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Strain softening and strain localisation in irreversible deformation of snowBarraclough, Thomas William January 2015 (has links)
The aim of this work was to visualise heterogeneous deformation in snow under controlled laboratory conditions. Heterogeneous deformation was observed for both homogenous and heterogeneous loading conditions. Understanding deformation of snow is important in many scientific fields including vehicle traction, avalanche forecasting, and winter sports. This thesis investigates the deformation behaviour of snow on the centimetre scale under moderate strain rates (0.005 to 0.1 s-1) when subject to one-dimensional compression or to indentation. In order to allow controlled and repeatable snow deformation experiments, a new type of artificial snow was developed. This snow type was examined by low temperature scanning electron microscopy and by traditional avalanche observer’s methodology. Penetrometer experiments were conducted on the artificial snow and on natural seasonal snow in Scotland. The two snow types were found to be similar: results obtained on artificial snow are thus applicable to natural snow. A reproducible technique of manufacture and a thorough characterisation of the artificial snow are presented. One-dimensional compression experiments were conducted on the artificial snow. The experiments were in confined compression in a specially constructed apparatus, designed to provide for back-lit photography. Images were taken at 0.25 second intervals and analysed using digital image correlation, thus providing 2D strain fields. With careful control of photographic parameters, it is demonstrated that process of applying tracer substances to the snow is not necessary, thus allowing an unprecedented resolution. Spontaneously-forming strain localisations were observed for the first time, indicating strain softening behaviour. Damage was observed to propagate through the specimen as a moving front, resembling a wave. The force required to propagate the front remained nearly constant until the whole specimen was compacted, at which point a new front formed and the process repeated. The experimental method was extended to 2D indention experiments with a range of sizes and shapes of indenter. Complex deformation fields were observed, extending up to 6 times the width of the indenter on each side. Observed deformation included tensile tearing as well as compression and shear. The maximum local strain achieved in the indentation experiments was similar to that achieved by the first compaction front in one-dimensional compression. The work here presented has implications for snow deformation generally: strain localisation introduces a characteristic length, which may prevent scaling of models or results. The indentation results are particularly relevant to snow penetrometry, where indentation experiments are used to try and extract microstructural information from buried snow layers for the purpose of avalanche prediction. The common assumption that the penetrometer interacts only with snow very close to its tip may need to be reconsidered.
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Hydraulic performance and stability of geosynthetic landfill cover systems with constrained drainage at the outletYates, Trevor Butler 30 September 2011 (has links)
Sliding failures of landfill cover systems are common, and the slip surface is often at the interface between a geosynthetic drainage layer and an underlying textured geomembrane. In an effort to understand the sliding failures, the objectives of this research project are to summarize current regulation and practice in landfill cover design, use experimental methods to characterize the behavior of geosynthetic landfill materials in cover systems approaching failure, and develop models to evaluate the hydraulic performance and stability of landfill cover systems.
Inclined plane tests were conducted to explore the behavior of a geosynthetic drainage material/textured geomembrane interface. The interface had effective normal stress dependent strain softening behavior, with more strain softening measured at higher effective normal stresses.
A numerical model for confined flow in a drainage layer with a constrained outlet was developed. The model was used to evaluate how water fills and empties from a geosynthetic drainage layer for a variety of inflow conditions and constraints to flow at the outlet. The model was used to demonstrate that a drainage layer that effectively conveys water out of a cover system with a free flowing drainage outlet quickly fills with water when the outlet has a modest constraint to flow.
An iterative, numerical model was developed to calculate stability solutions for landfill cover slopes that satisfy force equilibrium and strain compatibility while accounting for effective normal stress dependent strain softening and various pore water pressure conditions. Stability solutions reveal that depending on the water pressure in the drainage layer, the geosynthetic drainage material may experience tension at many points along the slope.
It is crucial for the stability of the landfill cover system to maintain free-flowing conditions at the drainage layer outlet. A modest constraint to flow at the outlet has a significant adverse effect on the ability of the landfill cover drainage layer to convey water out of the system, which can lead to instability. The drainage layer outlet should be designed to ensure free flow of water out of the drainage layer. / text
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Modeling Adjustable Passive Stiffness in Detrusor Smooth MuscleQuintero, Kevin E 01 January 2006 (has links)
Passive detrusor smooth muscle exhibits both viscoelastic softening and strain softening. Strain softening is a loss of stiffness following a stretch to a longer length and is reversible upon muscle activation. Because of this behavior, steady state passive force in detrusor is not constant for a given muscle length and can be adjusted by an intracellular mechanism. Thus, passive detrusor exhibits adjustable passive stiffness. Existing three-component mechanical models for muscle, the Kelvin and Voigt, are insufficient to display this characteristic. The goal of this thesis is to develop a new biomechanical model for passive force in detrusor by adding additional elements to the Kelvin or Voigt models. Eight mechanical characteristics of detrusor are identified from the literature and with three new experiments, and a novel adjustable passive stiffness model for smooth muscle is proposed. Simulations are performed to demonstrate that the model qualitatively exhibits each of the eight tissue characteristics.
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Assessment of Roof Stability in a Room and Pillar Coal Mine in the U.S. Using Three-Dimensional Distinct Element MethodSherizadeh, Taghi January 2015 (has links)
Roof falls and accumulation of dangerous gasses are the most common hazards in any underground coal mine. Different mechanisms can jeopardize the stability of the roof in underground excavations and successful roof control can only be obtained if the failure mechanism is identified and understood properly. The presence of discontinuities, the inherent variability of the rock mass and discontinuity properties, and the uncertainties associated with directions and magnitudes of the in-situ stress makes the rock engineering problems challenging. The numerical modeling can assist the ground control engineers in designing and evaluating the stability of the underground excavations. If extensive geological and geotechnical data are available, then detailed predictions of deformation, stress and stability can be accomplished by performing numerical modeling. If not, still the numerical modeling can be used to perform parametric studies to gain insight into the possible ranges of responses of a system due to likely ranges of various parameters. The parametric studies can help to identify the key parameters and their impact on stability of underground excavations. The priorities of the material testing and site investigation can be set based on the selected key parameters from parametric studies. An underground coal mine in western Pennsylvania is selected as a case study mine to investigate the underlying causes of roof falls at this mine. The immediate roof at the case study mine consists of laminated silty shale, shale, or sandstone that changes from area to area, and the floor is shale or soft fireclay. This study was mainly focused in the stability analysis of the roofs with the laminated silty shale rock type, where the majority of roof falls had taken place in the roof with this type of roof material. Extensive laboratory tests were performed on the core samples obtained from the case study mine to estimate the intact rock and discontinuity properties of the materials that occur in large extent at the selected interest area of the case study mine. In this research, the three-dimensional distinct element method was used to investigate the stability of the roof in an underground room-and-pillar coal mine. The implemented technique was able to accurately capture the failure of the major discontinuities and rock masses which consist of intact rock and minor discontinuities. In order to accurately replicate the post failure behavior of the rock layers in the immediate roof area, the strain-softening material constitutive law was applied to this region. Extensive numerical parametric studies were conducted to investigate the effect of different parameters such as the variation of immediate roof rock mass strength properties, variation of discontinuity mechanical properties, orientations and magnitudes of the horizontal in-situ stresses, and the size of pillars and excavations on stability of the excavations. The distribution of post failure cohesion along with other measures such as accumulated plastic shear strain, distribution of Z-displacements at the roofline, failure state (joint slip and tensile failure) and displacement (normal and shear displacements) of discontinuities were used to accurately assess the roof stability in this case study. The research conducted in this dissertation showed that the bedding planes play an important role on the behavior of roof in underground excavations. Therefore, an appropriate numerical modeling technique which incorporates the effect of discontinuities should be employed to simulate the realistic behavior of the discontinuous rock masses such as the layered materials in roof strata of the underground coal mines. The three-dimensional distinct element method used in this research showed the clear superiority of this technique over the continuum based methods.
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Numerical Analysis of Coal Pillar Stability on Variable Weak Floor with Paste BackfillJessu, Kashi Vishwanath 01 December 2016 (has links)
This thesis investigates the stability of coal pillars under realistic conditions of varying weak floor thickness with and without the use of paste backfill. Weak floor strata underlying coal seams are common in the Illinois Basin. They consist mainly of underclay, which is a gray, argillaceous rock that usually occurs immediately beneath beds of coal. Underclay thickness may vary from less than a foot to twenty feet at different locations in the basin (Grim and Allen, 1938). Locally, underclay thickness may vary gradationally over a distance of two pillars. Even though weak floor thickness is not consistent (Gadde, 2009), most research to date has focused on parametric studies with a fixed underclay thickness and formulated coal pillar designs on the basis of the maximum underclay thickness measured in the field. Therefore, it is necessary to investigate more realistic field conditions and quantify the influence of a gradated weak floor thickness using additional parametric studies. This research is primarily numerical modeling incorporating various constitutive models and using some calibration. Therefore, the two dimensional plane strain finite difference model in FLAC 3D is employed to carry out parametric studies on gradated weak floor conditions. Underclay exhibits Mohr Coulomb elastic plastic behavior; hence, the Mohr Coulomb constitutive model is used for the behavior of overburden, coal, and floor. Well-calibrated numerical models can assist in understanding load and failure processes provided that coal, overburden, and weak floor are modeled with sufficient realism. The theoretical approach considers a friction angle of 0° to calculate the load bearing capacity of the weak floor for design of pillars with long-term stability, even if the weak floor has a non-zero friction angle. The stiffness of the weak floor increases with an increase in friction angle (Gadde, 2009; Kostecki and Spearing, 2015). As stiffness increases, a point can be reached where floor bearing capacity exceeds coal pillar strength and coal pillar strength becomes the governing factor. For this scenario, the Mohr Coulomb strain softening model is more realistic in estimating loads carried by coal pillars in the post-failure stage. The three-dimensional Mohr Coulomb strain softening model in FLAC 3D is employed to study qualitatively the floor response in strain softening coal behavior conditions. Maintaining stable coal pillar responses has been a challenge for the coal mining industry due to attempts to increase the primary extraction ratio. Presently, the best available solution seems to be backfilling when considering short-term pillar stability (i.e., less than the long-term factor of safety) with increased extraction ratio. There are various types of mine backfill that have benefits to the mining industry depending on the application, but paste backfill produced from total mill tailings containing no free water is the best option for post-mining ground control in room-and-pillar mines as it prevents weakening of the floor and will not contaminate the ground water. The influence of paste backfill on floor bearing capacity and coal pillar response is studied with numerical modeling using the same constitutive models already identified. Finally, an economic analysis is carried out to look at cost implications of a proposed system with backfill.
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Shear Strength Behavior of Unsaturated Soils During Strain-SofteningYang, Xiuhan 13 February 2023 (has links)
The shear stress in an unsaturated soil increases rapidly with limited shear strain to a peak value and then drops gradually with a further increase in the shear strain until a residual value is reached. In other words, there is a significant strain-softening behavior under large shear deformation. A variety of geotechnical structures (e.g., slopes, foundations, retaining walls and piles) associated with unsaturated soils typically undergo a large progressive deformation prior to reaching failure conditions due to the influence of environmental factors (e.g., rainfall infiltration and wetting-drying cycles). As a result, the shear strength of soils in sliding zones typically reduces from a peak to a residual value with the progressive development of large shear deformation, while the shear strength of soils in other zones are still at the peak level. In other words, in many scenarios the strain-softening behavior of unsaturated soils can significantly influence the mechanical behavior of geo-structures. Therefore, a thorough understanding of the shear strength behavior of unsaturated soils during strain-softening is required to reliably interpret the mechanical behavior of geo-structures that undergo large shear deformation.
Significant advances have been made during the last thirty years to understand and model the strain-softening behavior of unsaturated soils. Most of these studies however focus on the strain-softening behavior within a relatively small shear deformation due to the limitations of the experimental apparatuses. Only limited experimental studies under large shear deformation were reported based on the modified suction-controlled ring shear apparatus. Therefore, more investigations are still required to provide a comprehensive understanding of the shear strength behavior of unsaturated soils during strain-softening under large shear deformation.
Studies presented in this thesis are directed towards investigating the shear strength behavior of unsaturated soils during strain-softening and its application in geotechnical engineering practice. The following studies have been conducted:
(i) A state-of-the-art review of the strain-softening behavior of unsaturated soils published in the literature during the past three decades is summarized. The physical mechanisms and modelling methods of the strain-softening behavior and the peak, critical and residual shear strength of unsaturated soils are investigated.
(ii) A disturbed state concept model is proposed to predict the variation of shear stress in unsaturated soils during strain-softening process under drained condition. Five sets of experimental data gathered from the literature on unsaturated soils varying from coarse- to fine-grained soils are used to verify the proposed model. The proposed model can provide reasonable predictions for the strain-softening stress-strain relationships of various types of unsaturated soils. The model is simple in concept and all the required parameters can be obtained from conventional saturated and unsaturated shearing tests and pressure plate tests.
(iii) Two sets of suction-controlled multistage ring shear tests are conducted on unsaturated SP-SM soil and Indian Head till (IHT), respectively. The variation of the shear stress, void ratio, and water content of specimens during shearing (the shear displacement reaches 100 mm) under multi levels of net normal stress and matric suction are described and discussed. The influence of matric suction and net normal stress on the residual shear strength envelops of unsaturated soils are critically discussed.
(iv) A model for predicting the residual shear strength for a wide range of unsaturated soils comprising coarse- to fine-grained soils is developed in terms of two stress state variables (i.e., the net normal stress and matric suction) by using the soil water characteristic curve as a tool. The model is formulated and validated based on experimental data in a series of suction-controlled ring shear tests using the axis-translation technique, including the two sets of tests (SP-SM and IHT) conducted in this research and another three sets of tests (SM, SC-SM and CH) gathered from the literature. The fitting parameters are related to the plasticity index (Iₚ); thus, only four basic parameters (i.e., cᵣ', φᵣ', Sᵣ and Iₚ) are included in this approach.
(v) A series of slope stability analyses of a landslide in unsaturated condition are conducted using Geoslope software based on the peak and residual shear strength parameters. The analyses results highlight the role of residual shear strength in the slope stability of unsaturated soils.
In summary, the mechanical behavior of unsaturated soils under large shear deformation is comprehensively investigated in this thesis. The experimental results of the suction-controlled ring shear tests reported in this research contribute towards understanding the fundamental shear strength behavior of unsaturated soils during strain-softening under large shear deformation. The models proposed in this research provide simple tools to predict the shear strength of unsaturated soils under different levels of shear deformation.
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Mechanical properties of polymer glasses : Mechanical properties of polymer glasses / Propriétés mécaniques des polymères vitreux : théorie et simulationConca, Luca 02 May 2016 (has links)
Ce manuscrit présente des récentes extensions au modèle PFVD, basé sur l'hétérogénéité de la dynamique des polymères vitreux à l'échelle de quelques nanomètres et résolu par simulation en 3D, afin de fournir une description physique unifiée des propriétés mécaniques et dynamiques des polymères vitreux soumis à déformation plastique. Trois sujets principaux sont traités : La plastification. Sous déformation, les polymères atteignent le seuil de plasticité (yield) à quelques pourcents de déformation et quelques dizaines de MPa. Nous proposons que l'énergie élastique absorbée à l'échelle des hétérogénéités dynamiques accélère la dynamique locale. On observe contraintes ultimes de quelques dizaines de MPa à quelques pourcents de déformation et que la plastification est due à un nombre relativement petit d'événements locaux. Il a été observé que la dynamique devient plus rapide et homogène dans le régime plastique et que la mobilité moyenne atteint une valeur stationnaire, linéaire avec le taux de déformation. Nous proposons que la contrainte locale stimule la diffusion de monomères des domaines lents à ceux rapides (mécanisme de facilitation) et accélère dynamique locale. Ceci permets d'observer l'homogénéisation de la dynamique, avec des caractéristiques proches de l'expérience. L'écrouissage, dans les polymères enchevêtrés ou réticulés. A grande déformation, la contrainte augmente avec une pente caractéristique d'ordre 10 – 100 MPa au-dessous de la transition vitreuse. De manière analogue à une théorie récente, nous proposons que la déformation locale oriente les monomères dans la direction d'étirage et ralentie la dynamique, suite à l'intensification des interactions locales. Les modules d'écrouissage mesurés, les effets de la réticulation et du taux de déformation sont comparables aux données expérimentales. En outre, on trouve que l'écrouissage a un effet stabilisateur sur les phénomènes de localisation et sur les bandes de cisaillement / This manuscript presents recent extensions to the PFVD model, based on the heterogeneity of theh dynamics of glassy polymers at the scale of a few nanometers et solved by 3D numerical simulation, which aim at providing a unified physical description of the mechanical and dynamical properties of glassy polymers during plastic deformation. Three main topics are treated: Plasticization. Under applied deformation, polymers undergo yield at strains of a few percent and stresses of some 10 MPa.We propose that the elastic energy stored at the scale of dynamical heterogeneities accelerates local dynamics. We observe yield stresses of a few 10 MPa are obtained at a few percent of deformation and that plastification is due to a relatively small amount of local yields. It has been observed that dynamics becomes faster and more homogeneous close to yield and that the average mobility attains a stationary value, linear with the strain rate. We propose that stress-induced acceleration of the dynamics enhances the diffusion of monomers from slow domains to fast ones (facilitation mechanism), accelerating local dynamics. This allows for obtaining the homogeneisation of the dynamics, with the same features observed during experiments. Strain-hardening, in highly entangled and cross-linked polymers. At large strain, stress increases with increasing strain, with a characteristic slope (hardening modulus) of order 10 – 100 MPa well below the glass transition. Analogously to a recent theory, we propose that local deformation orients monomers in the drawing direction and slows dows the dynamics, as a consequence of the intensification of local interactions. The hardening moduli mesured, the effect of reticulation and of strain rate are comparable with experimental data. In addition, strain-hardening is found to have a stabilizing effect over strain localization and shear banding
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Investigation of Rock Mass Stability around Underground Excavations in an Underground Mine in USAXing, Yan, Xing, Yan January 2017 (has links)
Underground excavations break the balance of the initial stress field and cause stress redistributions in the surrounding rock masses. Problems normally arise as the stress exceeds the rock mass strength. In addition, the rock mass contains preexisting defects, such as the fissures, fractures, joints, faults, shear zones, dikes, etc., which could significantly weaken the rock mass strength and make the rock mass behavior complicated. The stability of underground excavations is of great importance to an operating mine project since it ensures the safety of the working environment and the successful ore exploration.
Due to the complex geological conditions and engineering disturbances, the assessment of rock mass stability for a practical engineering problem is extremely challenging and difficult, which needs to be solved by the modern numerical methods. In this dissertation, the rock mass stability around tunnels in an underground mine in the USA was investigated by performing three-dimensional modeling using the 3DEC 3-Dimensional Distinct Element Code. Comprehensive stress analyses were respectively carried out on a preliminary model and a more advanced model.
In the preliminary study, the built model contains the inclined lithologies, a non-persistent fault, and a convoluted tunnel system. The geomechanical property values used for the rock masses and discontinuities in the numerical model were estimated using the available geotechnical information and the experience of the research group. The Mohr-Coulomb and strain softening constitutive relations were prescribed for the rock masses; the coulomb slip joint model was assigned for the discontinuities. The influence of the boundary conditions, block constitutive models, horizontal in situ stress and rock support system on the tunnel stability was investigated. The rock mass behavior was quantified using the results of stress, displacement, and yielded zones around the tunnels. It showed that the roller boundary conditions resulted in slightly different but comparable results with the combined boundary conditions (roller and stress combined) where K0 equals to 0.4 or 0.5. Whereas the in-situ stress field for a complex geological system can only be obtained by applying proper boundary stresses and then by performing stress analysis. The softening behavior of the rock masses caused more deformations and yielded zones around the tunnels; the rock masses around the tunnels were observed to reach the residual strength values, which can be treated as failed areas. In addition, the M-C and s-s rock masses reacted differently as the K0 value changed. At K0=1.0, the tunnels seemed to be the most stable; K0=1.5, however, provided the worst scenario with roof and floor problems. With respect to the effectiveness of the support system, a large amount of the bonds of the supports was failing, thus, the deformations and yielded zones around the tunnels were slightly improved. Finally, comparisons between the numerical modeling results and the field measurements implied the applicability of strain softening behavior and a K0 value between 0.5 and 1.0 for the mine.
Based on the specific geological, geotechnical, and construction information, a numerical model incorporating accurate features was developed. It includes a non-planar, weak interlayer, the persistent and non-persistent faults, and the open and backfilled excavations. The mechanical property values used for the rock masses and faults were estimated based on the laboratory test results of the intact rock and smooth joints. The strain softening behavior was specified for the rock masses belonging to the average quality, and the rock masses that reached residual strengths were assumed to be failing. The linear relations between the fault stiffnesses and normal stress were described using the continuously yielding joint model. To simulate the mine construction process in the field, the sequential excavation, backfilling, and supporting procedures were numerically implemented; additionally, a novel routine was applied to account for the delayed installation of the supports. Results showed that the tunnels close to the fault and the backfilled area were less stable. Most of the displacements around the tunnels occurred within a distance of zero to 2 or 3 m from the tunnel surface. The varying K0 value caused great changes in the rock mass behavior and the shear behavior of the major fault; significant instability of the tunnels was triggered by the high horizontal in situ stress. Parametric studies on the rock mass condition, rock mass residual strengths, and fault property values showed that the tunnel stability was more sensitive to the former two factors than the last one. A systematic investigation was conducted to evaluate the current rock supports installed at the mine where the increasing stress relaxation was incorporated. The deformations and of the failure zone thicknesses around the tunnels were reduced up to 8% and 20% after applying the supports instantaneously, and the reductions were improved by the delayed installation of supports. Additionally, the safety of supports was evaluated by the bond shear and bolt tensile failures, which was also improved with incorporation of delayed supporting. It was found that the current rock supports are insufficient in length, bond and tensile strengths. Therefore, a stronger support system was suggested. The stronger supports worked better in stabilizing the tunnels. Based on the deformations and failures of the rock masses, the length of the bolts on walls was suggested to be 4-5 m. At the end, the horizontal convergence strain predicted by the numerical simulations were calculated at two locations where the tape extensometers were installed. Good agreements with the field measurements were obtained for the cases that have the average rock mass properties and K0 values in the range 0.5-1.25.
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From Strain Stiffening to Softening—Rheological Characterization of Keratins 8 and 18 Networks Crosslinked via Electron IrradiationElbalasy, Iman, Wilharm, Nils, Herchenhahn, Erik, Konieczny, Robert, Mayr, Stefan G., Schnauß, Jörg 02 June 2023 (has links)
Networks of crosslinked keratin filaments are abundant in epithelial cells and tissues, providing resilience against mechanical forces and ensuring cellular integrity. Although studies of in vitro models of reconstituted keratin networks have revealed important mechanical aspects, the mechanical properties of crosslinked keratin structures remain poorly understood. Here, we exploited the power of electron beam irradiation (EBI) to crosslink in vitro networks of soft epithelial keratins 8 and 18 (k8–k18) filaments with different irradiation doses (30 kGy, 50 kGy, 80 kGy, 100 kGy, and 150 kGy). We combined bulk shear rheology with confocal microscopy to investigate the impact of crosslinking on the mechanical and structural properties of the resultant keratin gels. We found that irradiated keratin gels display higher linear elastic modulus than the unirradiated, entangled networks at all doses tested. However, at the high doses (80 kGy, 100 kGy, and 150 kGy), we observed a remarkable drop in the elastic modulus compared to 50 kGy. Intriguingly, the irradiation drastically changed the behavior for large, nonlinear deformations. While untreated keratin networks displayed a strong strain stiffening, increasing irradiation doses shifted the system to a strain softening behavior. In agreement with the rheological behavior in the linear regime, the confocal microscopy images revealed fully isotropic networks with high percolation in 30 kGy and 50 kGy-treated keratin samples, while irradiation with 100 kGy induced the formation of thick bundles and clusters. Our results demonstrate the impact of permanent crosslinking on k8–k18 mechanics and provide new insights into the potential contribution of intracellular covalent crosslinking to the loss of mechanical resilience in some human keratin diseases. These insights will also provide inspiration for the synthesis of new keratin-based biomaterials.
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Fault Tree Analysis of Quick Clay Slides / Felträdsanalys av kvicklereskredBäckström, Karl, Linder, Andreas January 2021 (has links)
Quick clay slides are quite rare but often leads to major consequences for the society. These type of slides are complex and the true causes leading to a slide is difficult to map since the evidence is destroyed during the slide. Because of this, different theories develop of the causes of the slide based on the same information. It is also problematic to back-calculate the sliding event because the commonly applied concept of perfectly plastic limite quilibrium cannot be applied on many of the landslides in quick clay. The objectives of this thesis were to construct a fault tree that facilitate risk identification and risk analysis of quick clay slides and to evaluate the applicability of the constructed fault tree, especially in the feasibility study and design phase. Uncertainties within the subject require a careful approach when dealing with quick clay. An implementation of a fault tree for quick clay slides in a risk management could reduce the risk of a slide and better understand the phenomenon. Two case studies were approached with the created fault tree and two advanced calculation methods that account for the special behaviour of quickclay. The use of a qualitative fault tree analysis in combination with calculation methods enables an evaluation of isolated singular events that in the end can lead to a quick clay slide. With the possibility to study isolated events, the implementation of more advanced calculation methods may be facilitated in an early stage to predict and prevent quick clay slides. / Kvicklerskred är sällsynta men leder ofta till stor skada för samhället. Dessa skred är komplexa och orsaken till utlösandet av skredet är svårt att identifiera då bevisen förstörs under händelseförloppet. Detta leder till att olika teorier om orsaken av kvicklerskred kan variera från samma information. Det är också svårt att beräkna skredets omlopp i efterhand den vanliga beräkningsmetoden baseras på idealplastiska samband, något som inte går att applicera på kvicklera. Målet med denna studie var att konstruera ett felträd som underlättar riskidentifiering och riskanalyser av kvicklerskred. Målet var även att utvärdera användandet av felträdet i en byggnadsprocess, framförallt under förstudien och under projekteringsskedet. Osäkerheter inom området kräver en försiktig arbetsmetod när kvicklera finns i områden. Att använda sig av ett felträd för kvicklerskred i en riskhantering skulle kunna minska risken för ett skred och samtidigt öka systemförståelsen över fenomenet. Två fallstudier gjordes med det konstruerade felträdet, under dessa fältstudier gjordes även beräkningar med två avancerade beräkningsmetoder som tar hänsyn till det töjningsmjukande beteendet hos kvicklera. Användningav ett kvalitativt felträd i kombination med beräkningsmetoder möjligör en utvärdering av isolerade händelser som i slutändan kan leda till ett kvicklerskred. Möjligheten av att studera isolerade händelser kan underlätta en implementering av mer avancerade beräkningsmetoder i ett tidigt skede och på så vis förutse och förhindra kvicklerskred.
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