Pile Material Research Articles

Workers' exposure to bioaerosols from three different types of composting facilities

ABSTRACTComposting is a natural dynamic biological process used to valorise putrescible organic matter. The composting process can involve vigorous movements of waste material piles, which release high concentrations of bioaerosols into the surrounding environment. There is a lack of knowledge concerning the dispersal of airborne microorganisms emitted by composting plants (CP) as well as the potential occupational exposure of composting workers. The aim of this study was to investigate the workers exposure to bioaerosols during working activities in three different types of composting facilities (domestic, manure, carcass) using two different quantification methods (cultivation and qPCR) for bacteria and moulds concentrations. As expected, even if there are differences between all CP frameworks, independently of the type of the raw compost used, the production of bioaerosols increases significantly during handling activities. Important concentrations of mesophilic moulds and mesophilic bacteria were noted in the working areas with a respective maximal concentration of 2.3 × 105 CFU/m3 and 1.6 × 105 CFU/m3. A. fumigatus and thermophilic Actinomycetes were also detected in all working areas for the 3 CP. This study emphases the risks for workers to being in contact with aerosolized pathogens such as Mycobacterium and Legionella and more specifically, L. pneumophila. The presence of high concentration of these bacteria in CP suggests a potential occupational health risk. This study may lead to recommendations for the creation of limits for occupational exposure. There is a need for identifying the standards exposure limits to bioaerosols in CP and efficient recommendation for a better protection of workers' health.

Experimental study on the effect of particle shape on stress dip in granular piles

ABSTRACT The purpose of this study is to identify the effect of particle shape on stress dip underneath granular piles based on the results of laboratory-scale experiments using a high sensitivity stress sensor mat system. Two different granular materials with contrasting particle shapes but in similar size ranges were evaluated. Wedge-shaped and conical piles of granular materials were formed by pouring using a local source method. Stress dip at the center was measured in all piles but with different developing situations. We suggest the use of the ratio of the maximum stress over the dipped stress value at the center as a quantitative index to assess the stress dipping effect. We observed that a higher elongation of the particle shape would yield a more profound stress dip under the pile. When piles of the same material but in various pile shapes are compared, stress dip is found to be more profound, and the influence of the particle shape is more obvious in a 3-d axisymmetic conical pile than in a 2-d plane-strain wedge-shaped pile. The reason is that a larger elongation of the particle shape be helpful for more steady arches with strong force chains formed to support more weight of the middle part of the pile, especially in a 3-d axisymmetic configuration.

Experimental study on axial response of different pile materials in organic soil

Sixty four tests were performed in a steel tank to investigate the axial responses of piles driven into organic soil prepared at two different densities using a drop hammer. Four different pile materials were used: wood, steel, smooth concrete, and rough concrete, with different length to diameter ratios. The results of the load tests showed that the shaft load capacity of rough concrete piles continuously increased with pile settlement. In contrast, the others pile types reached the ultimate shaft resistance at a settlement equal to about 10% of the pile diameter. The ratios of base to shaft capacities of the piles were found to vary with the length to diameter ratio, surface roughness, and the density of the organic soil. The ultimate unit shaft resistance of the rough concrete pile was always greater than that of other piles irrespective of soil condition and pile length. However, the ultimate base resistance of all piles was approximately close to each other.

Field Tests of Cement Fly-Ash Steel-Slag Pile Composite Foundation

Abstract Steel slag is one of the main waste materials in the steelmaking process. As a result, a tremendous amount of steel slag is produced and deposited into storing yards every year. Recycling of the abandoned steel slag is of great environmental and economic value. This study investigates the usage of steel-slag concrete with fly ash as a kind of composite foundation pile material, which can be applied to multi-pile composition foundations for ground improvement involving different pile types. The micromorphology of the concrete, which uses steel slag as aggregate, is analyzed using scanning electron microscopy (SEM). The bearing characteristics of cement fly-ash steel-slag pile (CFS pile) composite foundations are investigated via field load tests, including settlement of the foundation base, horizontal displacement at different depths, distribution of vertical stress increase of the composite foundation, and stress increase of the soil around the pile hole. In addition, the effect of soil squeezing caused by the construction of a CFS pile is studied. To accomplish this, the variation in the increase in stress of the foundation at different distances in the horizontal direction is measured. The results suggest that the usage of steel slag as an aggregate can effectively satisfy the strength requirement of the pile. CFS pile composite foundations have the advantages of high bearing capacity, small settlement deformation, and limited horizontal deformation. This study demonstrates the potential usage of steel slag as aggregate in pile composite foundations, which can bring significant economic and environmental benefits.

The load-bearing capacity of hanging piles by the strength criterion of a pile or soil material

The load-bearing capacity of hanging piles by the strength criterion of a pile or soil material

Sedimentation Calculation Based on Alamgir Model of Composite Foundation in Biding Material Pile

Sedimentation Calculation Based on Alamgir Model of Composite Foundation in Biding Material Pile

Retrofitting of bridge abutment timber piles using fiber-reinforced polymer composites

Fiber-reinforced polymer (FRP) composites offer a versatile and effective retrofitting option for deteriorated bridge timber piles. Although full confinement using FRP is not feasible for abutment piles, reinforcing the tension side of the pile can effectively improve the stiffness and strength of abutment piles. In this study, three full-scale timber piles are tested. Nondestructive stress wave timing methods are used to assess the initial condition of the piles and two inferior specimens are retrofitted with Glass-FRP (GFRP) composites in different configurations. To simulate typical loading on abutment piles, a unique test set-up is developed to apply a bending moment through eccentric loading. Test results show that a reliable estimate of the existing timber pile material properties is in order to design effective FRP retrofits. Using timber pile material models calibrated using the experimental results, a finite element (FE) model of the test set-up is developed to investigate FRP retrofit design requirements. Finite element analysis shows that the retrofit methods used in the experimental study are highly effective especially under high-bending moments. However, the FRP configuration and amount of FRP required must be determined based on the timber pile condition.

Construction Technology and Mechanical Properties of a Cement-Soil Mixing Pile Reinforced by Basalt Fibre

A new type of cement-soil mixing pile reinforced by basalt fibre is proposed for increasing the bearing capacity of cement-soil mixing piles. This work primarily consists of three parts. First, the process of construction technology is proposed, which could allow uniform mixing of the basalt fibre in cement-soil. Second, the optimal proportions of the compound mixtures and the mechanical properties of the pile material are obtained from unconfined compression strength test, tensile splitting strength test, and triaxial shear test under different conditions. Third, the reliability of the construction technology, optimal proportions, and mechanical properties are verified by testing the mechanical properties of the drilling core sample on site.

Surface topography and roughness of high-speed milled AlMn1Cu

The aluminum alloy AlMn1Cu has been broadly applied for functional parts production because of its good properties. But few researches about the machining mechanism and the surface roughness were reported. The high-speed milling experiments are carried out in order to improve the machining quality and reveal the machining mechanism. The typical topography features of machined surface are observed by scan electron microscope(SEM). The results show that the milled surface topography is mainly characterized by the plastic shearing deformation surface and material piling zone. The material flows plastically along the end cutting edge of the flat-end milling tool and meanwhile is extruded by the end cutting edge, resulting in that materials partly adhere to the machined surface and form the material piling zone. As the depth of cut and the feed per tooth increase, the plastic flow of materials is strengthened and the machined surface becomes rougher. However, as the cutting speed increases, the plastic flow of materials is weakened and the milled surface becomes smoother. The cutting parameters (e.g. cutting speed, feed per tooth and depth of cut) influencing the surface roughness are analyzed. It can be concluded that the roughness of the machined surface formed by the end cutting edge is less than that by the cylindrical cutting edge when a cylindrical flat-end mill tool is used for milling. The proposed research provides the typical topography features of machined surface of the anti-rust aluminum alloy AlMn1Cu in high speed milling.

Three-dimensional simulations of turbulent convective mixing in ONe and CO classical nova explosions

Classical novae are thermonuclear explosions that take place in the envelopes of accreting white dwarfs in binary systems. The material piles up under degenerate conditions, driving a thermonuclear runaway. The energy released by the suite of nuclear processes operating at the envelope heats the material up to peak temperatures of ~(1-4) × 108 K. During these events, about 10-3-10-7 M⊙, enriched in CNO and, sometimes, other intermediate-mass elements (e.g., Ne, Na, Mg, Al) are ejected into the interstellar medium. To account for the gross observational properties of classical novae (in particular, the high concentrations of metals spectroscopically inferred in the ejecta), models require mixing between the (solar-like) material transferred from the secondary and the outermost layers (CO- or ONe-rich) of the underlying white dwarf. Recent multidimensional simulations have demonstrated that Kelvin-Helmholtz instabilities can naturally produce self-enrichment of the accreted envelope with material from the underlying white dwarf at levels that agree with observations. However, the feasibility of this mechanism has been explored in the framework of CO white dwarfs, while mixing with different substrates still needs to be properly addressed. We performed three-dimensional simulations of mixing at the core-envelope interface during nova outbursts with the multidimensional code FLASH, for twomore » types of substrates: CO- and ONe-rich. We also show that the presence of an ONe-rich substrate, as in “neon novae”, yields higher metallicity enhancements in the ejecta than CO-rich substrates (i.e., non-neon novae). Finally, a number of requirements and constraints for such 3D simulations (e.g., minimum resolution, size of the computational domain) are also outlined.« less

Influence of vertical loads on lateral response of pile foundations in sands and clays

Although the load applied to pile foundations is usually a combination of vertical and lateral components, there have been few investigations on the behavior of piles subjected to combined loadings. Those few studies led to inconsistent results with regard to the effects of vertical loads on the lateral response of piles. A series of three-dimensional (3D) finite differences analyses is conducted to evaluate the influence of vertical loads on the lateral performance of pile foundations. Three idealized sandy and clayey soil profiles are considered: a homogeneous soil layer, a layer with modulus proportional to depth, and two-layered strata. The pile material is modeled as linearly elastic, while the soil is idealized using the Mohr–Coulomb constitutive model with a non-associated flow rule. In order to confirm the findings of this study, soils in some cases are further modeled using more sophisticated models (i.e. CYsoil model for sandy soils and modified Cam-Clay (MCC) model for clayey soils). Numerical results showed that the lateral resistance of the piles does not appear to vary considerably with the vertical load in sandy soil especially at the loosest state. However, the presence of a vertical load on a pile embedded in homogeneous or inhomogeneous clay is detrimental to its lateral capacity, and it is unconservative to design piles in clays assuming that there is no interaction between vertical and lateral loads. Moreover, the current results indicate that the effect of vertical loads on the lateral response of piles embedded in two-layered strata depends on the characteristics of soil not only surrounding the piles but also located beneath their tips.

CHD pile performance: part II – numerical modelling

A set of simple finite-element modelling procedures that can be used to estimate the load–settlement behaviour of continuous helical displacement (CHD) piles in sand is presented. The approach makes use of a stress- and strain-dependent non-linear soil model that can be parameterised using basic soil data that can be determined through routine site investigation. The procedures are validated against a database of physical model tests (reported in a companion paper), where they are shown to be suitable for estimating the load–settlement behaviour of CHD piles within the serviceability range. In this way they are complementary to the analytical method reported in the companion paper for estimating the ultimate capacity of a CHD pile. In this paper, the finite-element method and analytical model are applied to four historical load tests on CHD piles conducted at three different sand sites. The modelling is further validated and used to discuss potential savings in pile material and therefore cost due to additional confidence in performance determination at both ultimate and serviceability limit states.

Hyperbolic model to evaluate uplift force on pile in expansive soils

The piles in expansive soils would experience uplift force on the shaft of the piles due to the swelling of the soils. For a given soil, the magnitude of interface shear stress (uplift force) on pile depends on the interface friction between the pile material and the soil, normal stress acting on the pile surface and the magnitude of swelling, which in turn creates the relative movement at the interface between the soil and the pile material. The hyperbolic representation of stress strain curves has been found to be a convenient and useful means of representing the non-linearity of the stress strain curves of soils and forms an important part of the stress strain relationship. In this paper a simplified hyperbolic model is proposed to evaluate the pile uplift in expansive soil. The hyperbolic model is developed based on the model pile uplift tests, interface shear tests and consolidation test results. The interface shear stress is also evaluated using a program PIES (Axial response of Pile In Expansive Soils). Both the analytical studies gave a good correlation of interface shear stress profile obtained by laboratory studies. Finally a design procedure is proposed to evaluate the uplift force along the shaft of pile in expansive soils.

Laboratory investigations of the thermal performance of an energy pile with spiral coil ground heat exchanger

Spiral coil energy pile is a new type of ground heat exchanger (GHE) used in the ground coupled heat pump (GCHP) system. In this manuscript, a model experimental apparatus of energy pile with spiral coil was set up based on the similarity principle. The experimental investigations of influences of inlet water temperature, intermittent operation mode, spiral pitch and pile material on the thermal behavior of the spiral coil energy pile and soil temperature distribution around it were performed on the experimental apparatus. The experimental results indicate that increasing the inlet temperature contributes to the increase of heat release rate of coil, and the heat release rate increases approximately linearly with the inlet temperature. At the same time, the higher the inlet temperature, the more the heat storage in the pile. For a given inlet temperature, the soil temperature at a level gradually increases from center to outer surface of the pile, and then drops sharply across the outer surface. Under the intermittent operation mode, the soil temperature rise can be stayed effectively by a reasonable intermittent operation control, and thus the performance of GCHP can be improved. As for the spiral pitch, reducing the spiral pitch can increase the total heat release rate of the coil, but also result in the decrease of heat release rate per unit pipe length. Thus, the spiral pitch cannot be reduced unlimitedly and should be optimized through considering the total heat release rate, the heat release rate per unit pipe length, available pile area, and the costs of installation and material. Additionally, increasing the thermal effusivity of pile material can enhance the heat release rate of coil, but also reduce the temperature restoration effect of the soil surrounding the pile. Thus, the selection of pile materials should be overall considered according to the construction requirement of building foundation pile and the heat transfer optimization of energy pile.

Railway Infrastructure to Support Inter-modal Transportation from Port to Hinterland (Case Study-Manyar Port)

It has been encountered that port operations where lines of trucks are queuing at the port entrance, flotillas of vessels are waiting at sea, piles of freight, raw materials or containers are clogging the dockside and could led to significant congestions. This research aims to evaluate railway infrastructure surrounding new East Java Province port that can be used to reduce traffic congestions to allow the general public to move efficiently around the city and to facilitate the smooth passage of freight from port to the hinterland.

A review on soil–structure interaction analysis of laterally loaded piles

Abstract Soil–structure interaction plays an important role in the behavior of structure under static or dynamic loading. It influences the behavior of soil, as well as the response of pile under loading. The analysis is highly essential for predicting a more accurate structural behavior so as to improve the safety of structures under extreme loading conditions. The soil–pile system behavior is predominantly nonlinear and this makes the problem complicated. In a laterally loaded pile the load is resisted by the soil–pile interaction effect, which in turn depends on soil properties, pile material, pile diameter, loading type and bed slope of ground. The difficulty in the accountability of the influencing factors necessitates a careful study on soil–structure interaction problem. The analysis became easier with the debut of powerful computers and simulation tools such as finite element analysis software. A detailed literature review on soil–structure interaction analysis of laterally loaded piles is presented in this paper.

Aerodynamic properties of Faba bean (<italic>Vicia faba</italic> L.) Seeds

Aerodynamic properties of agricultural materials are the physical properties considering the reaction of agricultural material piles or seeds against airflow. The airflow resistance of faba bean (<italic>Vicia faba</italic> L.) seed piles was experimentally determined and mathematically modeled for two different moisture contents (11.4 % and 25.8% w.b.) for the superficial air velocities ranging from 0.0225 to 1.395 m<sup>3</sup>·m<sup>−2</sup>·s<sup>−1</sup>. Modified Shedd’s equation and Hukill-Ives equation can be interchangeably used to design aeration systems for the storage and drying bins of faba bean seeds. The terminal velocity values are 11.68 and 12.87 m·s<sup>−1</sup> for the moisture contents of 11.4% and 25.8% (w.b.), respectively. The drag coefficient values are 1.02 and 0.88 for the moisture contents of 11.4% and 25.8% (w.b.), respectively. Moisture content increased terminal velocity but decreased drag coefficient.

Numerical Modeling of Granular Anchor Pile System in Loose Sandy Soil Subjected to Uplift Loading

During the last few decades various researchers have proposed appropriate experimental and numerical methods to estimate the uplift capacity of granular anchor piles (GAPs) in expansive soils. Surprisingly, very few studies have been performed to determine the uplift capacity of GAPs in loose sands. This paper presents the results of the numerical study to estimate the ultimate uplift capacity of group piles. Numerical analysis is performed using finite element software PLAXIS-3D. The foundation system is assumed to consist of a different number of regularly spaced GAPs installed in loose sandy soils. The analysis examines the influence of factors such as number of piles n and length L to width D ratio, and properties of the granular pile material and compares the efficiency of group of GAP systems of different configurations.

토목섬유로 보강된 성토지지말뚝 구조에 적합한 말뚝재료의 개발

ABSTRACT It is a current trend that the concrete track is applied for high speed railway. In the case of the railway embankment constructed on soft ground, the damage to concrete track which is sensitive to settlement such as distortion and deflection could be caused by very small amount of long term settlement. Pile Supported Embankment method can be considered as the effective method to control the residual settlement of the railway embankment on soft ground. The Geosynthetics is used inside of the embankment to maximize the arching effect transmitting the load of the embankment to the top of the piles. But, PHC piles that are generally used for bridge structures are also applied as the pile supporting the load of embankment concentrated by the effect of the Geosynthetics. That is very low efficiency in respect of pile material. So, in this study, the cast in place concrete pile was selected as the most suitable pile type for supporting the embankment by a case study and the optimum mixing condition of concrete using a by-product of industry was induced by performing the mixing designs and the compressive strength designs. And it is shown that the cast in place pile with the optimum mixing condition using the by-product of industry is 2.8 times more efficient than the PHC pile for the purpose of Pile Supported Embankment by the finite element analysis method.

A new design chart for estimating friction angle between soil and pile materials

Frictional forces between soil and structural elements are of vital importance for the foundation engineering. Although numerous studies were performed about the soil-structure interaction in recent years, the approximate relations proposed in the first half of the 20th century are still used to determine the frictional forces. Throughout history, wood was often used as friction piles. Steel has started to be used in the last century. Today, alternatively these materials, FRP (fiber-reinforced polymer) piles are used extensively due to they can serve for long years under harsh environmental conditions. In this study, various ratios of low plasticity clays (CL) were added to the sand soil and compacted to standard Proctor density. Thus, soils with various internal friction angles (φ) were obtained. The skin friction angles (δ) of these soils with FRP, which is a composite material, steel (st37) and wood (pine) were determined by performing interface shear tests (IST). Based on the data obtained from the test results, a chart was proposed, which engineers can use in pile design. By means of this chart, the skin friction angles of the soils, of which only the internal friction angles are known, with FRP, steel and wood materials can be determined easily.