arisen a need for sustainable energy sources. Many countries have started investing in small modular reactors (SMR) instead of large-scale nuclear power plants as they can be mass-produced and are easy to build, making them cost-effective. This study focused on the most optimal location for SMRs within the fourth electrical bidding zone, disregarding section 17-chapter 6a§ of the Swedish Environmental Code. Bidding zone four was chosen as it produces the least amount of electricity and has the largest deficit. This was done using a multicriteria analysis (MCA) and a subsequent sensitivity analysis with a total of six restriction criteria and nine factors considering guidelines taken from Swedish legislation, previous studies on the subject, and the International Atomic Energy Agency (IAEA). To evaluate the placement interviews and questionnaires with four different people with different areas of expertise in nuclear power were carried out as a basis for the average weighting. The Analytic Hierarchy process (AHP) where used to evaluate the factors relative weights to each other. An average MCA map was made to determine the most optimal location based on the average weighting and a separate map for the different experts' own weightings. This was followed by a sensitivity analysis using one factor at a time (OAT) method, and by eliminating a factor to determine how the most optimal location changes, and the percentage of how much the area changes between the different models. The results show that the most optimal site to place an SMR is around Barsebäck where there was a large-scale nuclear power plant previously. One can conclude that the sensitivity analysis is robust and is not significantly impacted by changes.

This thesis compares foundation methods for buildings on low-strength, limited-depth soil. The study focuses on soil replacement and piling, specifically concrete and steel piles. The studyaims to answer the key questions about the possibility to use short piles on limited depth, cost-efficiency, and environmental impact of these methods. Geotechnical and structural calculations are used to assess the loads on the piles and evaluate their strength. WIN-statik Frame Analysis helps analyze deformations, moments, and stresses. The foundation transfers vertical loads to three piles, generating horizontal loads at the pile tops. However, the challenge lies in short piles in clay, which experience low earth pressure and may rotate due to bad stabilization. The analysis reveals that concrete piles are unable to transfer loads to solid rock effectively. Without fixed anchorage points, they are prone to rotation due to insufficient stiffness and lateral earth pressure. In contrast, steel piles are preferred because they can be drilled into the rock, providing fixed anchorage at the clay-rock transition and enabling them to withstand loads transferred through the foundation. Soil replacement is considered as an alternative method but proves economically expensive, approximately three times more than piling with steel piles. From an environmental standpoint, piling contributes only slightly more carbon dioxide emissions, about 0.4 tons, compared to soil replacement. Considering the significant cost advantage and minor environmental impact difference between soil replacement and piling, piling with steel piles is recommended as the optimal foundation method. Concrete piles are dismissed due to their instability. This choice ensures stability, cost-efficiency, and reduced environmental impact for buildings on low-strength, shallow-depth soil.