Journal articles: 'Preconsolidation stress'

1

Grozic, J. L. H., T. Lunne, and S. Pande. "An oedometer test study on the preconsolidation stress of glaciomarine clays." Canadian Geotechnical Journal 40, no. 5 (October 1, 2003): 857–72. http://dx.doi.org/10.1139/t03-043.

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Stress history is usually determined by interpreting the results of oedometer tests to obtain the preconsolidation stress using traditional methods such as those proposed by Casagrande and Janbu. Both these methods are based on the assumption that the soil experiences a change in stiffness, from a stiff response to a soft response, close to the preconsolidation stress. Disturbed soils, however, especially overconsolidated clays of low plasticity, exhibit a soft response at low stresses, thereby making the interpretation of oedometer tests using traditional methods extremely difficult. Using data mainly from the Haltenbanken area, offshore Norway, a study was undertaken to investigate the various methods and testing procedures available to determining stress history. Oedometer verification tests were also performed on reconstituted specimens to compare interpreted values with the actual applied preconsolidation stress. This paper describes the results of the study by illustrating the variation in the interpretation methods and testing procedures used to determine preconsolidation stress.Key words: preconsolidation stress, yield stress, overconsolidated, low plastic clays, oedometer test, stress history.

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Peri, Elena, Lars Bo Ibsen, and Benjaminn Nordahl Nielsen. "How to interpret consolidation and creep in Yoldia clay." E3S Web of Conferences 92 (2019): 05005. http://dx.doi.org/10.1051/e3sconf/20199205005.

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The aim of this paper is to define a guideline for an objective interpretation of oedometer tests on Yoldia clay. The approach followed consists in a first analysis where the separation of strains is applied to the consolidation curves. During this phase, primary consolidation strains are filtered from creep by using Brinch-Hansen, Taylor and ANACONDA method. The second phase of the interpretation aims to determine the preconsolidation stress according to three different theories (Akai, Janbu and Casagrande - Terzaghi). The preconsolidation stress values, as well as the consolidation curves, are slightly influenced by the separation of strains method applied, while using different preconsolidation stress theories deeply affects the final results.

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Shao, Yan, Chang Yong Li, and Yuan Wei. "Determining Preconsolidation Pressure of the Lakeside New District Soft Clay of Hefei Based on Casagrande Method by Matlab." Applied Mechanics and Materials 291-294 (February 2013): 1113–16. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.1113.

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The preconsolidation pressure is an important index to determine the stress history of soil and also a major calculation parameter for the analysis of soil stratum’s deformation in the different stress history. Casagrade method is worldwide applied to determine the preconsolidation pressure. On the basis of research on consolidation test about the lakeside new district soft clay of Hefei by high pressure consolidation apparatus, and conformed to Casagrande method, the paper adopts quartic polynomial and least square method to fit the compression curve, and the preconsolidation pressure of the lakeside new distract soft clay of Hefei is determined by matlab software. The result provides reference for the calculation of foundation settlement considering stress history.

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Xu, Yali, Panpan Guo, Chengwei Zhu, Gang Lei, and Kang Cheng. "Experimental Investigation into Compressive Behaviour and Preconsolidation Pressure of Structured Loess at Different Moisture Contents." Geofluids 2021 (March 20, 2021): 1–9. http://dx.doi.org/10.1155/2021/5585392.

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This paper investigates the influence of the structured property of loess on its compressive behaviour and proposes a new method for determining the preconsolidation pressure of structured loess soil. A series of oedometer tests were carried out on undisturbed and remoulded loess samples prepared at various moisture contents. The effects of moisture content on the structured yield stress, the preconsolidation pressure, and the structural strength were also captured. It was found that the influence of the structured property of loess on the compression behaviour is divergent between undisturbed and remoulded loess samples. The discrepancy before and after structural yielding is more remarkable for the undisturbed soil. The Casagrande method realized through the MATLAB program can effectively eliminate human factors and accurately calculate the corresponding preconsolidation pressure for undisturbed soil. The effects of moisture content on the method for determining the preconsolidation pressure considering the structured property of loess were discussed. The determination method can accurately evaluate the loess consolidation state in loess regions. The influencing rules which the moisture content exerts on the structured yield stress, the preconsolidation pressure, and the structural strength all conform to exponential functions. The study is of great significance to correctly differentiating the foundation consolidation states and calculating the ground settlement in loess regions.

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Chen, B. SY, and P. W. Mayne. "Statistical relationships between piezocone measurements and stress history of clays." Canadian Geotechnical Journal 33, no. 3 (July 2, 1996): 488–98. http://dx.doi.org/10.1139/t96-070.

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A database containing piezocone soundings from 205 clay sites around the world has been compiled for the calibration of an analytical cone penetration model and the development of statistical correlations. Yield stresses from laboratory oedometer tests were used as reference values for determining the stress history of natural clay deposits. Both simple and multiple regression analyses were performed on these data to evaluate correlative trends. Several simplified empirical relationships were identified for use in practice with the most reliable in relating preconsolidation stress to net cone tip resistance. Key words: cone tip resistance, overconsolidation ratio (OCR), preconsolidation pressure, piezocone, statistical relationships, stress history.

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Yoon, Hyung-Koo, Changho Lee, Hyun-Ki Kim, and Jong-Sub Lee. "Evaluation of preconsolidation stress by shear wave velocity." Smart Structures and Systems 7, no. 4 (April 25, 2011): 275–87. http://dx.doi.org/10.12989/sss.2011.7.4.275.

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7

Boone, Storer J. "A critical reappraisal of “preconsolidation pressure” interpretations using the oedometer test." Canadian Geotechnical Journal 47, no. 3 (March 2010): 281–96. http://dx.doi.org/10.1139/t09-093.

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Over the past 70 years, a number of methods have been proposed for the interpretation of the characteristic vertical effective yield stress, or “preconsolidation pressure,” of compressible soils as defined using the standard oedometer test. The concept of the “preconsolidation pressure” has been extraordinarily useful in geotechnical engineering for analysing and predicting settlement behaviour and for normalizing other engineering parameters for comparative purposes. Defining this characteristic stress, however, is often problematic and relies heavily on graphical techniques that are subject to some uncertainty, particularly when using semi-log plots for this purpose. This paper illustrates fundamental difficulties with the interpretation of oedometer test and presents an alternative technique for defining unambiguous values of the vertical effective yield stress.

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8

Sauer, E. Karl, and E. A. Christiansen. "Preconsolidation pressures in intertill glaciolacustrine clay near Blaine Lake, Saskatchewan." Canadian Geotechnical Journal 25, no. 4 (November 1, 1988): 831–39. http://dx.doi.org/10.1139/t88-091.

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Soft, intertill, glaciolacustrine clays are of concern for stability of slopes and foundations. An intertill clay deposit between 32 and 54 m below the surface was continuously cored. Index properties were determined for 46 samples and 10 samples were tested on the oedometer. Stratigraphic evidence indicates that the glaciolacustrine clay (Blaine Lake Member), lying between the till of the Sutherland and Saskatoon groups, was glaciated three times. However, preconsolidation pressures of this intertill clay show the degree of consolidation is less than 20% based on a total stress from an estimated ice thickness extrapolated from the Cypress Hills. This low preconsolidation pressure suggests there was insufficient time for dissipation of excess pore-water pressure created by thickening of the advancing glacier. Key words: preconsolidation pressure, excess pore-water pressure, glaciers, intertill clay.

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Tavares, Uilka Elisa, Mário Monteiro Rolim, Veronildo Souza de Oliveira, Elvira Maria Regis Pedrosa, Glécio Machado Siqueira, and Adriana Guedes Magalhães. "Spatial Dependence of Physical Attributes and Mechanical Properties of Ultisol in a Sugarcane Field." Scientific World Journal 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/531231.

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This study investigates the effect of conventional tillage and application of the monoculture of sugar cane on soil health. Variables like density, moisture, texture, consistency limits, and preconsolidation stress were taken as indicators of soil quality. The measurements were made at a 120 × 120 m field cropped with sugar cane under conventional tillage. The objective of this work was to characterize the soil and to study the spatial dependence of the physical and mechanical attributes. Then, undisturbed soil samples were collected to measure bulk density, moisture content and preconsolidation stress and disturbed soil samples for classification of soil texture, and consistency limits. The soil texture indicated that soil can be characterized as sandy clay soil and a sandy clay loam soil, and the consistency limits indicated that the soil presents an inorganic low plasticity clay. The preconsolidation tests tillage in soil moisture content around 19% should be avoided or should be chosen a management of soil with lighter vehicles in this moisture content, to avoid risk of compaction. Using geostatistical techniques mapping was possible to identify areas of greatest conservation soil and greater disturbance of the ground.

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10

Yin, Jian-Hua, and James Graham. "Equivalent times and one-dimensional elastic viscoplastic modelling of time-dependent stress–strain behaviour of clays." Canadian Geotechnical Journal 31, no. 1 (February 1, 1994): 42–52. http://dx.doi.org/10.1139/t94-005.

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This paper describes the recent concept of equivalent time and how it can be used in a revised version of an earlier elastic viscoplastic model for one-dimensional straining of clays. It clarifies how parameters in the model can be determined using data from single-stage or multistage creep tests. The model can describe one-dimensional stress or strain responses under general conditions that include multistage loading with creep straining, continuous loading, and unloading or reloading. It also describes modelling for constant rate of straining tests, constant rate of stressing tests, and relaxation tests. Preconsolidation pressures are shown to depend on unloading–reloading, aging, and other loading processes. Key words : clay, compression, creep, equivalent time, elastic viscoplastic, preconsolidation pressure.

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11

Åhnberg, Helen. "On yield stresses and the influence of curing stresses on stress paths and strength measured in triaxial testing of stabilized soils." Canadian Geotechnical Journal 44, no. 1 (January 1, 2007): 54–66. http://dx.doi.org/10.1139/t06-096.

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Studies on the behaviour of stabilized soils under different loading conditions are essential to identify which parameters are relevant in the design of deep mixing. An investigation has been performed on soils stabilized with different types of binders with the purpose of demonstrating the effects of quasi-preconsolidation pressures, i.e., yield stresses that are not primarily linked to previous consolidation pressures but to the cementation taking place, on the strength behaviour of stabilized soil. The effect of stresses applied during curing has also been studied. Drained triaxial compression tests and undrained triaxial compression and extension tests were performed on two stabilized clays. The binders used were cement, lime, slag, and fly ash in different combinations. Comparisons have also been made with results from previous tests on two organic soils stabilized with much the same types of binder. The results show that both the cementation processes involved and the stresses applied during curing affect the quasi-preconsolidation pressure. This pressure is strongly linked to the strength of the stabilized soil and has a considerable influence on its deformation behaviour. A model is proposed which describes the strength behaviour in the same effective stress plane that is commonly used for natural clays.Key words: stabilization, triaxial tests, strength, quasi-preconsolidation pressure, strain, binders.

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12

Sauer, E. Karl, Anne K. Egeland, and E. A. Christiansen. "Preconsolidation of tills and intertill clays by glacial loading in southern Saskatchewan, Canada." Canadian Journal of Earth Sciences 30, no. 3 (March 1, 1993): 420–33. http://dx.doi.org/10.1139/e93-031.

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Preconsolidation of pre-Battleford tills and intertill clays resulted in a narrow range of effective pressures (1800 ± 200 kPa) at 10 sites along a 1300 km transect across southern Saskatchewan. These data suggest an almost invariant loading system that is independent of total ice thickness, which ranged from 1150 to 2000 m. The preconsolidation process apparently took place in a temperate glacier environment. The loading system is characterized as a variable thickness of ice related to distance from the glacier terminus. A steady hydraulic "grade line" sustained a potentiometric surface within the subglacial sediments at an elevation consistently 69–76% of the total ice thickness. This mechanism maintains small fluctuations in effective stress.

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13

Kim, Jiseong, Eun-Sang Im, Sei-Yeon Kang, and Gichun Kang. "Study on the Design Settlement of Over-Consolidated Clay for a Complex Development." Journal of the Korean Society of Hazard Mitigation 20, no. 4 (August 31, 2020): 219–30. http://dx.doi.org/10.9798/kosham.2020.20.4.219.

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The purpose of this study was to understand the consolidation settlement characteristics of the west coast, where overconsolidation has occurred, and to identify the problems of existing consolidation design through field tests and the re-evaluation of design parameters. The settlement ratio (measurement settlement/design settlement) obtained using the existing design method was calculated to be 56.0%; however, the settlement ratio obtained through the re-evaluation of the preconsolidation stress and compression index suggested in this study was 95.6-96.6%. It was applicable to the west coast region, where the condition of overconsolidation developed. In addition, the consolidation test curve of the low-plasticity silt ground in the west coast region showed a rounded curve with no clear inflection point. It was difficult to determine the preconsolidation stress when applying the Casagrande method, and it tended to be underestimated. Analysis showed that it is preferable to apply the compression index obtained from the compaction curve as it is, rather than to apply Schmertmann's modified compression index.

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14

Becker, D. E., J. H. A. Crooks, K. Been, and M. G. Jefferies. "Work as a criterion for determining in situ and yield stresses in clays." Canadian Geotechnical Journal 24, no. 4 (November 1, 1987): 549–64. http://dx.doi.org/10.1139/t87-070.

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A method of interpreting conventional oedometer test data using work per unit volume as a criterion for determining both in situ effective and yield stresses in clay is presented. This technique was applied to the results of oedometer tests carried out on samples of natural clay deposits and on specimens consolidated anisotropically from a slurry to a known effective stress state. The work per unit volume – effective stress relationship, using arithmetic scales, can be approximated or fitted using linear relationships. The intersections of these fitted lines are demonstrated to provide accurate values for in situ current and yield (preconsolidation) stresses. The yield stress is defined as the intersection of the initial fitted line and the linear relationship observed at higher stresses. The current effective stress is indicated by the first significant divergence of the data from the initial fitted line. These relationships apply to both conventionally (horizontally) trimmed specimens and to vertically trimmed oedometer samples. It is hypothesized that the in situ effective and yield stresses (in both the vertical and horizontal directions) in a natural clay can be determined by the work per unit volume interpretation of oedometer tests carried out on horizontally and vertically trimmed specimens. Key words: in situ, stress, yield, oedometer, interpretation, clays, work, state, K0, preconsolidation pressure.

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15

McBride, R. A., and P. J. Joosse. "Overconsolidation in Agricultural Soils: II. Pedotransfer Functions for Estimating Preconsolidation Stress." Soil Science Society of America Journal 60, no. 2 (March 1996): 373–80. http://dx.doi.org/10.2136/sssaj1996.03615995006000020007x.

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16

Drnevich, VP, and PW Mayne. "Determining Preconsolidation Stress and Penetration Pore Pressures from DMT Contact Pressures." Geotechnical Testing Journal 10, no. 3 (1987): 146. http://dx.doi.org/10.1520/gtj10947j.

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17

Ma, Boning, Balasingam Muhunthan, and Xinyu Xie. "Mechanisms of quasi-preconsolidation stress development in clays: A rheological model." Soils and Foundations 54, no. 3 (June 2014): 439–50. http://dx.doi.org/10.1016/j.sandf.2014.04.012.

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Mun, W., C. J. R. Coccia, and J. S. McCartney. "Application of Hysteretic Trends in the Preconsolidation Stress of Unsaturated Soils." Geotechnical and Geological Engineering 36, no. 1 (July 27, 2017): 193–207. http://dx.doi.org/10.1007/s10706-017-0316-7.

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Ching, Jianye, and Tsai-Jung Wu. "Probabilistic transformation models for preconsolidation stress based on clay index properties." Engineering Geology 226 (August 2017): 33–43. http://dx.doi.org/10.1016/j.enggeo.2017.05.007.

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Wang, L. B., and J. D. Frost. "Dissipated strain energy method for determining preconsolidation pressure." Canadian Geotechnical Journal 41, no. 4 (August 1, 2004): 760–68. http://dx.doi.org/10.1139/t04-013.

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The dissipated strain energy method (DSEM), a new method for determining the preconsolidation pressure, is presented in this paper. Compared with the energy method, the DSEM uses dissipated strain energy and the slope of the unloadingreloading cycle (in the strain energy effective consolidation stress space) for the plot to minimize the sample disturbance effects and eliminate the effect of elastic deformation. Dissipated strain energy, in terms of micro mechanics, is directly related to the irreversible process of consolidation and can be supported by theories dealing with consolidation and compaction. The use of the unloadingreloading slope to simulate the elastic reloading for the recompression stage can minimize sample disturbance effects. Examples presented indicate that the proposed new method is less operator dependent than most of the existing methods.Key words: dissipated strain energy, preconsolidation pressure, consolidation, energy method, dissipated strain energy method.

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Carducci, Carla Eloize, Geraldo César de Oliveira, Walmes Marques Zeviani, Henrique Aparecido Laureano, Samara Martins Barbosa, Eduardo da Costa Severiano, and Nilton Curi. "Preconsolidation stress of gibbsitic and kaolinitic Oxisols under a multipractice conservationist coffee system." Semina: Ciências Agrárias 42, no. 3 (March 19, 2021): 1049–68. http://dx.doi.org/10.5433/1679-0359.2021v42n3p1049.

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Our goal was to analyze the impact of a multipractice soil conservationist system on coffee production in tropical soils (LATOSSOLO VERMELHO-AMARELO caulinítico/kaolinitic Haplustox and LATOSSOLO VERMELHO-gibbsítico/gibbsitic Acrustox) in Minas Gerais, Brazil. In the experimental area, the soil management involved a set of multiple conservationist practices during cultivation for more than 3.5 yrs. Soil samples were collected at 0-5, 10-15, and 20-25 cm depths at two positions: planting rows and between rows. The soil physical and mechanical properties were determined, with a focus mainly on the preconsolidation stress model (preconsolidation stress versus matric tension). For the purpose of analysis, a split-split plot experimental design was implemented. A linear mixed regression model (LMR) was fitted, and Wald’s test was performed (P < 0.05). An improvement of soil physical quality for both Oxisols was observed at the planting row position. The effects of multipractice soil management after 3.5 yrs of cultivation in association with increased gibbsite content could promote new soil structure organization, as revealed by LMR, resulting in more resilient soils (between rows) and increasing the resistance to external pressures on gibbsitic Acrustox. Overall, the findings herein are in concordance with global trends towards conservationist practices that may alleviate soil compaction in agricultural systems to maintain environmental sustainability.

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Kootahi, Karim, and Paul W. Mayne. "Index Test Method for Estimating the Effective Preconsolidation Stress in Clay Deposits." Journal of Geotechnical and Geoenvironmental Engineering 142, no. 10 (October 2016): 04016049. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0001519.

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23

Shorten, Graham G. "Quasi-overconsolidation and creep phenomena in shallow marine and estuarine organo-calcareous silts, Fiji." Canadian Geotechnical Journal 32, no. 1 (February 1, 1995): 89–105. http://dx.doi.org/10.1139/t95-007.

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Nearshore, estuarine deposits of Holocene organo-calcareous silt provide the most common setting for foundation failure in Fiji. Creep is implicated in long-term settlement. Although the geological history indicates the deposits should be normally consolidated throughout, there is increasing apparent overconsolidation towards the surface. This finding is contrary to what might be expected if delayed compression alone was operating. The phenomenon appears to be related instead to organic content and may be affected by strain rates during consolidation. Oedometer tests extending over 7 months indicate the rate of volume change due to creep follows the Singh–Mitchell relationship, but calculation of secondary compression from radiocarbon dates suggests that the very long-term rate is higher than might be expected. Creep appears to be stress dependent, at least below the preconsolidation pressure, in common with other marine sediments. Key words : silt, organic, preconsolidation pressure, overconsolidation ratio, secondary compression, creep, radiocarbon dating.

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Bobet, Antonio, Joonho Hwang, Cliff T. Johnston, and Marika Santagata. "One-dimensional consolidation behavior of cement-treated organic soil." Canadian Geotechnical Journal 48, no. 7 (July 2011): 1100–1115. http://dx.doi.org/10.1139/t11-020.

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This paper addresses the effects of cement treatment on the one-dimensional (1D) consolidation behavior of a highly organic soil (LOI ∼ 40%–60%, where LOI is the loss on ignition), based on 1D constant rate of strain and incremental loading tests. The effects of Portland cement addition are evaluated for dosages ranging from 8% to 100% by dry mass of soil, corresponding to values of the cement factor of 24 and 296 kg of cement per cubic metre of untreated soil, within the range used in deep mixing practice. Additional parameters investigated are the impact of curing surcharge and duration. The most evident effect of the treatment is the development of a cementation-induced preconsolidation stress: the greater the cement dosage, the greater the preconsolidation stress and the greater the vertical effective stress that can be sustained at any void ratio. The results also provide a consistent picture of the effects of cement treatment on stiffness, hydraulic conductivity, coefficient of consolidation, and creep. Comparison to data obtained for the untreated soil demonstrates the “stable” nature of the structure generated as a result of treatment. The consolidation results are complemented by pH measurements, extraction tests, elemental analyses, and Fourier transform infra-red (FTIR) spectroscopy analyses, which provide insight into the interaction between soil organic matter and cement.

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Malinowska, Edyta E., and Marek Bajda. "Analysis of yield stress ratio and overconsolidation ratio as parameter determination preconsolidation in eemian gyttja." Annals of Warsaw University of Life Sciences – SGGW. Land Reclamation 50, no. 2 (June 1, 2018): 109–18. http://dx.doi.org/10.2478/sggw-2018-0009.

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Abstract The preconsolidation stress is an important phenomenon that determines the value of stress history exerted in the past on the subsoil in the geotechnical engineering. Overconsolidation ratio (OCR) is one of the main criteria conditioning soil behaviour and its characteristics. Here thought, the yield stress ratio (YSR) is used to determine the value of preconsolidation stress resulting from mechanical overburden than can be changed by many post depositional processes like secondary and tertiary compressibility, cementation, aging, temperature change and others. The yield stress ratio (YSR) is defined as the relationship between vertical yield stress (σ’vy) to the effective vertical stress (σ’v0). The eemian gyttja was used as a foundation in the engineering construction. In practical geotechnical engineering, evaluation of stress history is usually based on the overconsolidation ratio (OCR). The yield stress ratio (YSR) was used in the laboratory as one of the basic parameters for the geotechnical design of the structure. To know the relation between geological background, history and mechanical behaviour in long-time process of the soil aims a knowledge that can help engineers who often have to predict soil behaviour based upon the soil geological history and a few geotechnical data. In order to evaluate the yield stress ratio of eemian gyttja it is necessary to restore this soft, organic soil as much as possible to the in situ conditions. The laboratory tests were used to determinate the vertical yield stress and then the yield stress ratio. The laboratory tests were made in the automatic oedometer and the in situ tests were carried out on the dilatometer test (DMT). The comparison between the determination the yield stress ratio of eemian gyttja from the laboratory and the overconsolidation ratio from in situ test has been done. The studies have shown that the values of the overconsolidation ratio determinate from the laboratory tests are a little higher than determinate from the in situ tests.

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Meriggi, R., P. Paronuzzi, and L. Simeoni. "Engineering geology characterization of lacustrine overconsolidated clays in an alpine area of Italy." Canadian Geotechnical Journal 37, no. 6 (December 1, 2000): 1241–51. http://dx.doi.org/10.1139/t00-059.

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This study reports the main geotechnical characteristics of the Steggio Clay unit, a lacustrine sequence located in a valley of the Veneto Piedmont area (northern Italy). Analyzing the variations of overconsolidation pressure with depth, and the compressibility characteristics of natural, swelled, and reconstituted samples, one can hypothesize about the existence and influence of swelling processes on the stress history of the deposit. The yield pressures, determined by oedometric tests for the various lithostratigraphic units, are compared with the preconsolidation pressures deduced from the geological analysis, and a reduction in apparent preconsolidation pressures is evident in the upper layers. Comparing the natural water content of each stratigraphic unit with that of the overconsolidated and normally consolidated states, it can be seen that the same layers are softened. These phenomena could have been caused by swelling induced by erosion of the overlying deposits, sliding of glacial masses, and unloading due to deglaciation. The results of undrained consolidated triaxial compression tests indicate that the variations between the parameters of mechanical resistance of some lithological units can be attributed to the different values of the void index, Ivo, corresponding to the lithostatic in situ stress.Key words: overconsolidated clays, stress history, swelling, intrinsic characteristics, post-depositional processes, glaciation.

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Agaiby, Shehab S., and Paul W. Mayne. "CPTU identification of regular, sensitive, and organic clays towards evaluating preconsolidation stress profiles." AIMS Geosciences 7, no. 4 (2021): 553–73. http://dx.doi.org/10.3934/geosci.2021032.

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<abstract> <p>Soil classification by piezocone penetration tests (CPTU) is mainly accomplished using empirical soil behavior charts (SBT). While commonly-used SBT methods work well to separate fine-grained soils from granular coarse-grained soils, in many instances, the groupings often fail to properly identify different categories of clays, specifically: (a) "regular" clays that are inorganic and insensitive, (b) sensitive and quick clays; and (c) organic soils. Herein, a simple means of screening and sorting these three clay types is shown using three analytical CPTU expressions for evaluating the preconsolidation stress profile from net cone resistance, excess porewater pressure, and effective cone resistance. A number of case studies are utilized to convey the methodology.</p> </abstract>

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Clementino, Renato V. "Discussion of "An oedometer test study on the preconsolidation stress of glaciomarine clays"." Canadian Geotechnical Journal 42, no. 3 (June 1, 2005): 972–74. http://dx.doi.org/10.1139/t05-010.

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Dawidowski, J. B., and A. J. Koolen. "Computerized determination of the preconsolidation stress in compaction testing of field core samples." Soil and Tillage Research 31, no. 2-3 (August 1994): 277–82. http://dx.doi.org/10.1016/0167-1987(94)90086-8.

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Mesri, G., and T. M. Hayat. "The coefficient of earth pressure at rest." Canadian Geotechnical Journal 30, no. 4 (August 1, 1993): 647–66. http://dx.doi.org/10.1139/t93-056.

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Laboratory experiments on undisturbed specimens of a large number of soft clay deposits, as well as previous measurements on clays and granular soils, were used to examine and explain the magnitude and behavior of the coefficient of earth pressure at rest, K0: (i) after sedimentation – primary consolidation, (ii) during secondary-compression aging, (iii) after active or passive preshearing away from the laterally constrained condition, (iv) during a decrease in effective vertical stress, and (v) during an increase in effective vertical stress in the recompression or compression range, in terms of [Formula: see text], the slope of the effective horizontal [Formula: see text] versus effective vertical[Formula: see text] stress path. The behavior of K0 is explained using the concept of mobilized angle of friction in laterally constrained deformation condition. The Jaky equation provides, in terms of the angle of internal friction, a good estimate of K0 of sedimented, normally consolidated young clays and granular soils, as well as of [Formula: see text] of presheared clays and sands, and of densified granular soils that are subjected to laterally constrained compression from [Formula: see text]. Empirical equations provide reasonable estimates of K0 for clays and granular soils after secondary-compression aging, after preconsolidation by unloading, and for soft clay deposits that display a preconsolidation pressure [Formula: see text] greater than in situ effective vertical stress [Formula: see text]. Proposed empirical equations and methods successfully predict K0 of presheared clays. Key words: coefficient of earth pressure at rest, soft clays, granular soils, presheared soils, sampling and laboratory testing.

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Józsa, Vendel. "Estimation and Separation of Preconsolidation Stress Using Triaxial,- and Oedometer Test in Kiscelli Clay." Periodica Polytechnica Civil Engineering 60, no. 2 (2016): 297–304. http://dx.doi.org/10.3311/ppci.9068.

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Yang, Xiujuan, Yonggang Jia, Hongjun Liu, and Hongxian Shan. "Characteristics and causes of the preconsolidation stress of soils in the Yellow River Delta." Journal of Ocean University of China 8, no. 3 (July 25, 2009): 215–22. http://dx.doi.org/10.1007/s11802-009-0215-5.

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Moulin, G. "Caractérisation de l'état limite de l'argile de Pornic." Canadian Geotechnical Journal 26, no. 4 (November 1, 1989): 705–17. http://dx.doi.org/10.1139/t89-081.

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This paper describes a natural clay, the Pornic clay, in accordance with the yield state and critical state concepts. The author has carried out a series of axisymmetrical triaxial tests on a natural overconsolidated clay and has clearly shown the yield state curve of the material; the curve is defined as the intersection of the yield state and "overconsolidated state" surfaces. The stress-strain paths are plotted either in the original p′-q-ε-v diagram or in the normalized diagram where the stresses are defined with respect to the preconsolidation pressure [Formula: see text], thus allowing one to characterize the reciprocity of the stress and strain paths and to follow their evolution mainly near the yield state curve. Key words: clay, yield state, overconsolidated state, stress path, strain path.

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Caldo, M., and F. Massad. "Geotechnical Parameters for the Variegated Soils of São Paulo Formation by Means of In Situ Tests." Soils and Rocks 39, no. 2 (May 1, 2016): 189–200. http://dx.doi.org/10.28927/sr.392189.

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The purpose of this paper is to present geotechnical parameters of the variegated soils from the São Paulo Formation, aiming in particular to establish correlations between stress history parameters, earth pressure coefficients at rest, deformability modules and resistance obtained through piezocone and dilatometer tests. The performance of in situ tests has, as the major advantage over laboratory tests for obtaining soil parameters of the project site, minimization of sample disturbance effects. Using data from geotechnical investigation carried out during the basic design of the Green Line expansion for the Metrô – SP it was possible to obtain preconsolidation pressure (σ’p), over consolidation ratio (OCR), earth pressure coefficients at rest (K0), Young’s module (Ei), initial shear module (G0), constrained module (M) and undrained shear strength (su) for the variegated soils of the São Paulo Formation. These soils are characterized by interlayered levels of clays and sands, constituting a characteristic with different geotechnical parameters and perched water tables. These characteristics explain some of the knowledge gaps on these soils. Nevertheless, it was possible to validate the correlations between earth pressure coefficients at rest (K0), over consolidation ratio (OCR), Young’s module (Ei), undrained shear strength (su) and preconsolidation pressure (σ’p) through field tests and the results of laboratory testing conducted by other authors.

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D'Ignazio, Marco, Tom Lunne, Knut H. Andersen, Shaoli Yang, Bruno Di Buò, and Tim Länsivaara. "Estimation of preconsolidation stress of clays from piezocone by means of high-quality calibration data." AIMS Geosciences 5, no. 2 (2019): 104–16. http://dx.doi.org/10.3934/geosci.2019.2.104.

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Thanh Duong, Nguyen, and Duong Van Hao. "Consolidation Characteristics of Artificially Structured Kaolin-Bentonite Mixtures with Different Pore Fluids." Advances in Civil Engineering 2020 (September 15, 2020): 1–9. http://dx.doi.org/10.1155/2020/8856404.

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The consolidation characteristics of kaolin, bentonite, their mixtures, and natural clays have been widely evaluated. However, the effect of pore fluid on the consolidation characteristics of artificially structured kaolin-bentonite mixtures should be more investigated. In this study, the oedometer tests were carried out on mixtures of kaolin with 10%, 20%, and 30% bentonite reconstituted with distilled water and 1 M NaCl. The testing samples with an “artificial structure” were prepared using the preconsolidation procedure. The test results show that bentonite greatly affects the consolidation behavior of mixture samples, especially when the pore fluid is distilled water. In the case of distilled water, the addition of bentonite to kaolin clay significantly increased the compression index (Cc), swelling index (Cs), and coefficient of volume change (mv). In this case, the mv of mixture samples increased significantly at low effective axial stress (σ′a) levels (less than the preconsolidation pressure) and then decreased as the σ′a further increased. In the case of 1 M NaCl as the pore fluid, the Cc, Cs, and mv slightly changed with the increase of bentonite content. The research results also confirmed that the effect of saline water on the compression index was noticeable when the liquid limit of soil with distilled water was higher than 110%, and the compression index of soil with distilled water was higher than 1. Regarding the coefficient of consolidation (Cv), the Cv of kaolin sample increased as the σ′a increased, and this trend was independent of the pore fluid chemistry. By contrast, the Cv − σ′a trend of mixture samples depended not only on the pore fluids but also on the stress level.

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Berre, Toralv, Tom Lunne, Knut H. Andersen, Stein Strandvik, and Morten Sjursen. "Potential improvements of design parameters by taking block samples of soft marine Norwegian clays." Canadian Geotechnical Journal 44, no. 6 (June 1, 2007): 698–716. http://dx.doi.org/10.1139/t07-011.

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Undrained triaxial and direct simple shear tests on samples reconsolidated to the in situ effective stresses and oedometer tests have been carried out on standard piston tube and on high quality block samples from 12 deposits of soft Norwegian marine clays. Based on the results of a selected number of these tests, empirical procedures for estimating the effect of sample disturbance have been developed. These procedures can be used to show the potential increase that may be achieved in undrained shear strength and apparent preconsolidation stress by taking high quality block samples. Suggestions are also given regarding corrections for rate of loading and temperature effects; as well, examples are given regarding possible consequences for design if higher strengths are utilized.Key words: soft clays, sample disturbance, consolidation procedures, stress–strain–strength behaviour.

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Ching, Jianye, and Kok-Kwang Phoon. "Modeling parameters of structured clays as a multivariate normal distribution." Canadian Geotechnical Journal 49, no. 5 (May 2012): 522–45. http://dx.doi.org/10.1139/t2012-015.

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This study explores the possibility of modeling liquidity index, undrained shear strength, remolded undrained shear strength, preconsolidation stress, and vertical effective stress of structured clays (sensitive or quick clays) as a multivariate normal distribution. The literature is replete with correlation equations between two soil parameters. Consistent synthesis of more than two soil parameters through construction of a multivariate probability distribution function is rare, despite obvious practical usefulness of such an approach. This study compiles a large database of structured clays to construct the multivariate probability distribution among the aforementioned five soil parameters. This multivariate distribution is then used to simulate the correlations between soil parameters of interest and to derive useful equations for Bayesian inference. This constructed multivariate distribution and equations are further validated by another independent database of structured clays as well as by empirical equations proposed in the literature.

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Lo, K. Y., I. I. Inculet, and K. S. Ho. "Electroosmotic strengthening of soft sensitive clays." Canadian Geotechnical Journal 28, no. 1 (February 1, 1991): 62–73. http://dx.doi.org/10.1139/t91-007.

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A comprehensive experimental investigation on the electroosmotic strengthening of soft sensitive clay was performed to assess the effectiveness of the treatment and to study the mechanism of the process. A specially designed electroosmotic cell was developed to prevent gas accumulation near the electrodes, to allow better electrode-soil contact, and to improve the treatment efficiency. This apparatus also enables the monitoring of the generated negative pore-water pressure along the sample length, settlement, voltage distribution, and current variation during treatment. The investigation covered two different types of soil trimmed at different orientations: the vertically and horizontally trimmed overconsolidated Wallaceburg clay and the vertically trimmed slightly overconsolidated soft sensitive Gloucester (Leda) clay. Results of this study showed that the voltage distribution and induced negative pore pressure at equilibrium along the sample are linear with steady current flow across the sample, indicating that the electrode design in the electroosmosis test apparatus is efficient. The electroosmotic consolidation curve is similar to that of the conventional consolidation curve, and the preconsolidation pressure was increased by 51–88% with an applied voltage up to 6 V. The undrained shear strength increased to a maximum of 172%, and the moisture content decreased by 30%. The technique of electrode reversal is employed, and a relatively uniform strength increase between the electrodes is observed. Key words: electroosmosis, electroosmotic cell, soft sensitive clay, negative pore-water pressure, preconsolidation pressure, stress–strain behaviour.

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Liu, K., and S. L. Chen. "Analysis of cylindrical cavity expansion in anisotropic critical state soils under drained conditions." Canadian Geotechnical Journal 56, no. 5 (May 2019): 675–86. http://dx.doi.org/10.1139/cgj-2018-0025.

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This paper presents a semi-analytical solution for the drained cylindrical cavity expansion problem using the well-known anisotropic modified Cam clay model proposed by Dafalias in 1987. The prominent feature of this elastoplastic model, i.e., its capability to describe both the initial fabric anisotropy and stress-induced anisotropy of soils, makes the anisotropic elastoplastic solution derived herein for the cavity problem a more realistic one. Following the development by Chen and Abousleiman in 2013 of a novel solution scheme that establishes a link between the Eulerian and Lagrangian formulations of the condition of radial equilibrium, the plastic zone solution can eventually be obtained by solving a system of eight partial differential equations with the three stress components, three anisotropic hardening parameters, specific volume, and preconsolidation pressure being the basic unknowns. Parametric studies have been conducted to explore the influences of K0 consolidation anisotropy and overconsolidation ratio (OCR), and their pronounced impacts on the stress patterns outside the cavity as well as on the development of stress-induced anisotropy are clearly observed.

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Taukoor, Vashish, Cassandra J. Rutherford, and Scott M. Olson. "A semi-empirical relationship for the small-strain shear modulus of soft clays." E3S Web of Conferences 92 (2019): 04005. http://dx.doi.org/10.1051/e3sconf/20199204005.

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The small-strain shear modulus (Gmax) is a soil property that has many practical applications. The authors compiled a database of Gmax measurements for 40 normally consolidated to slightly overconsolidated low to high plasticity clays. Using these data, the authors propose a semi-empirical relationship between Gmax, effective stress (σ'v or σ'c), preconsolidation stress (σ'p) and in-situ void ratio (e0) for four ranges of plasticity index (Ip): Ip < 30%, 30% ≤ Ip < 50%, 50% ≤ Ip < 80% and 80% ≤ Ip < 120%. With results from bender element tests on a Gulf of Mexico clay subjected to multiple load-unload consolidation loops, the authors were able to validate the proposed relationships for 30% ≤ Ip < 50% and 50% ≤ Ip < 80%. The proposed relationship for 30% ≤ Ip < 50% and 50% ≤ Ip < 80% captures changes in laboratory Gmax resulting from variations in effective stress (σ'c), maximum past stress (σ'v,max), and void ratio. The proposed relationships are a simple and efficient tool that can provide independent insight on Gmax if the stress history of a clay is known, or on stress history if Gmax is known.

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Massarsch, K. Rainer, and Bengt H. Fellenius. "Vibratory compaction of coarse-grained soils." Canadian Geotechnical Journal 39, no. 3 (June 1, 2002): 695–709. http://dx.doi.org/10.1139/t02-006.

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The variation of the coefficient of earth pressure in normally consolidated and overconsolidated soil and the effect of soil compaction on the change of the horizontal effective stress are discussed based on cone penetration test (CPT) data. A method is outlined for estimating the increase in the effective earth pressure based on sleeve friction measurements. Soil compaction increases not only soil density, but also horizontal effective stress. Since the cone stress is influenced by the vertical and horizontal effective stress, particularly at shallow depths, the cone stress needs to be adjusted for effective mean stress. A relation is presented for determining the soil compressibility from the adjusted cone stress. A case history is presented where a 10 m thick sand fill was compacted using vibratory compaction. Cone penetration tests indicated a significant increase in cone stress and sleeve friction and a decrease in compressibility (increase in modulus number) due to compaction. The friction ratio was unchanged. It was concluded that the earth pressure about doubled corresponding to an increase in the overconsolidation ratio of at least 5. The results of settlement calculations based on the Janbu method demonstrate the importance of considering the preconsolidation effect in the analyses.Key words: sand, CPTU, vibratory compaction, earth pressure, overconsolidation, modulus number, settlement.

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Tulaczyk, Barclay Kamb, Hermann F., Slawek. "Estimates of effective stress beneath a modern West Antarctic ice stream from till preconsolidation and void ratio." Boreas 30, no. 2 (June 1, 2001): 101–14. http://dx.doi.org/10.1080/03009480120262.

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Tulaczyk, Slawek, Barclay Kamb, and Hermann F. Engelhardt. "Estimates of effective stress beneath a modern West Antarctic ice stream from till preconsolidation and void ratio." Boreas 30, no. 2 (June 1, 2001): 101–14. http://dx.doi.org/10.1080/030094801750203134.

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Poodt, M. P., A. J. Koolen, and J. P. van der Linden. "FEM analysis of subsoil reaction on heavy wheel loads with emphasis on soil preconsolidation stress and cohesion." Soil and Tillage Research 73, no. 1-2 (October 2003): 67–76. http://dx.doi.org/10.1016/s0167-1987(03)00100-4.

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Kootahi, Karim. "Discussion on: “Probabilistic transformation model for preconsolidation stress based on clay index properties” [Eng.Geo.226:33–43]." Engineering Geology 246 (November 2018): 412–16. http://dx.doi.org/10.1016/j.enggeo.2017.10.017.

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TULACZYK, SLAWEK, BARCLAY KAMB, and HERMANN F. ENGELHARDT. "Estimates of effective stress beneath a modern West Antarctic ice stream from till preconsolidation and void ratio." Boreas 30, no. 2 (June 28, 2008): 101–14. http://dx.doi.org/10.1111/j.1502-3885.2001.tb01216.x.

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48

Bąkowska, Anna, Dobak Dobak, Ireneusz Gawriuczenkow, Kamil Kiełbasiński, Tomasz Szczepański, Jerzy Trzciński, Emilia Wójcik, and Piotr Zawrzykraj. "Stress-strain behaviour analysis of Middle Polish glacial tills from Warsaw (Poland) based on the interpretation of advanced field and laboratory tests." Acta Geologica Polonica 66, no. 3 (September 1, 2016): 562–86. http://dx.doi.org/10.1515/agp-2016-0026.

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Abstract The selected parameters of the Wartanian and Odranian tills, with relation to their spatial occurrence, grain size distribution, mineralogical composition, matric suction and other physical characteristics, are presented. The assessment of the lithogenesis and stress history on the microstructure is attempted. The comparison of the compression and permeability characteristics from field and laboratory tests has been performed. Laboratory consolidation tests carried out with up to 20MPa vertical stress, revealed two yield stress values, one in the range of a couple hundreds kPa, the other in the range of a couple thousands kPa. Based on those results, the reliability of the soil preconsolidation assessment, with the use of the two different methods is discussed. The aspect of the triaxial strength reduction under the dynamic loading of diverse frequency and amplitude is raised. The research results depict a variety of possible geological-engineering characteristics, under the divergent constraints scenarios, of compression or strength weakening origin. The effects of the specialized research program will widen the possibilities of physio-mechanical and structural characterization of soils for geological-engineering purposes.

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Uchaipichat, Anuchit. "Effect of Curing Pressure on Compression and Consolidation Behaviors of Cement Admixed Clay." Key Engineering Materials 744 (July 2017): 71–76. http://dx.doi.org/10.4028/www.scientific.net/kem.744.71.

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The cemented soils are typically produced and cured under confining pressure of soil. The cemented soil properties are, however, obtained from laboratory tests on the cement admixed clay samples cured under atmospheric pressure. Thus, the parameters of cemented soil obtained from laboratory tests are not representative of the actual values in the field. In this research, a series of consolidation tests using oedometer apparatus on cement admixed clay samples with different curing pressure conditions was carried out. The samples was cured under pressure values of 0 kPa (atmospheric pressure) and 50 kPa. The test samples with values of cement content of 0, 1 and 2 percent were cured for 28 days before testing. The compression curves of cement admixed kaolin showed the elasto-plastic deformation in all cases of the tests. It was found that the range of void ratio of the samples with curing pressure of 0 kPa (atmospheric pressure) was higher than that of the samples with curing pressure of 50 kPa. With increasing curing pressure and cement content, the value of recompression index decreased while the value of compression index was approximately constant. It was also observed that the preconsolidation pressure increased with increasing cement content for both cases of curing pressure. It should be noted that the values of preconsolidation pressure increased with increasing curing pressure. Moreover, the values of coefficient of consolidation decreased with increasing effective vertical stress in all cases. It was also found that the values of coefficient of consolidation increased with increasing curing pressure and cement content.

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Cundi, M. "Numerical Analysis of Test Embankment on Soft Ground Using Multi-Laminate Type Model with Destructuration / Analiza Numeryczna Nasypu Drogowego Posadowionego Na Gruncie Słabonosnym Z Zastosowaniem Modelu Wielopłaszczyznowego Z Destrukturyzacja." Archives of Civil Engineering 57, no. 1 (March 1, 2011): 27–44. http://dx.doi.org/10.2478/v.10169-011-0004-6.

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Abstract A multi-laminate constitutive model for soft soils incorporating structural anisotropy is presented. Stress induced anisotropy of strength, which is present in multi-laminate type constitutive models, is augmented by directionally distributed overconsolidation. The model is presented in the elastic-plastic version in order to simulate strength anisotropy of soft clayey soils and destructuration effects. Performance of the model is shown for some element tests and for the numerical simulation of a trial road embankment constructed on soft clays at Haarajoki, Finland. The numerical calculations are completed with the commercial finite element code capable to perform coupled static/consolidation analysis of soils. Problems related to the initiation of in situ stress state, conditions of preconsolidation, as well as difficulties linked to estimation of the model parameters are discussed. Despite simple assumptions concerning field conditions and non-viscous formulation of the constitutive model, the obtained final results are of a sufficient accuracy for geotechnical practice.

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Journal articles on the topic 'Preconsolidation stress'

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