The Kristianstad plain contains one of the most interesting and exciting groundwater of Sweden. It is also one of Northern Europe´s largest groundwater resources. The layers of gravel, limestone, sand, and sandstone is prime location. The amount of available water is veryhigh. The groundwater is consumed by four municipalities; Kristianstad, Eastern Goinge, Bromölla, and Hässleholm, including several industrial zones. Large quantities of groundwater have been used for agricultural irrigation. Groundwater resource carrying capacity refers to the maximum ability of groundwater system for supply industrial production, people’s lives and protection of the eco-environment under certain technical level and social condition in different periods of the future. Groundwater is a part of this cycle, which eventually flows into rivers, different types of wetlands, lakes or directly into the Baltic Sea. Withdrawal of groundwater is also part of the cycle. A waterbed, also known as an aquifer, is a geological formation containing groundwater and it is so permeable that groundwater may be extracted in larger quantity. Aquifers are filled with water by infiltrating precipitation, leakage from other aquifers or through infiltration from rivers. The extraction of groundwater may not exceed the inflow for a long time. If this occurs it is a risk of progressive lowering of the water quality or its deterioration. Area of reservoir, groundwater Färlöv– Vinnö is I think a good limit of economic water.

Numerical modelling is often needed as a tool to predict the behaviour and assess the safety of dam structures. Embankment dam structures analyses are quite complex and potential failures are hazardous. Predictions of dam behaviour by numerical modelling rely on knowledge about the mechanical properties of the materials the dam is constructed with. The materials included in a dam vary significantly because zones in the dam have different functions. In order to conduct reliable modelling, parameter values defining the stress-strain relationship of the materials are needed to be assigned.  Obtaining information about the mechanical behaviour in already existing embankment dams is usually challenging. As many dams are old, there might be a limited amount of information available of the materials used, construction methods and mostly about the stress-strain relationship of the soil. Traditionally, field sampling is performed in order to obtain such information. However, conventional field sampling might negatively affect the dam body and thereby the performance as well as the safety of the dam. This is of special importance if sampling is performed in the impervious (core) part. Since traditional sampling might harm the dam body, use of non-destructive methods would be advantageous to utilise for obtaining information about the stress-strain relationship and the strength in a dam structure.  An option for a non-destructive method is parameter identification by inverse analysis. The idea of inverse analysis is to calibrate finite element models towards field measurements. In the calibration process, the input for a stress-strain relationship (constitutive model) is modified until the discrepancy between the output of the numerical model and the associated chosen field measurement is minimised. The agreement between output from the numerical model and reality is measured by an objective function that will calculate the error. In order to automatically search for the minimum a search algorithm is utilised in the optimisation process. When the objective function is minimised, the calibration of the material parameters is done.  In previous research at Luleå University of Technology, the method of inverse analysis was applied to an embankment dam. The finite element program PLAXIS was used in combination with an optimisation code. The optimisation code includes an objective function (for error evaluation) and a search algorithm. The genetic algorithm was employed as search algorithm, since it is known for its robustness and efficiency as well as the fact that it provides a set of solutions instead of one unique answer. This is beneficial from a geotechnical point of view, since engineering judgement can be included in the final choice of solution.     The first study in the present thesis deals with a case study of an embankment dam, where a simple model calibration was performed. This was a part of a larger study, at the ICOLD Benchmark Workshop in 2017, where the work presented here was forming one of the contributions. In order to have a model response similar to reality, the contributors were asked to choose constitutive models and calibrate them. The calibration was done by manually changing the input for the constitutive model chosen. While the response of the numerical finite element model was capturing the trends of measured total stresses and pore pressure in the dam quite well, there were difficulties in capturing the long term deformations of the dam. This was a challenge for all contributors. An idea for improving the model response, is to run a more advanced calibration by inverse analysis.  In the second study in the thesis, predictions are presented for the embankment dam that inverse analysis was previously conducted for at LTU. Strengthening actions in form of a new berm were performed at the dam. With identified material parameter values from the inverse analysis, predictions were conducted both before and after the strengthening measures. The predicted deformations were compared to deformation data from inclinometer measurements.  A reasonably well agreement was obtained with the real deformations. The trend of the deformations was replicated and the magnitudes of the deformations were in the right order. The study is indicating that predicting future dam behaviour based on results from inverse analysis can be done reasonably well.  In the third and final study in the thesis, effects of random measurement error on the performance of the genetic algorithm for soil parameter identification are assessed. Also here, with the application to the embankment dam used in previous research at LTU. Optimisations were performed against inclinometer measurements. To be sure that the constitutive model can find the correct solution, synthetic (i.e. numerically generated) inclinometer data was utilised. Perturbations were randomly generated within chosen intervals of error and added to the numerically generated deformations.  The genetic algorithm showed its robustness, by continuing to search for solutions without breaking down even if the field data was substantially perturbed. Considering usual errors for inclinometer measurements, the genetic algorithm can deliver good solutions. The inclinometer errors used were taken from literature, and thereafter related to the perturbations of the numerically generated data. Dealing with errors that are becoming gradually larger than what can be considered as usual, problems are faced by the genetic algorithm. In this cases it is difficult to find a solution, and if solutions are found they might significantly deviate from the unperturbed optimum solution.  The three studies handled in this thesis are treating aspects of back analysis of embankment dams; from a simple calibration, to predictions based on material parameters from advanced inverse analysis and finally effects of errors on the genetic algorithm. It been shown that using inverse analysis for already existing embankment dams is very beneficial for the material characterisation and is forming a step towards better predictions of future dam behaviour.

Contact erosion is a type of  internal erosion which develops at the boundary between two varying soil layers inside a dam body under the condition of tangential water flow inside the coarser soil parallel to the boundary. As the behaviour of foundation is unknown as the grout curtain starts eroding after a couple of years. This zone between the embankment and foundation also leads to contact erosion.  Laboratory methods are a fast method of assessing the conditions for contact erosion to initiate as they do not involve a large investment like field testing methods. They also give an insight of the filter designs and long term stability of the dam core due to erosion.

The selection of a landfill site is considered as a complicated task because the whole process is based on many factors and restrictions. This study shows the present status of solid waste management, solid waste sources, staffing for solid waste collection, machinery and equipment used in the waste collection process, finance and financial management at Babylon Governorate and its Qadhaa. The management of collection and disposal of waste in Babylon Governorate and its Qadhaa is done through open dumping of waste and the quality of the collection process is poor. This is the case in Al-Hillah Qadhaa, which is located in the central part of the governorate, Iraq and Al-Qasim Qadhaas, which is situated in the southern part of the Babylon Governorate, Iraq. These sites do not conform to the scientific and environmental criteria applied in the selection of landfill sites.  In the first part of the current study, to find out how much solid waste will be produced in the future; two methods were used to calculate the population growth in Al-Hillah and Al-Qasim Qadhaas to the year 2030. The results showed that the total waste in 2030 according to the first and second methods respectively will be 394,081 tonnes and 472,474 tonnes in Al-Hillah Qadhaa, and (54,481 tonnes and 76,374 tonnes) in Al-Qasim Qadhaa. The cumulated quantity of solid waste expected to be produced between 2020 and 2030 according to the first and second methods respectively was 3,757,387 tonnes and 4,300,864 tonnes in Al-Hillah Qadhaa, whilst in Al-Qasim Qadhaa it was 519,456 tonnes and 695,219 tonnes. The generation rate in 2020 will be (0.88 and 0.62) kg/ (capita. day) in Al-Hillah and Al-Qasim Qadhaas respectively; in year 2030, the generation rate will be (0.97 and 0.69) kg/ (capita. day) based on method 2 and an expected incremental increase in generation rate of 1 kg/ (capita. day) per year.  The second part of this study aims to find the best sites for landfills in Al-Hillah and Al-Qasim Qadhaas. For this reason, 15 criteria were adopted in this study (groundwater depth, rivers, soil types, agricultural land use, land use, elevation, slope, gas pipelines, oil pipelines, power lines, roads, railways, urban centres, villages and archaeological sites) using GIS (geographic information system), which has a large capacity for managing input data. In addition, the AHP (analytical hierarchy process) method was used to derive the relative weightings for each criterion using pairwise comparison. The suitability index map for candidate landfill sites was obtained. Two suitable candidate landfill sites were found to fulfill the scientific and environmental requirements in each Qadhaa, with areas of 9.153 km2 and 8.204 km2 respectively in Al-Hillah Qadhaa, and with areas of 2.766 km2 and 2.055 km2 respectively in Al-Qasim Qadhaa. The area of these sites can accommodate solid waste from 2020 until 2030 based on the required areas, which were 4.175 km2 and 4.778 km2 (Ali-Hillah Qadhaa) and 0.577 km2 and 0.772 km2 in (Al-Qasim Qadhaa) according to the first and second methods respectively.

Excavation damage is usually regulated in Swedish infrastructure tunnel contracts as it can influence the quality and lifecycle cost for tunneling projects. The topic is important for underground constructions with a long operation period such as tunnels for public transport, permanent access tunnels in mines or underground repositories for nuclear waste. In competent crystalline rock, excavation damage is often simplified to macro fractures induced by blasting as this has the most significant impact on the remaining rock. Blasting in Scandinavian tunneling projects is mostly conducted with pumpable emulsion explosives and a good result is often dependent on control of the charging process, i.e. that the explosives are charged according to the blast design. This thesis is based on data from five field investigations carried out in Sweden and Finland. In addition, data from a case study on quality control and documentation in a tunnel excavation project in Äspö Hard Rock Laboratory (HRL) is also included. Data on blast fracture length and frequency have been compiled from all sites, where emulsion explosives were used. The sites include experimental tunnels, a road tunnel, an underground depot for subway trains and a wastewater tunnel. Data from the field investigations have been analyzed using statistical methods including statistical hypothesis test and multivariate data analysis by means of Principal Component Analysis (PCA). The evaluation method gives indications as to how blast design and geology influence the development of blast fractures. Charge concentration was found to be the most influential design variable and simultaneous initiation of contour holes (delay time <1 ms) gave shorter blast fractures with a longest blast fracture of approx. 25 cm compared to approx. 40 cm from pyrotechnical initiation. However, the delay time had limited influence on the number of blast fractures in the remaining rock. Results from the PCA suggest that blast fractures length could be dependent also on geology. Three main groups of fracture patterns were identified, one group with relatively few and short fractures, a group with several longer blast fractures and a group with few or a single long blast fracture. The result shows differences in fracture length between the column and bottom charge part of the contour holes, with blast fracture lengths up to approx. 40 cm for the column charge and up to approx. 60 cm for the bottom charge. The case study showed that good precision in charging with string emulsion can be achieved and documented using modern logger technology in drilling and charging equipment. However, the methods applied for evaluation of charging precision as well as documentation require manual processing and interpretation of data. Further development of the logger systems and processing software is needed in order to follow up logged amounts of emulsion explosive during production.

I och med EG:s avfallsdirektiv från 1999 är det förbjudet att deponera hela däck från och med 2003 och förbjudet att deponera fragmenterade däck (gummiklipp) från och med 2006. Lagstiftningen syftar till ökad återanvändning eller återvinning av uttjänta däck. I Nordamerika, där liknande lagstiftning finns, har hela och fragmenterade däck använts i 30 år i vägbyggnadssammanhang som bland annat tjälisolerings- och lättfyllnadsmaterial. Syftet med detta licentiatarbete är att samla ihop och värdera den idag tillgängliga kunskapen om gummiklipps tekniska och miljömässiga egenskaper samt skaffa praktisk erfarenhet av att använda materialet i mark- och anläggningstekniska tillämpningar. Med gummiklipp avses fragmenterade däck där de enskilda bitarna varierar från ca. 30×30 mm2 till ca. 100×300 mm2. De övergripande målen med detta licentiatarbete är att: a) Identifiera, analysera och presentera den idag tillgängliga kunskapen om gummiklipps tekniska och miljömässiga egenskaper kopplat till mark- och anläggningstekniska tillämpningar. b) Genom egna fält- och laboratorieförsök skaffa praktisk erfarenhet av att använda materialet i vägkonstruktioner. c) Ge rekommendationer angående användande av materialet i mark- och anläggningstekniska tillämpningar. En vägsträcka med gummiklipp som skyddslager har byggts och utvärderats. Utrustning har installerats i vägkonstruktionerna för mätning av temperaturer, tjälfronten, sättningar och lakvatten. Konstruktionernas styvhet har bestämts genom fallviktsmätning. Tekniska egenskaper och erhållet lakvatten har jämförts mellan provsträckor och referenssträckan. Syftet med byggandet av provsträckan med gummiklipp som skyddslager är att: a) Erhålla kunskaper om att bygga med materialet. b) Studera funktionen av materialet ur tjälisoleringssynpunkt. c) Studera hur överbyggnaden ska dimensioneras för att kompensera för elasticiteten och styvheten i materialet. Målet med teststräckan är att kunna genomföra mätningar och utvärdering av sättningar av gummiklippslagret, temperaturer och tjälgränsen i vägkonstruktionen, konstruktionens styvhet (bärförmåga) och lakvatten från konstruktionen. Litteraturstudien visar att de karakteristiska egenskaperna för gummiklipp, i jämförelse med friktionsjord, är att materialet är lätt (låg densitet), elastiskt, dränerande och värmeisolerande. Gummiklipp är ett relativt kompressibelt material och många tekniska egenskaper beror av aktuell belastning. Materialet blir styvare med ökad belastning. De ämnesgrupper hos gummiklipp som främst är undersökta ur miljösynpunkt är metaller, PAH och i viss mån fenoler. I en anläggningsteknisk tillämpning är det normalt vattenburna föroreningar som är av intresse för vilken miljöpåverkan materialet kan ha på omgivningen. Lakförsök visar att metaller lakar ut från däcklipp, främst järn, koppar, mangan och zink. Metalläckaget är av samma storleksordning som för bergmaterial. Av studerade organiska föreningar lakar PAH och fenoler ut, i låga koncentrationer. Toxikologiska studier visar att lakvatten från däckmaterial har påvisbar negativ effekt på organismer. Färskt däckmaterial uppvisar större negativ respons på organismer än äldre material. Vägen med gummiklipp i skyddslager byggdes under perioden 2002-2003. Dimensioneringsarbetet med provsträckan visade att den uppskattade livslängden på konstruktionen inte påverkades nämnvärt av att styvhetsmodulen för skyddslagret varierades inom intervallet 0,25-2,0 MPa. Gummiklipp kan hanteras med konventionell utrustning som används vid vägbyggande. I vissa avseenden är gummiklipp mer lätthanterligt än konventionella vägbyggnadsmaterial som bergkross och friktionsjord, exempelvis håller materialet ihop bättre. Utvärderingen av vägkonstruktionen fram till färdigställandet av vägen visade att: a) Den utvärderade bärförmågan hos gummiklippslagret var lägre än förväntat. b) Den primära kompressionen av gummiklippet skilde mycket i storlek mellan de två delsträckorna med olika material i förstärkningslagret. c) Gummiklipp har en tjälisolerande förmåga. d) Gummiklippen lakar ut små mängder metaller och PAH. PAH-halterna var något högre än förväntat. Den färdigställda vägkonstruktionen kommer framledes att utvärderas fortlöpande dels för att jämföra dimensioneringsresultaten med verkliga konstruktionens egenskaper avseende bärförmåga och livslängd, och dels för att följa upp deformationer och tjälisoleringsförmåga samt bestämma lakvattnets sammansättning. Utifrån kunskapsnivån avseende de tekniska parametrarna som redovisats i denna avhandling kan tillämpningar pekas ut där kunskapsläget är tillräckligt för att rent tekniskt kunna använda materialet och tillämpningar där forskningsbehovet är större. Tillämpningar där tillräcklig kunskap avseende tekniska egenskaper idag kan anses finnas är bankfyllningar, dräneringslager, tjälisolering och motfyllnad. De tekniska begränsningarna som idag finns när det gäller användning av gummiklipp rör främst de elastiska egenskaperna i materialet, främst avseende styvhet och kompressibilitet. Miljöaspekten måste beaktas vid användning av gummiklipp. Vid känsliga recipienter och där avrinningsvatten kan ansamlas i små volymer kan materialet i extremfallet innebära en negativ påverkan. Placerat i applikationer där perkolationen är liten och kontakttiden mellan vatten och gummiklipp är kort bör materialet inte innebära mer påverkan än andra material. Uppföljningsstudier av provobjekt där gummiklipp använts som skyddslager i vägar och bankfyllnader visar att metaller och organiska ämnen lakar ut i låga koncentrationer från konstruktionerna. / <p>Godkänd; 2004; 20061031 (ysko)</p>

This licentiate thesis presents results of laboratory experiments regarding the effectiveness of adding small amounts of binders in order to modify and improve the mechanical performance of low organic clayey silt soil. Two types of binders have been used i.e. cement and an industrial by-product named Petrit T. The study covered both the immediate and longterm effects on the soil material. Binder content was added by soil dry weight, Petrit T at 2, 4 and 7% and cement at 1, 2, 4 and 7%. An experimental program has been carried out, including tests of consistency limits, unconfined compressive strength, density, solidification, grain size distribution (by laser particle size analyzer) and pH. The tests were conducted on the treated soil with varying binder contents and after different curing periods, i.e. after 7, 14, 28, 60 and 90 days. Results show that cement is more effective in improving the physical and engineering properties than Petrit T. Plasticity index decreases after treatment and leads to an immediate increase in workability. This is found directly after treatment and it increases with time. Soil density increased, whilst water content decreased, with increasing binder content and curing time. Particle size distribution of soil is changed toward the granular side by the reduction of the particles in clay size fraction and increasing silt size particles after 28 days of treatment. Both binder types resulted in an immediate effect on the soil pH value. This value increased to 12.3 after adding 7% of the binder and then it gradually decreased as curing time increased. The cement treated soil exhibits a more brittle failure behavior than the soil treated with Petrit T. In this case a more ductile behavior was observed. The findings confirmed that adding small binder contents of cement and by-product Petrit T significantly improved the physical and mechanical properties of soil, which can contribute to reduce the environmental threats and costs that are associated with using high binder contents in various construction projects.

No description available.

End-of-life tyres are a disposal problem regarding the large volumes produced every year. Tyre shreds are primarily produced to reduce the transportation volumes of end-of-life tyres after collection. Within the European Union, there is a ban for landfilling tyre material in order to reduce the total landfilling volumes and to encourage recycling measures. Until recently the main disposal option has been energy recovery in industrial processes. However, legislation acts has recently been taken in the European Union to encourage recycling and recovery of end-of-life-tyres and re-use of tyre materials in construction works is listed as one disposal option.Tyre shreds possess interesting technical properties that could be beneficially used in civil engineering applications. Some characteristic properties of tyre shred materials are the low density, high elasticity, low stiffness, high drainage capacity and high thermal insulation capacity. These properties open up possibilities for utilisation of the material in an innovative manner.The overall aim of this thesis work has been to describe and evaluate tyre shreds as a civil engineering construction material from environmental and technical point of view. The thesis work has included laboratory tests and full scale field tests to investigate technical and environmental properties of tyre shreds and to investigate the tyre shred material behaviour in a real road construction. Furthermore, the state-of-the-art knowledge in the area has also been analysed and presented.In the laboratory studies technical properties focused on compaction and compression behaviour of tyre shreds have been investigated. In a field study of a built road, tyre shreds has been tested and evaluated, during four years, as lightweight fill and frost insulation material. Environmental properties of tyre shreds, mainly leaching characteristics, have been studied in laboratory tests and monitored in two full scale field tests.Based on the results in the laboratory studies a model is proposed for evaluation of stressstrain properties and prediction of compression behaviour. Recommendations for construction works and pavement design are suggested based on the road construction field study results.Conclusions regarding the studied leaching properties of tyre shreds, based on the laboratory tests and the field monitoring, are that zinc and iron are the metals mainly released and that the release of the studied organic compounds, i.e. PAH and phenols, are low. From an environmental point-of-view focus should be moved from PAH-compounds towards other compounds that are more interesting from mobility perspective and lack of knowledge. It is concluded from this thesis work that PAH is not a pollution problem in the area of use of tyre material covered by this work.Applications where tyre shreds have been successfully utilised as construction material, are e.g. as draining layers in landfills and as material in trotting tracks and paddocks. The utilisation of the material in trotting tracks and paddocks is especially interesting since the unique elasticity of the material is utilised. The potential of utilising tyre shreds in civil engineering construction is big. Since the available amounts of material is limited there is a possibility to direct the use of tyre shreds to the most favourable applications of tyre shreds and still solve the disposal problem of end-of-life tyres. / Uttjänta däck är ett avsättningsproblem avseende de stora volymerna som produceras varje år. Däckklipp produceras främst med avseende på att reducera transportvolymen av insamlade däck. Inom EU har det införts ett förbud mot att deponera däck och däckklipp för att dels reducera den totala volymen avfall som deponeras och dels för att uppmuntra återvinning av däckmaterial. Den huvudsakliga avsättningen för uttjänta däck har fram tills nu varit energiåtervinning, främst inom cementindustrin.Däckklipp har intressanta tekniska egenskaper som fördelaktigt kan utnyttjas i anläggningstekniska tillämpningar. Karakteristiska egenskaper för däckklipp är låg densitet, hög elasticitet, låg styvhet, hög dränerande och hög värmeisolerande förmåga. Kombinationen av dessa egenskaper möjliggör tekniskt innovativa lösningar inom anläggningsbyggande.Det övergripande syftet med avhandlingen har varit att beskriva och utvärdera däckklipp som ett anläggningsmaterial ur både teknisk och miljömässig synvinkel. Arbetet har inkluderat både laboratorie- och fullskaleförsök för att utreda tekniska, miljö- och anläggningstekniska egenskaper. Vidare har det aktuella kunskapsläget om däckklipp som anläggningsmaterial utvärderats och presenterats.I laboratorieförsök har tekniska egenskaper med fokus mot packnings- och kompressionsegenskaper för däckklipp undersökts. I ett fältförsök har en vägkonstruktion med däckklipp som lättfyllnads- och tjälisoleringsmaterial byggts och utvärderats under fyra år. I laboratorieförsök har lakningsegenskaper för däckmaterial och miljöövervakningsprogram för tre olika konstruktioner utvärderats.Baserat på laboratoriestudier har en utvärderingsmodell för spännings-töjningsegenskaper och beräkning av kompression föreslagits. Rekommendationer för anläggningsteknik och vägdimensionering presenteras baserat på utvärderingen av vägkonstruktionen.Slutsatser baserat på lakningsstudierna i laboratoriemiljö och utvärderingen av miljöövervakningsprogrammen för fältkonstruktionerna är att de metaller som främst lakar ut är zink och järn och att lakningen av de studerade organiska föreningarna, d.v.s. PAH och fenoler, är låg. Från ett miljöperspektiv bör fokus flyttas från PAH mot organiska föreningar som har hög mobilitet och där kunskapsläget är lågt. Slutsatsen i detta arbete är att PAH-föreningar inte utgör ett föroreningsspridningsproblem för konstruktioner med däckklipp.Tillämpningar där däckklipp framgångsrikt har använts som konstruktionsmaterial är t.ex. i dräneringslager i deponier, i travbanor, och i paddockar. Användningen av däckklipp i travbanor och paddockar är särskilt intressant eftersom belastningen på hästarnas ligament kan minskas.Potentialen att använda däckklipp som ett anläggningsmaterial är stor. Eftersom tillgången är begränsad finns det en möjlighet att styra användningen till de lösningar där materialet används optimalt, både tekniskt och miljömässigt, och ändå avsätta all tillgänglig volym uttjänta däck. / Godkänd; 2006; 20070108 (mlk)

Snow has been a subject of research since the mid-20th century. Research on mechanical properties of snow started as an off-shoot of soil mechanics, where methods, tools and instruments used often are the same. However, during the last decades the winter business industry has been growing requiring a number of new fields of research. The aim with this PhD thesis is to investigate and contribute to solutions of some of the new research problems appearing in this area. Machine-made snow is commonly used for buildings and artwork of snow. Only minor scientific studies of machine-made snow and its properties have been published. Therefore, mechanical properties of machine-made snow were investigated. Strength and deformation properties were evaluated through uniaxial compressive tests where cylindrical test specimens were subjected to different constant deformation rates. Creep deformation, bending strength and ultimate load were also evaluated through beam tests. The results showed that the deformation rate is crucial if the snow will deform plastically or if brittle failure will occur. The grain size and structure of the snow had a strong influence on the strength properties. Snow is a constantly changing material with a large variety of grain sizes and shapes. Therefore it is of importance to classify snow. Classication of snow can be done using different methods depending on the property that is to be investigated. Several non-contact detection methods to evaluate snow properties exist. In this thesis, spectral reflectance measurements were performed to investigate liquid water content in snow using two different systems, a spectrometer and an optical sensor called Road Eye. The Road Eye sensor was also used to classify snow in cross-country ski tracks. This method enables a fast classication of a complete track where different types of snow can be distinguished. The properties of a ski track and the characteristics of the snow determine the type of skis that should be selected for optimum sliding properties. Cross-country skis have different mechanical properties, which to a large extent can be evaluated from the span curve of the ski. Depending on the skiing style, the skier's skills, terrain and track conditions different ski properties are required, which is particularly important for competitive skiing. Span curves of cross-country skis were measured using a digital instrument called Skiselector. Results from the investigations showed that skis within the same pair may have signicantly different properties. Moreover, temperature influences the span curve and thus the mechanical properties of the skis. Therefore, skis should be measured at a temperature close to where they are aimed to be used. Field tests of skis with similar span curves but different ski base topography were tested during wet and cold snow conditions. The results indicate that different topographies are preferable during different snow conditions. Due to the climate change, winters have become shorter and warmer with less natural snow. To compensate for the lack of natural snow, ski resorts and other stakeholders produce machinemade snow in order to run their business. Storing snow in insulated piles is an alternative and sometimes a complement to snow production. Studies on stored snow show that the surface area of the pile should be minimized in order to reduce the melt rate. Furthermore, the pileshould be covered with a suciently thick insulating layer, preferably with good evaporation properties. Theoretical calculations can be used to estimate the amount of snow that melts and to predict the efficiency of different materials as thermal insulation on snow. These calculations coincide well with experiments performed in northern Sweden where snow melt was measured. This PhD thesis consists of five publications and an introduction to this area which in particular puts these publications into a more general frame.