This thesis has experimentally studied the strength and stiffness properties of bedding planes and discontinuities in the immediate roof layers overlying Herrin No. 6 coal seam in Illinois. Rock joints and bedding planes are typical discontinuities in bedded rock mass and they control failure initiation and propagation of failure through the rock mass. Strength as well as deformation properties of bedding planes, joints and discontinuities are influenced by their surface roughness, inclination, intact rock properties, and pre-mining stress values and their orientation. The strength and deformation properties (stiffness values) are characterized by peak and residual strength values. Since support loads in excavations are due to deformations of the rock mass, their analysis should consider their strength and stiffness values. The overall goal of this research is to determine the shear strength and associated stiffness properties of bedding planes and joints of the immediate roof strata rocks within 25-30 ft. (7.5-9 m) overlying Herrin no. 6 coal seam (within the pressure arch zone) using direct shear tests. A shear test loading device was designed and integrated into the 150 t (1,334 kN) [*]Forney compression loading machine in the department. It was used to perform direct shear tests in accordance with ASTM D5607-08 " Standard test method for performing laboratory direct shear strength tests of rock specimens under constant normal force". The equipment also allows for determination of peak and residual friction angles along with the dilation angle. A total of 49 bedding plane samples were tested, out of which 46 (36 intact and 10 relatively weak and loose) samples passed QA/QC procedures in accordance to ASTM D5607. Samples from eight (8) different bedding planes- shale/limestone (SL), shale/sandstone (SSs), shale/bone (SB), laminated sandstone (LS), shale/shale (SS), bone/bone (BB), bone/limestone (BL), and limestone/limestone (LL) were tested. The number of samples tested for each bedding plane were: SL- 11, SSs- 8, SB- 5, BB- 4, LS- 6, SS- 9, BL- 1, and LL- 2. Moisture content and as-received unit weight values of samples range 0.9% to 5% and 111 pcf (17.5 kN/m3) to 165 pcf (25 kN/m3), respectively. Shear strength values were developed at 400 psi (2.75 MPa) normal stress. Upon failure, residual shear strengths were determined at 600 psi (4.13 MPa) and 800 psi (5.5 MPa) normal stresses to calculate the angle of sliding friction and to develop the failure criterion for each rock type. Peak and residual shear strength values at 400 psi (2.75 MPa) normal stress range 153 - 907 psi (1.06 - 6.26 MPa) and 119 - 600 psi (0.82 -4.14 MPa), respectively. The average normal and shear stiffness values are 44,000 psi/in (11.98 GPa/m) and 11450 psi/in (3.11 GPa/m). Dilation angles are typically very low (<10◦) and negative in some cases. Joint roughness values with JRC index were typically below 10. Angle of sliding friction values range from 9◦ to 42◦. Failure criterion for different bedding planes and a composite failure criterion representing the behavior of all bedding planes were developed using linear regression. A numerical modeling case study of remnant pillar stability in a southern Illinois mine was performed that used the shear strength and stiffness parameters developed above. FLAC3D, Phase2D, and LaModel were also used to assess the stability of remnant pillars. This study would significantly aid in the design and stability analysis of both surface and underground mines. Data developed can be successfully implemented in safe geotechnical design of any surface and underground structure (both civil and mining) viz. slope stability of open pit mining, subsidence prediction during longwall and room and pillar mining. Results from this thesis would significantly improve in the safe and accurate design of mine excavations. * Equipment mentioned is not for endorsement

The stability of rock masses is influenced by the occurrence of rock joints. Therefore, the shear strength of rock joints must be considered in dimensioning of underground constructions. One way to predict the shear strength is through usage of failure criteria, which are validated from results of direct shear tests under controlled laboratory conditions. Consequently, the quality of the results from the tests are crucial to the accuracy with which the criteria will be able to predict the shear strength. Since rock joints are unique by nature usage of replicas (man-made copies of rock joints) is of importance in parameter studies. The overall objective of this work is to facilitate the development of improved criteria for predictions of the shear strength of rock joints. To support this objective, two sources of uncertainty have been investigated, namely the geometry of replicas and the influence of the normal stiffness of test systems. Two quality assurance parameters for evaluation of geometrical differences between replicas and rock joints based on scanning data have been derived. The first parameter describes the morphological deviations. The second parameter describes the deviations in orientation with respect to the shear plane. The effective normal stiffness approach, which compensates for the influence of the normal stiffness of the test system in direct shear testing, has been developed, validated, and applied. With help of the quality assurance parameters it is demonstrated that it is possible to reproduce replicas within narrow tolerances. Application of the effective normal stiffness approach basically eliminates the normal load error. In all, the results support generation of improved quality of test data and consequently, the development of shear strength criteria with improved accuracy will also be facilitated. / <p>Academic Dissertation which, with due permission of the KTH Royal Institute of  Technology, is submitted for public defence for the Degree of Licentiate of Engineering on Wednesday the 9th June 2021, at 9:00 a.m. in M108, Brinellvägen 23, Stockholm.</p><p><strong>Paper A</strong>: Larsson J, Flansbjer M, Portal N W, Johnson E, Johansson F, and Mas Ivars D. (2020) Geometrical Quality Assurance of Rock Joint Replicas in Shear Tests – Introductory Analysis. Paper presented at the ISRM International Symposium - EUROCK 2020, physical event not held. https://onepetro.org/ISRMEUROCK/proceedings-abstract/EUROCK20/All-EUROCK20/ISRM-EUROCK-2020-101/451187  In Diva: http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-51987 </p><p><strong>Paper B:</strong> Larsson J, Johansson F, Mas Ivars D, Johnson E, Flansbjer M and Portal N W. (2021) Rock joint replicas in direct shear testing – Part 1: Extraction of geometrical quality assurance parameters. To be submitted to Rock Mechanics and Rock Engineering  In DiVA: http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-53111 </p><p><strong>Paper C:</strong> Larsson J and Flansbjer M. (2020) An Approach to Compensate for the Influence of the System Normal Stiffness in CNS Direct Shear Tests. Rock Mechancis and Rock Engineering 53, 2185–2199 https://doi.org/10.1007/s00603-020-02051-0  In DiVA: http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-44085  </p><p><strong>Paper D:</strong> Larsson J. (2021) Experimental investigation of the system normal stiffness of a 5 MN direct shear test setup and the compensation of it in CNS direct shear tests. Submitted to ISRM International Symposium - EUROCK 2021  In DiVA: http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-53112 </p>

Wheel loaders are fundamental construction equipment to assist handling of bulk material e.g. gravel and stones. During digging operations, it withstands forces that are both large and very complicated to predict. Moreover, it is very expensive to develop prototypes of wheel loader for verification. Consequently, the Discrete Element Method (DEM) was introduced for gravel modeling a couple of years ago to enable prediction of these forces. The gravel model is connected with a Multibody System (MBS) model of the wheel loader, in this thesis a Volvo L180G. The co-simulation of these two systems is a very computer intensive operation and hence, it is important to investigate which parameters that have the largest influence on the simulation results. The aim of this thesis is to investigate the simulation sensitivity with respect to co-simulation communication interval, collision detection interval and gravel normal stiffness.The simulation results are verified by comparison with measurement data from previous tests performed by Volvo CE. The simulations are compared to investigate the relevant parameters. The conclusion of this thesis is that DEM is a method that in a very good way can predict the draft forces during digging operations.

The stability of rock masses is influenced by the occurrence of rock joints. Therefore, the shear strength of rock joints must be considered in dimensioning of underground constructions. One way to predict the shear strength is through usage of failure criteria, which are validated from results of direct shear tests under controlled laboratory conditions. Consequently, the quality of the results from the tests are crucial to the accuracy with which the criteria will be able to predict the shear strength. Since rock joints are unique by nature usage of replicas (man-made copies of rock joints) is of importance in parameter studies. The overall objective of this work is to facilitate the development of improved criteria for predictions of the shear strength of rock joints. To support this objective, two sources of uncertainty have been investigated, namely the geometry of replicas and the influence of the normal stiffness of test systems. Two quality assurance parameters for evaluation of geometrical differences between replicas and rock joints based on scanning data have been derived. The first parameter describes the morphological deviations. The second parameter describes the deviations in orientation with respect to the shear plane. The effective normal stiffness approach, which compensates for the influence of the normal stiffness of the test system indirect shear testing, has been developed, validated, and applied. With help of the quality assurance parameters it is demonstrated that it is possible to reproduce replicas within narrow tolerances. Application of the effective normal stiffness approach basically eliminates the normal load error. In all, the results support generation of improved quality of test data and consequently, the development of shear strength criteria with improved accuracy will also be facilitated. / Bergmassors stabilitet påverkas av bergssprickor. Bergssprickors skjuvhållfasthet behöver därför beaktas vid fastställandet av vilka laster berganläggningar skall dimensioneras mot. Skjuvhållfastheten predikteras bland annat med hjälp av brottkriterier, vilka valideras med hjälp av resultaten från skjuvtester i kontrollerad laboratoriemiljö. Kvaliteten på resultaten från testerna är därför av avgörande betydelse för med vilken noggrannhet kriterierna kommer att kunna prediktera skjuvhållfastheten. Det övergripande målet med detta arbete är att underlätta utvecklingen av förbättrade kriterier för prediktioner av bergssprickors skjuvhållfasthet. Som ett bidrag till att uppnå detta mål har två osäkerhetsfaktorer undersökts, nämligen geometrin av replikor (kopior) av bergssprickor och inverkan av testsystems normalstyvhet. Två kvalitetssäkringsparametrar för utvärdering av de geometriska skillnaderna mellan replikor och bergprov baserade på skanningdata har tagits fram. Den första parametern beskriver de morfologiska avvikelserna. Den andra parametern beskriver avvikelserna i orientering med avseende på skjuvplanet. Ett tillvägagångssätt med en effektiv systemnormalstyvhet, vilken kompenserar för inverkan av testsystemets normalstyvhet, har utvecklats, validerats och tillämpats. Med hjälp av kvalitetssäkringsparametrarna påvisas att det ar möjligt att reproducera replikor inom snäva toleranser. Genom tillämpning av tillvägagångssättet med en effektiv normalstyvhet kan felet i normallast i princip elimineras. Sammantaget stödjer resultaten framtagning av testdata med förbättrad kvalitet och därigenom underlättas även utvecklingen av skjuvhållfasthetskriterier med förbättrad noggrannhet. / <p>QC 210518</p>

<p>Detta examensarbete har utförts på Fläktwoods AB i Växjö, som producerar stora axialfläktar för olika industriapplikationer. Syftet är att öka kunskapen om fettsmorda axiella kullager genom FE analyser.</p><p>Projektet har genomförts i fem delsteg för att avgöra påverkan av en eller några få parametrar i taget. De studerade parametrarna är: elementstorlek, kontaktstyvhet, last, lagergeometri (dvs. oskulation), ickelinjär geometri och ickelinjära materialegenskaper (dvs. plasticitet).</p><p>Slutsatsen är att elementstorleken bör väljas fint nog för att ge ett jämnt resultat men grovt nog för att beräkningstiden skal vara rimlig. Kontaktstyvheten har inte stor, men tydlig, inverkan på kontakttrycket och penetrationen. Förändringar av oskulationen leder till förändringar i kontaktellipsens form medan olika laster inte påverkar formen på ellipsen, utan snarare storleken. När det handlar om plasticitet är sträckgränsen den viktigaste faktorn att beakta.</p> / <p>This thesis project was carried out at Fläktwoods AB in Växjö who produces large axial fans for different industry applications. The purpose is to increase the knowledge of grease lubricated axial ball bearings through FE analyses.</p><p>The project was executed into five sub steps to determine the influence of one or few parameters at a time. The studied parameters are: mesh density, contact stiffness, load, bearing geometry (i.e. osculation), geometrical nonlinearity and material nonlinearity (i.e. plasticity).</p><p>It is concluded that the mesh density should be selected fine enough to give a smooth result but course enough to give a reasonable calculation time. The contact stiffness has not a major, but a clear, impact on the contact pressure and penetration. Changes of the osculation lead to changes of the contact ellipse shape and applying different load level does not affect the shape of the ellipse but rather the size. When dealing with plasticity the yield strength is the most important factor to take in consideration.</p>

Detta examensarbete har utförts på Fläktwoods AB i Växjö, som producerar stora axialfläktar för olika industriapplikationer. Syftet är att öka kunskapen om fettsmorda axiella kullager genom FE analyser. Projektet har genomförts i fem delsteg för att avgöra påverkan av en eller några få parametrar i taget. De studerade parametrarna är: elementstorlek, kontaktstyvhet, last, lagergeometri (dvs. oskulation), ickelinjär geometri och ickelinjära materialegenskaper (dvs. plasticitet). Slutsatsen är att elementstorleken bör väljas fint nog för att ge ett jämnt resultat men grovt nog för att beräkningstiden skal vara rimlig. Kontaktstyvheten har inte stor, men tydlig, inverkan på kontakttrycket och penetrationen. Förändringar av oskulationen leder till förändringar i kontaktellipsens form medan olika laster inte påverkar formen på ellipsen, utan snarare storleken. När det handlar om plasticitet är sträckgränsen den viktigaste faktorn att beakta. / This thesis project was carried out at Fläktwoods AB in Växjö who produces large axial fans for different industry applications. The purpose is to increase the knowledge of grease lubricated axial ball bearings through FE analyses. The project was executed into five sub steps to determine the influence of one or few parameters at a time. The studied parameters are: mesh density, contact stiffness, load, bearing geometry (i.e. osculation), geometrical nonlinearity and material nonlinearity (i.e. plasticity). It is concluded that the mesh density should be selected fine enough to give a smooth result but course enough to give a reasonable calculation time. The contact stiffness has not a major, but a clear, impact on the contact pressure and penetration. Changes of the osculation lead to changes of the contact ellipse shape and applying different load level does not affect the shape of the ellipse but rather the size. When dealing with plasticity the yield strength is the most important factor to take in consideration.