Geotechnicans in Sweden and rest of Scandinavia have a wide experience of stability calculations in cohesive soils. The two main parameters for this type of calculations are the undrained shear strength and the preconsolidation pressure. The most common methods in Sweden to determine the undrained shear strength in field is the vane shear strength test and CPT-test, in laboratories the fall cone test is well used. To determine the preconsolidation pressure CRS-analyses are well used. For more accurate measurements the odeometer tests are more suitable. However this method is both expensive and time-consuming form of analysis from a commercial aspect. Therefore is different correlation equations used as a compliment in these different stability evaluations.  This research will focus on the empirical Hansbo Correlation and its relation to results from commercial surveys. The commercial data come from Atkins Sverige’s project data base. The results after comparing Hansbo correlation with the commercial data showed on a significant divergence, which indicate a great unsureness of the Hansbo correlation. As a result of this contingency it is of importance to take cautiousness in the use of empirical correlations in stability calculations.

This research takes a multidisciplinary approach to comprehensively investigate the material and mechanical properties as well as pore water chemistry of the Bearpaw shale. This made it possible to characterize how these properties relate to the mechanical strength of this material. The results of this research challenge our ideas of the hydrogeology and of the geological history of the region. Core samples of the Bearpaw Formation and the overlying glacial till were collected from a field site in southern Saskatchewan, Canada. A combination of laboratory tests including multi-staged oedometer tests, constant rate of strain oedometer tests, specialized triaxial swell tests, along with pore water chemistry and finite element modelling were used to meet the following objectives: (1) To investigate the material properties and compression behaviour of the Bearpaw in addition to assessing disturbance due to specimen size; (2) Examine the time dependent behaviour of the Bearpaw and the transferability of time rate models developed for soft soils to stiff soils; (3) Examine the swelling potential and behaviour of the Bearpaw Formation and the influence of boundary conditions on this behaviour, while assessing the applicability of the swell concepts developed for compacted materials to a naturally swelling clay material; and (4) Constrain the depositional age of the till overlying the Bearpaw Shale. Contrary to what is seen in soft soils, smaller sized specimens were found to reduce disturbance, and produce more accurate and consistent results. Creep was found to follow the same laws as it does in soft soils, calling into question whether the use of preconsolidation pressure to predict geological history in stiff clays is appropriate. There was significant variation in the observed swell pressures of samples of the same size and depth. Finally, the glacial till at site was found to belong uniquely to the Battleford Formation and ranges in age from 22,500 to 27,500 years which is much younger (over 100,000 years younger) than previously believed. / Thesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2010-01-29 01:34:14.071

Há poucos estudos sobre a influência da mineralogia no comportamento do solo em relação aos atributos de resistência física. Neste sentido, o estudo tem como hipótese que independentemente do potencial matricial de água no solo a composição mineralógica da fração argila interfere na pressão de préconsolidação, modificando a capacidade de suporte de carga dos solos. Assim, objetivou-se caracterizar a composição mineralógica de classes de solos representativas no Rio Grande do Sul; Determinar parâmetros físico-mecânicos dos solos; E estabelecer correlações entre parâmetros físico-mecânicos com mineralógicos melhorando o entendimento da capacidade de suporte de carga. Para tal, foram selecionados sete solos de duas classes de solos; três Argissolos e quatro Latossolos. As amostras deformadas e indeformadas foram coletadas sob vegetação natural na camada de 10 a 15 cm de profundidade. Na fração TFSA, foram realizadas análises físicas (granulometria e área superficial específica), químicas (carbono orgânico total, teor de óxidos de ferro pedogênicos e óxidos de baixa cristalinidade) e mineralógicas (difratometria de raio x e refletância difusa). Nas amostras indeformadas foram realizadas as análises de permeabilidade ao ar e o ensaio de compressão uniaxial. Os dados foram analisados por correlações de Pearson. Os solos avaliados possuem a caulinita como principal mineral da fração argila, no entanto diferenças com relação aos óxidos de ferro foram encontradas, os quais correlacionaram com a pressão de pré-consolidação. A hematita influenciou positivamente sobre a pressão de pré-consolidação à 100 kPa, assim, dependendo do potencial matricial de água no solo. / There are few studies on the influence of mineralogy on the ground behavior in relation to physical resilience attributes. The is study has hypothesized that regardless of the matric potential of soil water the mineralogical composition of the clay fraction interferes with the pre-consolidation pressure by modifying the soil bearing capacity. Therefore, this study aimed to characterize the mineralogical composition of representative soil classes in Rio Grande do Sul; determine physical-mechanical parameters of the soil; and establish correlations between physico-mechanical parameters mineralogical improving the understanding of the load-bearing capacity. To this end, it was selected seven soils of two soil classes; three Ultisols and four Oxisols. The disturbed and undisturbed samples were collected under natural vegetation in the layer from 10 to 15 cm deep. In TFSA fraction, physical analyzes were performed (particle size and specific surface area), chemical (total organic carbon content of pedogenic iron oxides and low crystallinity oxides) and mineralogical (x ray diffraction and diffuse reflectance). In undisturbed soil samples were carried out air permeability tests and uniaxial compression test. Data were analyzed by Pearson correlations. The evaluated soils have kaolinite as the main mineral of the clay fraction, however differences with respect to iron oxides were found, which correlated with the pressure of pre-consolidation. The hematite had a positive effect on the pre-consolidation pressure of 100 kPa, thus depending on the matric potential of soil water.

Made available in DSpace on 2014-06-11T19:31:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-02-06Bitstream added on 2014-06-13T20:22:39Z : No. of bitstreams: 1 castroneto_p_dr_botfca.pdf: 1413886 bytes, checksum: ea446972915050c39ff614a5f1ea18c9 (MD5) / Um dos fatores mais críticos na determinação do número de dias trabalháveis com máquinas agrícolas se refere à determinação das condições do solo que forneçam informações para a decisão se o tráfego de máquinas em uma determinada gleba poderá ser realizado sem provocar alterações nas suas propriedades físicas e dinâmicas. Este trabalho teve como objetivos o desenvolvimento e avaliação de equipamentos e metodologia para a determinação de parâmetros físicos do solo relacionados a dias trabalháveis com máquinas agrícolas, com ênfase nas características do conjunto trator-implemento e na pressão máxima aplicável ao solo sem que este sofra compactação adicional. Foi construído um equipamento hidráulico-eletrônico para realização de determinações físicas de solo em campo, o qual se mostrou eficiente para a finalidade a que foi proposto. O modelo para a determinação da pressão de contato pneu-solo, foi desenvolvido com base nas características do rodado, obtidas pelo seu coeficiente de deformação e pela sua largura relativa, e nas características de recalque do solo, representadas pelos coeficientes kc(módulo de deformação devido à coesão do solo), k (módulo de deformação devido ao atrito interno do solo) e n( constante de deformação do solo). A pressão máxima exercida pelo rodado no solo, antes que houvesse uma compactação adicional, foi caracterizada pela pressão de preconsolidação. Para tanto, construiu-se uma prensa, de acionamento pneumático e aquisição eletrônica de dados, para a realização dos ensaios de compressão uniaxial. Realizou-se um ensaio de campo com delineamento em blocos casualizados com quatro tratamentos, representados pelo tráfego de um trator um, dois, quatro e seis dias após uma chuva, em quatro repetições... / Decision information about machinery traffic in a certain plot is one of the most critical factors to obtain the number of agricultural machine workdays. The soil conditions is the indicator if the machinery traffic will promote significantly physical and dynamic property changes. This work aimed to develop and evaluate equipments and methodology to obtain soil physical parameters related to agricultural machine workdays, with emphasis on tractor-implement set characteristics and maximum pressure on soil that do not increase this compaction situation. A hydraulic-electronic equipment was built for accomplishment of soil physical determinations, showing efficiency and versatility when used on field. The tire-soil contact pressure model was developed based on wheel and sinkage characteristics, the first one represented by their deformation coefficient and relative width, and the other by kc, k and n coefficients. The maximum wheel pressure on soil, before additional compaction, was characterized by its previous consolidation (preconsolidation) pressure. A pneumatic and electronic consolidometer was built, for uniaxial compression tests. A field research was done using a random block experimental design with four treatments, represented by the tractor traffic, number of days after a rain (1, 2, 4 and 6), with four repetitions. The obtained results, under this research conditions, evidenced that the developed methodology allowed to obtain soil physical parameters that can be used on forecast and soil trafficability monitoring and, finally, incorporated on agroclimatic models used to determine the number of agricultural machine workdays. It was observed increments of 25%, 19% and 15% on soil bulk density, respectively, for one, two, and four days after the rain traffic conditions and no statistical significant increment for six days after the rain... (Complete abstract, click electronic access below)

Há poucos estudos sobre a influência da mineralogia no comportamento do solo em relação aos atributos de resistência física. Neste sentido, o estudo tem como hipótese que independentemente do potencial matricial de água no solo a composição mineralógica da fração argila interfere na pressão de préconsolidação, modificando a capacidade de suporte de carga dos solos. Assim, objetivou-se caracterizar a composição mineralógica de classes de solos representativas no Rio Grande do Sul; Determinar parâmetros físico-mecânicos dos solos; E estabelecer correlações entre parâmetros físico-mecânicos com mineralógicos melhorando o entendimento da capacidade de suporte de carga. Para tal, foram selecionados sete solos de duas classes de solos; três Argissolos e quatro Latossolos. As amostras deformadas e indeformadas foram coletadas sob vegetação natural na camada de 10 a 15 cm de profundidade. Na fração TFSA, foram realizadas análises físicas (granulometria e área superficial específica), químicas (carbono orgânico total, teor de óxidos de ferro pedogênicos e óxidos de baixa cristalinidade) e mineralógicas (difratometria de raio x e refletância difusa). Nas amostras indeformadas foram realizadas as análises de permeabilidade ao ar e o ensaio de compressão uniaxial. Os dados foram analisados por correlações de Pearson. Os solos avaliados possuem a caulinita como principal mineral da fração argila, no entanto diferenças com relação aos óxidos de ferro foram encontradas, os quais correlacionaram com a pressão de pré-consolidação. A hematita influenciou positivamente sobre a pressão de pré-consolidação à 100 kPa, assim, dependendo do potencial matricial de água no solo. / There are few studies on the influence of mineralogy on the ground behavior in relation to physical resilience attributes. The is study has hypothesized that regardless of the matric potential of soil water the mineralogical composition of the clay fraction interferes with the pre-consolidation pressure by modifying the soil bearing capacity. Therefore, this study aimed to characterize the mineralogical composition of representative soil classes in Rio Grande do Sul; determine physical-mechanical parameters of the soil; and establish correlations between physico-mechanical parameters mineralogical improving the understanding of the load-bearing capacity. To this end, it was selected seven soils of two soil classes; three Ultisols and four Oxisols. The disturbed and undisturbed samples were collected under natural vegetation in the layer from 10 to 15 cm deep. In TFSA fraction, physical analyzes were performed (particle size and specific surface area), chemical (total organic carbon content of pedogenic iron oxides and low crystallinity oxides) and mineralogical (x ray diffraction and diffuse reflectance). In undisturbed soil samples were carried out air permeability tests and uniaxial compression test. Data were analyzed by Pearson correlations. The evaluated soils have kaolinite as the main mineral of the clay fraction, however differences with respect to iron oxides were found, which correlated with the pressure of pre-consolidation. The hematite had a positive effect on the pre-consolidation pressure of 100 kPa, thus depending on the matric potential of soil water.

Há poucos estudos sobre a influência da mineralogia no comportamento do solo em relação aos atributos de resistência física. Neste sentido, o estudo tem como hipótese que independentemente do potencial matricial de água no solo a composição mineralógica da fração argila interfere na pressão de préconsolidação, modificando a capacidade de suporte de carga dos solos. Assim, objetivou-se caracterizar a composição mineralógica de classes de solos representativas no Rio Grande do Sul; Determinar parâmetros físico-mecânicos dos solos; E estabelecer correlações entre parâmetros físico-mecânicos com mineralógicos melhorando o entendimento da capacidade de suporte de carga. Para tal, foram selecionados sete solos de duas classes de solos; três Argissolos e quatro Latossolos. As amostras deformadas e indeformadas foram coletadas sob vegetação natural na camada de 10 a 15 cm de profundidade. Na fração TFSA, foram realizadas análises físicas (granulometria e área superficial específica), químicas (carbono orgânico total, teor de óxidos de ferro pedogênicos e óxidos de baixa cristalinidade) e mineralógicas (difratometria de raio x e refletância difusa). Nas amostras indeformadas foram realizadas as análises de permeabilidade ao ar e o ensaio de compressão uniaxial. Os dados foram analisados por correlações de Pearson. Os solos avaliados possuem a caulinita como principal mineral da fração argila, no entanto diferenças com relação aos óxidos de ferro foram encontradas, os quais correlacionaram com a pressão de pré-consolidação. A hematita influenciou positivamente sobre a pressão de pré-consolidação à 100 kPa, assim, dependendo do potencial matricial de água no solo. / There are few studies on the influence of mineralogy on the ground behavior in relation to physical resilience attributes. The is study has hypothesized that regardless of the matric potential of soil water the mineralogical composition of the clay fraction interferes with the pre-consolidation pressure by modifying the soil bearing capacity. Therefore, this study aimed to characterize the mineralogical composition of representative soil classes in Rio Grande do Sul; determine physical-mechanical parameters of the soil; and establish correlations between physico-mechanical parameters mineralogical improving the understanding of the load-bearing capacity. To this end, it was selected seven soils of two soil classes; three Ultisols and four Oxisols. The disturbed and undisturbed samples were collected under natural vegetation in the layer from 10 to 15 cm deep. In TFSA fraction, physical analyzes were performed (particle size and specific surface area), chemical (total organic carbon content of pedogenic iron oxides and low crystallinity oxides) and mineralogical (x ray diffraction and diffuse reflectance). In undisturbed soil samples were carried out air permeability tests and uniaxial compression test. Data were analyzed by Pearson correlations. The evaluated soils have kaolinite as the main mineral of the clay fraction, however differences with respect to iron oxides were found, which correlated with the pressure of pre-consolidation. The hematite had a positive effect on the pre-consolidation pressure of 100 kPa, thus depending on the matric potential of soil water.

The Constant Rate of Strain (CRS) test is currently the most widely used method for determination of consolidation parameters in Sweden. These parameters are used to calculate the probable settlements and behavior of soils. With the Swedish standard strain rate, the duration of a single the test is about 24h, but a higher strain rate would allow for more tests to be performed in the same amount of time. For all clays in Sweden, the Swedish standard for the CRS test suggests a fixed rate of strain that is independent of soil properties, while the North American standard proposes a strain rate that generates a pore pressure ratio of 3-15%. Soil properties such as water content, liquid limit, sensitivity and shear strength vary greatly between different regions of Sweden. It would be beneficial if these properties could be used to find the ideal strain rate for the CRS test. Performing the tests at a higher strain rate, and thus performing more tests within a shorter amount of time, would save both time and money. In this report, 24 CRS tests are performed on three different clays with distinctive properties. Each clay is tested with three different strain rates: the Swedish standard rate of 0.680%/h, a higher rate of 3.00%/h and a lower rate of 0.154%/h. The results are evaluated according to both standards, and are compared and analyzed to determine whether there is any indication that the strain rate can be selected based on the soil properties. The results indicate that the selection of the strain rate is dependent on the soil properties. In addition, the majority of the tests can be conducted with higher strain rates than what is required by the Swedish standard and still manage to lie within the 3-15% limit of the pore pressure ratio, which is acceptable for the North American standard. However, the preconsolidation pressure does rise with increased strain rates, which can generate problems and erroneous results when calculating the settlements. A more extensive testing program with CRS tests and full-scale field tests must be carried out before any recommendation of a higher strain rate can be made.

The aim of this study is to determine if the mini block sampling technique couldoffer a complement to the Swedish standard StII piston sampler for achieving higherquality samples. The principle is that having a greater diameter the sample is meticulouslytrimmed to the usual geometry, so that the periphery of the sample is not disturbedby the sampling procedure and the same testing equipment can be employed.Hence, the test would provide higher and more accurate values of deformation andshear strength properties.The testing campaign executed for this study includes routine analysis with fallcone tests, CRS oedometer tests, DSS tests, CAUC triaxial tests and sedimentationtests. All of them have been performed on East-Sweden varved clay from Barkarby,Stockholm. Afterwards, the results and the sampling procedure were analysed toevaluate the performance of the mini block sampler.The mini block sampler provided more pronounced preconsolidation pressureson CRS tests as well as higher values of the quality index Mi=ML. DSS tests presenthigher values of undrained shear strength but no difference in shear strain at failure.In addition, the values of shear modulus show stiffer behaviour for block samplesas a prove of better clay structure preservation. Regarding triaxial results, theundrained shear strength values are higher for block samples with higher stresspeaks and lower strain to failure in the stress-strain graphs. Finally, several qualityindex were analysed obtaining better results for block sampling in most of them.It can be concluded that mini block sampler generally presents better qualitysamples than piston sampler for East-Swedish clay. Additionally, it is highlyfavourable for commercial projects due to each block provides up to 8 standard 50mm samples

Continental glaciers covered as much as thirty percent of the present-day inhabited earth during the Quaternary period. Traditionally, one-dimensional consolidation has been considered as the main process of formation for the soils deposited during glaciation. One of the outcomes of accepting one-dimensional consolidation as the main process of formation is that the geomechanical properties of soil in a horizontal plane are isotropic (known as cross-anisotropy). Recent measurements of subglacial pore pressure and preconsolidation pressure profile have indicated that this might not be the case. The role of subglacial shear action has probably been long neglected. The main objective of this research is to investigate the effects of subglacial shearing on the geomechanical properties of glaciated soils. <p> Recent research has found evidence of horizontal property anisotropy associated with the direction of the ice-sheet movement. A testing program was thus proposed to explore the relationship between the anisotropy of property and the direction of past glacier movement. The program involves several fundamental engineering parameters of soils. These parameters together with the corresponding test methods are as follows: (i) Conventional oedometer test yield stress anisotropy; (ii) Oedometer test with lateral stress measurement stiffness anisotropy; (iii) Load cell pressuremeter (LCPM) test in situ stress anisotropy. <p> The physical meaning of yield stress determined by conventional oedometer tests was interpreted as the critical state of structural collapse. The literature review and an experimental study on kaolin samples with a known stress history suggested that yield stress possesses certain dependency on the sampling direction. The anisotropy of yield stress for Battleford till from Birsay, Saskatchewan was also explored by testing directional oedometer samples. In addition, the anisotropy of stiffness was also investigated using a newly developed lateral stress oedometer that is capable of independent measurement of horizontal stresses at three different points with angles of 120 degrees. Preliminary evidence of a correlation between the direction of maximum stiffness in a horizontal plane and the known direction of glacial shear was observed. The correlation between the direction of maximum yield stress and known direction of glaciation was rather poor. Anisotropy of in situ stresses was investigated by conducting LCPM tests in Pot clay in the Netherlands. Based on the LCPM test results, it was concluded that the evidence of a correlation between the anisotropy of in situ stress and known direction of glacial advance is still rather obscure. <p> Although both the laboratory studies and field studies cannot sufficiently confirm the existence of lateral anisotropy of geomechanical properties and its relationship to the direction of the Quaternary ice-sheet movement, the effects of subglacial shearing should not be neglected in assessing the geotechnical properties of glaciated soils. In practice, it is usually found that the preconsolidation pressure profile does not follow the gravitational line as predicted by the one-dimensional consolidation theory and its magnitude is not compatible with the measured effective pressure values at the base of the glacier. It has been suggested that changes in seepage gradient (upward or downward) are responsible for the deviation of preconsolidation pressure profile away from the gravitational line. In this thesis, a new glacial process model consolidation coupled shearing was proposed. This model is based on the framework of traditional soil mechanics (critical state theory, Modified Cam-clay model and one-dimensional consolidation theory) and is consistent with the general geological and glaciological evidences. This model may provide an alternative explanation for the preconsolidation pressure patterns generally observed in practice. It can also be combined with groundwater flow characteristics to explain the diversity of the preconsolidation consolidation patterns. The proposed model was used successfully to obtain the preconsolidation pressure profile observed in Battleford till at Birsay and the subglacial shear-softening phenomenon.

Continental glaciers covered as much as thirty percent of the present-day inhabited earth during the Quaternary period. Traditionally, one-dimensional consolidation has been considered as the main process of formation for the soils deposited during glaciation. One of the outcomes of accepting one-dimensional consolidation as the main process of formation is that the geomechanical properties of soil in a horizontal plane are isotropic (known as cross-anisotropy). Recent measurements of subglacial pore pressure and preconsolidation pressure profile have indicated that this might not be the case. The role of subglacial shear action has probably been long neglected. The main objective of this research is to investigate the effects of subglacial shearing on the geomechanical properties of glaciated soils. <p> Recent research has found evidence of horizontal property anisotropy associated with the direction of the ice-sheet movement. A testing program was thus proposed to explore the relationship between the anisotropy of property and the direction of past glacier movement. The program involves several fundamental engineering parameters of soils. These parameters together with the corresponding test methods are as follows: (i) Conventional oedometer test yield stress anisotropy; (ii) Oedometer test with lateral stress measurement stiffness anisotropy; (iii) Load cell pressuremeter (LCPM) test in situ stress anisotropy. <p> The physical meaning of yield stress determined by conventional oedometer tests was interpreted as the critical state of structural collapse. The literature review and an experimental study on kaolin samples with a known stress history suggested that yield stress possesses certain dependency on the sampling direction. The anisotropy of yield stress for Battleford till from Birsay, Saskatchewan was also explored by testing directional oedometer samples. In addition, the anisotropy of stiffness was also investigated using a newly developed lateral stress oedometer that is capable of independent measurement of horizontal stresses at three different points with angles of 120 degrees. Preliminary evidence of a correlation between the direction of maximum stiffness in a horizontal plane and the known direction of glacial shear was observed. The correlation between the direction of maximum yield stress and known direction of glaciation was rather poor. Anisotropy of in situ stresses was investigated by conducting LCPM tests in Pot clay in the Netherlands. Based on the LCPM test results, it was concluded that the evidence of a correlation between the anisotropy of in situ stress and known direction of glacial advance is still rather obscure. <p> Although both the laboratory studies and field studies cannot sufficiently confirm the existence of lateral anisotropy of geomechanical properties and its relationship to the direction of the Quaternary ice-sheet movement, the effects of subglacial shearing should not be neglected in assessing the geotechnical properties of glaciated soils. In practice, it is usually found that the preconsolidation pressure profile does not follow the gravitational line as predicted by the one-dimensional consolidation theory and its magnitude is not compatible with the measured effective pressure values at the base of the glacier. It has been suggested that changes in seepage gradient (upward or downward) are responsible for the deviation of preconsolidation pressure profile away from the gravitational line. In this thesis, a new glacial process model consolidation coupled shearing was proposed. This model is based on the framework of traditional soil mechanics (critical state theory, Modified Cam-clay model and one-dimensional consolidation theory) and is consistent with the general geological and glaciological evidences. This model may provide an alternative explanation for the preconsolidation pressure patterns generally observed in practice. It can also be combined with groundwater flow characteristics to explain the diversity of the preconsolidation consolidation patterns. The proposed model was used successfully to obtain the preconsolidation pressure profile observed in Battleford till at Birsay and the subglacial shear-softening phenomenon.