Behaviour Of Fine-grained Soils Research Articles

Prediction of Liquefaction Behaviour of Fine-Grained Soil Using Nature-Inspired Optimized Algorithms Coupled with Neural Network

Prediction of Liquefaction Behaviour of Fine-Grained Soil Using Nature-Inspired Optimized Algorithms Coupled with Neural Network

Experimental investigation into the mechanical behavior of fine-grained soils reinforced with a newly developed branched fiber: a comparative study

Experimental investigation into the mechanical behavior of fine-grained soils reinforced with a newly developed branched fiber: a comparative study

Effect of temperature on the mechanical properties of fine-grained soils - A review

Contemporary geotechnical engineering practice encompasses design and construction of thermo-active geo-structures or structures which would encounter thermal cycles throughout its service life. Therefore, understanding the effect of temperature on soil mechanical properties becomes inevitable. Being a complex and coupled phenomenon it has been quite challenging for the researchers to study experimentally and theoretically the thermo-mechanical behaviour of fine-grained soil. Nonetheless, there are numerous studies which contribute significantly to gain insight about thermo-mechanical behaviour of soils. Incidentally, till date, on this arena of research, no comprehensive review, which provides a holistic development of the subject and its connection with the field application, is available. The prime objective of the present study is to critically appraise the state-of-the-art understanding on thermo-mechanical behaviour of fine-grained soils through a comprehensive literature review. Moreover, this paper also describes the concept of thermo-elasto-plastic strain and thermal creep behaviour of fine-grained soils.

Isotropic Pressure Membrane Sensor to Establish Shrinkage Stress Evolution in Clayey Soil

Abstract The shrinkage behavior of clay has been identified to have a significant influence on many geotechnical problems that include foundation failure, slope instability, damages in buried pipelines, crack formation in liner systems, etc. In this context, researchers have focused on understanding and quantifying the effect of shrinkage behavior of fine-grained soils in terms of volumetric shrinkage and crack propagation. But it has been realized that shrinkage stresses would also develop in fine-grained soil mass in tandem with volumetric shrinkage owing to tensile stresses and particle rearrangement. This necessitates mapping shrinkage stress evolution in clayey soils of distinct mineralogical and plasticity characteristics. Under these circumstances, the authors have developed a novel isotropic pressure monitoring device (I-PMD) and test protocols to measure shrinkage stress in clayey soil. The results obtained from the present study demonstrate the efficacy of employing I-PMD for establishing (i) soil shrinkage stress curve and (ii) maximum shrinkage stress σsmax of clayey soils while drying. From the present study, it has been inferred that the shrinkage stress initiation point is dependent on its liquid limit, and also, a steady increase in stress generation has been identified in its semisolid state. The result obtained from the experimental studies has been utilized to establish the empirical relationship to estimate shrinkage stress from clay characteristics.

Effect of soil hydrophobicity on soil-water retention curve of a silt loam soil

Soil wettability is an important property that affects the behaviour of fine-grained soils. Previous studies have shown that hydrophobicity induced by organic or silane additives may affect the soil-water retention curve (SWRC). However, current findings regarding the effect of hydrophobicity on the SWRC are controversial. Previously, organic or silane additives were assumed to change only the soil wettability. Nevertheless, this study shows that polyvinyl alcohol (PVA) can change the hydrophobicity, pore size distribution (PSD), and specific surface area (SSA) of soil, thus affecting the SWRC. PVA-treated soil is hydrophobic when cured at 20 ℃, but hydrophilic when cured at 100 ℃. No thermal degradation is indicated in the PVA at 100 ℃ based on thermogravimetric analysis and a comparison of mass loss, and the sole difference between the PVA-treated soils cured at 20 and 100 ℃ is their wettability. This study managed to make the hydrophobicity caused by PVA to become an independent variable separated from the PSD and SSA by controlling the ambient temperature. The wetting and drying curves are measured under isopiestic humidity control in the high-suction domain (2.7–298.7 MPa), whereas pressure plates are used for the drying curves in the low-suction domain (0–800 kPa). The results obtained indicate that soil hydrophobicity significantly accelerates drainage when the matric suction is between 100 and 400 kPa, and an increase in PVA content increases the water retention capacity of soil. When the matric suction exceeds 2.7 MPa, the effect of soil hydrophobicity on the SWRC of the soil weakens. At this time, the SWRC is dominated by the van der Waals force, and the SSA contributes significantly to the process. Additionally, this study enables some controversial findings from previous studies to be explained, which is of great significance in soil and agriculture sciences.

Insights into the mechanism of earthquake-triggered landslides in plastic fine-grained soils

This article seeks to investigate the cyclic behaviour of fine-grained soils and clarify the mechanism of earthquake-triggered landslides in this material. Six soils with different plasticity and mineralogy were tested in a series of undrained ring-shear experiments using different stress histories. The obtained results were analyzed in relation to the soil plasticity, clay mineralogy, and soil microfabrics to better understand the main factors leading to failure. It was found that the low-plasticity soil mixtures containing either kaolinite or illite were susceptible to liquefaction, while more plastic soil specimens that contained smectite were resistant to liquefaction. The mechanism of earthquake-triggered landslides and the factors affecting them were discussed, and it was experimentally shown that the failure in plastic fine-grained soils was not driven by the excess pore water pressure. Instead, it occurred mostly due to the large permanent shear displacements developed during cyclic loading.

Effects of Strain Rate and Specimen Size on the Behavior of Fine-Grained Soils

Effects of Strain Rate and Specimen Size on the Behavior of Fine-Grained Soils

Influence of index properties on the cyclic failure of fine-grained soils

The purpose of this study is to develop an easy procedure to diagnose the cyclic behavior of fine-grained soils, leading to liquefaction.There are approaches to this problem with reference to liquid limit (wL), plasticity index (PI), clay content, (C%), in-situ water content compared to the liquid limit (wn/wL), average grain size (D50), and liquidity index (IL). Previous research has indicated that fine-grained soils defined as “sand-like” are prone to liquefaction. There is consensus that liquefiable silty soils have “sand like” characteristics. In the transition from sandy to clayey, it is generally accepted that it would be appropriate to make a judgment by making use of mechanical testing and that clayey soils do not liquefy.This paper presents the results of dynamic triaxial shear testing (CTX), where excess pore water pressures and axial strains are evaluated compared to the physical properties to reach the threshold for cyclic failure. Samples of undisturbed soil procured from different locations of the city of Adapazarı, Turkey, were subjected to CTX testing. The results were interpreted in the light of the physical properties to arrive at a judgment of cyclic failure.Being able to identify a liquefaction prone fine grained soil by merely measuring a few physical properties without resorting to arduous cyclic testing would be an advantage to the practising engineer. This however necessitates the elimination of the ‘gray zone’ for which most researchers recommended the use of cyclic testing.The main finding of this study is that samples reaching double strain amplitude (DSA) of <5% in the CTX test contain no sand and have a clay content of 20% or more. An attempt to establish a relationship between sensitivity to cyclic loading and physical properties is also made.

Compressibility, permeability and microstructure of fine-grained soils containing diatom microfossils

Fine-grained soils containing diatom microfossils of biological origin are found worldwide. However, although these soils are acknowledged to have unique physical and mechanical properties, the exact role of diatoms in determining their compression and hydraulic behaviours remains unclear, especially when high effective stress is involved, and the underlying micromechanism is yet to be revealed. This study investigated the compression and permeability of diatomaceous soils prepared by mixing pure diatom and kaolin powders through one-dimensional constant rate of strain compression tests with a maximum vertical stress of 10 MPa. The microstructure of the soils studied was observed by atomic force microscopy, scanning electron microscopy and mercury intrusion porosimetry, and the microstructural evolution during compression was traced. The results indicate that the special hollow structure of diatom particles with internal pores contributes significantly to the high void ratio, compressibility and permeability of diatomaceous soils, and increasing the diatom content improves the pore distribution non-uniformity of the diatom–kaolin mixtures. In addition, the diatom particles have high brittleness and breakage potential, leading to microstructural rearrangement during compression, especially pore-structure adjustment. Lower compressive stress deforms the inter- and intra-aggregate pores, but higher vertical stress damages the diatoms’ hollow structure, which changes the compression and hydraulic parameters in a different manner from the case of conventional clay. This paper enriches the knowledge concerning the multilevel behaviour of fine-grained soils containing diatom microfossils and provides a fundamental dataset.

Enhancement of a hydro-mechanical hypoplastic model for unsaturated fine-grained soils accounting for small strain stiffness

Due to global climate change, larger extreme seasonal and daily moisture variations have been occurring more frequently in the last decades. This phenomenon can affect geotechnical structures by inducing cyclic coupled hydro-mechanical loads. However, reproducing this behaviour from a numerical point of view requires robust constitutive models that can predict the coupling between the hydraulic and mechanical behaviour of fine-grained soils, combined with predictions of history-dependent stiffness evolution at small strains. For this reason, in the present work the hypoplastic model for unsaturated finegrained soils was further modified to better predict the water retention behaviour of unsaturated soils incorporating a smoothed hysteretic Water Retention Curve (WRC). In addition, the constitutive model wascalibrated using experimental data available on the literature of a completely decomposed tuff (CDT) from Hong Kong. At the end, the capabilities of the extended model to predict cyclic behaviour of unsaturated soils were evaluated using cyclic constant water triaxial tests at different suctions The results indicate that the extended model is able to describe with more accuracy the cyclic hydro-mechanical behaviour of the decomposed tuff if additional suction-dependency of one of its small-strain parameters is considered. Without this, the model can be calibrated to data at a given suction but its cyclic predictions for different suctions are not reasonably accurate.

Strength Behaviour of Expansive Subgrade Soil Stabilized with Coronus Material

Expansive subgrade soil needs to be re-engineered to enhance the load-bearing capacity as it lacks the capacity to sustain traffic and pavement load. Although various chemical modification techniques have proven to be effective for stabilization, they are expensive and unsustainable. Coronus aggregate material is an uplifted coralline deposit abundantly available in the Pacific. The current study focuses on the strength behavior of fine-grained soil notably clayey soil when blended with coronus material as a potential alternative to the usual soil stabilization methods employed in the construction industry. To successfully stabilize the clayey soil sample with the coronus material, the particle size distribution, coefficient of uniformity, and curvature of the clayey soil sample and coronus material were determined. The results indicate that the coronus material is well-graded. The consistency of the soil sample was determined using the four-point Casagrande method for Atterberg limits i.e, the liquid limit, plastic limit, and shrinkage limit of the clayey soil. The load-bearing capacity of the clayey soil stabilized with coronus material was determined using standard compaction tests to calculate the maximum dry density and optimum moisture content of clay before and after blending with 10% increments of coronus material. The California Bearing Ratio (CBR) test results of all the samples were determined using standard CBR laboratory tests. It has been observed that the addition of coronus material has improved the load-bearing capacity of clayey soil. Hence, it is recommended that, wherever possible, coronus material be utilized as a stabilizing agent to improve the geotechnical properties of expansive subgrade soil.

A thermodynamically consistent two surface/bubble thermo-mechanical model considering thermal and mechanical cyclic behaviour of fine-grained soils

The formulation of a two surface/bubble thermo-mechanical constitutive model consistent with the principles of thermodynamics is presented. This allows plastic deformations inside the outer yield surface, resulting in a smooth stress–strain prediction and progressive cyclic deformations. This is achieved by the translation of the inner yield surface (also known as the bubble surface) with the stress state of the soil, inside the outer yield surface, by using a kinematic rule. The constitutive equations, including the hardening rules, are derived by specifying a Gibbs-type energy potential and a rate of dissipation potential function, ensuring thermodynamic consistency. The kinematic rule is divided into isothermal and non-isothermal parts. With the isothermal component, the model is capable of capturing the hysteresis behaviour of soils during cyclic mechanical loading. With the non-isothermal part, the model is able to predict the shakedown behaviour of soils observed when they are subjected to heating–cooling cycles. The performance of the model is compared with various experimental data for isothermal and non-isothermal conditions, and is shown to be in good agreement.

Laboratory Testing of Kinetic Sand as a Reference Material for Physical Modelling of Cone Penetration Test with the Possibility of Artificial Neural Network Application.

Cone Penetration Testing (CPT) is a quick survey in situ method through which soil parameters are not determined directly, but have to be estimated using derived relations between required soil parameter and soil resistance at the testing probe. Boundary conditions affect the reliability of the estimated soil parameters, therefore controlled laboratory conditions were applied to the intended CPT procedure analysis. Density, pycnometry, oedometer and direct shear tests of kinetic sand were performed to prove its usability as a reference testing material for further CPT laboratory analysis. The results of testing the kinetic sand are presented in this paper. Executed tests proved the kinetic sand as a reliable material in terms of the homogeneity and consistency of its physical and mechanical parameters. The material is utilizable as a substitution of cohesive sandy soils in physical modeling without the negative impact of the consistency-dependent behavior of fine-grained soils. However, some differences in parameters with respect to the natural soils should be taken into account. Neural network theory and numerical approach will be applied to the intended CPT laboratory analysis under controlled boundary conditions using kinetic sand to evaluate its potential for the determination of soil parameters.

Prediction of the Seismic Effect on Liquefaction Behavior of Fine-Grained Soils Using Artificial Intelligence-Based Hybridized Modeling

Prediction of the Seismic Effect on Liquefaction Behavior of Fine-Grained Soils Using Artificial Intelligence-Based Hybridized Modeling

Parametric study of glass fiber reinforced fine-grained soil with emphasis on microstructural analysis

ABSTRACT A comprehensive experimental programme was undertaken to study the parametric effect on mechanical behaviour of fine-grained soils by inclusion of glass fibres. The behaviour of both unreinforced and reinforced soil specimens under uni-axial compression was systematically investigated corresponding to fibre length, fibre content, soil density, moisture content and loading rate. The unconfined compression strength test (UCS) results confirmed the reliance of UCS improvement index () on the selected parameters. For 18 mm fibre length and 0.9% fibre content, UCS improvement index of 71.68% was observed. The interface morphologies were studied by analysing the failure patterns and microstructural mechanisms through scanning electron microscopy. Artificial neural network (ANN) was used to develop an estimation model of the relationship between soil strength and different reinforcement parameters. This study is expected to help in better understanding of mechanical behaviour of FRS and its subsequent application in the field.

Experimental and modeling study of water-retention behavior of fine-grained soils with dual-porosity structures

Experimental and modeling study of water-retention behavior of fine-grained soils with dual-porosity structures

Shear strength and stiffness behavior of fine-grained soils at different surface hydration conditions

We developed an experimental program to monitor how interparticle forces control the mechanical behavior of fine-grained soils when saturation changes from the tightly adsorbed regime to saturation. The testing program uses stiffness (i.e., S-wave velocity) and strength (i.e., Brazilian tensile strength) tests on kaolinite, silica flour, and diatomaceous earth soil samples at very low confining stresses (&lt;5 kPa). Three fine-grained soils yield a range of different properties, including particle size, specific surface area, negative charge density, and internal or external particle porosity. Results show that shear stiffness and tensile strength follow similar trends, emphasizing that the same interparticle forces control the mechanical responses. In particular, the interpretation of S-wave velocity measurements shows three different behavior ranges: a van der Waals attraction range, a capillary-dominated interparticle forces range, and the continuous decrease in the capillary forces from the saturation at the air-entry pressure until full saturation. We show that the interparticle forces respond to a complex function of water content, particle size, particle separations, surface charge density, and the presence of internal particle porosity.

Strength and Deformation Behavior of Fine-Grained Soils Reinforced with Hair Fibers and Its Application in Pavement Design

ABSTRACT Although waste hair fibers are consumed in agricultural and pharmaceutical industries, etc., their use in civil engineering is very limited. Because of fibrous nature, it can be used as reinforcement material in soil for sustainable development, similar to other commercially used fibers in practice. In this study, an effort is made to improve the properties of the Delhi silt and Dhanauri clay using the human hair fiber. All the tests on Delhi silt and Dhanauri clay were performed with optimum fiber content, i.e., 2%. The results indicate that the shear strength, modulus and CBR value of soil reinforced with human hair fibers have increased considerably. And then, the suitability of human hair fibers in pavement engineering is examined by designing both rigid and flexible pavements using improved properties. Results indicate that there is a reduction in thickness of both pavements, which means that there can be saving of cost in major projects, when human hair fiber is used.

Laboratory study and measurement of stiffness and compaction of unsaturated clay soil by using the innovative rebound hammer

Defining soil behavioral parameters, which eventually results in predicting every short-term and long-term soil behavior, has continually been one of the interests of soil mechanics and has been of exceptional value. To this end, in this study, a novel method has been reviewed to determine the compressive behavior of fine-grained soils in the laboratory and the field, without sampling by the patented electronic device. In the lab, homogeneous materials of the intended soil underwent the compaction test, mechanical and physical tests, direct shear test, and impacts of the innovative rebound hammer in the horizontal and vertical directions in the test-box. The impact shear waves produce resistance and voltage output by force and dislocation sensors with high-sensitivity proportional to the pressure based on the soil surface stiffness. The obtained voltages are then converted to digital by an analog-to-digital converter and a microcontroller. Next, a number is shown on display by the "CodeVision" program. Then, by solving a quasi-dynamic equation (Viscoelastic spring-damper model) by MATLAB software and with the aid of laboratory-field results and correlation equations, a fitting connection between all effective mechanical soil parameters has been estimated to an acceptable extent. The effective mechanical parameters of the soil include the compaction percentage, specific gravity, and frequency of the system in the damped and non-damped states, the energy imposed on the soil, and the plastic stage strain in the range of less than 15% humidity. The results determine that increased hammering numbers are directly related to increased soil compaction and stiffness. In more detail, the reading of hammer numbers less than 2 corresponds to compaction of less than 75%, while the reading of hammer numbers greater than 3 in the vertical and 2.94 in the horizontal directions on clay surfaces designates compaction of 90%.

An investigation into the effects of lime on compressive and shear strength characteristics of fiber-reinforced clays

To meet the ever-increasing construction demands around the world during recent years, reinforcement and stabilization methods have been widely used by geotechnical engineers to improve the performances and behavior of fine-grained soils. Although lime stabilization increases the compressive strength of soils, it reduces the soil ductility at the same time. Recent research shows that random fiber inclusion modifies the brittleness of soils. In the current research, the effects of lime and polypropylene (PP) fiber additions on such characteristics as compressive and shear strengths, failure strain, secant modulus of elasticity ( E 50 ) and shear strength parameters of mixtures were investigated. Kaolinite was treated with 1%, 3% and 5% lime by dry weight of soil and reinforced with 0.1% monovalent PP fibers with the length of 6 mm. Samples were prepared at optimum conditions and cured at 35 °C for 1 d, 7 d and 28 d at 90% relative humidity and subsequently subjected to uniaxial and triaxial compression tests (UCT and TCT) under cell pressures of 25 kPa, 50 kPa and 100 kPa. Results showed that inclusion of random PP fibers to clay–lime mixtures increases both compressive and shear strengths as well as the ductility. Lime content and curing period were found to be the most influential factors. Scanning electron microscopy (SEM) analysis showed that lime addition and the formation of cementitious compounds bind soil particles and increase soil/fiber interactions at interface, leading to enhanced shear strength. The more ductile the stabilized and reinforced composition, the less the cracks in roads and waste landfill covers.