Coefficient Of Consolidation Research Articles

Penurunan Konsolidasi Tanah Lempung Kecamatan Sambi Kabupaten Boyolali yang Distabilisasi dengan Limbah Keramik

Based on the preliminary test results, the original soil of the Sambi Boyolali area is classified as inorganic clay with high plasticity. It has a plasticity index value of 31.93%, therefore stabilization is required so that the soil is able to withstand the load of the structure above it. Stabilization was carried out by mixing the soil with ceramic waste that passed the No. 4 sieve with variations of ceramic waste 2.5%, 5%, 7.5%, and 10% of the weight of the soil sample, which aims to determine changes in physical properties and mechanical properties (consolidation settlement) before and after the soil is stabilized. The results of the physical properties test of the soil after being stabilized with ceramic waste showed a decrease in the value of water content, specific gravity, liquid limit value, and plasticity index as well as an increase in the plastic limit value, shrinkage limit value and the amount of soil that passed sieve No. 200. Soil classification changed from inorganic clay with high plasticity in the original soil, to inorganic clay with low plasticity when mixed with 10% ceramic waste. The results of the mechanical test showed an increase in the value of the maximum dry volume weight of the soil (γdmax) as well as the value of the consolidation coefficient (Cv), and a decrease in the compression index value (Cc) and the consolidation settlement value (Sc).

Undrained strength of clay determined from simple shear test

The undrained shear strength of clay is an important parameter for the design of embankments, shallow foundations, and pile foundations. Among the various methods of testing undrained strength, the simple shear is essential when the shearing mode of the soil surrounding the pile is similar to that in a simple shear test. This study employs a series of undrained strength tests with a Berkeley simple shear apparatus. Three reconstituted natural clays and one artificial clay were tested with a range of coefficients of consolidation. The influence factors, including sample pre-consolidation pressure, saturation back pressure, shearing rate, height of specimen, consolidation stress, and lateral stress ratio, were investigated in undrained simple shear tests. The failure mode in simple shear and corresponding strength parameters are also examined. Based on the test data set, models for describing the undrained strength with simple shear for high plasticity clays are developed and compared to test data for normally consolidated reconstituted clay. Good agreement between models and intact Onsoy clay is also observed when allowance is made for the coefficient of consolidation and strength parameters of undisturbed clay and in situ stress state.

BIOCHEMICAL INDEXES OF BLOOD SERUM AND THEIR RELATIONSHIP WITH SOME SIGNS OF GROWTH OF BULL-CALFS OF GRAY UKRAINIAN AND UKRAINIAN MEAT BREEDS IN THE POSTNATAL DEVELOPMENT PERIOD

Goal. The paper presents the results of the study of indicators of individual development of gray Ukrainian and Ukrainian beef cattle, biochemical indicators of blood serum, and also calculated the level of correlations between traits. Methods. The research was conducted at the State Enterprise "Experimental Farm "Polyvanivka", the Animal Husbandry Laboratory of the State Establishment "Institute of Grain Crops NAAS" and the testing center of the Institute of Animal Science NAAS (Kharkov) using generally accepted zootechnical, statistical, biochemical and laboratory research methods. Results. Research has established that the biochemical parameters of blood serum in Ukrainian gray and Ukrainian beef cattle correspond to the physiological norm of clinically healthy animals. It was determined that the minimum requirements of the elite class prevailed by +1.45 - + 0.6 1 % according to the live weight indexes of Ukrainian gray and Ukrainian beef cattle at the age of 12 months; at the age of 6 months, this index ranges from -2.09 (Ukrainian gray bull-calfs) to +2.61 % (Ukrainian meat bull-calfs). The average daily gain in live weight of animals of the studied breeds during the growing period from birth to 6 months of age and from birth to 12 months of age varies from 830.1 to 1052.4 g. Coefficients of phenotypic consolidation of bull-calfs of gray Ukrainian and Ukrainian beef cattle vary from +0.241 (K1, live weight of bull-calfs Ukrainian beef cattle at birth) to +0.794 (K2, live weight of bull-calfs gray Ukrainian beef cattle at 6 months of age). The pairwise correlation coefficient between serum biochemical parameters and live weight of bull-calfs of gray Ukrainian and Ukrainian beef cattle varies from -0.600+0.2830 to + 0.635+0.25765. This indicates the possibility of using total protein content, activity of aspartate aminotransferase (AsAT), alanine aminotransferase (AlAT) and alkaline phosphatase for early prediction of live weight of animals of the studied breeds. Conclusions. Young cattle of Ukrainian meat and gray Ukrainian breeds are characterized by sufficiently high growth rates and their phenotypic consolidation. The presence of reliable correlation coefficients between indexes of individual development and interior indicates the possibility of their use for early prediction of live weight and average daily growth. Key words: cattle, bull-calfs, breed, biochemical parameters of blood serum, live weight, average daily live weight gain, variability, correlation

Effect of fiber length on the consolidation parameters of coir fiber-reinforced soft clay

Coir fibers are natural fibers with high tensile strength and pressure resistance, making them an alternative soil reinforcement material. However, the effect of fiber length on improving soil consolidation properties has yet to be largely explored. Therefore, this study investigated the effect of the length and content of coir fibers on soft soil mechanical behavior through a series of one-dimensional consolidation tests. Fibers of >10 mm to 30 mm and >30 mm to 50 mm lengths were mixed randomly into the soil with varying content, ranging from 0.00% to 1.25% of the total weight of the mixture. The relationship between the effective stress and the void ratio was explored, unveiling that the void ratio of soil specimens reinforced with coir fibers decreased more gradually than those unreinforced. An increase in the fiber content reduced the compression index (Cc) value and enhanced the coefficient of consolidation (Cv) value, with longer fibers producing more significant values due to more excellent interactions between fibers. Fibers of >30 mm-50 mm yielded optimum Cc and Cv values at the fiber contents of 0.50% to 0.75%.

Assessment of Land Consolidation Project in Burdur-Yeşilova-Sazak Village Using Metric Indexes

Burdur Yeşilova Sazak köyü arazi toplulaştırma projesinin metrik indeksler kullanılarak değerlendirilmesi amacı ile yürütülen bu çalışmada, toplam parsel sayısı, ortalama parsel büyüklüğü, toplulaştırma oranı (TO), toplulaştırma katsayısı (CC), toplam kenar (TE), kenar yoğunluğu (ED), şekil indeksi (SI), fraktal boyut (FD), ortalama şekil indeksi (MSI), alan ağırlıklı ortalama şekil indeksi (AWMSI) ve çift logaritmalı fraktal boyut indeksi (DLFD) kullanılmıştır. Belirtilen bu indeksler proje sahasının tamamında ve hisseli parseli olmayan işletmelerde değerlendirilmiştir. Proje sahasında TO ve CC sırasıyla %63,11 ve %36,97 olarak gerçekleşmiştir. Tüm proje sahasında TK, ED, SI, FD, MSI, AWMSI ve DLFD toplulaştırma öncesinde sırasıyla 451467 m, 998 m/ha, 1,23, 1,42, 1,37, 1,4 ve 1,5 iken toplulaştırmadan sonra bu değerler sırasıyla, 262298 m, 609 m/ha, 1,31, 1,38, 1,35, 1,3, 1,3’tür. Hissesiz işletmelerde bu değerler toplulaştırmadan önce sırasıyla 112941 m, 1101 m/ha, 1,23, 1,42, 1,31, 1,33 ve 1,3 iken toplulaştırmadan sonra sırasıyla, 66483 m, 824 m/ha, 1,34, 1,34, 1,34, 1,35 ve 1,1’dir. Araştırma sonunda, kullanılan indekslerden sadece kenar yoğunluğu, fraktal boyut ve çift logaritmalı fraktal boyut indeksinin toplulaştırma projesinin değerlendirilmesinde kullanılabileceği anlaşılmıştır.

Evaluation of Subsoil Competence for Foundation Design in Rumuokwuta, Port Harcourt, Eastern Niger Delta

Aim: A subsurface geotechnical investigation was carried out for the purpose of establishing the depth of competent soil for foundation design and construction of a one-storey building.
 Study Design: The study was aimed at assessing the subsoil competence for a foundation design in the Eastern Niger Delta using engineering geology and geotechnics.
 Place and Duration of Study: The research was conducted in three locations along the Rumuokwuta axis of Port Harcourt (the eastern Niger Delta) between April and September 2019.
 Method: The study involved both field sampling and laboratory analysis. This involved soil boring for the retrieval of disturbed and relatively undisturbed samples for analysis, which involves grain size analysis, the Atterberg limits, moisture content, and unit weights. Also, Oedometer consolidation Oedometer and undrained, unconsolidated triaxial tests were carried out.
 Results: The study revealed two main stratigraphic layers that are mostly fine within the shallow foundation level (0.0–3.0m). From the results, the soil exhibited the following geotechnical properties: liquid limit (41-46%), plastic limit (21-23%), plasticity index (18-24%), and moisture content range (20.6-24.7%). The undrained cohesion value is 55 kPa, and the average frictional angle is 5o. The coefficients of compression (Mv) and consolidation (Cv) were 0.20 m2 /MN and 40.7 m2/yr, respectively.
 Conclusion: With the moderate bearing and settlement values within the shallow foundation level, the feasibility of adopting a shallow foundation for the purposed structure is tolerable. A shallow foundation (1.4m minimum) with an allowable bearing pressure of 100 kPa is therefore recommended.

A Survey on the Relationships between Compression Index, Coefficient of Consolidation, and Atterberg Limits

Correlations between compression index and atterberg limits found in the literature are very important for preliminary estimation. These equations are usually interpreted based on the R-square parameter and classified according to the conditions of the data (disturbed, undisturbed, remoulded, etc.). Although correlations reliable enough to eliminate oedometer tests are not yet fully available, these correlations can be useful in local calculations. In this study, correlations obtained from studies conducted after 2000 on the relationship of compression index and consolidation coefficient with atterberg limits and water content are mentioned and clearly shown. While the compression index equations are quite high in the literature, the equations produced with the consolidation coefficient are less in number. This is because consolidation calculations take a lot of time. Using 105 data obtained from researches in the literature, two equations were formed between the compression index, liquid limit and plasticity index. This study does not propose new equations, only relationships are generated using the Linear Regression method with data obtained from independent studies, based on the belief that the compression index has a stronger relationship with the liquid limit and plasticity index

REPRODUCTIVE QUALITIES OF SOWS OF DIFFERENT TYPES OF ADAPTATION AND THE LEVEL OF THEIR PHENOTYPE CONSOLIDATION

Introduction. The intensification of the breeding process in pig breeding involves, along with the introduction of modern methods of assessing the breeding value of animals, the use of pigs of foreign breeding. At the same time, it is important to study their adaptive and productive qualities in the conditions of industrial maintenance technology and the steppe zone of Ukraine (Topikha V. S., 2009, Khalak V. I., 2009, 2020, 2022, Kislyns’ka A. I. and others, 2012, Dudka O. I., 2020). The paper presents the results of the study of the reproductive qualities of sows of super-adaptive and minus-adaptive types, as well as the coefficients of phenotypic consolidation (К1, К2) of the main traits and the economic efficiency of the use of animals in experimental groups are calculated. The research was carried out in the agricultural formations of the Dnipropetrovsk region and the animal husbandry laboratory of the State Institution "Institute of Grain Crops of the National Academy of Agrarian Sciences of Ukraine". The work was carried out in accordance with the program of scientific research № 31 "Genetic improvement of agricultural animals, their reproduction and preservation of biodiversity (Genetics, preservation and reproduction of biological resources in animal husbandry)", the task – "Determine adaptive features and the nature of inheritance of polygenic and hereditary traits of pigs of different genotypes and develop an integrated a system of creating a highly productive population".
 Materials and methods of research. The object of the study were sows of the large white breed of Hungarian origin. Based on the results of own research and data of primary zootechnical records (form 2-SV "Card of breeding sow", form 4-SV "Accounting journal of mating (insemination) of pig breeding stock", form 5-SV "Accounting journal of farrowings of sows and offspring piglets" (Instructions on the grading of pigs, 2003) the following quantitative characteristics were investigated: sow life expectancy, months; duration of breeding use of the sow, months; farrowings obtained; total live piglets obtained, head; fertility, head; nest weight at the time of weaning at the age of 30 days, kg, preservation of piglets until weaning, %.
 A comprehensive evaluation of sows for reproductive qualities was carried out according to M. D. Berezovsky’s index (cited by P. A. Vashchenko, 2019), the “level of adaptation” index was calculated according to the method of V. S. Smirnov (2003), phenotypic consolidation coefficients (К1, К2) of the main quantitative characteristics - according to the methods – by Yu. P. Polupan (1996, 2005). Biometric processing of research results was carried out according to the methods of V. P. Kovalenko. etc. (2010).
 Research results. It was established that the life expectancy of sows of the controlled population is 50.1 months (Сv = 35.97%), the duration of breeding use is 40.9 months (Сv = 42.24%), the "adaptation level" index is 10.56 points (Сv = 32.77%). During the breeding period, sows produced 7.0 farrowings (Сv = 44.10%), a total of 77.8 live piglets (Сv = 46.46%). The average rate of multiple fertility is 11.1 piglets per farrowing (Сv = 10.08%), the weight of the litter at the time of weaning at the age of 30 days is 76.1 kg (Сv = 14.10%), the weight of the nest at the time of weaning at the age 60 days – 181.5 kg (Сv = 9.35%), survival of piglets before weaning – 91.6 ± 0.50%. The index of M. D. Berezovs’ky in sows of the controlled population ranges from 33.00 to 50.83 points. Taking into account the intrabreed differentiation of sows according to the type of adaptation, it was established that animals of the super-adaptive type prevailed over the animals of the minus-adaptive type in terms of life expectancy, duration of breeding use, total farrowings, total live piglets, fertility and litter weight at the time of weaning at the age of 30 days by an average of 37.96%. Coefficients of pair correlation between traits characterizing the level of adaptation of sows and their reproductive qualities range from –0.704 to +0.982. Coefficients of phenotypic consolidation of reproductive qualities of sows of different types of adaptation range from –0.082 to +0.682.
 Conclusions. Studies show that sows of the super-adaptive type (the "adaptation level" index ranges from 5.48 to 8.20 points) outweigh the animals of the controlled population by litter weight at the time of weaning at the age of 30 days +4.63%. The cost of additional products obtained from the sow of the specified group is UAH 125.52.

Secondary consolidation characteristics of organic soil modified by bio-enzyme based on the Gibson model

In order to study the secondary consolidation characteristics of organic soil improved by bio-enzyme, the secondary consolidation test was carried out. First, the Gibson rheological model parameters were fitted according to the experimental results. Then, the relationship between rheological model parameters, Ca/Cc value, secondary consolidation coefficient Ca, and load was analyzed for different ratios of bio-enzyme. The results showed that: 1) the rheological model parameters were negatively correlated with the ratios of bio-enzyme and positively correlated with the load value. The rheological model parameters E1 (Kelvin elastic modulus) and η (Kelvin viscosity coefficient) reached the maximum value when the ratio of bio-enzyme was 0.01%. 2) The secondary consolidation coefficient was related to the load and showed a certain law. At 100 kPa, the secondary consolidation coefficient of samples reached the peak. When it was less than 200 kPa, the secondary consolidation coefficient changed obviously with the increase in load. When the load was greater than 200 kPa, the variation trend of the secondary consolidation coefficient tended to be gentle with the increase in load and finally tended to be constant. With the increase in load, the secondary consolidation coefficient Ca finally approached to a stable value. 3) The value of Ca/Cc of improved organic soil varied from 0.042 to 0.1 under various loads. In this article, the secondary consolidation characteristics of organic soil modified by bio-enzyme were studied. The secondary consolidation strain can be predicted by the established rheological model parameter equations.

Compressibility Characteristics of Southwest Bangladesh Organic Soil Stabilized with Sand Column

This research investigates the characteristics of organic soil from southwest Bangladesh and the influence of sand columns on the void ratio (V0), consolidation coefficient (CC), and volume compressibility (CV) of stabilized soil. On the laboratory scale, cylindrical columns of varying diameters were extruded through organic soil samples and stabilized with 3%, 5%, 8%, 10%, and 23% sand in various geometries. After evaluating the engineering parameters, a series of 1-D consolidation experiments were performed to assess the effect of the sand column on stabilized soil samples. According to the Unified Soil Classification System (USCS), the organic soil used in this research is defined as organic silt (OH). According to the findings, the organic soil has a liquid limit of 118% and its particles pass through a 0.075 mm sieve. By incorporating sand columns, rapid consolidation was obtained, and the sample containing 77% organic soil and 23% sand exhibited the best consistent compressibility features. The effects of column number and geometry on the compressibility behavior of organic soil samples were also examined. The results for the 77% organic soil and 23% sand in a single column and the 82% organic soil and 8% sand in a double column are nearly identical. This study reveals that stabilization with sand columns may significantly enhance the physical and consolidation behavior of organic soil in southwest Bangladesh.

ANALISIS DERAJAD KONSOLIDASI PADA PERBAIKAN TANAH DENGAN METODE PRE-FABRICATED VERTICAL DRAIN (PVD) PADA PROYEK PEMBANGUNAN JALAN TOL SEMARANG – DEMAK PAKET 2

Soft soil is a type of soil that has low shear strength, small coefficient of permeability, compressibility and low soil bearing capacity. 1-D consolidation theory by Terzaghi (1925), assumes that during the consolidation process the value of the consolidation coefficient (Cv) is constant. Flow is only vertical direction. The analysis carried out is to know magnitude of decline and time required to achieve 90% consolidation. Quantitative data is used to analysis numerical data and calculated using existing formulas. Value of settlement using Terzaghi method and principle of normal consolidation is 1.68834 m. To achieve a degree of consolidation of 90% without PVD is 274350 days with a decrease of 1.5196 m. With triangular pattern PVD installation on distance of 0.9 m is 75 days with a large reduction of 1.523 m. Based on the result, time required to achieve a degree of 90% consolidation using PVD is onliy 75 days, while on same day without using PVD consolidation results are around 0.017%. This shows that PVD can speed up the time required for soil consolidation.

GEOMETRY ASSESSMENT ON THE SLOPE STABILITY OF MANYAR POND

Lateritic soil was treated with 0%, 4%, 8%, 12%, and 16% Rice Husk Ash (RHA) by dry soil weight to determine its consolidation properties. Test carried out include particle size distribution, specific gravity, compaction test with varying compactive efforts (British Standard Light (BSL), West African Standard (WAS) as well as British Standard Heavy (BSH)) and consolidation test. Samples for consolidation test were compacted and then cured for 7, 28 and 56 days; then subjected to one dimensional consolidation testing to observe the influence of curing period and compactive effort on its consolidation characteristics. Index tests showed improved geotechnical properties. The Maximum Dry Density (MDD) for BSL compaction decreased with a rise in RHA content from 1.72 to 1.42 Mg/m3 while optimum moisture content (OMC) increased from 16.5% to 27.3% with rise in RHA doses from 0% up to 16%. Similar trend was observed for WAS and BSH energies. Pre-consolidation pressure rise with increment in RHA content and also with increase in both compactive efforts and curing period with few exceptions. At 12% RHA content, Pre-consolidation pressure increased from 65 to 66.5 kN/m2 at 7 days and 56 days respectively. Increase in RHA content caused a decrease in Compression Index and Swelling Index. Compression Index also decreased with increase in both compactive efforts and curing period. There was no observed trend in the Swell Index with curing period. As the compactive efforts increased, the swell index decreased. The RHA reduced the Coefficient of Volume Compressibility (Mv) and the Coefficient of Consolidation (Cc). Curing period and compactive effort have no effect on Mv and Cc. Based on the results obtained, curing period at least 28 days using up to 12% RHA compacted at energy level of BSH improved the properties of the treated soil and can be used for geotechnical engineering applications like embankment or rural roads.

Mitigation of lateral slope movement and soil improvement using the vacuum-PVD scheme

This paper interprets the results from field monitoring which was carried out during vacuum-PVD improvement in a site located near an actively moving slope. Interestingly, the monitoring results showed, among other things, mitigation in the outward lateral movements during and after the preloading process indicating relative stability in the slope and the efficiency of vacuum to mitigate lateral movements during the preloading period. Analyses were made on other field parameters such as pore pressure and settlement, as well as back-calculation of flow parameters to be considered during vacuum preloading design, such as permeability ratio (kh/ks) and horizontal consolidation coefficient (Ch) due to vacuum-PVD, were carried out. Post improvement, appropriate geotechnical properties were obtained from laboratory tests of clay specimens from borehole samples and undrained shear strengths were measured from unconfined compression and field vane shear test. The obtained properties indicated improvement in soft soil properties with a reduction in water content and an increase in maximum past pressure, OCR and undrained shear strengths. The prediction made for final shear strength using past literature, where applied additional incremental stress was reduced with depth, matched well with the shear strengths recorded from field testing.

The effect of the ryanodine receptor gene on the reproductive traits of Welsh sows

The reproductive performance of sows largely determines the efficiency of the entire pig farming industry. The purpose of our work is the evaluation of polymorphism of the ryanodine receptor gene and its impact on the reproductive traits of sows of the Welsh breed of pigs. For this study, 148 pigs of the Welsh breed were used. The reproductive traits of sows were evaluated in two adjacent generations. We conducted a comprehensive assessment of the reproductive ability of sows using the SIRQS (selection index of reproductive qualities of sows), determined phenotypic consolidation coefficients and assessed the genetic potential of the animals’ productivity. The polymorphism of the RYR1 gene was determined using polymerase chain reaction-restriction fragment length polymorphism analysis (PCR-RFLP). Data processing was performed using single-factor analysis of variance (ANOVA). Polymorphism of the ryanodine receptor gene in sows of the Welsh pig breed was evaluated. 8.0% of the animals were identified as carriers of the mutant allele of the RYR1 gene. However, no homozygous RYR1-nn animals were found. Pigs of the maternal generation carrying the homozygous NN genotype had better reproductive performance in all indicators. Sows that were carriers of the mutant allele were characterized by lower values of the genetic productivity potential compared with the entire estimated population for all productive traits. Sows which were free of the mutant allele of the RYR1 gene were characterized by large values of the SIRQS index. The values of the coefficients of phenotypic consolidation of the number of live born piglets in sows without the mutant allele were lower than in sows with the mutant allele n. Better performance of sows free of the mutant allele of the RYR1 gene was established over sows carrying it in all evaluated traits of reproductive capacity (for different traits P ranged from 0.021 to 1.0*10–4), except for number of piglets born alive per sow in the daughter generation. Sows with the NN genotype had better selection index values by 15.7% in the maternal generation and by 10.2% in the daughter generation. In order to increase the reproductive ability of sows in the studied population of Welsh pigs and achieve similar results in other herds of this breed, animals free from the mutant allele of the RYR1 gene should be selected for further reproduction in the process of breeding, while on the contrary, carriers of this gene should be gradually eliminated from the herd. To carry out breeding work, further research is needed on the entire population of Welsh pigs for the RYR1 gene.

Comparative assessment of transient- and steady-state soil thermal conductivity using a specially designed consolidometer

Precise estimation of soil thermal conductivity is crucial for reliable heat flow analysis in soil. Research indicates variations in soil thermal conductivity values estimated using transient- and steady-state temperature measurements. However, sources of such reported differences cannot be specified with certainty. This paper presents the development of a soil thermal conductivity measurement device that enables simulation of a specified stress condition on soil specimens and estimation of both transient- and steady-state soil thermal conductivity values from different segments of a single test. A series of thermal conductivity tests were performed on seven different soils using the specially-designed test setup. The difference in soil thermal conductivity values obtained from transient- and steady-state responses are compared to those reported in the literature. In contrast to steady-state soil thermal conductivity, results indicate an increase in transient-state soil thermal conductivity beyond a threshold value of the rate of soil temperature increment during the transient-state measurement. Furthermore, empirical relations are suggested to correlate soil thermal conductivity of fine-grained soils with plasticity index, hydraulic conductivity, and coefficient of consolidation.

Interpretation of pore pressure dissipation of CPTu in intermediate soil considering partial drainage effect

The degree of drainage that occurs during structure-soil interaction is a crucial factor that affects the stress on the structure in the intermediate soil. The consolidation coefficient is the most important index to evaluate partial drainage conditions, but the pore pressure dissipation curve used for consolidation coefficient inversion is also affected by drainage conditions. This paper adopts an effective stress numerical analysis work which combines finite-element penetration analysis and critical-state soil mechanics considering the partial drainage effect through changing the penetration rate. The significant advances of this work are the evaluation of the partial drainage effect on pore pressure test data and the influence mechanism of partial drainage on consolidation coefficient test results of intermediate soil. A modified consolidation coefficient inversion method can describe the pore-pressure response curve for dissipation tests performed in soils where pore pressure has dissipated partially. The modified theoretical relationship of vertical and horizontal consolidation coefficient and the theoretical relationship of ch under partial drainage and undrained condition are given. The consolidation coefficient inversion method of intermediate soil with high permeability is proposed, and the inversion results are consistent with the actual value.

Assessment of soil parameters during post-liquefaction reconsolidation of loose sand

Saturated deposits of loose sand may suffer liquefaction under earthquake shaking. Liquefaction-induced damage occurs during the earthquake loading and may continue during the post-liquefaction reconsolidation stage in which excess pore pressures gradually dissipate. An accurate evaluation of soil parameters is of great significance for the full depiction of this process. Consolidation-related problems are typically investigated using Terzaghi's one-dimensional consolidation theory, assuming a constant permeability, one-dimensional stiffness, and consolidation coefficient throughout this process. Some studies based on physical model tests suggest that an assumption of a single and constant value of soil parameter is not appropriate to study the reconsolidation of liquefied sand. This paper presents the results of three geotechnical centrifuge experiments to contribute to the current understanding of this phenomenon. The centrifuge data is combined with oedometer and fluidization test data, producing several empirical relationships to estimate the soil parameters related to the reconsolidation of liquefied sand. A simplified method is adopted to reproduce the time histories of excess pore pressure dissipation and ground surface settlement using the estimated soil parameters as the input. It is shown that the coefficient of consolidation and one-dimensional stiffness vary as a function of effective stress or excess pore pressure ratio, markedly increasing during the reconsolidation of liquefied sand. The predictions of the proposed methodology appear to match the experimental measurements reasonably well as long as appropriate soil parameters are used.

Spatial variation of permeability and consolidation behaviors of soil using ordinary kriging method

The present study is aimed at finding out spatial distribution of permeability characteristic of soil using ordinary kriging method at any location using the data from a few boreholes at NIT (National Institute of Technology) Patna Bihta campus. Kriging is also popularly known as BLUE (i. e. Best Linear Unbiased Estimator) which can be used to interpolate the data obtained from a few locations to get an estimate of any parameter at other locations throughout the study area. In the present work, soil samples collected from eight boreholes have been tested to obtain various geotechnical properties including liquid limit (LL), plastic limit (PL), plasticity index (IP), coefficient of volume compressibility (mv) etc. These values have been used as inputs in an Ordinary Kriging model to calculate coefficient of consolidation (Cv) and coefficient of permeability (k) throughout the NIT Patna, Bihta campus and build contour plots of (Cv) and (k) over the NIT Patna campus to show their spatial variation. The novelty of the current work lies in the first time proposed method for developing the spatial distribution of(Cv) and(k). Markov correlation matrix has been used to develop the correlation behavior of the parameters considering different values of correlation length. In the present study, it is found that the coefficient of consolidation Cv of soil ranges 10−8 (m2/sec). The Kriged values of k are in the range of 10−11 to 10−10 (m/s). Finally, semi-variogram have been shown to display the auto-correlation of the measured data points and cross-validation of data set which establish that the Kriged data are reasonably correlated. Also, various error estimators such as Mean Error, Root Mean Square Error, Average Standard Error, Root Mean Square Standard Error, Mean Standard Error have been calculated using the Kriged data points over the entire area and, it is found that the error level in the predicted Kriged data are reasonably small.

Sustainable use of soda lime glass powder (SLGP) in expansive soil stabilization

The focus of this experimental study is to ameliorate the engineering behavior of Palygorskite-rich medium Expansive soils (ES) by utilizing soda lime glass powder (SLGP). The hydrophilic ES are problematic and tend to damage the pavements, boundary walls, and slab-on-grade members Whereas, the accumulation of huge amounts of SLGP is responsible for multitude of environmental issues. Therefore, SLGP was added to the ES using various dosage levels (0 %, 6 %, 10 %, 14 %, 16 %, 18 %, and 22 % by dry weight of the ES to assess the compaction, consolidation and strength characteristics by performing geotechnical laboratory tests. Also, the effect of curing on th unconfined compressive strength of ES (UCS-ES) after 3, 7, 14, and 28 days was studied by considering the mineralogical changes. The microscopic mechanisms of the virgin ES and the SLGP-treated mixtures was evaluated by X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. The results revealed that, plasticity dropped by almost 80 % (due to filler effect, cohesionless character, and higher silica amount of the SLGP), MDD increased from 18.25 to 19.16 kN/m3, and the OMC lowered down (due to the reduction in volume of clay minerals and interlayer spaces). With increasing SLGP dosage levels the coefficient of compression (Cc) decreased by 42.86 %, coefficient of volume (mv) by 60 %, coefficient of consolidation (cv) by 91.53 %, and the pre-consolidation pressures (Pc) witnessed an increase of 240 %. The UCS-ESunsoaked values exceed than the UCS-ES soaked values, particularly at early days of curing (1–7 days) such that UCS-ESsoaked = 13 × UCS-ESsoaked after one day, whereas UCS-ESsoaked = 5.25 × UCS-ESsoaked after 28 days. Similarly, a remarkable improvement (of six -fold) in strength was recorded based on California bearing ratio (CBR) values with 16 % replacement of the SLGP additive. Also, the compactability and strength characteristics were significantly improved and the plasticity plummeted due to formation of C-S-H and C-A-H compounds. Thus, the inclusion of 16 % SLGP in the medium ES was found as the optimum amount in reducing plasticity, improving consolidation characteristics and imparting strength.

Insights into conditioning landfill sludge with freeze-thaw method: Effects on the physical-mechanical properties and micro characteristics

With the rapid increase of sludge production, large quantities of sludge with high water content (WC) are difficult to dispose of. It is necessary to evaluate sludge's physical-mechanical properties for waste sludge resource utilization and stability of landfills. In this study, freeze-thaw method is used to treat sludge. A series of tests, such as particle size analysis test, consolidation test, direct shear test, and SEM test, were carried out on the sludge treated by freeze-thaw. The influence of different refrigerating temperatures on the physical-mechanical properties is investigated. By analyzing the sludge morphology, particle distribution, pore change, consolidation and compression characteristics, shear characteristics, and microstructure, the influence mechanism of refrigerating temperature on sludge's physical-mechanical properties are revealed. The results show that after the freeze-thaw, the sludge particles gathered together, the water is easy to separate from solid particles. In addition, compressibility and void ratio of sludge decrease. At the same time, the permeability coefficient and consolidation coefficient increased by 1–2 orders of magnitude. When the freezing rate is slow, the sludge particles are pushed and squeezed by the ice layer, destroying the floc structure; when the freezing rate is high, the bound water can be better removed, which is conducive to forming a denser structure. Therefore, the cohesion of sludge decreases, and the internal friction angle increases after freeze-thaw treatment. Shear performance improved. The results of this study provide a reference for waste sludge resource utilization.