When a rigid shaft such as a jacked pile or the sleeve of a cone penetrometer penetrates soil, the soil mass at the shaft tip fails. This failed soil mass flows around the shaft surface and creates a disturbed soil zone. The soil in this zone, which is at a failure or critical state (CS), flows and behaves like a viscous fluid. During continuous penetration, the shaft surface is subjected to an additional viscous shear stress above the static shear stress (interfacial solid friction). The total resistance on the shaft in motion is due to the static and viscous shear components. Current methods of calculating the penetration resistance in soils are based on static interfacial friction, which determine the force required to cause failure at the shaft-soil interface and not the viscous drag. The main aim of this research is to understand the viscous soil resistance on penetrating shafts in clays.This research consists of two components. First, a theoretical analysis based on creeping flow hydrodynamics is developed to study the viscous drag on the shaft. The results of this analysis reveal that the size of the CS zone, the shear viscosity of the soil and velocity of the shaft influence the viscous drag stress. Large increases in viscous drag occur when the size of the CS zone is less than four times the shaft radius.Second, a new experimental procedure to estimate the shear viscosity of clays with water contents less than the liquid limit is developed. Shear viscosity is the desired soil parameter to estimate viscous drag. However, there is no standard method to determine shear viscosity of clays with low water contents (or Liquidity Index, LI). Soils can reach CS for water contents in the plastic range (LI<1) and exhibit viscous behavior. The fall cone test is widely used to interpret the index (liquid and plastic limit) and strength properties of clays. In this study the existing analysis of the fall cone test is reexamined to discern the viscous drag as the cone penetrates the soil. This reexamination shows that the shear viscosity of clays with low water contents (LI<1.5) can be estimated from time-penetration data of the fall cone. Fall cone test results on kaolin show that the shear viscosity decreases exponentially with an increase in LI.The results of this research can be used to understand practical problems such as jacked piles in clays, cone penetrometer sleeve resistance and advancement of casings in soil for drilling or tunneling operations.

Due to an increasing amount of aging tendencies in Swedish embankment dams, failures such as internal erosion has become a more common problem. Internal erosion is a phenomenon where certain soil material within the embankment dam is removed, often over a longer period of time. It is most common to occur at the inner core of the dam, and if it is allowed to continue for a longer time period the consequences can be disastrous. During the internal erosion, the inner material is washed out, creating larger voids and lowering the geotechnical stability of the dam. When larger voids start to appear, the seepage will increase allowing more material to be washed out and accelerating the process.  In order to repair an embankment dam, exposed to inner erosion, it requires both the location of the faults as well as a suitable method of repairing. A method to repair internal erosion is by using grout and injecting it into the location of the fault. The knowledge regarding what type of grout and how it should be treated is today lacking.  There are reasons to believe that a hardening mixture within an embankment dam using a till core will not cooperate well. For that reason, a grout with non-hardening properties is of interest. this thesis focuses on the Geomechanical strength parameters of two similar experimental non-hardening grouts. One with maximum grain size of 2 mm referred as grout 0/2, and one with maximum grain size of 4 mm, referred to as grout 0/4. The grouts consist of natural aggregates, calcium carbonate, water, bentonite, superplasticizer and defoamer.   The grouts are evaluated by its undrained shear strength, water content, bulk- and dry density using fall cone tests and uniaxial compressive strength tests. To evaluate the grouts angle of friction and angle of dilatancy together with young’s modulus, consolidated, drained triaxial tests were performed. Three tests with different consolidation pressures (50, 150 and 300 kPa) were performed for each grout. Since the grout will gain strength with time, the tests have been performed after certain number of days in order to see the development of the grouts. The laboratories stretch from 0 to 112 days since the time of mixing the grout, and was performed at Luleå University of technology.  Fall cone tests showed that the grout should most likely be mixed on site and left unstirred. Continuously stirring the grout quickly removed the grouts flowability which is why longer transportation should be avoided. At the same time, the accuracy of the grouts mixing is very demanding which needs to be taken into consideration.  Triaxial tests showed that the grout 0/2 had dilatant behavior for 50 and 150 kPa consolidation pressure while 300 kPa showed contractive behavior. The grout 0/4 had dilatant behavior for 50 kPa consolidation pressure while 150 and 300 kPa showed contractive behavior. A theory to explain this behavior was constructed where the bentonite is believed to be behind it. Bentonite slurries behave as a Bingham fluid, where it requires a certain amount of shear stress for the fluid to start to flow. With the same reasoning, the low consolidation pressures do not exceed that threshold, resulting in dilatant behavior. But once that threshold is surpassed the grout starts to contract. In addition, flow curve tests were performed for additives, superplasticizer and defoamer. Both these substances showed Newtonian behavior which leaves Bentonite to be the only additive with Binghamian behavior. / På grund av en ökad mängd med föråldrandetendenser hos svenska jordfyllningsdammar har brott så som inre erosion blivit ett alltmer vanligt problem. Inre erosion är ett fenomen där en viss jord inom jordfyllningsdammen är avlägsnad, generellt över en längre tidsperiod. Oftast inträffar detta vid den inre damkärnan och om erosionen är tillåten att fortskrida sig över en längre period kan konsekvenserna bli förödande. Inre erosion fungerar så att jordmaterial tvättas ut vilket skapar hålutrymmen och minskar den geotekniska hållfastheten för dammen. När större hålutrymmen bildats ökar läckaget som i sin tur tillåter mer material att bli urtvättat och processen blir accelererad. För att kunna reparera en jordfyllningsdam, utsatt för inre erosion, krävs både att platsen för brottet och metoden för att reparera är kända. En metod för att reparera inre erosion är genom att använda injektering och injektera hålutrymmet. Dock är kunskapen gällande vad för typ av injektering och hur den ska hanteras icke existerande i dagsläget. Det finns anledning att tro att ett härdande bruk inom en jordfyllningsdam, med en moränkärna, inte kommer samarbeta särskilt bra. På grund av det har ett bruk med icke-härdande egenskaper undersökt. Den här uppsatsen fokuserar på de geotekniska hållfasthetsegenskaperna för två liknande experimentella icke-härdande bruk. Ett med maximal kornstorlek på 2 mm benämnd som bruk 0/2 och ett med maximal kornstorlek på 4 mm, benämnd som bruk 0/4. Bruket består av natursand, kalciumkarbonat, vatten, bentonit, mjukgöringsmedel och skumdämpare. Bruken är utvärderade genom deras odränerade skjuvhållfasthet, vattenkvot, skrym- och torrdensiteten som har tagits fram från fallkorns-test och enaxiella trycktest (UCS).  För att utvärdera brukens friktionsvinkel och dilationsvinkel tillsammans med styvheten (initiella och 50 %) har konsoliderat, dränerat triaxiala tests utförts. Tre test med varierande konsolideringstryck (50, 150 och 300 kPa) har utförts för båda bruken. I och med att brukens hållfasthet kommer att öka med tiden, har testerna utförts efter ett visst antal dagar, för att se hur utvecklingen ser ut. Laborationerna har sträckt sig från 0 till 112 dagar sedan det att bruken har blandats, och utfördes vid Luleå Tekniska Universitet. Fallkornstesten visade att bruken bör med största sannolikhet blandas på arbetsplatsen och därefter förbli orörda. Kontinuerlig omrörning visade sig frånta brukens flytförmåga, vilket också är anledning till varför längre transporter bör undvikas. Samtidigt så är noggrannheten vid brukens blandning krävande vilket bör tas i beaktning. De triaxiala tester visade att bruk 0/2 visade ett dilatant beteende för både 50 och 150 kPa konsolideringstryck medan 300 kPa hade ett kontrakterande beteende. Bruket 0/4 hade dilatant beteende för 50 kPa konsolideringstryck medan 150 och 300 kPa visade kontrakterande beteende. En teori för att förklara detta beteende togs fram där bentoniten är den troliga orsaken. Bentonitblandningar (bentonite slurry) beter sig som en Bingham-vätska, där det krävs en viss mängd skjuvspänning för att få vätskan att börja flyta. Med samma resonemang applicerade på bruken innebar det att de låga konsolideringstrycken inte översteg tröskelvärdet, vilket resulterade i ett dilatant beteende. Däremot, när tröskelvärdet väl är överstiget börjar bruket att kontraktera istället. Det gjordes även flödestester på tillsatsmedlen, mjukgöringsmedel och skumdämpare. Testerna visade att båda medel betedde sig Newtoniskt, vilket lämnar bentoniten som det enda tillsatsmedlet med Bingham-beteende.

Um dos maiores problemas na utilização de ensaios geotécnicos de laboratório está na obtenção de amostras indeformadas. Os solos moles estão entre os mais difíceis de amostrar e há um grande trabalho de pesquisa no desenvolvimento de técnicas de amostragem. A fim de obter amostras de alta qualidade para o estudo do comportamento do material do depósito, foi desenvolvido nesta pesquisa uma modificação do Equipamento de Amostragem Japonês e foram adaptadas algumas das técnicas utilizadas para amostragem indeformada. O processo usual de extrusão de solo de dentro do tubo amostrador foi substituído pelo corte transversal do tubo, o que reduz a perturbação do solo. Para facilitar esta operação, os tubos foram construídos de latão (substituindo o aço inoxidável original). O depósito sedimentar objeto de estudo desta dissertação foi escolhido por ter apresentado em ensaios de campo um índice de sensibilidade (razão entre as resistências ao cisalhamento não drenadas indeformada e amolgada) bastante elevado, o que torna a sua amostragem cuidadosa ainda mais importante. A sensibilidade dos solos é um parâmetro importante em projetos de engenharia geotécnica, pois as deformações reduzem severamente a resistência ao cisalhamento não drenada nestes materiais. Foram utilizados diferentes ensaios de laboratório para permitir a determinação da resistência ao cisalhamento não-drenada do solo nas condições indeformada e amolgada, e para avaliação da sensibilidade (ensaio de cone de laboratório, ensaio de palheta de laboratório e ensaio triaxial), além de ensaios de caracterização do depósito. O depósito estudado apresenta lentes com dois materiais distintos (um argiloso e outro arenoso), entretanto apresentam ângulos de atrito interno semelhantes (~34°). Em ambos o solos as resistências ao cisalhamento não drenada foram baixas (Su ~10 kPa na condição indeformada e Su = 0,5 - 2,0 kPa na condição amolgada). A sensibilidade do material argiloso ficou em torno de 10 e no solo arenoso foi de aproximadamente 20. Análises qualitativas dos resultados indicam que as amostras coletadas pelo novo amostrador tiveram elevado grau de qualidade. Os resultados obtidos (a) confirmam o bom desempenho do novo equipamento amostrador; (b) permitiram determinar com precisão as resistências não-drenadas dos materiais; (c) comprovaram a grande sensibilidade das lentes arenosas; (d) ajudam a explicar o comportamento do depósito em campo. / One of the most difficult problems in the use of laboratory geotechnical tests is related to obtaining undisturbed samples. The soft soils are among the most difficult soils to sample and there is a great research effort in developing new sampling techniques. In order to obtain high quality samples for the study of the soil sensitivity, a modification of the Japanese thin-walled tube sampler has been build for this research and some modifications of the sampling techniques have been made. The conventional extrusion of the soil sample from the tube was substituted by a traverse cut of the tube in order to reduce the soil perturbation during its extraction. To make this operation easier, the material used for the tubes was brass (substituting the usual stainless steel). The sedimentary deposit studied on this research has been selected for having presented an high sensitivity on vane field tests (relation between peak and large deformation strengths) which gives even more importance to careful sampling. The sensitivity is an important parameter for geotechnical design as the deformations can severely reduce the undrained shear strength of these materials. Various laboratory testing techniques have been used to determine the undrained shear strength of these soils both in undisturbed and disturbed conditions (fall cone tests, lab vane tests and triaxial tests), besides characterization tests of the deposit. The studied deposit presents lenses of two distinct materials (clayey and sandy lenses), however they present similar internal angles of friction (~34°). In both soils the undrained shear strength are quite low (Su ~10 kPa in undisturbed condition and Su = 0,5 - 2,0 kPa in disturbed condition). The sensitivity of the clayey material is around 10 and around 20 in the sandy soil. Qualitative analyses of the results indicate that the samples taken with the new sampler have an high quality level. The results obtained (a) confirm the good performance of the sampler built; (b) allowed the undrained shear strength to be determined with precision; (c) showed the great sensitivity of the sandy lenses; (d) helped to explain the field behaviour of the soil.

Um dos maiores problemas na utilização de ensaios geotécnicos de laboratório está na obtenção de amostras indeformadas. Os solos moles estão entre os mais difíceis de amostrar e há um grande trabalho de pesquisa no desenvolvimento de técnicas de amostragem. A fim de obter amostras de alta qualidade para o estudo do comportamento do material do depósito, foi desenvolvido nesta pesquisa uma modificação do Equipamento de Amostragem Japonês e foram adaptadas algumas das técnicas utilizadas para amostragem indeformada. O processo usual de extrusão de solo de dentro do tubo amostrador foi substituído pelo corte transversal do tubo, o que reduz a perturbação do solo. Para facilitar esta operação, os tubos foram construídos de latão (substituindo o aço inoxidável original). O depósito sedimentar objeto de estudo desta dissertação foi escolhido por ter apresentado em ensaios de campo um índice de sensibilidade (razão entre as resistências ao cisalhamento não drenadas indeformada e amolgada) bastante elevado, o que torna a sua amostragem cuidadosa ainda mais importante. A sensibilidade dos solos é um parâmetro importante em projetos de engenharia geotécnica, pois as deformações reduzem severamente a resistência ao cisalhamento não drenada nestes materiais. Foram utilizados diferentes ensaios de laboratório para permitir a determinação da resistência ao cisalhamento não-drenada do solo nas condições indeformada e amolgada, e para avaliação da sensibilidade (ensaio de cone de laboratório, ensaio de palheta de laboratório e ensaio triaxial), além de ensaios de caracterização do depósito. O depósito estudado apresenta lentes com dois materiais distintos (um argiloso e outro arenoso), entretanto apresentam ângulos de atrito interno semelhantes (~34°). Em ambos o solos as resistências ao cisalhamento não drenada foram baixas (Su ~10 kPa na condição indeformada e Su = 0,5 - 2,0 kPa na condição amolgada). A sensibilidade do material argiloso ficou em torno de 10 e no solo arenoso foi de aproximadamente 20. Análises qualitativas dos resultados indicam que as amostras coletadas pelo novo amostrador tiveram elevado grau de qualidade. Os resultados obtidos (a) confirmam o bom desempenho do novo equipamento amostrador; (b) permitiram determinar com precisão as resistências não-drenadas dos materiais; (c) comprovaram a grande sensibilidade das lentes arenosas; (d) ajudam a explicar o comportamento do depósito em campo. / One of the most difficult problems in the use of laboratory geotechnical tests is related to obtaining undisturbed samples. The soft soils are among the most difficult soils to sample and there is a great research effort in developing new sampling techniques. In order to obtain high quality samples for the study of the soil sensitivity, a modification of the Japanese thin-walled tube sampler has been build for this research and some modifications of the sampling techniques have been made. The conventional extrusion of the soil sample from the tube was substituted by a traverse cut of the tube in order to reduce the soil perturbation during its extraction. To make this operation easier, the material used for the tubes was brass (substituting the usual stainless steel). The sedimentary deposit studied on this research has been selected for having presented an high sensitivity on vane field tests (relation between peak and large deformation strengths) which gives even more importance to careful sampling. The sensitivity is an important parameter for geotechnical design as the deformations can severely reduce the undrained shear strength of these materials. Various laboratory testing techniques have been used to determine the undrained shear strength of these soils both in undisturbed and disturbed conditions (fall cone tests, lab vane tests and triaxial tests), besides characterization tests of the deposit. The studied deposit presents lenses of two distinct materials (clayey and sandy lenses), however they present similar internal angles of friction (~34°). In both soils the undrained shear strength are quite low (Su ~10 kPa in undisturbed condition and Su = 0,5 - 2,0 kPa in disturbed condition). The sensitivity of the clayey material is around 10 and around 20 in the sandy soil. Qualitative analyses of the results indicate that the samples taken with the new sampler have an high quality level. The results obtained (a) confirm the good performance of the sampler built; (b) allowed the undrained shear strength to be determined with precision; (c) showed the great sensitivity of the sandy lenses; (d) helped to explain the field behaviour of the soil.

Um dos maiores problemas na utilização de ensaios geotécnicos de laboratório está na obtenção de amostras indeformadas. Os solos moles estão entre os mais difíceis de amostrar e há um grande trabalho de pesquisa no desenvolvimento de técnicas de amostragem. A fim de obter amostras de alta qualidade para o estudo do comportamento do material do depósito, foi desenvolvido nesta pesquisa uma modificação do Equipamento de Amostragem Japonês e foram adaptadas algumas das técnicas utilizadas para amostragem indeformada. O processo usual de extrusão de solo de dentro do tubo amostrador foi substituído pelo corte transversal do tubo, o que reduz a perturbação do solo. Para facilitar esta operação, os tubos foram construídos de latão (substituindo o aço inoxidável original). O depósito sedimentar objeto de estudo desta dissertação foi escolhido por ter apresentado em ensaios de campo um índice de sensibilidade (razão entre as resistências ao cisalhamento não drenadas indeformada e amolgada) bastante elevado, o que torna a sua amostragem cuidadosa ainda mais importante. A sensibilidade dos solos é um parâmetro importante em projetos de engenharia geotécnica, pois as deformações reduzem severamente a resistência ao cisalhamento não drenada nestes materiais. Foram utilizados diferentes ensaios de laboratório para permitir a determinação da resistência ao cisalhamento não-drenada do solo nas condições indeformada e amolgada, e para avaliação da sensibilidade (ensaio de cone de laboratório, ensaio de palheta de laboratório e ensaio triaxial), além de ensaios de caracterização do depósito. O depósito estudado apresenta lentes com dois materiais distintos (um argiloso e outro arenoso), entretanto apresentam ângulos de atrito interno semelhantes (~34°). Em ambos o solos as resistências ao cisalhamento não drenada foram baixas (Su ~10 kPa na condição indeformada e Su = 0,5 - 2,0 kPa na condição amolgada). A sensibilidade do material argiloso ficou em torno de 10 e no solo arenoso foi de aproximadamente 20. Análises qualitativas dos resultados indicam que as amostras coletadas pelo novo amostrador tiveram elevado grau de qualidade. Os resultados obtidos (a) confirmam o bom desempenho do novo equipamento amostrador; (b) permitiram determinar com precisão as resistências não-drenadas dos materiais; (c) comprovaram a grande sensibilidade das lentes arenosas; (d) ajudam a explicar o comportamento do depósito em campo. / One of the most difficult problems in the use of laboratory geotechnical tests is related to obtaining undisturbed samples. The soft soils are among the most difficult soils to sample and there is a great research effort in developing new sampling techniques. In order to obtain high quality samples for the study of the soil sensitivity, a modification of the Japanese thin-walled tube sampler has been build for this research and some modifications of the sampling techniques have been made. The conventional extrusion of the soil sample from the tube was substituted by a traverse cut of the tube in order to reduce the soil perturbation during its extraction. To make this operation easier, the material used for the tubes was brass (substituting the usual stainless steel). The sedimentary deposit studied on this research has been selected for having presented an high sensitivity on vane field tests (relation between peak and large deformation strengths) which gives even more importance to careful sampling. The sensitivity is an important parameter for geotechnical design as the deformations can severely reduce the undrained shear strength of these materials. Various laboratory testing techniques have been used to determine the undrained shear strength of these soils both in undisturbed and disturbed conditions (fall cone tests, lab vane tests and triaxial tests), besides characterization tests of the deposit. The studied deposit presents lenses of two distinct materials (clayey and sandy lenses), however they present similar internal angles of friction (~34°). In both soils the undrained shear strength are quite low (Su ~10 kPa in undisturbed condition and Su = 0,5 - 2,0 kPa in disturbed condition). The sensitivity of the clayey material is around 10 and around 20 in the sandy soil. Qualitative analyses of the results indicate that the samples taken with the new sampler have an high quality level. The results obtained (a) confirm the good performance of the sampler built; (b) allowed the undrained shear strength to be determined with precision; (c) showed the great sensitivity of the sandy lenses; (d) helped to explain the field behaviour of the soil.

Sulphide soils in Sweden are mainly found along the northeast coastline. These soils area characterized by their fine grain size, low shear strength and black, or grey, color. These soils are also found further south, in the Sundsvall area in Västernorrland, but have slightly lower sulphide content there. They are therefore often classified as sulphide-bearing soils. It is presumed that the undrained shear strength is underestimated in these soils. The undrained shear strength is used in the design of different geotechnical reinforcements. To obtain the undrained shear strength of a soil, several methods can be used. In situ, cone penetration tests or field vane tests can be used for example. In a laboratory environment, the undrained shear strength can be obtained from fall cone test or direct shear tests on undisturbed samples. Depending on how the soil is classified, they can be evaluated as a sulphide soil or as inorganic clay.  The objective of this master's thesis is to investigate if there are any indications showing that the undrained shear strength of sulphide-bearing soils in the Sundsvall area is being underestimated. It has also been investigated whether these soils should be evaluated as inorganic fine-grained soils instead of sulphide soils. Attempts have also been made to find a more suitable and site-specific reduction factor, cone factor, for the cone penetration tests. In order to enable this study, data from the mentioned investigation methods have been collected from Sweco's project Dubbelspår Dingersjö-Sundsvall C. The Project was separated into three subareas, since there were mainly three areas with direct shear tests. The data was evaluated both as sulphide soil and as inorganic clay, and then compared with the reference values from the direct simple shear tests. The site-specific cone factors for the cone penetration tests were also derived by using the undrained shear strength from the direct simple shear tests.  The result from the comparison with the reference values shows that the undrained shear strength of the sulphide-bearing soils in the Sundsvall area is underestimated if it is evaluated as sulphide soil. This applies to all three methods, cone penetration tests, fall cone tests and field vane tests. The fact that the undrained shear strength is currently underestimated means that costs and environmental impact could be reduced in many projects in Västernorrland if a more accurate reduction were to be used. New cone factors were also derived as a part of the result. The new cone factors were 20.55, 18.84 and 17.04 for the three subareas. This can be compared to the current cone factor for sulphide soil, which is 20. At the end of this report it is discussed whether the direct simple shear tests are the most suitable method for obtaining reference values in these soils. It is also discussed which parameters are believed to affect the cone factors. Future research should investigate how the silt and organic content affects the undrained shear strength. This should be done to be able to find a more accurate reduction for sulphide-bearing soils. Whether the direct simple shear tests are best suited to use as a reference values should also be investigated further. / Sulfidjordar i Sverige återfinns främst längst den nordöstra kustlinjen. Dessa jordar är generellt sett finkorniga, har låg skjuvhållfasthet och är ofta svarta eller gråa. Sulphidjordar återfinns även längre söder ut, i Sundsvallsområdet i Västernorrland, men sulfidinnehållet är något lägre i det området. De klassas därför ofta som sulfidhaltiga. Det förmodas att den odränerade skjuvhållfastheten underskattas i dessa jordar. Den odränerade skjuvhållfastheten används när olika geotekniska lösningar ska dimensioneras. Det finns flera olika metoder som kan användas för att erhålla den odränerade skjuvhållfastheten. I fält kan till exempel CPT-sonderingar och vingförsök utföras. I en laboratoriemiljö kan den odränerade skjuvhållfastheten erhållas från fallkonförsök och direkta skjuvförsök på ostörda jordprover. Beroende på hur jordarten klassificeras kan de utvärderas som en sulfidjord eller oorganisk lera. Syftet med detta examensarbete är att undersöka om det finns indikationer som tyder på att den odränerade skjuvhållfastheten i sulfidhaltiga jordar i Sundsvallsområdet underskattas om de utvärderas som sulfidjord. Det har även undersökts om dessa jordar ska utvärderas som en oorganisk finkornig jord istället för en sulfidjord. Det har också gjorts försök att hitta mer passande och platsspecifika, reduktionsfaktorer, konfaktorer, för CPT-sondering. För att möjliggöra undersökningen har data från de nämnda undersökningsmetoderna sammanställts från projektet Dubbelspår Dingersjö-Sundsvall C. Projektet har delats upp i tre delområden, eftersom det främst finns tre områden där direkta skjuvförsök har utförts. Undersökningarna utvärderades både som sulfidjord och oorganisk lera och jämfördes sedan med referensvärden från de direkta skjuvförsöken. Även de platsspecifika konfaktorerna för CPT härleddes med hjälp av den odränerade skjuvhållfastheten från de direkta skjuvförsöken.  Resultaten från jämförelsen med referensvärdena visar att den odränerade skjuvhållfastheten i sulfidhaltiga jordar i Sundsvallsområdet underskattas när den utvärderas som sulfidjord. Detta gäller alla tre metoder, CPT, fallkonförsök och vingförsök. Faktumet att den odränerade skjuvhållfastheten underskattas innebär att kostnad och klimatpåverkan skulle kunna minska i många projekt i Västernorrland om en mer exakt reduktion skulle göras. Nya konfaktorer härleddes också som en del av resultatet. De nya konfaktorerna var 20.55, 18.84 och 17.04 i de tre delområdena. Det kan jämföras med den nuvarande konfaktorn för sulfidjord, som är 20. I slutet av rapporten diskuteras det huruvida direkta skjuvförsök är den bäst lämpade metoden för att ta fram referensvärden i dessa jordar. Det diskuteras även vilka parametrar som tros påverka konfaktorn. Framtida forskning borde undersöka hur siltinnehållet och det organiska innehållet påverkar den odränerade skjuvhållfastheten. Det borde göras för att kunna erhålla en mer lämplig reduktion för sulfidhaltiga jordar. Om direkta skjuvförsök är bäst lämpad att använda som referensvärde borde också undersökas vidare.

Previous thread rolling methods for the plastic limit are shown to be inadequate and inaccurate. Alternative methods for the plastic limit are shown to be imprecise and unreliable. The strength-based concept and use of the fall-cone test to determine the plastic limit are shown to be flawed. An apparatus that replicates Atterberg’s rolling technique, devised and developed by the author, is described, referred to as the Barnes Apparatus. A thread of soil is rolled between two plates configured to permit extrusion and reduction of diameter with much less operator interference than with the standard test and judgement of the crumbling condition is eliminated. Using a loading device nominal stresses are derived and from dial gauge readings diametral strains are determined for each rolling traverse of the soil thread. Toughness has previously only been studied in an empirical or qualitative manner. From plots of nominal stress vs. strain the workability or toughness of the plastic soil is determined as the work/unit volume. The apparatus and test are appropriate to a wide range of soils. Threads are tested over a range of water contents from near the sticky limit to the brittle state. Good correlations between toughness and water content display an abrupt ductile-brittle transition and give an accurate definition of the plastic limit. From the correlations useful properties are obtained such as the maximum toughness at the plastic limit, the toughness limit, the water content at zero toughness, the stiffness transition, the toughness coefficients, the toughness index and the workability index. An investigation into the significance of the soil thread diameter of 3 mm in the standard plastic limit test has found that as the water content of a soil reduces it undergoes a transition from fully plastic, to cracked, to brittle, largely regardless of the diameter of the thread. It is recommended that the 3 mm diameter requirement is withdrawn from the standard test procedure as unnecessary and emphasis placed on observing the behaviour of the soil thread as it is rolled by hand. A review of the relationship between the clay matrix and the granular particles in a soil has found that the linear law of mixtures and activity index are appropriate only at high clay contents. The terms granular spacing ratio and matrix porosity are introduced to explain the effect of the granular particles on the toughness and plastic limit. An analysis confirms that with small diameter soil threads large granular particles affect the results disproportionately. An aggregation ratio term is introduced to explain the change in toughness in the clay matrix as its water content reduces towards the plastic limit. To assess the effect of granular particles in a clay matrix on the toughness and plastic limit the results of tests conducted on mixtures of a high plasticity clay and silt, and sand particles of two different sizes are discussed. Smaller particle sizes are found to have a greater effect on reducing the toughness and the plastic limit of the clay. In the ceramics industry mixing different clays together to obtain suitable properties is common. The toughness and plastic limits of two pairs of mixed clays do not follow the linear law of mixtures but are dependent on the total clay content and the content of a dominant clay mineral.

The undrained shear strength and preconsolidation pressure are key parameters in describing the characteristics of soft clays. The two parameters both reflect the clay’s structure and state of stress, and hence empirical correlations for undrained shear strength normalized with respect to preconsolidation pressure are widely used to assess soil behavior. The empirical correlations given in the literature are typically dependent on liquid limit, or plasticity index, but some studies have questioned the dependency and proposed correlations constant for consistency limits. Data from geotechnical projects often display a considerable scatter and deviate from established empirical correlations. In this thesis, statistical analyses are performed and evaluated qualitatively on direct simple shear, constant rate of strain and fall cone test data from 146 sampling points with a total of 596 soil samples from Stockholm, Gothenburg and Uppsala. The aim is to investigate the correlation between shear strength and the preconsolidation pressure. The thesis evaluates the normalized shear strength’s dependency on liquid limit, how the data corresponds to Hansbo’s (1957) and Swedish Geotechnical Institute’s (2007) linear empirical correlations, and the correction factor applied to shear strength measured by the fall cone test. The results of the study show that the correction factor typically reduces the shear strength from fall cone tests too much with respect to shear strength from direct simple shear tests. The normalized shear strength’s dependency on liquid limit may be rejected for the fall cone test data. The results for direct simple shear test data however, indicates a correlation with liquid limit. The data scatter is considerable, especially for fall cone test data, and the relevance of describing the normalized shear strength from fall cone test with a linear empirical correlation to liquid limit may conclusively be questioned. / Skjuvhållfasthet och förkonsolideringstryck är två viktiga jordparametrar för lösa leror. Båda parametrar reflekterar lerans struktur och spänningstillstånd, och empiriska korrelationer för odränerad skjuvhållfasthet, normaliserad mot förkonsolideringstrycket, används därför ofta för att bedöma en leras egenskaper. De empiriska korrelationerna är vanligen kopplade till flytgräns eller plasticitetsindex. Dessa korrelationer har däremot ifrågasatts av studier som i vissa fall istället föreslagit ett konstant förhållande mellan normaliserad odränerad skjuvhållfasthet och plasticitetsgränser. Mätvärden från geotekniska projekt i Sverige visar allmänt stor spridning avseende dessa parametrar och data avviker ofta från etablerade empiriska korrelationer. I examensarbetet har data från direkta skjuvförsök, ödometerförsök och fallkonförsök utvärderats statistiskt och kvalitativt. Totalt omfattar studien 596 jordprover från 146 provtagningspunkter från Stockholm, Göteborg och Uppsala. Syftet med studien är att undersöka korrelationen mellan odränerad skjuvhållfasthet och förkonsolideringstryck. Studien behandlar den normaliserade skjuvhållfashetens flytgränsberoende, Hansbos (1957) och Statens Geotekniska Instituts (2007) empiriska korrelationer, samt den korrektionsfaktor som ska tillämpas på skjuvhållfastheter från fallkonförsök. Resultatet visar att korrektionsfaktorn reducerar skjuvhållfastheten för mycket och att korrigerade skjuvhållfastheter är i sämre samstämmighet med skjuvhållfastheter från direkta skjuvförsök än okorrigerade. Data från fallkonförsök uppvisar inget tydligt flytgränsberoende, medan resultaten från direkta skjuvförsök indikerar ett beroende. Spridningen i data är dock påfallande, särskilt för fallkonförsöket. Relevansen i att tillämpa en linjär empirisk korrelation för odränerad normaliserad från fallkonförsök mot förkonsolideringstryck beroende av flytgräns bör ifrågasättas.