Size Distribution Sand Research Articles

Shear Mechanism and Optimal Estimation of the Fractal Dimension of Glass Bead-Simulated Sand

Spherical glass beads weaken the influences of particle morphology, surface properties, and microscopic fabric on shear strength, which is significant for revealing the relationship between macroscopic particle friction mechanisms and the particle size distribution of sand. This paper explores the shear mechanical properties of glass beads with different particle size ratios under different confining pressures. It obtains the particle size ratio and fractal dimension D through an optimal mechanical response. Simultaneously, we explore the range of the fractal dimension D under well-graded conditions. The test results show that the strain-softening degree of Rs is more obvious under a highly effective confining pressure, and the strain-softening degree of Rs can reach 0.669 when the average particle size d¯ is 0.5 mm. The changes in the normalized modulus ratio Eu/Eu50 indicate that the particle ratio and arrangement are the fundamental reasons for the different macroscopic shear behaviors of particles. The range of the peak effective internal friction angle φ is 23 °~35 °, and it first increases and then decreases with the increase in the effective confining pressure. As the average particle size increases, the peak stress ratio MFL and the peak effective internal friction angle φ first increase and then decrease, and both can be expressed using the Gaussian function. The range of the fractal dimension D for well-graded particles is 1.873 to 2.612, and the corresponding average particle size d¯ ranges from 0.433 to 0.598. Under the optimal mechanical properties of glass beads, the particle size ratio of 0.25 mm to 0.75 mm is 23:27, and the fractal dimension D is 2.368. The study results provide a reference for exploring friction mechanics mechanisms and the optimal particle size distributions of isotropic sand.

Experimental Analysis of the Changes in Coral Sand Beach Profiles under Regular Wave Conditions

This study utilized 50 laboratory experiments to document the evolution of coral beaches under varying regular wave conditions, including five distinct wave periods and ten wave heights. Both the type of equilibrium beach and the shape of sand bars were used to represent beach evolution. The evolution of coral sand beaches was then compared to quartz sand beaches. The experimental results show that the predicted (modeled) equilibrium profile of a quartz sand beach was not applicable to coral sand beaches. Compared to sand bars on quartz sand beaches, the distance from bar crests to the beach berm in coral sand beaches was greater, whereas the erosional depth of sand troughs was deeper. However, the grain size distribution of sand associated with the coral sand beach under wave action was consistent with Celikoglu’s law. Both an equilibrium beach profile classification model and a sand bar shape prediction model for coral sand beaches were developed based on the experimental data.

Smartphone Digital Image Processing Method for Sand Particle Size Analysis

The grain size distribution of sand provides crucial information for understanding coastal erosion and sediment deposition. The commonly used sieve analysis for grain size distribution analysis has limitations such as time-consuming processes and the inability to obtain information about individual particle shapes and colors. In this study, we propose a grain size distribution analysis method using smartphone digital images, which is simpler and more efficient than the sieve analysis method. During the image analysis process, we effectively detect particles from relatively low-resolution smartphone digital images by extracting particle boundaries through image gradient calculation. Using samples collected from four beaches in Gyeongsangbuk-do, we compare and validate the proposed boundary extraction image analysis method with the analysis method that does not extract boundaries, against sieve analysis results. The proposed method shows an average error rate of 8.21% at <i>D</i><sub>50</sub>, exhibiting a 65% lower error compared to the method without boundary extraction. Therefore, grain size distribution analysis using smartphone digital images is convenient, efficient, and demonstrated accuracy comparable to sieve analysis.

Assessment of a new pluviation system designed to prepare uniform samples of sand

In soil and soil-structure interaction laboratory experiments, the technique applied to prepare the sand deposit remarkably influence the performance of the system, including the stress–strain behavior. Air pluviation techniques represent the most suitable choice when a wide range of densities is required. This study presents the details of a simple and effective air pluviation system designed to be suitable for reconstituting small specimens of sand. Many of the previous studies have focused on traveling the pluviator in the horizontal direction only, without paying much attention to the vertical movement during pluviation. The apparatus described in this paper has the ability to overcome this issue by providing automatic lifting tools to the sand container while the thickness of the sand deposit builds up inside the collecting mold. To understand the influence of grain size distribution of sand on the achieved relative density (RD), three different samples of poorly graded sands were used in the experiments. Parametric studies, including the influence of the height of drop (HD) and deposition intensity (DI) on the relative density, were carried out on the three sand samples. It was observed that the range of obtained RDs depends mainly on the grain size distribution of the sand used. Three distinguished zones were observed in the RD-HD relationship, starting with a linear variation, followed by a nonlinear relationship until achieving a constant RD regardless of the increase of HD value. The uniformity of pluviated sand was assessed using a cone penetration test (CPT). Results of the CPT test showed that denser and more uniform samples could be obtained by raising the container up during the pluviation process.

Predicting sand size distribution based on well logs of east Malaysia basins

Sand management is an integral part of petroleum production especially in brown fields. A big influence in sand control strategy is sand size distribution, which is not always accessible due to difficult and costly coring analysis. Hence, this paper aims to test the ability of selected numerical models in predicting the sand size distribution based on well logs and reports. Three models were tested namely Krumbein and Monk, Berg, and Van Baaren, with the estimations later were compared with the actual data from the fields of Sabah and Sarawak located in East Malaysia basins. From the result, the model by Van Baaren showed the closest agreement with the actual data, with excellent accuracy for particle size close to 100 µm. This was followed by Berg, while Krumbein and Monk model displayed the least fitting. The models then were fine-tuned by introducing correction coefficients determined via numerical solver, and the calibrated formulas improved the accuracy by 12%. Despite more studies and refinement are required before this method can be proliferated, the result from this study indicates its huge potential.

Pengaruh curing time dan pemanasan cetakan pasir kering terhadap kadar air, kuat tekan, dan lost of ignition (LOI) untuk aplikasi sand casting

Sand molding has the advantage of being able to cast metals with high melting points, such as steel and nickel. Sand for the mold media generally uses a lot of silica sand. Some sand molds contain alphaset binders as well as other binders. Alphaset sand molding is a technique for making molds and metal casting cores that use resin as a binder and catalyst between sands. The addition of a catalyst as a mixture of resin. The process of making specimens for the sand mold test using silica sand SiO 2 with a weight of 1000 g using 2.1% alphaphenolic resin and 25% catalyst from resin as additional elements for the resin hardening process. with a manual mixing process and making a sample with a diameter of 50mm in the form of a silencer with the tests carried out are water content, lost of ignition compressive strength and sand size distribution. Good moisture content data on alphaset molds are shown in temperature variations with heating. the results of testing the value of increasing compressive strength with variations in heating curing time 30, 60, 90 get results of 20.45, 22.8 and 31.85. data from the lost of ignition test sample curing time 30 get results of 2.05 The results of the distribution of sand are suitable for steel castings with large, medium and small sizes of castings, water content of curing time of 120, get results of more than 1%, namely 1.06 factors causing the mixin process. The above test shows an increase in compressive strength with variations in heating with lost of ignition testing temperature. The more often sand is used as the mold produces a higher LOI value.

Influence of sand grain size distribution and supplementary cementitious materials on the compressive strength of ultrahigh-performance concrete

ultrahigh-performance concrete is a type of advanced concrete that can improve the resilience and durability of concrete structures. The utilization of available supplementary cementitious materials is a critical step in saving energy and materials, as well as lowering the cost of concrete. This research investigated the impact of sand grain size distribution, supplementary cementitious materials, and curing regimes (CRs) on the compressive strength of ultrahigh-performance concrete. The findings showed that a 90-d strength of 175 MPa could be obtained with a microsilica volume of 5 % and without heat-curing. The highest strength was obtained after curing for 48 h at 60 °C, followed by 72 h at 90 °C. Moreover, when compared to natural grain size distribution sand, the usage of finer sand enhances compressive strength. When microsilica is added, however, this impact is minimized.

PENGUKURAN GAYA REAKSI TANAH DENGAN SATU BUAH SIRIP RODA SANGKAR TRAKTOR TANGAN DI BAK PENGUJIAN TANAH

The ability of a cage wheel to climb slopes depends on the grip of the lug on the sloped soil. A lug wheel that sinks deeper will generate more force when climbing. This study aimed to measure the soil reaction force on a single flat lug wheel in the slope soil bin so that the optimal lug angle is obtained to enhance the ability of cage wheels to climb sloped soil. The experiment was carried out using a model of a single flat lug wheel (length of 10 cm, width of 3.5 cm, radius of 30.4 cm, and slope of 30o). Measurements of soil reaction forces on the lug were carried out on five lug angles (-15o, 0o, 15o, 30o, 45o) at three various sinkage depths (2.5 cm, 5 cm, 7.5 cm) at a rotational speed of 11 rpm. The moisture content, density, porosity used in this study were 45.61% (d.b.), 1.02 (g/cm), 44.02%. In addition, the particle size distribution of sand, clay, and silt are 8.038%, 13.396%, and 78.564%, respectively. The limits of soil consistency used in this study, including the plastic limit, water limit, and index limit, were 64.57%, 80.86%, and 16.29%, respectively. A set of measurement and data logger equipment is used to measure the reaction forces of the soil. The results showed that at the angles of -15 and 0 the lugs were able to penetrate the soil faster and deeper to produce a greater pulling force. This implies that a smaller angle of inclination will be more beneficial to the tractors wheel applied for climbing than a greater angle of inclination.

Relationship between fine aggregate size and the air void system of six mortars: I. Air void content and diameter distribution

Precisely determining the characteristics of the air void system in cement-based materials is important in material design and freeze-thaw durability evaluation. X-ray computed tomography (XCT) has been used to characterize air void systems, since it is able to measure the 3D spatial arrangement of the voids. Though the factors influencing air void formation and arrangement have been well-studied, the role of fine aggregate size and gradation has mainly been ignored. In this paper, six mortars were prepared with varying sand size distributions and their air void system quantitatively characterized via XCT. The role of sand size distribution and blended proportions were combined via calculation of the fine aggregate specific surface area (SSA). A linear relationship between SSA and global air void volume fraction was observed, with increasing air void volume fraction as SSA increased (and sand size decreased). The 2D circle diameter distribution was derived from 2D analysis of each XCT slice and the 3D sphere diameter distribution was derived from 3D analysis of the stacked 3D XCT microstructure. The distributions for 2D and 3D were calculated from each other using stereological methods and compared with the original experimental results. All three methods used were in reasonable agreement. The air void size distributions obtained via high resolution (small voxel size, small scan volume) and low resolution (large voxel size, large scan volume) XCT scans compared favorably in a compatible air void size range, which illustrates how the problems of differing XCT resolutions can be resolved.

Over 30 years of research on crushed salt as a barrier material: fundamental findings and open questions

Abstract. Repositories for high-level radioactive waste in geological formations require knowledge on thermal, mechanical and fluid transport properties of the whole repository system, including the engineered barriers and backfill materials. For about 30 years, crushed salt has been considered the most suitable geotechnical barrier material to backfill cavities and encapsulate radioactive waste in rock salt repository sites (e.g., Czaikowski et al., 2020). Over time, when the surrounding cavity walls converge by the creep of salt, it can become strongly compacted and safely encapsulates radioactive waste from any fluid flow. Hence, crushed salt has been characterized in detail for its physical material properties and its response to environmental controls (stress, temperature and moisture). This characterisation provides a basis for long-term numerical simulations (e.g., Liu et al., 2018), which verify so-called safety cases in radioactive waste disposal. Displacement-controlled oedometric compaction tests mimic the long-term in situ behaviour of crushed salt. The tests show that it can be compacted to a state comprising physical rock properties similar to natural rock salt. In general, compaction is easier with an increase in humidity and temperature (e.g., Stührenberg, 2007; Kröhn, et al., 2017). Triaxial test series address the compactions' response to differing confining pressures and help to identify generalized constitutive equations for crushed salt. Both BGR procedures, the oedometric and the triaxial compaction, are verified by the German accreditation body (DAkkS). Figure 1 illustrates the history of oedometric tests at the BGR laboratory since 1993, which examined crushed salt from various origins and differing temperature conditions. Most tests focused on material from the Asse mine, revealing the compactions' response to the materials' humidity and to brine flow. Moreover, systematic test series with synthetic grain size distributions and bentonite additives provided a basis for barrier material design. More recent tests on bedded salt formations (e.g., Teutschenthal and Sondershausen mines) allow the differentiation from characteristics from domal salt deposits (e.g. Gorleben). The current research continues the history of oedometric and triaxial tests, but has a new focus on late compaction stages with marginal remaining porosities (<5 %). The approach of systematic material characterization under best-controlled conditions essentially benefits from the international research collaboration in the KOMPASS project (Czaikowski et al., 2020). The aim of its current phase two is to synthetically generate, identify and quantify dominant grain-scale deformation processes in response to changes in environmental controls. Subsequently, these laboratory results will be embedded in numerical models on the long-term in situ rheology of crushed salt.

Depositional setup and characteristics of the storm deposit by the 2007 Cyclone Sidr on Kuakata Coast, Bangladesh

This study examines the sedimentary characteristics, provenance, and depositional processes of the storm deposits from 2007 Cyclone Sidr that have been identified on the southern coast of Bangladesh. Three sedimentary units up to 70 cm thick have been identified in fifteen geological core collected at a distance of 135–277 m from the coast. Laboratory analyses of grain size, TOC, TN, δ13C, and diatom assemblages were carried out to characterize the deposits. Massive to parallel laminated bluish gray mud underlies the storm overwash deposits. White to light gray, massive to parallel laminated, normal graded 1–17 cm thick sand overlies the mud unit with sharp to erosional contact. The mean grain size and thickness of this sand unit decrease landward with increasing sorting value, where grain size distribution of sand is comparable with modern beach sand. The unimodal sand that dominated the base of the storm deposits grades into bimodal olive-gray sandy silt in the upper part of the deposits. The grain size implies that the sand carried from the beaches and mud likely sourced from the suspended, nearshore sediment of the bay and adjacent rivers. TOC/TN, δ13C values and the presence of brackish mudflat origin diatoms with silty sand laminae in bluish gray mud indicate a tide-influenced environment. Post-storm sand and sandy silt sediments unit contain freshwater and marine-brackish diatoms that have likely been deposited from flooding caused by storm surge water from the bay and overbank flooded river water due to subsequent heavy rainfall. These sediments were sorted according to storm waves and settled over the study area. This study indicates that the low-lying delta coast gets the influences of high water levels both from the bay and the river during a storm. The modern storm deposit will help to characterize the paleo/prehistoric tropical cyclone in geological time for future studies in this area.

Optimization of the composition and technological processes of dispersed cement systems with high performance properties

The technological parameters of obtaining cement disperse systems are considered. It is shown that the optimization of technological processes allows the development of dis-persed cement systems with high protective resistance during the operation of buildings and structures. It was determined that optimization of the parameters makes it possible to select the most effective ratio of cement and finely ground filler from concrete scrap, the optimal amount of modifier additives, and then the ratio of colloidal cement glue and sand (aggregate) in order to obtain mortar compositions for decorative coatings with high strength properties. It was found that grinding sand or crushed concrete scrap allows not only to increase their specific surface and obtain the required particle size distribution, but also to improve the surface quality of particles by removing and destroying surface inactive films, which increases the reactivity of the filler in various processes. Mechanical activation in combination with modifying additives allows to give the necessary properties to colloidal cement composites using optimal techno-logical parameters of processing. The influence of the particle size distribution of sand on the strength characteristics of decorative coatings based on colloidal cement glue is determined de-pends on the ratio of colloidal cement binder to sand. Studies have shown that the fractional characteristics of sand are optimal, in which dense packing of grains and approximately equal fractions of fractions are ensured. It has been established that dispersed cement systems with an optimal fractional composition of the filler have a water-holding capacity that significantly ex-ceeds the standard values.

Experimental Investigation of the Flow Characteristics in Crude Oil Containing Sand and Gas Flowing Along Vertical Pipelines

An experimental study on the flow behavior of crude oil containing sand and air in a vertical pipe with 50 mm diameter was carried out. The experiments were conducted under the following input superficial phase velocities: oil from 0.1 to 2.23 m/s and gas from 0 to 0.34 m/s. Oil was blended with sand in three different volume concentrations, namely, 0.7, 2, and 3%. Two different types of sand were used to investigate the effect of sand size distribution. A comparison between rheological measurements and pipe flow data showed that the stress–strain relationship obtained by the rheometer could be used to predict the transport characteristics in the vertical pipe flow. It was demonstrated that a small gas injection and sand addition can decrease the total pressure and friction pressure gradients. In the oil flow, the injection of air generally increased the friction factor compared to the single-phase flow, especially at low Reynolds numbers. However, the friction factor decreased by adding a small amount of fine sand. The accuracy of the correlation developed in this study was compared with other three correlations widely used in gas–liquid vertical pipe flow.

Particle breakage of sand subjected to friction and collision in drum tests

This paper presents a laboratory experimental study on particle breakage of sand subjected to friction and collision, by a number of drum tests on granular materials (silica sand No. 3 and ceramic balls) to investigate the characteristics of particle breakage and its effect on the characteristics of grain size distribution of sand. Particle breakage increased in up convexity with increasing duration of drum tests, but increased linearly with increasing number of balls. Particle breakage showed an increase, followed by a decrease while increasing the amount of sand. There may be existence of a characteristic amount of sand causing a maximum particle breakage. Friction tests caused much less particle breakage than collision tests did. Friction and collision resulted in different mechanisms of particle breakage, mainly by abrasion for friction and by splitting for collision. The fines content increased with increasing relative breakage. Particle breakage in the friction tests (abrasion) resulted in a sharper increase but with a smaller total amount of fines content in comparison with that in the collision tests (splitting). For the collision tests, the fines content showed a decrease followed by an increase as the amount of sand increased, whereas it increased in up convexity with increasing number of balls. The characteristic grain sizes D 10 and D 30 decreased in down convexity with increasing relative breakage, which could be described by a natural exponential function. However, the characteristic grain sizes D 50 and D 60 decreased linearly while increasing the relative breakage. In addition, the coefficients of uniformity and curvature of sand showed an increase followed by a decrease while increasing the relative breakage.

Assessing the habitat suitability of paddy fields for avian indicators based on hydropedological parameters of the wet agricultural soil along the Cauvery delta basin, India

Paddy fields provide a broad range of habitats to wintering waterbirds as natural wetlands have declined worldwide. However, the intensification of farming practices has altered the microclimates of the wet agricultural soil, the composition of soil invertebrates, thus indirectly affecting the avifauna. This study evaluated the importance of paddy fields as wintering grounds for two avian indicators Asian openbill stork (Anastomus oscitans), and the Black-headed ibis (Threskiornis melanocephalus) along the Cauvery delta basin, widely known as the granary of Tamil Nadu, South India. Several stretches of this agricultural belt have recorded a drastic reduction in crop cover thereby threatening the species that forage these mosaics. This entire delta region is under threat and is increasingly shrinking due to indiscriminate sand mining activities causing irreparable damage to soil, fauna, and agriculture. The erratic monsoons have forced wading species to initiate long migrations in response to climatic adaptations, thus impairing the existing population. The present study focused on the abundance patterns of two wading birds and their association with the hydropedological parameters of the flooded soil along the deltaic dynamic mosaic. The relative abundance of the avifauna was documented for 24 months using unlimited radius point counts. The hydropedological parameters recorded were pH, electrical conductivity, total alkalinity, calcium carbonate, organic matter, total organic carbon, nitrogen, phosphorus, potassium, chloride, sodium, magnesium, calcium, sulfur, moisture, the particle size distribution of sand, silt and clay, water holding capacity, and bulk density. The results indicate that paddy fields are excellent habitat for A. oscitans and T. melanocephalus and are strongly influenced by landscape characteristics, availability of feeding grounds, and hydropedological parameters of the wet soil. Among the hydropedological parameters, organic matter and nitrogen exhibited a negative correlation and the percent silt content showed a positive correlation to A. oscitans. Similarly, T. melanocephalus showed a negative correlation to chloride and sodium, and a positive correlation to nitrogen. The contrasting effects of hydropedological parameters could be explained by differential thermal tolerance levels and metabolic requirements of the species or may be mediated by changes in the macrofaunal composition. The wet agricultural soil exhibited fewer differences across salinity classes, particle size distribution especially silt and clay, organic matter, total organic carbon, pH and bulk density, and greater differences among calcium content, water holding capacity, the particle size distribution of sand, and electrical conductivity across delta zones. Our study highlights the need to consider hydropedological factors of the wet paddy soil when selecting conservation sites on agro-landscapes for migratory wetland birds. Agricultural policies should aim at considering these cultural landscapes along the delta region as high nature value avian farmlands under the protected agricultural Cauvery zone network to sustain biodiversity and vital ecosystem services of birds in the paddy fields.

Effect of Particle Size Distribution of Sand on Mechanical Properties of Cement Mortar Modified with Microsilica

Effect of Particle Size Distribution of Sand on Mechanical Properties of Cement Mortar Modified with Microsilica

Experimental Analysis on the Properties of Concrete Brick With Partial Replacement of Sand by Saw Dust and Partial Replacement of Coarse Aggregate by Expanded Polystyrene

An experimental study had been conducted to study the effects of saw dust and EPS as partial replacement of sand and coarse aggregate in various percentages such as 0%, 10%, 20% and 30% in concrete brick samples of M20 and M15 Grade. Compressive strength, Bulk density and Water absorption of prepared saw dust and EPS M20 and M15 concrete brick were determined. The properties of materials were first determined before the conduction of experimental works. The normal consistency, initial and final setting time and compressive strength of cement used for the experiment were found as 31%,115 minutes, 265 minutes and 39.5 N/mm2 respectively. Sieve analysis to determine the particle size distribution of sand, coarse aggregates, saw dust and EPS was performed. From the sieve analysis, the nominal maximum size of sand, coarse aggregate, saw dust and EPS used for preparing concrete brick sample were 2.36 mm, 12.5 mm, 2.36 mm and 4.75 mm respectively. Impact value of coarse aggregate obtained was 11.20 %.The experimental results showed that water absorption of prepared M15 and M20 concrete brick samples increased with increase in percentage replacement of sand by saw dust and EPS by coarse aggregate. Compressive strength and Bulk density of prepared M15 and M20 concrete brick sample decreased with increase in percentage content of saw dust and EPS. The results showed that the partial replacement of sand by saw dust and coarse aggregate by EPS in concrete brick sample had sufficient strength as compared to common bricks.

A new laboratory protocol to study the plugging and sand control performance of sand control screens

Sand retaining media plugging in sand control wells has become a common and urgent problem in the oil and gas industry. Yet, no unified analysis or industry standards on the evaluation of the sand retaining media has been reported recently.In this paper, a systematic approach was presented to investigate the performance of sand control screens. A series of tasks were performed, including the processing of sand control simulation unit, the analysis of formation parameters such as the size of formation sand and reservoir fluid viscosity, the determining of pressure drop through the sand retaining medium, the calculation of oil-production index and so on.The importance of using the sand control unit was clearly demonstrated. The pressure drop along block sand media was determined in three different positions simultaneously with the high precision pressure sensor. The process of forming the sand bridge was recorded for all tests using a Digital Camera. The oil-production index and permeability of the sand control screen were calculated based on the flow rate and pressure drop. An electron microscope was conducted to observe the plugging of the sand control screens. This process is conducive to analyze the clogging process of sand control screens and optimize the design of sand control parameters. The amount and particle size distribution of sand produced and sand arch also were determined. These parameters are very important to the sand control properties of sand control screens. A set of novel sand control physical simulation experiment device was introduced to measure the above parameters. The measurement techniques and procedures presented in this paper provide a standard measurement protocol for the characterization of different sand control screens. The result of a case test shows that the new test method presented in this paper can effectively improve the drawbacks of existing methods.

A simple model to estimate emission of wind-blown particles from a granular bed in comparison to wind tunnel experiments

Dust emissions due to aeolian erosion of exposed granular materials are strongly influenced by grain size distribution. Non-erodible particles that are too heavy to be lifted into the air play a protective role in the aeolian erosion process attenuating emission, which is known as the pavement phenomenon. To date, there is no approach that reliably predicts the reduction in emissions caused by their presence on an aggregate surface. In this work, an analytical model was developed to quantify emissions from particle beds with a wide size distribution. As non-erodible particles accumulate, changes in surface characteristics create increasing shelter for the erodible portion of the bed until the shear on the erodible surface reaches a minimum and emissions cease. The proposed emission model describes the relationship between this minimum value of wind shear and the eroded depth of the bed after the pavement, which in turn gives the emitted mass. In addition, wind tunnel experiments were carried out in order to broaden knowledge of the pavement phenomenon and validate the modelling. A bimodal particle size distribution of sand with erodible and non-erodible particles was used for the tested velocities. Three experimental measurements were carried out: (i) continuous weighing of the emitted mass, (ii) eroded depth of the bed at regular time intervals and (iii) final cover rates of the non-erodible particles using digital analysis of sand bed pictures after experiments. Good agreement between the modelling and experimental results was found. The emission model proposed herein is a simple algebraic expression that demands low computational effort. This approach may serve as a base for an emission model for application in granular materials stockpiles.

Effect of particle size distribution of cohesionless soils on the ultimate carrying capacity of open ended pipe piles under different saturation conditions

This research is performed to study the effect of grain size distribution of cohesionless soils (i.e., fine, medium, and coarse sand) on the ultimate carrying capacity of open-ended pipe pile models of different diameters under different saturation conditions (i.e., fully and partially saturated). Poorly graded clean sand of rounded particles was used as natural soil in the present study. The soil is sieved on standard sieves to obtain fine-, medium-, and coarse-graded soil according to (ASTM D 422-02). Experimental model tests were performed on four open-ended steel pipe piles models with diameters of (25, 30, 35, and 40 mm) embedded within different grain size distribution of sand prepared under fully and partially saturated conditions with specified relative density of 65%. The unsaturated states was achieved by lowering of water table according to matric suction values of soil. The relationship between matric suction and depth of ground water table was measured in suction profile set by using three Tensiometers. The soil water characteristic curve (SWCC) was estimated by applying fitting methods through the program (SoilVision). The results show that the ultimate load carrying capacity of pipe pile under unsaturated conditions is higher than those of saturated condition and increases with increasing of matric suction values. On the other hand, the fine sand shows an increase in ultimate load carrying capacity more than the other grain size distributions under unsaturated conditions for all different types of pipe pile diameters. However, the coarse sand gives a lower resistance at different saturation conditions.