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Prior research has primarily focused on Atterberg limits, void ratios, and/or water content, often disregarding the impact of coarse material percentage in the soil, which significantly affects compressibility behavior. This paper examines the effects of sand content, initial degree of saturation, and initial dry unit weight on the compressibility behavior of expansive soils. Ninty-six oedometer tests were performed in order to accurately predict the compressibility behavior of expansive soils. The previous studies have attempted to correlate compressibility with different index properties separately, but no single study has taken into consideration all properties influencing compressibility behavior, especially for expansive soils. The findings show that compressibility is greatly influenced by the sand content, initial degree of saturation, and initial dry unit weight. Increasing the initial dry unit weight specifically lowers the compression index and permeability while raising the recompression index for the same percentage of added sand. Moreover, since swelling reduces with increasing initial saturation, raising the saturation degree also lowers the permeability, recompression index, and compression index. The results indicate that a sand content of more than 30 % is recommended for achieving desired properties in expansive clayey soil. This is a result of sand taking the dominant role in the soil mixture, which lowers soil suction and improves soil properties by reducing swelling, permeability, and compressibility. Symbolic regression equations were created to predict the compression and recompression indices, outperforming previous models in accurately predicting the compressibility behavior of expansive soils, considering the percentage of sand. The validation of these equations demonstrates their predictive capabilities.

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We developed a coupled hydro-mechanical (HM) model based on a semi-logarithmic swelling law to reproduce the outcomes of swelling tests of a clay-sulfate rock specimen collected from the Freudenstein tunnel, which was constructed in Triassic Grabfeld Formation (formerly Gipskeuper = "Gypsum Keuper") in Southwest Germany in the period of 1987–1991. The swelling tests were conducted using an oedometer apparatus under constrained (no strain) or constant load conditions. We used the strain–time data obtained from the laboratory testing to calibrate the HM model. We then ran a sensitivity analysis to reveal the importance of influential parameters, namely the maximum swelling pressure σ max sw , swelling parameter k , and diffusion coefficient D on the long-term swelling behaviour of clay-sulfate rocks under the oedometer conditions. The HM model is capable of predicting long-term swelling deformations, i.e., model results were found to agree reasonably well with the experimental data. The results also show that using only 12 months experimental strain–time data to calibrate the HM model leads to an underestimation of swelling strains at the equilibrium condition. The findings show that at least 24 months experimental data is required for the model calibration. Highlights: We developed a coupled hydro-mechanical model to simulate swelling tests of clay-sulfate rock specimens. The hydro-mechanical model describes the long-term swelling behaviour under oedometer conditions well. The findings show that at least 24 months strain-time experimental data is required to properly calibrating the HM model. [ABSTRACT FROM AUTHOR]

This study examines the influences of the cement to clayey-silt (c/cs) ratio on the strength, compressibility, and usability in embankments. Laboratory experiments were conducted to determine the influence of the c/cs ratio on the shear strength, stress–strain behavior, and volumetric compressibility, which in turn determine whether cemented soil can be advantageous in controlling the failure of canal embankments. Canal embankment breaches occur for a variety of reasons, the most common being the loss of embankment strength. Our results indicate that the strength parameters, namely cohesion (c) and friction angle (Φ), increased by up to 30% when the c/cs ratio was 0.15/0.85. When the c/cs ratio was 0.1/0.9, there was more compressibility than when the ratio was 0.05/0.95. For vertical strains, a c/cs ratio of 0.1/0.9 showed 13% more strains than that of natural soil. The cs/c ratio is what leads to the strain hardening along the axial strains. The preliminary results suggest that using cemented soils with proper compaction, canal embankments can be strengthened to avoid failures. [ABSTRACT FROM AUTHOR]

Soft sedimentary rocks, especially mudstones, disintegrated or crumbled when subjected to cyclic drying and wetting, known as slaking, which was the cause of severe slope failures and ground settlement. Drying/wetting and temperature variation are the influential factors of the slaking. In this study, a conventional oedometer was modified to make a drying/wetting cycle with temperature variation to examine the effects of slaking for four materials with different slaking ratios. Further, one of the four materials (Hamamatsu mudstone), showing higher vertical strains along the drying/wetting cycle, was experimented with under three loading conditions (100 kPa, 200kPa & 500 kPa) and drying/wetting cycles, in which the particle breakage was also measured along the drying/wetting cycles. In addition, a needle penetration test was conducted along the drying/wetting cycles. In the continuous drying/wetting cycles, the occurrence of particle breakage was higher in lower-stress conditions, where the void ratio became a governing factor for the breakage over vertical stress. The needle penetration resistance is dependent on two factors which are density and particle size, and there was a trade-off between them along the drying/wetting cycles. After a couple of drying/wetting cycles, the particle crushing resulted in a noticeable reduction in penetration resistance in lower stress conditions.

This study investigated the compressibility of clay deposits in Toronto, Canada, through an inverse analysis. A series of oedometer test results from a local transit project were collected and used to calibrate the stiffness parameters according to the Hardening Soil (HS) model. The inverse analysis was conducted by coupling UCODE, a universal inverse modeling tool, and PLAXIS to fit the simulated stress–strain curves to the test results. First, a sensitivity analysis was performed to identify the most critical model parameters and simplify the problem by removing less sensitive parameters. Second, the selected HS model parameters were calibrated for a total of 71 oedometer tests conducted on different soil types. Third, a statistical analysis was performed on the calibrated HS model parameters according to soil type. In the end, a series of prediction formulas were derived to estimate the compressibility parameters from soil index properties and standard penetration test measurements, which can be used to better simulate the deformation behavior of local soils in practice.

Centrifuge modelling has been widely used to study the geotechnical behaviour of structures built on soft soils and to calibrate and validate numerical models. In the finite element method (FEM), the mechanical behaviour of the soils is established through a constitutive model, and the correct selection and calibration of its parameters are essential to obtain accurate results. In this article, the mechanical parameters of an artificial reconstituted soft soil proposed for centrifuge modelling are obtained, calibrated and validated for the hardening soil (HS) model based on laboratory test results. The reconstituted soil consists of 50% kaolin clay and 50% diatomaceous soil from Bogotá, Colombia. First, geotechnical characterization of the reconstituted soil is presented. The model preparation technique to generate the effective stress profile for the centrifuge model is described. The strength and compressibility parameters are obtained from CU triaxial tests and a one-dimensional consolidation test, respectively. Finally, the obtained parameters are calibrated via explicit numerical modelling using the FEM and the SoilTest module of Plaxis software. It is concluded that the reconstituted artificial soft soil proposed herein mimics most of the natural lacustrine deposits of soft soils worldwide and can be modelled using the HS model for FEM analyses. [ABSTRACT FROM AUTHOR]

Volcanic soil is often used as fill material in road embankment construction in Java island-Indonesia. An understanding of the engineering properties of compacted volcanic soils is needed, especially during the preliminary design phase and during the detailed design phase of the road embankment. Carrying out a field compaction trial test will significantly assist in the design of the compaction process of the road embankment construction. Selecting the correct number of passes from the compactor and the engineering properties of compacted volcanic soils can be obtained from field compaction trial tests. Constrained modulus is one of the engineering properties that can indicate the stiffness of the fill material used in a road embankment. This study aims to determine the constrained modulus of compacted volcanic soil and compare it to the number of passes of a compactor from the field compaction trial test. The volcanic soil used in this study is classified as pumiceous tuff, which is derived from older volcanic rocks. The highest value of the oedometer modulus of compacted volcanic soils is 10.38 MPa which comes from eight (8) times passes of smooth drum roller conducted on field compaction trial test. [ABSTRACT FROM AUTHOR]

An updated DEM simulation scheme for clay is implemented by incorporating convex polygon shaped platelets and robust algorithm for physico-chemical–mechanical interaction between clay platelets. Clays with two typical microscopic structures, i.e., card-house structure and book-house structure, are simulated in oedometer test and triaxial compression test. Virtual Mercury Intrusion Porosimetry (MIP) and pore segmentation algorithms are utilized to extract pore statistics from the numerical samples. The simulation results and experimental results from the literature are thoroughly compared at both macroscopic and microscopic scales. It is found that the implemented DEM simulation scheme can satisfactorily reproduce the experimentally observed macroscopic behavior of clay. Especially, in triaxial compression tests, the critical state behavior, stress-dilatancy relationship and over-consolidation effects are generally consistent with existing experimental results. General consistency in pore size, orientation and shape distributions in DEM simulations and experiments can be observed. Clay platelets tend to rotate to align their normal directions along the major principal stress direction, while pores tend to align their long-axis directions in the confinement direction, leading to dynamically evolving fabric anisotropy. In the book-house structure clay, clay domains experience multiple deformation modes, including uniaxial compaction, shear distortion, spatial spin, and their combinations. [ABSTRACT FROM AUTHOR]

The scope of this investigation is to compare the coefficient of consolidation (cv) values defined by the Taylor’s Square Root of Time Fitting Method, which is obtained from the conventional oedometer tests, with the cv values calculated by Terzaghi’s One Dimensional (1D) Consolidation Theory, which is obtained from the permeability-consolidation tests performed with a combined apparatus specifically designed for this study. In addition, an empirical relation is developed to determine cv using the coefficient of permeability (k) and index properties of the soils. The cv values obtained from the permeability-consolidation tests using the combined apparatus were found to be larger than the cv values defined by the Taylor’s method, which is one of the oedometer tests. The findings showed that the difference was more prominent in the soil samples with a high plasticity. It was also found that the cv calculated by the Taylor’s method exhibited a distribution in a wide range with the increased load depending on the degree of plasticity of the soil. The cv obtained from the combined apparatus it decreased with low load values and increased with higher load levels. The cv obtained by the proposed empirical relationship showed good agreement with the cv defined by permeability-consolidation relationships.

Land subsidence is an important environmental problem in the North China Plain (NCP). A typical subsidence area mainly located on adjoining areas of Beijing and Hebei provinces was selected to study the consolidation characteristics of deep clayey soil. Clay samples were collected from 14 boreholes at different depths, and the compression and consolidation behavior of the soil was analyzed by high-pressure oedometer tests. Results show that the deformation amount and deformation stabilization time in the primary consolidation stage increase with the load but decrease with the sampling depth. The nonlinear compression model of e-log(p) does not fit well for deep normally-consolidated clayey soil, the log(e+ec)–logp model fit the shallow clayey soil better than the deep clayey soil, and the hyperbolic model fits almost all soil samples well. Based on statistical theory, the soil consolidation equation CE_NCP was established for calculating the relationship between the degree of consolidation and the time factor in subsidence areas. The equations were fitted with the data obtained from high-pressure consolidation tests to obtain three parameters a, b and c, which are applied to the consolidation calculations for soil samples at depths of 0–100 m, 100–200 m, 200–300 m and 300–400 m, respectively. The applicability of CE_NCP equation was evaluated by comparing it to the analytical solution of Terzaghi’s consolidation equation, results showing that CE_NCP equation is more suitable for the calculation of the consolidation in the study area than the Terzaghi’s analytical solution. Eventually, the CE_NCP equation was successfully used to estimate the degree of consolidation in a subsidence area of Lang Fang City in the NCP.

In this research work, one-dimensional (1D) oedometer load-unload tests are performed on unreinforced monofilament PVA (poly vinyl alcohol) fibre alone, cement only, and Toyoura sand specimens with fibres and cement to evaluate compression behaviour and obtain critical state line slope (), elastic loading and unloading line slope () and K0 normal compression line (N or K0 NCL) parameters. The K0 NCL of monofilament PVA fibre only, cement only, and Toyoura sand specimens containing monofilament PVA fibres plus cement is shown to differ from that of clean cohesionless samples. The addition of additives (fibre and/or cement) to cohesionless soil (Toyoura sand) has no effect on the K0 NCL slope, but increasing the amount of these additives pushes it beyond the K0 NCL of unreinforced sand. It demonstrates that cementitious connections and lock-in influence caused by short discrete/monofilament PVA fibres are strong enough in contrast to clean sand particles. The migration of the K0 NCL to the right has been recorded in the prior literature for monofilament PVA fibre only, cement only, and Toyoura sand specimens containing fibres and cement. The findings of this investigation are consistent with previous studies. [ABSTRACT FROM AUTHOR]

The impact of temperature and unsaturation on the creep behaviour of bentonite is an important topic for environmental geotechnics as in the case of waste storage and energy geostructures. This paper presents an experimental study on the one-dimensional creep of Maghnia bentonite (MB), using two high-pressure oedometer cells, allowing to impose temperature and suction conditions for an unsaturated medium. The characteristics of these two cells and the protocol developed in the framework of this experimental study are briefly presented. The findings highlight a new perspective on the hypothesis (A) which distinguishes between primary and secondary consolidation, and hypothesis (B), which is governed by structural viscosity. The results indicated that the creep behaviour followed the principle of hypothesis (A) under temperature effect, while it followed hypothesis (B) principle under the suction effect. The void ratio variability under secondary compression depends not only on the vertical stress, but also on the temperature and the first load level. Moreover, as soil suction descreases, the normalized void ratio become higher. The creep coefficient (Cαe) increased as temperature and vertical stress increased, while they decreased as the suction increased. [ABSTRACT FROM AUTHOR]

Abstract This paper focuses on the physicochemical changes that happen in cold mix asphalts during curing, and more specifically, while and after transitioning to different simulated seasons. Several tests were carried out in order to better grasp the influence of the weather (temperature and humidity) on the curing of such materials. The mechanical behaviour of the mix was assessed using oedometer tests. The physicochemical evolutions of extracted binders, such as oxidation and rheology, were evaluated. The results show stiffening of the mix and ageing of the binder linked to a higher temperature and a lower humidity. A low temperature and high moisture seem to slow down these evolutions. However the binder behaviour does not explain the whole mix behaviour as the kinetics between them are not always similar. Thus other mechanisms are yet to be found and taken into account to fully understand cold mix asphalts behaviour.

Loess covers more than 10% of continental lands all around the world. The macrostructure of these soils collapses when water content increases, greatly decreasing soil volume. Two mechanisms are responsible for the collapse: the expansion of clay bridges and/or the dissolution of precipitated salts that join coarse particles forming an open microstructure. Double oedometer tests are widely used in geotechnical practice to estimate relative collapse or collapse potential. The main goal of this work is to evaluate the stress–strain behavior under zero-lateral displacement conditions of undisturbed loess samples tested at natural moisture content and inundated with water. Numerical models are developed by using the Comsol Multiphysics Software. Two elastoplastic models were implemented: the modified Cam Clay model (MCC) and the extended Barcelona Basic model (EBB). Numerical models were calibrated with experimental data by using a least square technique. The results show the capacity and limitations of the MCC and EBB models to represent the mechanical behavior of collapsible loess before and after water flooding. This work demonstrates the potential of the EBB model to predict the mechanical behavior of loess, using a limited amount of data obtained from uncontrolled-suction oedometer tests. [ABSTRACT FROM AUTHOR]

Pore water pressure and effective stress development within cemented paste backfill (as one of the most popular local and regional underground mining supports) depends on rates of change of hydraulic conductivity and stiffness, which in turn are functions of cement hydration and backfilling rates. Previous laboratory studies attempted to investigate these interactions; however, the loading conditions they used are not representative of effective stress paths recorded in field monitoring programs during mine backfilling. In this work, typical effective stress paths occurring in mining operations are characterized in terms of an initial period of zero effective stress ranging from 3 to 48 h, and subsequently developed effective stress rates ranging from 5 to 20 kPa/hr. Servo-controlled consolidation machines apply the prescribed stress paths with adjustments every minute, thereby achieving an essentially continuous stress rate. The stress paths are applied to samples with 3.0%, 5.3% and 7.5% binder contents, and electrical conductivity monitoring on control samples is used to correlate the stress levels to stages of cement hydration. The secant constrained modulus is used to quantify the degree to which different stress paths may damage developing hydration products, resulting in softer backfill. For instance, the secant constrained modulus at 2.5% axial strain of samples with 3.0% binder content and loaded at the fastest rate with 48 h delay time was almost half of the ones loaded at the slowest rate and 12 h delay time after 65 h of curing indicating cement hydration products damage due to faster loading rate. The test samples' void ratios are compared with similar CPB's in-situ void ratios and stress paths. Void ratios obtained from these experiments were very close to the average in-situ values under similar loading conditions. The test results help interpret the as-placed CPB's bulk properties and will lead to better sample preparation procedures for other tests intended to determine CPB's engineering properties. [ABSTRACT FROM AUTHOR]

Fifteen constant rate of strain consolidation tests were performed on Wenzhou clay specimens under various strain rates and initial water contents using an advanced oedometer to investigate the remolded yield stress during compression. The results for different initial water contents indicated that the remolded clay compression curves could be expressed by a unique trend line using the void index. The porosity parameter was proposed based on existing strain rate parameters to qualitatively describe the relationship between porosity and remolded yield stress. It was observed that the greater the strain rate, the smaller the strain under the same vertical effective stress. [ABSTRACT FROM AUTHOR]

Collapsible soils are metastable soils characterized by voids inside their building, at grain sizes ranging from silt to fine sand. On wetting, they collapse producing distortions that might cause failure of structures. In this study, addition to the natural collapsible soil, an artificial collapsible soil was prepared with the exact properties of the natural one taken from the deposit to avoid the remodel during transfer. Then, both the natural and artificial soil samples were stabilized with fly ash and cement kiln dust with several percentages. Kaolin particles were used to prepare the artificial samples with low density to represent the metastable soil structure. The fly ash and cement kiln dust were used in several percentages 5%, 10% and 15% to demonstrate the effect of using these stabilizing agents on Odometer test. The addition of fly ash (up to 15%) to the natural or artificial soil resulted in a decrease in the collapse potential (CP) from 15.4% to 4.4 % and from 13.8% to 2.6%, respectively. The obtained results showed that treatment of collapsing soils (natural and artificial) with CKD resulted in a reduction of collapse potential from 15.4% to 0.72% and from 13.8% to 0.95%, respectively. The results showed a significant improvement of the stabilized collapsible soil over the non-stabilized one whether treated by using fly ash or CKD. Additionally, CKD showed more effectiveness than fly ash in all the undergone tests.

Coral mud is widely distributed in the South China Sea. Studying deformation laws of coral mud is important to the infrastructure development in the South China Sea. In this article, a one-dimensional oedometer test of coral mud under near-natural conditions is performed. The exponential fitting model, Burgers model and ODGM model are used to analyse the time-strain relationship of coral mud under different vertical pressures. The self-fitting accuracy and prediction accuracy of the three models under different vertical pressures are compared. Then, the number of data points used in the model was reduced, and the associated change in accuracy and model stability of the three models were analysed. The study found that the ODGM model has high self-fitting, high prediction accuracy, and a high model stability when the number of data points is reduced, which describe the long-term nonlinear deformation of coral mud more accurately.

This article first introduces a new method of characterization of expansive clays after oedometer test results performed on intact saturated clay specimens. On the presumed expansive clays specimens, oedometer tests are preceded by the free swelling test from which the swelling pressure is measured. From current oedometer test results carried out on expansive and non-expansive clays, the ratio of compression index (Cc) by the swelling index (Cs) was determined. A threshold value of the ratio Cc/Cs was identified to distinguish between expansive clay specimens and non-expansive clay specimens. Second, a novel mitigation method of the swelling phenomena was validated by performing oedometer tests on expansive clay specimens preceding the measurement of swelling pressure. Oedometer tests performed on a 53% thickness clay specimen overlaid by a 47% thickness of sand showed a significant reduction of the swelling pressure compared to that measured on a full expansive clay specimen. The mitigation solution reduced the swelling effect by placing a compacted granular layer as an interface between the expansive clay and the foundation. This solution has been adopted and approved in forthcoming a lightweight building construction at the Faculty of Sciences of Tunis City.

An environmental improvement method using albumen, which is convenient, cost-effective, rapid and environmentally friendly, has been used for soil stabilization. In this research, the improvement influence of albumen added in various percentages to loess soil was investigated. Atterberg limits and compaction test were performed to study the influence of albumen on the soil. In addition, oedometer test and compression and extension triaxial tests were conducted to analyze geotechnical characteristics of the soil after treatment. From an engineering perspective, compression and extension strength of soils stabilized with 2% albumen at confining pressure of 200 kPa were 1.47 and 0.122 times larger than that of untreated soils, respectively. In all treated specimens, secant deformation modulus versus albumen content displayed higher values than untreated specimens, it means that deformability of treated specimens is less than untreated soil. In undrained compression test maximum pore water pressure decreased in treating specimens. Also, pore water pressure in extension triaxial test changed from negative to a positive value when treating the specimen with 2% albumen at confining pressure of 200 kPa. Treated specimens are shown more stable structure in comparison with untreated specimens. The behavior of the specimens changed to be more dilative, especially, in treating specimens with 2% albumen. Furthermore, settlement of the treated specimens decreased compared with untreated specimens. Field emission scanning electron microscopy images presented less porous and denser soil structure on the surface of treated specimens. Albumen additive can be implemented as a soil stabilizer in geotechnical projects. [ABSTRACT FROM AUTHOR]

Prior research has primarily focused on Atterberg limits, void ratios, and/or water content, often disregarding the impact of coarse material percentage in the soil, which significantly affects compressibility behavior. This paper examines the effects of sand content, initial degree of saturation, and initial dry unit weight on the compressibility behavior of expansive soils. Ninty-six oedometer tests were performed in order to accurately predict the compressibility behavior of expansive soils. The previous studies have attempted to correlate compressibility with different index properties separately, but no single study has taken into consideration all properties influencing compressibility behavior, especially for expansive soils. The findings show that compressibility is greatly influenced by the sand content, initial degree of saturation, and initial dry unit weight. Increasing the initial dry unit weight specifically lowers the compression index and permeability while raising the recompression index for the same percentage of added sand. Moreover, since swelling reduces with increasing initial saturation, raising the saturation degree also lowers the permeability, recompression index, and compression index. The results indicate that a sand content of more than 30 % is recommended for achieving desired properties in expansive clayey soil. This is a result of sand taking the dominant role in the soil mixture, which lowers soil suction and improves soil properties by reducing swelling, permeability, and compressibility. Symbolic regression equations were created to predict the compression and recompression indices, outperforming previous models in accurately predicting the compressibility behavior of expansive soils, considering the percentage of sand. The validation of these equations demonstrates their predictive capabilities., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

The time-dependent behavior of sands is one of the main issues that can influence many projects. In this study nine sand models with different particles shape and sizes and different grain distribution have been used to investigate creep behavior. The samples were prepared at 60% relative density and the constant stresses of 45 kPa for 30 days and 26 to 416 kPa for seven days (with the double increase in stress increment) under dry conditions in the Oedometer apparatus (one-dimensional consolidation) were tested. The results showed that the rotation, slipping, and crushing of the sand grains over time under constant load was the cause of creep deformation in the dry samples. Sand samples exhibit 1.5 to 4.2% creep strains in 30 days, and 0.61 to 2.5% creep strains in seven days' time interval. Finally, two linear equations are presented to predict the deformation of sands over time. The results were in good agreement with previous studies. [ABSTRACT FROM AUTHOR]

The improvement of sand and clay using lime or cement to control solidification is common practice. Among the many constitutive models for solidification proposed for clay and sand, few can reproduce the combined behavior of cement-treated clay and cement-treated sand. Here, four typical experimental results for cement-treated soil have been chosen from the literature to consider the shear and consolidation behavior for clay and sand, especially for a low cement mixing ratio. The elasto-plastic constitutive model was used to simulate this behavior considering the soil skeleton structure. The simulation results obtained using the model agreed with the experimental test results both for the cement-treated clay and the cement-treated sand. In the case of the clays, the experimental results were reproduceable using material constants for elasto-plastic and evolution parameters and only required changes in the initial state values, regardless of whether the soil was treated or untreated. In the case of the sands, the structure decay index of the treated sand became smaller than that of the untreated sand. Moreover, the cement-treated loose sand did not exhibit softening behavior. This was attributed to the slow rate of decay of the highly structured cement-treated loose sand due to the solidification of the cement. The degree of structure and the overconsolidation ratio both increased with higher amounts of admixed cement. The model developed in this study was capable of describing the mechanical behavior of both cement-treated clay and cement-treated sand. [ABSTRACT FROM AUTHOR]

The scope of this investigation is to compare the coefficient of consolidation (cv) values defined by the Taylor's Square Root of Time Fitting Method, which is obtained from the conventional oedometer tests, with the cv values calculated by Terzaghi's One Dimensional (1D) Consolidation Theory, which is obtained from the permeability-consolidation tests performed with a combined apparatus specifically designed for this study. In addition, an empirical relation is developed to determine cv using the coefficient of permeability (k) and index properties of the soils. The cv values obtained from the permeability-consolidation tests using the combined apparatus were found to be larger than the cv values defined by the Taylor's method, which is one of the oedometer tests. The findings showed that the difference was more prominent in the soil samples with a high plasticity. It was also found that the cv calculated by the Taylor's method exhibited a distribution in a wide range with the increased load depending on the degree of plasticity of the soil. The cv obtained from the combined apparatus it decreased with low load values and increased with higher load levels. The cv obtained by the proposed empirical relationship showed good agreement with the cv defined by permeability-consolidation relationships. [ABSTRACT FROM AUTHOR]

This paper focuses on the physicochemical changes that happen in cold mix asphalts during curing, and more specifically, while and after transitioning to different simulated seasons. Several tests were carried out in order to better grasp the influence of the weather (temperature and humidity) on the curing of such materials. The mechanical behaviour of the mix was assessed using oedometer tests. The physicochemical evolutions of extracted binders, such as oxidation and rheology, were evaluated. The results show stiffening of the mix and ageing of the binder linked to a higher temperature and a lower humidity. A low temperature and high moisture seem to slow down these evolutions. However the binder behaviour does not explain the whole mix behaviour as the kinetics between them are not always similar. Thus other mechanisms are yet to be found and taken into account to fully understand cold mix asphalts behaviour. [ABSTRACT FROM AUTHOR]

The paper presents the results of a series of Cone Penetration Test CPTu performed near the city of Wroclaw (Poland). The tests were carried out in 13 testing points located in close distance to each other. To verify the results of the penetration tests, fine-grained soil samples from selected depths were taken for laboratory tests. The study focuses on the evaluation of soil type, unit weight, and undrained shear strength cu, and compression index Cc. The grain size distribution of the soil and its mechanical parameters on the basis of a uniaxial compression and an oedometer tests were estimated. A comparison of laboratory and CPTu for selected values is presented. Determination of soil type was carried out on the basis of ISBT and IC values and good agreement with the granulometric composition was found. For undrained shear strength, commonly used correlations based on Nk, Nkt and Nke were adopted. However, the values obtained from the CPT are significantly lower than the results from laboratory tests. Therefore, values of cone factors suitable for investigated soil type and reference test were proposed. In the case of the compression index, the coefficient values ßc and am obtained agreed with those available in the literature. The findings presented in the paper indicate that laboratory tests remain necessary to identify soil properties from CPTu. The presented results are also a contribution to the knowledge of local soil conditions in the Lower Silesia area (Poland). [ABSTRACT FROM AUTHOR]

Shales play important roles in various civil, energy and environmental engineering applications. Shales are categorized as poroelastic materials due to their tight and very stiff structure, and reliable poroelastic properties are required when dealing with shales. This paper presents simple procedures to determine the poroelastic properties of rocks using oedometer and triaxial consolidation tests. The procedures, which avoid the difficulty to perform determination of the unjacketed bulk modulus of the rock minerals, are demonstrated on a North Sea shale. The experimentally obtained Biot coefficient α and the drained bulk modulus K of the shale range from 0.95 to 0.99, and from 0.17 to 2.00 GPa, respectively. The Biot coefficient α and the drained bulk modulus K values determined from the oedometer and triaxial tests are compared and show good agreement and consistency between the two test procedures. The Skempton's coefficient B-value of the triaxial samples was also experimentally measured prior to the triaxial consolidation tests. The theoretically predicted B-value varies from 0.81 to 0.96 which is, on the average, only about 10% higher than the experimentally obtained B-value which range from 0.80 to 0.85. [ABSTRACT FROM AUTHOR]

Keywords: Rock swelling; Cyclic moisture change; Oedometer test; Water tunnel; Rock texture EN Rock swelling Cyclic moisture change Oedometer test Water tunnel Rock texture 463 476 14 02/09/21 20210101 NES 210101 Introduction Swelling of rocks is often forecasted by the content of swelling clay minerals or anhydrite; however, the intensity of the expansion and subsequent swelling pressure cannot be attributed only to these rock constituents (Ruedrich et al. [10]). It is interesting to note that the intact sample Flysch E shows much higher swelling pressure than the powder sample, suggesting that the structural features of this rock have a strong effect on the swelling behavior. The measured swelling pressures of the pulverized samples are higher than the swelling pressures of the intact rock samples. The location of the swelling minerals within the rock texture seem to play an important role and underlines the importance of performing swelling tests on intact rock and to analyze the structure of the rock to assess the swelling characteristics of rocks containing even low amounts of swelling minerals. [Extracted from the article]

This paper discusses the hydraulic conductivity (k) of peat and organic clay as measured by laboratory and in-situ tests. The k of various peat soils and organic clay soils in Hokkaido, Japan, was investigated by the following tests: in-situ hydraulic conductivity test using a borehole, electric cone penetration test, oedometer test, and laboratory hydraulic conductivity test. The k of peat and organic clay dramatically decreases during consolidation. The index of change in k, which indicates consolidation-related changes in k, increases linearly with the increase in the in-situ void ratio and the ignition loss. The k of peat measured by oedometer test was found to range from approximately 1/20 to 1/180 of that measured by in-situ hydraulic conductivity test, which is considered to provide the macroscopic k of peat ground. Since large plant remnants must be removed for the oedometer testing of peat, the laboratory k obtained from this test underestimates the macroscopic k of the peat layer. The ratio of laboratory k to in-situ k can be simply expressed as a function of the ignition loss. Based on the results of a dissipation test of pore water pressure that used the electric cone penetration test, an equation for estimating the in-situ k of peat ground is presented. Using the above-mentioned experimental correlations, a suitable procedure for determining the permeability parameters of peat ground in practical applications is proposed. [ABSTRACT FROM AUTHOR]

Observing the fragmentation of individual particles within granular assemblies is a subject of evident theoretical and practical importance. A new technique using dyed gypsum particles (DGPs) to match the broken particles to their parents was adopted in this study. An image-based method of acquiring the shape information of particles from two orthogonal views was proposed. The mass survival probability and shape characteristics of the children particles were analyzed after a series of one-dimensional compression tests on the DGPs. It was found that medium-sized particles in the polydisperse samples underwent more breakage than the other particles, and this might have been attributed to the combined effects of the particle crushing strength and the coordination number. The shape evolution of broken particles and surviving particles showed opposite trends. Because the particles after the test within a given size range consisted of both the broken and surviving particles, their overall shape characteristics did not show a consistent trend. Furthermore, individual particle crushing tests on the children particles suggested that the breakage-induced shape irregularity did not change the Weibull modulus, but had a substantial effect on the magnitude of the survival probability. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A series of laboratory tests were conducted using a tall oedometer apparatus and a model retaining wall to evaluate the lateral pressure of EPS-sand composites and the effect of cement paste on the behavior of the composites both in at-rest and passive conditions. EPS beads were added to sand at different percentages by weight and at a variety of cement content range. The test results revealed that the factor K0 increases by addition of the EPS beads to the composites whereas the factor KP decreases. In addition, cement treatment results in a decrease in K0 and increase in KP factors. The justification behind such behavior is that the cement as a binder material, reduces the internal friction among soil particles which leads to such trends in increase and decrease of lateral earth pressure factors. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)