Coefficient Of Consolidation Research Articles

Pore Pressure Response and Dissipation of Piezocone Test in Shallow Silty Soil of Yellow River Delta

Soil dilatancy and partial drainage have great influence on the consolidation coefficient assessment of silty soils with clay content of less than 30% in the Yellow River Delta using the CPTu. This paper discussed the effect of soil dilatancy and partial drainage on the pore pressure response and dissipation of piezocone test in shallow silty soil of the Yellow River Delta through variable penetration rate tests in a pressure chamber and a series of supplementary soil element tests. The results show that the pore pressure dissipation curve is affected by soil type and degree of consolidation. The soil dilatancy is the key factor affecting consolidation coefficient inversion of shallow silt and silty clays. The initial pore pressure is negative and the pore pressure increases to umax first, but the umax value is very small in the Yellow River Delta silt. The inversion method used for shear contractile soil cannot be used to invert the mechanical properties of shallow silty soil directly, and a new consolidation curve normalization method is proposed. This paper provides a reference for the consolidation coefficient inversion of CPTu data in the Yellow River Delta area.

Analysis of prefabricated vertical drains with surcharge preloading of Hiep Phuoc clay

Finite-difference analysis of soft ground treatment with prefabricated vertical drains (PVDs) was performed using a newly developed consolidation model. The model uses the concept of multi-compression indices and coefficients of consolidation (CoCs) to investigate the behaviour of a soft ground deposit (pore water pressure dissipation, surface settlement and sub-layer ground settlement) and to validate the newly developed Consopro finite-difference procedure. The pre-consolidation pressures of the soft ground deposit were characterised using a combination of piezocone penetration profiling and constant rate-of-strain (CRS) consolidation tests (0.02%/min) on undisturbed samples that were retrieved from the Saigon premier container terminal in the south of Vietnam. After comparison of the back-calculated results with field-observed data, a correlation between the CoCs determined by CRS consolidation tests and the CoCs from piezocone dissipation tests, which were carried out after soil improvement, was determined.

Coal Sludge Permeability Assessment Based on Rowe Cell Consolidation, and Filtration Investigations

In this paper, an attempt has been made to investigate the possibility of using coal sludge to seal a landfill site by presenting the results of their compressibility and permeability tests. Coal sludge is a fine-grained waste from the coal enrichment process, and its permeability is also highly dependent on its degree of consolidation. The tests were carried out in a Rowe Cell, making it possible to determine the water permeability coefficient more precisely by determining the degree of the material consolidation during testing. The test was carried out using backpressure conditions. The test procedure in the Rowe Cell consisted of the following three steps: saturation, consolidation, and filtration. The coal sludge was taken directly from the filter presses as a by-product of the fines’ coal enrichment process. The paper presents the results of the individual stages performed in a Rowe Cell. The consolidation coefficient was determined using three different methods (Casagrande, Taylor, and Robbinson methods). The permeability coefficient was measured by the indirect and the direct method, the results of both were compared. The results (k < 10−9 m/s) indicated that the value of the permeability coefficient responds to the value for isolating barrier materials.

Assessment of long-term ground subsidence and groundwater depletion in Hanoi, Vietnam

Rapid urbanization and population growth in Hanoi city raise the demand for groundwater and the risk of land subsidence. This study is the first to conduct a long-term interferometric synthetic aperture radar (InSAR) analysis with different SAR sensors including ALOS, COSMO-SkyMed and Sentinel-1 to evaluate the spatiotemporal evolution of subsidence in Hanoi between 2007 and 2018. The results show that subsidence in Central Hanoi had been diminishing during these 12 years, while the southern and western outskirts (Ha Dong and Hoai Duc district) had become hot spots with peak rates of ~50 mm/yr. We further model the subsidence time-series with 22 years of piezometric records to estimate hydrogeological properties in the area. The modeling yields a mean consolidation coefficient of 0.56 m2/yr, a value typical for aquitards composed of >90% fine-grain materials. The model also predicts another 0.5–1.3 m of subsidence in Ha Dong by the end of this century. Based on these results, we propose zoning for subsidence susceptibility as the basis for future groundwater management in Hanoi. From a regional perspective, Hanoi is relatively less affected by land subsidence compared to other South East Asian cities due to geotechnical factors including small consolidation coefficients, as well as social factors such as lower population density.

Dimensionality reduction and prediction of soil consolidation coefficient using random forest coupling with Relief algorithm

Dimensionality reduction and prediction of soil consolidation coefficient using random forest coupling with Relief algorithm

Freeze-thaw vacuum treatment of landfill sludge: Mechanism of uneven frost heaving and dewatering performance

The method of freeze-thaw combined with vacuum pretreatment for landfill sludge (LS) has attracted extensive attention. However, most of the existing approaches are based on small-scale laboratory testing, and further testing studies must be performed to realize in situ treatment. To enhance the practicality of such approaches, the range of temperature effects on LS was analysed after field freeze-thaw model testing. After the freeze-thaw model test, samples were transported to the laboratory for unidirectional oedometer tests, and the remaining samples were retained in the field to continue vacuum model testing for exploring the differences in the consolidation and drainage effect of the LS. Results show that temperature changes during freeze-thaw process affect the distribution of sludge and water in the model boxes, resulting in frost heave and the appearance of “extrusion rings”. In addition, the coefficient of consolidation obtained from the unidirectional oedometer test shows that the consolidation coefficient is generally larger near the freezing tubes at a lower temperature. The settlement determined from the field vacuum preloading test shows that the subsequent vacuum consolidation settlement is larger at the position with a lower elevation of the frozen sludge surface. The comparison indicates that the consolidation and drainage effect in the field is not as significant as that in the laboratory. The findings can provide reference to optimize the field conditions during the in situ engineering practice of sludge treatment.

The Effect of Heat on the Settlement Properties of Cement-stabilized Clay Soil

Clay soil may be subjected to heat in various applications, such as nuclear waste burial sites and high voltage transmission lines. The impact of heat on clay soil's physical and mechanical properties has been explored in previous studies. However, previous studies have mainly focused on the mechanical properties of clay soil without stabilizers, and the effect of heat on the properties of the stabilized clay soil is scarcely studied. The present paper has analyzed and studied the combined effects of heat and cement on the settlement properties of kaolinite clay soil. To conduct the study, kaolinite clay mixed with various degrees of cement was exposed to a range of 25 to 600 degrees Celcius. The results showed that the coefficient of consolidation gradually decreased by increasing heat up to the dehydroxylation point. An increase in heat up to 200 degrees Celcius resulted in increasing the coefficient of consolidation in the specimens containing cement. In specimens containing 10 percent of the cement at temperatures higher than 200 degrees Celcius, the coefficient of consolidation in room temperature decreased by 73 percent compared to kaolinite. Moreover, the void ratio increased in kaolinite specimens without cement when subjected to heat up to 400 degrees Celcius. By increasing the heat, the void ratio decreased in specimens containing 10 percent cement.

Approximation of the Time Rate of Consolidation for Hydraulically Placed Fine Coal Refuse Using a Variable Coefficient of Consolidation Method

Abstract Terzaghi’s consolidation theory assumes strain in soil due to applied overburden pressure is small, and permeability and thus the coefficient of consolidation (Cv) remain constant during c...

Управління оборотними активами підприємства в особливих умовах

The article discusses the role of current assets in ensuring the normal (efficient) operation of enterprise. The objectives of the article are: studying the theoretical foundations of the assessment of current assets and searching for relevant ways to improve the efficiency of the use of current assets as factors influencing the state of the enterprise, as well as the creation for managers of numerous economic entities of an information platform for making managerial decisions on the formation and use of current assets of enterprises during the wartime. The article generalizes the likely variants for the formation of the initial value of current assets (stocks) upon receipt. Methods for assessing current assets upon disposal are considered. Indicators for assessing the efficiency of the use of current assets are systematized, including: the ratio of current assets turnover; coefficient of consolidation of current assets; the duration of one turnover of current assets; return on current assets. In special conditions (conditions of wartime), business entities are recommended to use ways to increase the efficiency of the use of current assets in the following stages: formation of current assets and their use (according to the stages of the cycle). At the stage of procurement of current assets – by improving the organization of the supply of assets; at the stage of production of current assets – applying the reuse of production waste, improving product quality, reducing the duration of the technological (production) process, reducing the cost of fuels and lubricants (FLM) and other stocks; at the stage of product sales – the introduction of sanctions or deprivation of privileges for rejection / violation of agreements / contractual conditions for the supply and payment of inventory (inventories), the formation of sources of financing of current assets (own and attracted), a rational choice of payment terms for current assets. The main instrument for managing the efficiency of current assets of modern business entities is proposed to be considered marketplaces that solve the problem of accelerating the asset turnover. The article considers the types of marketplaces, the main parameters of marketplaces: the structure of marketplaces and their functionality.

Improve Geotechnical Design Parameter of Some Soft Clayey Soils

The shallow Soft Clayey deposit is common in Alexandria-Egypt. Most soft clays in their natural state are unsuitable for supporting any structure. Thus, improvement treatments exist to strengthen these soils so that improved soil can have adequate bearing capacity without undergoing failure or producing substantial excessive settlement post construction and applied loads to them. This paper presents a case study of an improved site in the city center, which reclaimed part of Maryout Lake, where the highly compressible clay with water content varies from 200% near the surface to 90% at the base of the shallow clay deposit. A prefabricated vertical drain with preloading has been used to improve this soft soil. Values of shear parameters and consolidation coefficient back-calculated from field measurements and have been compared with the values from lab and in situ tests. The study provides different relationships from comparisons of prediction and estimation compressibility and consolidation settlement from laboratory studies and particularly field case studies. Also, some correlation related to the compressibility with index properties of soft clay is presented. The results display that a substantial improvement is noticeable in the compressibility properties.

INTERIOR PROFILE OF YOUNG PIGS OF DIFFERENT GENOTYPES AND THE USE OF ITS COMPONENTS FOR EARLY PREDICTION OF QUANTITATIVE CHARACTERS

The paper presents the research results of blood serum biochemical parameters, as well as fattening and meat qualities of Large White young pigs of different genotypes by melanocortin receptor gene 4 MC4R; the level of phenotypic consolidation of quantitative characters is calculated and their correlations are determined. It was found that the serum biochemical parameters of young pigs from the experimental groups correspond to the physiological norm of clinically healthy animals. Studies have shown that animals of the MC4R<sup<AG</sup< genotype exceed significantly their peers of the MC4R<sup<AA</sup< genotype in the age of achievement of live weight of 100 kg, in fatback thickness at the level of 6-7 thoracic vertebrae and in the length of the chilled carcass by 4.47% on average. The coefficients of phenotypic consolidation of fattening and meat qualities of young pigs from the experimental groups ranged from -0.101 to +0.370. The number of significant correlations between serum biochemical parameters, fattening and meat qualities of Large White young pigs of the MC4R<sup<AA</sup< genotype is 26.67%, of MC4R<sup<AG</sup< genotype is 33.34%. This indicates the possibility of using interior indicators for early prediction of fattening and meat qualities of Large White young pigs. The maximum increase in additional products was obtained from Large White young pigs of the MC4R<sup<AG</sup< genotype by the melanocortin receptor gene in amount of +2.02%.

Determination of Consolidation Parameters of Geomaterials Using Modified CRS Consolidation Testing System

Nowadays, the constant rate of strain (CRS) consolidation phenomenon has gained more attention as an alternate testing method to evaluate the consolidation characteristics of finegrained soils based on strain rate criterion. In the present study, a modified consolidation cell has been fabricated indigenously and carried out a series of CRS tests using a conventional triaxial loading frame at four different strain rates on reconstituted samples of marine clay at 0.002, 0.003, 0.004 and 0.005 mm/min, black cotton soil at 0.0025, 0.003, 0.005 and 0.0075 mm/min, red mud at 0.10, 0.125, 0.25 and 0.50 mm/min, and Varanasi local soil at 0.05, 0.075, 0.10 and 0.125 mm/min. Based on the pore pressure ratio (PPR) criterion, the best suitable strain rates for marine clay, black cotton soil, red mud, and Varanasi local soil were found to be 0.002, 0.0025, 0.1 and 0.05 mm/min, respectively. Further, the consolidation parameters namely primary compression index (cc), recompression index (cr), coefficient of consolidation (cv), coefficient of axial compressibility (av) and permeability (k) obtained through proposed CRS consolidation method are compared and validated successfully with the parameters obtained through Incremental Loading (IL) tests using both conventional and modified oedometer cells.

Unified model for the prediction of consecutivesolid–liquidfiltration and expression at the constant pressure

AbstractUnified nonlinear model is proposed for the prediction of consecutive solid–liquid filtration and expression at the constant pressure. This model is based on the Darcy–Terzaghi filtration‐consolidation equations modified to consider power‐law pressure dependence of the specific cake resistance, and transforming Darcy law to the linear form. The model considers nonuniform structure of compressible filter cakes obtained by filtration and following expression. The profiles of local compressive pressure and local cake characteristics are simulated and compared for different moderately and highly compressible filter cakes (H.K. kaolin, CaCO3, silica, activated sludge) based on the analytical and numerical solutions of the model. It is shown that the behavior of solid–liquid expression depends from the initial structure of compressed materials. Consolidation ratioUof the filter cakes with initially nonuniform structure formed by filtration differs from that of semi‐solid materials with initially uniform structure. Different methods of determination of consolidation coefficient are analyzed and compared for nonuniformly structured filter cakes.

Reproductive qualities and the level of their phenotypical consolidation in sows of different operational value

The results of studies of indicators of reproductive qualities of sows of different operational value, the level of their phenotypic consolidation are presented, and the economic efficiency of using sows in experimental groups is calculated. The experimental part of the research was carried out in LLC "Druzhba-Kaznacheevka" in the Dnepropetrovsk region and in the laboratory animal husbandry of the State Institution "Institute of Grain Crops of the NAAS of Ukraine". The work was carried out according to the program of scientific research of NAAS No. 31 "Genetic improvement of farm animals, their reproduction and preservation of biodiversity (Genetics, conservation and reproduction of biological resources in animal husbandry)" task "To determine the adaptive characteristics and the nature of inheritance of polygenic-hereditary traits of pigs of different genotypes and to develop an integrated system for creating a highly productive population". The object of research was sows of the Llarge White breed. It was found that the sows of the main herd, according to the characteristics of reproductive ability, belong to the I class and the elite class. The number of sows from which 100 or more live piglets were obtained during the breeding period is 27.45 %. Sows in the "high operational value" category exceed their peers in the "average operational value" category in terms of life expectancy and breeding use by 25.1 and 26.2 months respectively. A significant difference between the animals of the indicated groups was established according to the indicators "received farrowings", "received live pigs in total, head", "multiple births, head.", "weight of the nest at the time of weaning at the age of 28 days, kg" and the index of N. D. Berezovsky. The coefficients of phenotypic consolidation (К1, К2) range from – 0.050 to +0.231 units, which indicates an insufficient level of consolidation of reproductive qualities in sows of the controlled population and determines the vector of further work of agricultural specialists and research workers - curator of work in this direction. The coefficient of pair correlation between the breeding index of sow reproductive qualities (SIRQS) and the absolute indicators of reproductive qualities of sows of different operational value ranges from –0.525 (tr = 3.09) to +0.934 (tr = 81.8). The maximum increase in additional production was obtained from sows of the "high operational value" category – + 3.41 %, and its cost is 92.44 UAH /heard/ farrowing. Key words: sow, breed, reproductive qualities, operational value, coefficient of phenotypic consolidation, cost of additional production, variability, correlation.

Porosity estimation based on the rock skeleton general formula and comprehensive pore structure parameter — An application to a tight-sand reservoir

Most of the current 3D reservoir porosity estimation methods are based on analyzing the elastic parameters inverted from seismic data. It is well-known that elastic parameters vary with the pore structure parameters such as the pore aspect ratio, consolidation coefficient, and critical porosity. Thus, we may obtain inaccurate 3D porosity estimation if the chosen rock-physics model fails to properly address the effects of the pore structure parameters on the elastic parameters. However, most of the current rock-physics models only consider one pore structure parameter such as the pore aspect ratio or the consolidation coefficient. To consider the effect of multiple pore structure parameters on the elastic parameters, we have developed a comprehensive pore structure (CPS) parameter set that is generalized from current popular rock-physics models. The new CPS set is based on the first-order approximation of current rock-physics models that consider the effect of the pore aspect ratio on the elastic parameters. The new CPS set can accurately simulate the behavior of current rock-physics models that consider the effect of pore structure parameters on the elastic parameters. To demonstrate the effectiveness of the proposed parameters in porosity estimation, we use a theoretical model to demonstrate that our CPS parameter set properly addresses the effect of pore aspect ratio on elastic parameters such as velocity and porosity. Then, we obtain a 3D porosity estimation for a tight sand reservoir by applying it seismic data. We also predict the porosity of the tight sand reservoir using a neural network algorithm and a rock-physics model that is commonly used in porosity estimation. The comparison demonstrates that the predicted porosity has a higher correlation with the porosity logs at blind well locations.

Experimental evaluation of the classical and alternative consolidation theories in predicting the volumetric change of contaminated and non-contaminated soil

Several regions in Brazil and the world suffer from the presence of collapsible soils. The development of theories for understanding the phenomenon is significant because the increase of water content is associated with several reasons (e.g., precipitation, rupture of sewage, and water systems). Although some theories explain the behavior of various types of soils, they fail to explain collapsible and structured soils. In this research, an alternative interpretation of the consolidation theory is verified and calibrated for collapsible soil. The alternative model was applied to experimental data from a latosol from southeastern Brazil, and comparisons with the classical theory showed a difference in the saturated hydraulic conductivity of around 100 times. The observation showed promising results compared with the saturated hydraulic conductivity of the field (Guelph Permeameter). Furthermore, consolidation tests verified the collapse potential, the variation of consolidation coefficient and saturated hydraulic conductivity, and the total settlement prevision due to the presence of bleach and washing powder.

Recycled waste tire fiber as a sustainable reinforcement in compacted sand–bentonite mixture for landfill application

A layer of compacted sand-bentonite (CSB) mixture is employed as a liner at the landfill. The formation of desiccation-induced shrinkage cracks can increase the leachate migration into groundwater. The usefulness of the liner system may be endangered if the liner material's strength is insufficient. To address this issue, the CSB barrier can be modified by incorporating with waste tire fiber. This study aimed to assess the undrained shear strength, consolidation, and desiccation-induced crack of mixtures of CSB and reinforced CSB. An analytical model was derived to assess the behaviour of tire fiber composite soil from the experimental result. Positive excess pore water pressure was reduced significantly by the inclusion of tire fiber in the consolidated undrained triaxial test results. By the addition of 15% tire fiber, the effective frictional angle was raised from 21.0° to 24.2°, while the effective cohesion component was increased from 15.0 kPa to 24.2 kPa at the same fiber content. The crack density factor and crack intensity factor of the mixture without tire fiber were much higher than those of the CSB with fiber. By the addition of tire fiber, time for 90% consolidation was reduced, while the coefficient of consolidation increased. Although the permeability increased marginally, but it was within the limiting value. An analytical model adequately captured the stress-strain and pore water pressure responses of all proportion of tire fiber, and the yield surface of the composite was expanded maximally with only 10% tire fiber.

CORRELATION OF PERMEABILITY COEFFICIENT AND COEFFICIENT OF CONSOLIDATION IN PONTIANAK CITY’S SOFT SOIL

Soft soil is a type of soil that is difficult to use in construction because it has low bearing capacity and slow settlement due to its fine grain size. In statistics, the relationship or correlation between two data can be predicted using mathematical formulas to find out how much the two data can influence each other. Most of the soil on the surface of the city of Pontianak is dominated by soft soil, so it is important to know how much the coefficient of consolidation and coefficient of permeability can influence each other. From the results of the regression and correlation calculations, the relationship between the permeability coefficient and the consolidation coefficient for the combination of original soil and sand mixed soil is y = 674.7x + 0.0003 with a value of r = 0.4834. The relationship between the permeability coefficient and the original soil consolidation coefficient is y = 321.4x + 0.0003 with a value of r = 0.4173. The relationship between the coefficient of permeability and the coefficient of consolidation of the sand mixed soil is y = 1295.5x + 0.0003 with a value of r = 0.7994. from the experimental results it can be concluded that there is a significant influence between the value of the permeability coefficient and the consolidation coefficient.

CONSOLIDATION CHARACTERISTICS OF A SILTY CLAY: CONCERNING THE EFFECT OF SOIL DISTURBANCE

In this paper, undisturbed specimen of a silty clay constituting of Phu Bai formation (ambQ21-2 pb) was collected from boreholes in Hue city and surrounding areas. The soil, under both undisturbed and disturbed conditions, was then subjected to standard one-dimensional consolidation tests with 7 loading increments. It is shown from the experimental results that the time to the end of primary consolidation (EOP), determined by Log Time method (tLT) and 3-t method (t3T), decreases with the load increment and under the same vertical stress, the primary consolidation of disturbed silty clay finish at a shorter time than those of the undisturbed one. The coefficient of secondary consolidation (Cα) increases with the vertical stress and reaches the maximum values before decreasing. The obtained values of Cα = 0.005 - 0.020 suggest a relatively low secondary compressibility of the silty clay constituting of Phu Bai formation.

Hydraulic performance, consolidation characteristics and shear strength analysis of bentonites in the presence of fly-ash, sewage sludge and paper-mill leachates for landfill application

A rapid upsurge in urban and industrial developments leads to increased generations of solid wastes. The most accepted technique of waste discarding around the world is landfilling. Leaching chemicals from municipal dumping grounds can pollute the groundwater source and the surrounding environment without appropriate precautionary measures. Bentonite is a low-cost constituent used as a liner material in landfills due to its low permeability, high sealing ability, high specific surface area, and the ability to hold up the impurity migration through adsorption. However, leachate interaction with bentonite may alter its properties and reduce its usefulness as a barrier material in the long term. Also, bentonite having different chemical and mineralogical compositions will behave differently due to the leachate interaction. Therefore, it is necessary to compare the performance of various bentonites in the presence of leachates. In the present investigation, two Indian bentonites of different mineralogical compositions were studied for their change in the index properties, swelling, swelling potential, swelling pressure, hydraulic conductivity, consolidation parameters and shear strength properties in the presence of fly ash, sewage sludge and paper mill leachates. The outcomes showed that in the presence of all the leachates, liquid limit, free swell, compression index, swelling potential, swelling pressure, time to complete 90% of consolidation and shear strength dropped; whereas, hydraulic conductivity and coefficient of consolidation increased. Besides, the quality of bentonite prominently influenced the hydraulic, strength and swelling behaviour. The bentonite having a higher cation exchange capacity, liquid limit, specific surface area, and swelling capability undergoes a higher variability in the free swell (80.0, 73.8 and 76.9% decline), liquid limit (73.5, 61.7 and 69.2% decline), swelling potential (61.3, 55.7 and 51.0% decline), swelling pressure (53.3 and 56.4% decrease), and hydraulic conductivity (57.5, 8.6 and 41.1 times increase at a void ratio of 1.2) values when infused with fly ash, sewage sludge and paper mill leachates, respectively. The study also showed that the fly ash leachate interaction causes a higher variation in bentonite behaviour than sewage sludge and paper mill leachates. The study's findings would prove beneficial to design engineers for selecting bentonite types for landfill liners.