A transition piece has responsibility to transmit forces from one member to another member. But when doing it, the transition piece must be stiff enough. Studying what parameter of the transition piece is contributing to the stiffness the most, will give economic advantages. Studies on the stiffness when introducing a transition piece on a hybrid tower will be carried out with an analytical procedure through Finite element method, with the software Abaqus. A linear perturbation, with a frequency step where extraction of the eigenfrequency value will be obtained. The value will reflect the stiffness of the structure, because it has a linear relation between each other. Higher eigenfrequency means higher stiffness and vice versa. The first model (Case A) is model of a fixed tubular tower. The frequency of case A is desired because it’s stiff at the bottom. Therefore a comparison has been made when introducing the transition piece.The eigenfrequency of the tubular tower (Case A) is 0,36765 Hz. And The eigenfrequency of the structure (Case D) is 0,21964 Hz, which make a stiffness reduction of 40,3 % when introducing the transition piece. 60,6 % of the total reduction is due to the bridging ring. The most efficient change on the bridging ring that will obtain a higher stiffness on the entire structure is to increase mid-plates layers.

Byggbranschens utveckling är i ständig rörelse framåt tack vare att BIM går i spetsen. I teorin anses många av lösningarna som medföljer implementering av BIM vara enkla att förstå och arbeta med, men i praktiken ligger dock de tekniska lösningarna en bra bit från full implementering i branschen. I arbetet med mängdning inom ett byggprojekt har utvecklingen med BIM stått still länge och idag tar majoriteten fram mängder manuellt. En tidskrävande metod som med fördel ersätts med en teknisk lösning inkluderad i exempelvis en Revitmiljö.   Rapporten ämnar till att rekommendera en metod för att hantera mängdning på ett enklare sätt. Genom utförande av två i begynnelsen tekniska mängdningsmetoder på ett referensobjekt har tillvägagångssätt analyserats i form av möjligheter och problematik. Med hänsyn till process och information diskuteras bland annat Revits långa förlopp, tilläggets invecklade inställningar, givande data och användnings-områden. Till sist dras en slutsats om att tilläggets fördelar väger tyngre och därmed är MWF värd en rekommendation. / The development of the construction industry is in constant motion forward thanks to BIM. In theory, it seems like many of the solutions that come with the implementation of BIM are simple to understand and work with, but in practice, the technical solutions are far from being completely implemented in the industry. In the work with quantifying within a project the development has become stagnant and the majority compile quantities manually.  This is a time-consuming method that is advantageously replaced with a technical solution from for example a Revit-environment.   This report aims to recommend a method for managing quantifying in an easier way. By performing two technical methods of quantifying on a reference object, the approaches have been analyzed in terms of possibilities and problems. The long process of Revit is discussed and compared with the complicated settings of the application MWF. In summary, MWF is recommended because of the overall documents with rewarding data and drawings. The suggested usage for the data strengthens the conclusion.

Syftet med denna avhandling är att optimera fragmenteringen i Bolidens Minerals dagbrott Aitikgruvan. Sprängning är en av huvudprocesserna i gruvbrytning och dess resultat har stor inverkan på gruvans totala ekonomi. Resultatet av fragmenteringen påverkar inte bara gruvans produktivitet och enhetskostnader utan även de efterföljande processerna krossning och malning i anrikningsverket. Optimeringar av delar i ett system leder ofta till en suboptimering av hela systemet. Traditionellt har gruvan och anrikningsverket varit uppdelade i separata resultatenheter med följd att gruvan suboptimerad sprängningen mot gruvans kostnader, utan hänsyn till resultatet längre fram i produktionskedjan. I det här arbetet inriktas designen av sprängningen mot de optimering av hela processen gruva och anrikning, d.v.s. maximera genomsättningen. Primärkvarnarna i anrikningsverket har identifierats som flakhals i produktionssystemet, gruva/anrikningsverk, varför sprängoptimering inriktas mot att maximera genomsättningen i dessa. Aitikgruvan är utrustad med teknik som möjliggör spårning av malmen från position i gruvan genom anrikningsverk, vilket medför att även resultat i anrikningsverk, t.ex. genomsättning i primärkvarnarna, kan återkopplas till dess ursprungliga position i gruvan. Utifrån kvarnarnas beteende, fyllnadsgrad, effekt och ingående styckefall, under produktion, kan en optimal förändring i styckefall bestämmas. Med utgångspunkt från att malmen har lika fragmenteringsegenskaper i dess stupningsriktning kan antagandet göras att malmen i underliggande pall har liknande mekaniska egenskaper som den aktuella salvan/området, vilket antas ge lika resultat vid samma sprängdesign. Det optimala styckefallet återkopplas till gruvan och en sprängdomänsindelning och sprängdesign för dessa domäner kan göras för nästkommande brytningsnivå. Med utgångspunkt från det optimala styckefallet för primärkvarnarna för de olika områdena i gruvan, bestäms sprängdesignen för underliggande pall med hjälp av en sprängmodell och en krossmodell. För att modellera krossningen och sprängningen görs inga laboratorietest eller fältarbeten, utan de ingående parametrarna fås ur den styckefallsfördelning, både före och efter kross, som uppnås i de olika sprängdomänerna. För att undersöka om finare styckefall ger ökad genomsättning i primärkvarnarna har fem testsalvor skjutits och utvärderats. Salvorna har jämförts mot de salvor som låg rakt ovan i föregående pall. Testsalvorna fick 35% högre specifik laddning än vad som vanligtvis används. Salvornas position i gruvan var inte valda utifrån sprängdomänsindelningen, utan tagna när tillfälle gavs. Genomsättningsökningen för de fem testsalvorna blev i medel åtta procent. För de två testsalvorna som låg i sprängdomänen som har den högsta förväntade genomsättningsökningen blev genomsättningen 14 respektive 22 procent högre. Den samlade kunskapen om styckefallets inverkan på genomsättningen i primärkvarnarna pekar mot att finare styckefall i regel ger högre genomsättning. Innan metodiken med att bestämma det optimala styckefallet kan användas fullt ut, måste fler undersökningar göras för att fastställa sambanden, framförallt behövs fler testsalvor. För utveckling av kross- och sprängmodellerna måste styckefallsmätningen bli mer tillförlitlig. / Godkänd; 2005; 20061213 (haneit)

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The fracture of rock has been the subject of the extensive research in the mechanical fragmentation. With the rapid development of computing power, interactive computer graphics and topological data structure, numerical tool has become a good tool to gain some insights into the problem of rock fracture. However, most of the commercial programs are not so robust that they can model the fracture progressive process with rock fabric characteristics (heterogeneity) considered. Based on this background, a novel numerical code, rock and tool interaction code (R-T2D) has been developed to understand the fracture progressive process of heterogeneous rock. The research, development (R & D) and calibration of R-T2D code (Paper A and B) mainly consists of (1) characterization of rock heterogeneity, (2) mesoscopic constitutive law, nonlinear behaviour and associated seismicity, (3) Mohr-coulomb and double elliptic strength criterion, and (4) calibration of R-T2D code by simulating basic rock mechanics experiments. In the second part of the thesis (Paper C and D), preliminary industrial applications of R-T2D code in mechanical fragmentation are conducted. In rock cutting, the peculiarities in cutting heterogeneous brittle materials are investigated. Besides, the fracture processes induced by cutters with different back rake angles are examined and compared with each other. In indentation, indentation-induced fractures are researched by R-T2D code. The influences of confining pressure on the formation of side cracks are discussed. In the simultaneous loading by multiple indenters, the propagation, interaction and coalescence of side cracks induced by neighbour indenters are simulated to check how the side cracks propagate, interact and coalesce to form large rock chips. At last, the indexing-effect in the simultaneous loading is discussed. The major results for the two parts can be summarized as the following: On the basis of Weibull distribution, a heterogeneous material model is proposed to characterize the heterogeneity in rock, where rock is specified by a few characteristic parameters: the homogeneous index and the elemental seed parameters. Corresponding to the specific rock, the homogeneous index can be determined based on the defects distribution of microstructure and the elemental parameters can be gotten from the laboratory tests. Rock heterogeneity has an important influence on the crack initiation location and subsequent propagation path. Compared with the traditional Mohr-coulomb and Hoek-Brown strength criterion, the double elliptic strength criterion is more useful to model the fracture in mechanical fragmentation, which can represent the transition from brittle failure to ductile cataclastic failure with increasing confining pressure. A series of numerical experiments including both the intact rock and the notched rock are conducted by R-T2D code to obtain the physical-mechanical properties and fracture toughness, and to simulate the crack initiation, propagation and the whole fracture progressive process. The developed R-T2D code seems to have built a bridge between the physical-mechanical parameters and fracture toughness. The detailed visually shown stress distribution and redistribution; crack nucleation, initiation, stable and unstable propagation, interaction and coalescence; and corresponding load-displacement curves can be proposed as benchmarks for numerical programs for crack propagation. In mechanical fragmentation, a crushed zone is always available near the tool. The crushed zone has an important influence on the chipping process and energy utilization. The crushed zone is in fact the zone with a high density of microcracks and some of the rocks in this zone behave in a ductile manner with stress satisfying the ductile failure surface of the double elliptic strength criterion. A simple description and qualitative model of the rock fragmentation process induced by truncated indenters are summarized as follows: Little damage to the rock was observed at the linear elastic deformation stage. Then conical Hertzian cracks were initiated adjacent to both corners of the truncated indenter and propagated in the well-known conical Hertzian manner. As the loading displacement increased, some of the elements in the high confining pressure zone immediately under the indenter failed in the ductile cataclastic mode with the stress satisfying the ductile failure surface of the double elliptic strength criterion. With the cataclastic failures and tensile conical cracks releasing the confining pressure, the elements in the confining pressure zone were compressed into failure and the crushed zone came into being. In the crushed zone, microcracking was pervasive. The intensity of the microcracking within the zone increased and a re-compaction behaviour occurred with increasing loading displacement. Associated with this microcracked region there was a volumetric expansion and a tensile stress field, which drove side cracks to propagate in a curvilinear path. It is thought that the curvilinear path was caused by the heterogeneity of the rock. With an increased loading displacement, the side cracks rapidly propagated and intersected with the free rock surface to form rock chips. The confining pressure has an important influence on the failure mode in indentation test. As the confining pressure increases, a small but noticeable increase in the indentation strength was measured. With decreasing confining pressure, of particular interest is a change in the rock failure mode when the confining stress is reduced below a critical value. Instead of the usual formation of rock chips adjacent to the punch, vertical cracks are propagated beneath the punch, causing the specimen to be split in half when the confining pressure on the sample is less than a critical value. This result is of practical interest. In boring hard rock at low confining stresses, the creation of such tensile fractures beneath an indenter may serve to fragment the rock sufficiently to facilitate its removal. The simultaneous loading of the rock surface by multiple indenters seems to provide a possibility of forming larger rock chips, controlling the direction of subsurface cracks and consuming a minimum total specific energy. The simulated results by R-T2D code reproduce the progressive process of rock fragmentation under mechanical loading: the build-up of the stress field, the formation of the crushed zone, surface chipping, and the formation of the crater and subsurface cracks. Therefore, R-T2D code is indeed a valuable numerical tool to research rock fracture, which can be utilized to improve our understanding of rock-tool interaction and the rock failure mechanisms under the action of mechanical tools, which, in turn, will be useful in assisting the design of fragmentation equipment and fragmentation operations. Based on the above researches, a number of interesting problems are discussed and the future studies are suggested in the last part of the thesis. / Godkänd; 2003; 20070218 (ysko)

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No description available.

The process of choosing a site for a nuclear waste repository means that many aspects have to be taken into consideration. One of these is that the repository has to be mechanically stable for a long time. The mechanical stability of the rock is very difficult to determine. One of several factors, which determine the mechanical stability, is the virgin state of stress. The thesis project consists of two parts. In the first part the state of stress at Äspö Hard Rock Laboratory had to be defined. This was done based on earlier rock stress measurements conducted during the years 1988 to 1997. Two different measurement techniques have been used, hydraulic fracturing and overcoring. During the overcoring two types of cells have been used, CSIRO HI-cell and a cell developed by the Swedish State Power Board (SSPB). In the second part of the project, investigation of the correlation between the stress and geological structures are made using numerical modelling tools such as FLAC, UDEC and 3DEC. The rock stress measurements using the hydraulic fracturing gave orientations of the horizontal stress that coincide with earlier hydraulic fracturing measurements conducted in Scandinavia. The magnitudes of rock stresses are slightly lower than the earlier reported stress magnitudes for the Scandinavian part of the earth crust. The rock stresses obtained from the overcoring resulted in higher stresses than what was predicted by the hydraulic fracturing measurements. However, the orientation of the maximum horizontal stresses coincides well between the two techniques. The orientation is also more or less constant with respect to increasing depth. The state of stress at Äspö is defined by using the results from the hydraulic fracturing and the measurements conducted by SSPB-cell. The measurements from the SSPB-cell are used since these have a Poisson's ratio that corresponds well with the uniaxial tests of rock samples and since the measurements have been done at a distance from the opening where no influence from the openings can be expected. Since the magnitudes of the rock stresses differ between overcoring and hydraulic fracturing, some efforts have been made to find possible causes for this. The rock stresses when conducting overcoring gave higher values overall, which could be explained by high Poisson's ratios and a minor influence from the opening as the stress measurements might have been done in the disturbed zone. The high Poisson's ratio may depend on the stress-induced microcracks, which might be initiated during the overcoring of the cell, during the drilling of the pilot borehole, in which the cell is installed, and during biaxial testing. Statistical analysis showed that there is significant differences between the mean values of Poisson's ratio obtained from biaxial tests of cores containing the CSIRO HI-cell and the SSPB-cell. Poisson's ratio is about 0.34 for CSIRO HI-cell while the SSPB-cell gave a Poisson's ratio of 0.23. The analysis also showed that Young's modulus does not differ between the techniques. The modelling in FLAC was made to simulate the overcoring and biaxial testing. The result show that it is possible to obtained extensional strain in the core during overcoring if the major principal stress is perpendicular to the borehole axis. This may lead to microcracking occurring in the core causing high Poisson's ratio, which results in higher stresses. It can also be seen from the simulation of the biaxial testing that extensional strain is achieved even if the hollow core is not damaged during overcoring. The analyses using UDEC was made to study the effect of different properties of a discontinuity, such as the dip angle, Young's modulus, Poisson's ratio, density and the normal and shear stiffness. The analyses showed that an inclined discontinuity affects the stresses especially if sliding occurs. So, the dip angle does not solely, determine the amount of disturbance of the state of stress around a discontinuity. If slip will occur or not depends, thus, on a combination of dip angle, friction angle and the far field state of stress. A dip angle of 30 degrees affected the major principal stress most, while the minor principal stress is most affected by a dip angle of 45 degrees, for a friction angle of 10 degrees. The results from the simulation of a thick zone showed that the elastic properties of the zone material mainly affect the stresses within the zone. However, higher values of Young's modulus and Poisson's ratio in the zone than in the side rock resulted in higher stresses within the zone than outside. The orientation of the major principal stress becomes more perpendicular to the zone. The 3-dimensional analyses using 3DEC was made in order to investigate if the stresses at Äspö could be correlated with the major geological structures. The results show that the increase in the horizontal stress seen both in KAS02 and KAS03 is obtained in the model when using a bilinear stress state that is based on the measurements performed at Äspö. However, a satisfying coincidence is not obtained with the measured stresses in KAS02, KAS03, KAS05 and KZXSD8HL, which were the boreholes used as reference boreholes. One of the reasons for the disagreement may mainly be that the discontinuities used in the 3DEC model are more or less vertical. The least dip angle used is 60 degrees. Another reason may be that the measured stresses are influenced by far more parameters than are used in the 3DEC- model, such as different rock types, smaller discontinuities and mineral grains. / <p>Godkänd; 2000; 20070316 (ysko)</p>

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No description available.