Gravel Material Research Articles

Lithological characteristics of moraine in Torhanovychi 2 section (Forecarpathians)

The main lithological characteristics of the moraine sediments discovered in the Torhanovychi 2 section are analysed. The capacity of the moraine is low (up to 35 cm), in the lower part it is built of the medium, fine-grained sands, and in the upper part, it is mostly coarse-grained. The sands are horizontally layered, and the capacity of the layers varies from 4–5 to 8 cm. The stratification is emphasized by the layered inclusion of coarse fragments, the maximum size of which (granite boulders) reaches 25 cm. Lithological analysis disclosed that the main component of the moraine is a sandy-clay material, the weight of which reaches 60% of the total mass of the sample. Almost a quarter (up to 24 %) is made of pebble and gravel material, and the remaining 16 % is formed by the hard gravel component of the moraine. The petrographic composition of coarse pebbles and gravel (100–40 mm) is represented by fragments of two types of sediments: light gray, gray Carpathian sandstones and pink granites, with a significant predominance of sandstone content. Granites are medium-rounded, and sandstones are medium and well-rounded. The petrographic structure of small pebbles and gravel (40–10 mm) is much more diverse and is represented by fragments of five types of sediments: Carpathian sandstones, silicites (Carpathian flints), siltstones, granites and quartzites. The most common are fragments of Carpathian origin: mainly medium-rounded light gray Carpathian sandstones and multi-coloured medium-rounded silicates. Their total part reaches 74,2 % of the total amount of fragments of the fraction. The second component is formed by erratics – pink, red, often very weathered granites with a variable shape and one well-rounded fragment of quartzite. The total part of erratics reaches 13,4 % of the total amount of fragments of the fraction. The least common in moraine are fragments of local sediments – light gray, gray, weakly cemented siltstones, as well as strong siltstones on siliceous cement with a conchoidal fracture. The total content of fragments of local sediments reaches 12,4 % of the total amount of fragments of the fraction. Medium-rounded siltstones predominate. The petrographic spectrum of hard gravel sediments is generally identical to the composition of small pebbles and gravel. They also contain fragments of five types of sediments: Carpathian sandstones, silicites (Carpathian flints), granites, siltstones and quartz. In addition, fragments of Carpathian-origin sediments also predominate here: medium-, well- and very well-rounded gray sandstones; multi-coloured silicites and milky white, gray quartz, etc. Key words: granulometric composition, petrographic composition, roundness, grain shape, Carpathian material, erratics, sandstones, silicites, siltstones, granites.

Performance improvement of double slope solar still via combinations of low cost materials integrated with glass cooling

Solar-driven desalination methods, particularly solar stills (SS), and their improvements have been widely paid attention. Along with that, the current work aimed to evaluate the augmented evaporation/condensation performance of a modified double slope solar still (MDSSS) compared to conventional solar still (CSS). For evaporation enhancement, three alternative combinations were applied in the still basin, which consisted of nanoparticles/fluid (carbon black/water), heat localization (wick), and sensible storage (gravel) materials. In other meaning, three cases were experimented; namely: MDSSS-I with gravel immersed in carbon black (CB) nanofluid, MDSSS-II with gravel atop thermal insulation and covered with black wick, and MDSSS-III with dispersed CB nanoparticles on the top of the second case combination. These modifications were suggested to enlarge the wet area subjected to solar radiation, increase thermal conductivity, and localize the heat on the water surface. On the other hand, for condensation improvement, passive water-based glass cooling technique was integrated with all cases to degrade the glass cover temperature. Besides the experimental investigation, thermo-economic assessment analysis of the system was performed via estimating energy and exergy efficiencies, and production cost. The results proved the aimed enhancements for all cases and the best performance was achieved from the MDSSS-III. In this case, the yield, average energy efficiency, and average exergy efficiency were improved by 68, 50.6, and 146.3%, respectively, compared to CSS. In addition, MDSSS-III attained highest cost saving by 30.7% compared to CSS as the cost per liter of freshwater productivity was 0.0147 $/L, and 0.0212 $/L, respectively. Hence, integrating such locally-available materials with DSSS may open a new sight for further enhancement and increase the opportunities for establishing large-scale practical plants.

Grain Size Distribution of the Surface Layer of Bottom Sediments in the Barents Sea

The paper presents data from a granulometric analysis based on the results of studying of 44 surface (0–5 cm) sediment samples obtained on cruise 67 of the R/V Akademik Mstislav Keldysh (2016) from different parts of the Barents Sea. Pebble and gravel material is found in surface sediments as an admixture scattered throughout the sea. Such a chaotic distribution pattern is apparently associated with ice rafting. Coarse material is most common in the Barents Sea off the coast of the Kola Peninsula, Novaya Zemlya, and Svalbard, where it accumulates due to coastal abrasion, glacial exaration and bottom erosion. In addition, the >1 mm fraction is widespread at depths where fine fractions are stirred and washed away. The most common sediments in coastal shallow waters are sands. Sands (0.1–1 mm) are widespread in the southern and southeastern regions of the sea, in the region of the Pechora test area, the Kanin Shoal, the Kola Peninsula shallows; and in the northwest, off the coast of Svalbard. With increasing depth, coarse sediments are replaced by mixed sediments with a low pelite admixture. Fine-grained sediments are prevalent in the central part of the sea. Sediments with a pelitic fraction (<0.01 mm) of more than 50% occupy about 70% of the Barents Sea. They are widespread in deep-sea depressions and troughs, as well as in the numerous fiords of the Northern Island of Novaya Zemlya and Franz Josef Land.

A draft decision on the issue of urban expansion of a densely populated city

The problem of urbanization turns up from the urban compaction. This project is designed to solve this problem in the densely populated city of Tokyo, the population of which is more than 13 million people today. The project of a new neighborhood in the city takes into account social, economic, environmental and geographical characteristics of the Land of the Rising Sun. The project provides one to combine the idea of a universal city with high population density in a small territory. The territory involves a residential area, an industrial area and an agricultural area simultaneously that promotes well-balanced relations between man and nature. The purpose of the survey is to show that it is necessary and possible to use a new strategy of city planning and building, relevant for large, densely populated cities, to make cities more comfortable and economical. The quarter is located on a man-made island in Tokyo Bay. The quarter was built after burning solid household waste without causing damage to the environment by a waste burning plant located on this island to the north. In addition, the plant produces gravel material for creating an artificial island. Besides, it yields surplus electric energy that is fed into the power grid of Tokyo.

ESTIMATING COMPACT PARAMETERS WITH SIMPLE AND MULTIPLE REGRESSION ANALYZES AND ANALYSIS OF THE MEANING WITH THE F TEST

Compaction is the compaction of the moist soil by laying it in layers, rolling it by applying vibration. Compaction is widely used both for the frequency control of road embankments and embankment dams and in other important engineering projects. Therefore, it is important to determine the compaction parameters correctly. The lack of sufficient laboratory equipment at the construction sites and the limited deadline of work increased the importance of correlation equations. If there are sufficient data and results are obtained within tolerable safety limits, it is considered appropriate to use statistics in estimation of compaction parameters. This situation provides a gain both in terms of economy and time. In the study, the compaction parameters were tried to be estimated by subjecting the soil index properties of Adıyaman Balkar, Çelik and Pınaryayla Ponds to simple and multiple regression analyzes. First, the data of the soils belonging to the ponds were used, then, as a result of the sieve analysis, the index properties of fine-grained soils containing only clay and silt were evaluated and compaction parameters were tried to be determined. Simple and multiple regression analyzes were made with the help of the Eview program, where the statistical analysis of the existing data was made, and the statistical significance of the obtained models was examined by performing the F test. It was determined that higher correlations were obtained compared to other sample data, especially by using the data of samples that do not contain sand and gravel material.

What lies beneath: Material classification for autonomous excavators using proprioceptive force sensing and machine learning

The ability of robotic excavators to acquire meaningful knowledge about materials during digging can augment their autonomous functionality, as well as optimize downstream operations in construction and mining. Some material properties, such as rock sizes, can be determined visually, but these methods cannot see what lies beneath. In this work, a classification methodology that utilizes only proprioceptive force data acquired from an autonomous digging system and machine learning algorithms is proposed for excavation material identification. The consistent performance synonymous with autonomous digging systems allows for the use of basic features extracted from the force data for classification. A proof of concept of this novel approach to excavation material classification is demonstrated through a binary classification of rock and gravel materials. Force data were obtained from full-scale autonomous loading trials with a 14-tonne capacity load-haul-dump machine at a mining and construction test facility. Preliminary results achieved a classification accuracy of 90%.

Experimental Study of Structural Strategy on Debris Brake Performance

We performed an experimental study to investigate the effects of structural strategy for improving the debris brake performance. The stony debris flow was generated by releasing water discharge from a tank that contained gravel material. The efficiency of debris brake, debris accumulation pattern and its position parameters was used to evaluate the performance of the debris brake structure. The influences of debris brake slope, opening size and nonuniformity in deck opening size parameters that have not been studied before were investigated for different debris flow conditions. The results showed that the slope of debris brake was the most important factor on debris brake performance. The suitable slope was found to be a function of the debris flow velocity, and it can increase debris brake efficiency up to 10%. The analysis of the experimental data suggests the optimum opening size ratio (i.e., the ratio of opening size to median diameter of debris) smaller than or equal to one. Experimental data indicated that the nonuniformity in opening size of the debris brake cannot improve the debris brake efficiency.

Quantitative Analysis Investigation of the Water Stability of Asphalt Mixtures with Crushed Gravel Based on the Theory of Surface Free Energy

To quantitatively analyze and study the water stability of crushed gravel asphalt mixture by using surface energy theory, the surface energy parameters of crushed gravel samples at 20℃ are tested by using the gas sorption method, and the surface energy parameters of four anti-stripping agent asphalts with different dosages (0%, 0.2%, 0.4%, 0.6%) at 20℃ are tested by using the Wilhelmy plate method. Then, the binding energy of crushed gravel and anti-stripping agent asphalts with different dosages and the surface energy evaluation index of water stability are calculated. On this basis, quantitative analysis and sequencing of water stability of crushed gravel asphalt mixture were carried out. The microscopic mechanism of the anti-stripping agent's improvement on adhesion between crushed gravel and asphalt was analyzed from the angle of surface energy. Marshall test (immersion Marshall test, vacuum saturation Marshall test, freeze-thaw splitting test) with anti-stripping agent contents of 0%, 0.2%, 0.4%, and 0.6% was conducted through strict control of crushed gravel material, gradation, and oil-stone ratio. Results show that (1) the surface energy parameters of crushed gravel are dominated by polar alkali component; (2) the addition of anti-stripping agent will reduce the surface energy of asphalt, thus increasing the wettability of asphalt to aggregate; (3) the improvement of the adhesion between crushed gravel and asphalt by adding anti-stripping agent is mainly reflected in two aspects: reducing the cohesive energy of asphalt itself to increase its wettability to aggregate and increasing the surface energy acid component of asphalt to increase its adhesion binding energy to aggregate; and (4) the order of microscopic surface energy evaluation index of water stability of crushed gravel asphalt mixture is the same as that of macroscopic performance test index, thus demonstrating the accuracy of the surface energy system for quantitative analysis of the water stability of the crushed gravel asphalt mixture.

Applying MIKE 21 FM (HD + ST) model to evaluate the ability to regenerate sand and gravel for efficient management of river exploitation and protection, (A case study at Red River crossing Phuc Tho District, Hanoi)

Sand and gravel in River bed are common construction materials indispensable in urban development, infrastructure, and wharves ... due to the shortage of supply, throughout the rivers in Vietnam. Determination of the volume of regenerated sand annually or according to a certain cycle can use the MIKE 21 FM (HF + ST) hydraulic model given by Danish Institute of Water and Environmental Engineering. Calculation results of the experimental model for the river section across the Phuc Tho district, Hanoi city show that the Vinh Khang sand mine was more simulated during period from 2010 to 2019 and still lower regenaration in the comming years. These results will be significal basis for Mining lisener to orient mine development, adjust capacity and limit exploitation in sediment-deficient areas, avoid locations where there are high erosion trend. The simulation results from the model also are scientific basis for the state management to make master plane, locate sand and gravel material potential areas. But in completing a model it takes time, synthesized data of fields such as geology, hydrometeorology, surveying, geophysics,… it is essential that the functional ministries would make coordinate to bring benefits for organizations and individuals to use lifting data to get high reliability for model results.

Characteristics of Direct Shear and Particle Breakage of Pebble Gravel Materials

Particle size is an important factor affecting the Thermal-Hydraulic-Mechanical (THM) coupling behavior of graveled rock mass, especially for the shear mechanical properties. In this study, three groups of the particle size range and nine particle grading samples are designed for a large-scale direct shear test. The relationships between shear stress and shear displacement, shear strength, stress ratio, shear strength parameters, and particle breakage of pebble gravel are analyzed. The influence of particle size range and grade on the strength and particle breakage of gravel material is discussed. Results show evident particle breakage in the process of direct shear, and the degree of fragmentation is controlled by the normal load and the particle size distribution of the sample. The shear strength of the sample is no longer applicable to Mohr-Coulomb strength theory because of particle breakage that is more in line with the power function relationship. Shear strength of pebble gravel material has scale effect, and a corresponding relationship model between friction coefficient f of material and characteristic particle size of the sample is proposed.

Large-scale triaxial experiments on the static and dynamic behavior of an artificially cemented gravel material

This article presents the results of a set of 28 large-scale triaxial tests, including 12 consolidated-drained (CD) static tests and 16 consolidated-undrained (CU) dynamic tests, on an artificially cemented gravel. The strength, dilatancy, stiffness and damping behaviour of both the cemented and the uncemented specimens are compared. Cementation is found to have interrelated effects on increasing the peak strength, enhancing the dilative behaviour, increasing the static and dynamic stiffness, and reducing the damping ratio. Cementing the particles leads to a delayed but more evident dilative behaviour subsequent to an initial contraction, which is interpreted as the result of the existence of locked voids and the limited void-filling capacity of the cemented clusters. A cemented specimen generally yields before achieving its peak deviator strength, after which an increasing dilative behaviour is accompanied by strain softening. Cementation also increases the maximum shear modulus and reduces its dependence on the mean effective stress. Due to the bonds created near the contacts and their effect on restricting inter-particle sliding, the damping ratio of a cemented specimen is generally lower than that of an uncemented specimen, and the difference in the damping ratio becomes increasingly evident under an increasing shear strain amplitude.

Strengthening the clayey gravel and sand soils for Subbase course highway using different waste materials

The stabilization of clayey gravel and sand soil used in construction of subbase course pavement highway is one of the engineering solutions in order to increase structural capacity of underneath pavement layers. There are many sorts of soil stabilization which are classified into mechanical and chemical methods. Recently, there has been an increasing social concern about the issue of waste management, by production industrial waste and waste disposal. This project presents the study of the influence of waste ceramic dust (WCD) on strength of clayey gravel and sand materials used in construction of subbase course. The subbase collected locally was mixed with waste ceramic dust from (0 to 25%) by weight of dry soil. The target of this study is to clear that waste is often used as filling and reinforcement and for this reason California Bearing Ratio test (CBR) was conducted to research the strength of waste ceramic and plastic strip of subbase material. The application of plastic waste in various forms is one among the emerging areas of ground improvement technique and there are economic and eco-friendly advantages. A detailed analysis of their results depicts that it is often utilized in the fields effectively and economically as reinforcing materiel. Plastic strips with dimensions (12 mm × 6 mm) are mixed with soil containing the optimum proportion of ceramic dust and California bearing tests are conducted. The effect of waste plastic strip (WPS) content is 0.5% to2% (by weight of sub base material) on the CBR of strip reinforced subbase was studied. The ratio is decided by changing its length and width. From the CBR on soil with and without plastic reinforcements, it had been found that after reinforcement the soil gained its strength appreciably. The best percent of waste ceramic dust was (20%) with waste plastic strip is (1%) which gave higher percent of CBR.

Seismic analysis of stone column improved liquefiable ground using a plasticity model for coarse-grained soil

This paper presents the seismic analysis of stone column (SC) improved liquefiable ground using a three-dimensional (3D) plasticity model with unified description of coarse-grained soil (CGS). The model is a modification of an existing plasticity model for large post-liquefaction deformation of sand, with improvements on the formulation for strength characteristics exhibited by CGS. According to requirements of FLAC3D User-Defined-Model (UDM), the model is implemented into the finite difference code FLAC3D, for which a method synchronizing the mapping centres and sharing necessary internal variables of subzones is developed to resolve the computational stability issue caused by the mixed discretization technique of FLAC3D. The model is validated against monotonic/cyclic and undrained/drain laboratory tests under 8 different stress paths and initial states on a gravel material and Toyoura sand. A centrifuge shaking table test on SC improved liquefiable ground is simulated adopting the model. The results show that the constitutive model and analysis method are effective in reproducing the liquefaction behaviour of CGS ground under seismic loading. Parametric analysis for liquefaction mitigation effects of SCs is further conducted, highlighting the importance of densification and maintaining drainage efficiency of SCs. Results show that the SC’s effective improvement area is approximately 2–3 times its diameter.

DEM Analysis and Prediction for the Lateral Interaction of Monopile in Gravel Soil

Gravel is a common geotechnical material in civil engineering. To investigate the lateral bearing behavior of monopile in gravel materials and deeply understand the microscopic mechanisms, parametric three-dimensional discrete element analyses are performed to study the lateral interaction between the single pile and gravel. First, using the experimental data of two typical gravel samples, the discrete element methods (DEM) for monopile in gravel materials are investigated. A discrete particle flow model of pile segments that allows for the construction of p–y curves at various depths is proposed. The lateral mechanical behaviors (p–y curves) between monopile and different gravel material are then studied. The effects of gravel porosity, distribution and grain-size on both the strength and shape of the p–y curves are investigated. The results show that the influences of porosity and depth on the p–y behaviors of gravel are significantly different from those of sand. Furthermore, the obvious differences in p–y behaviors between the coarse gravel and fine sand are the effects of grain size and size distribution. Based on these results, corresponding equations for the estimation of the p–y curves are proposed and further validated by independent field test data. It is concluded that the proposed p–y curve is capable of modeling both different grain sizes and size distributions in gravel-monopile interaction analyses during lateral loading.

Coral reef islands can accrete vertically in response to sea level rise.

Increased flooding due to sea level rise (SLR) is expected to render reef islands, defined as sandy or gravel islands on top of coral reef platforms, uninhabitable within decades. Such projections generally assume that reef islands are geologically inert landforms unable to adjust morphologically. We present numerical modeling results that show reef islands composed of gravel material are morphodynamically resilient landforms that evolve under SLR by accreting to maintain positive freeboard while retreating lagoonward. Such island adjustment is driven by wave overtopping processes transferring sediment from the beachface to the island surface. Our results indicate that such natural adaptation of reef islands may provide an alternative future trajectory that can potentially support near-term habitability on some islands, albeit with additional management challenges. Full characterization of SLR vulnerability at a given reef island should combine morphodynamic models with assessments of climate-related impacts on freshwater supplies, carbonate sediment supply, and future wave regimes.

Numerical Analysis of the Seismic Response of a Vibration-Isolated Foundation in Deep Water

Natural hazards, such as earthquakes, flooding, hurricanes, and tornados, very often have devastating effects on civil structures, with the consequences of loss of human lives and negative economic impacts. The deepwater vibration-isolated foundation is a new bridge foundation that can prevent bridge damage due to large deformation under strong natural hazards because the laying of a specially designed gravel, sand and other materials between bridge foundation and subgrade can allow the foundation to slide and swing. Taking the main tower foundation of the Rion-Antirion bridge in Greece as an example of a deepwater vibration-isolated foundation structure, the a vibration-isolated numerical model which considers the influence of hydrodynamic pressure and hydrodynamic damping is established to study the seismic response characteristics of this structure to find the optimal vibration-isolated stiffness and damping. It is found that the structure mainly undergoes translational movements under the optimum stiffness and damping isolation conditions.

Automation of vibration modes of soil compaction machines

The relevance of high-quality compaction of soil foundations during the construction of embankments and foundations during the construction of engineering structures is given. An effective vibrodynamic method of compaction of gravel and sand materials for foundations of building structures for various purposes is substantiated and proposed. The method of continuous monitoring of the degree of compaction of the soil by measuring the magnitudes of the amplitudes and frequencies of harmonic oscillations of the compacted surface is determined. A schematic diagram of the automatic control system CAP of vibration modes of shock-absorbing soil compacting machines with a crank-oscillating exciter is proposed. The principle of regulating the operating modes of a vibrating machine using an automatic control pulse distributor is stated. A structural block diagram of the CAP elements is constructed and an analysis of the dynamic properties that determine the optimal control time is carried out. The main elements of the CAP are determined and their work in the control program is shown: the frequency of impact of the working mechanism on the soil surface being compacted, depending on the degree of compaction. Key words: soil compaction degree, operating mechanism, amplitude and frequency of harmonic oscillations of the surface of the soil being compacted, vibro-shock machines with a crank-connecting rod exciter, automatic control system, control pulse distributor, process parameters sensors, on-board microprocessor controller.

An Attempt to Characterize the Recharge of Alluvial Fans Facing the Northern Italian Apennines: Indications from Water Stable Isotopes

Nowadays, climate changes and increased water demand for human and agricultural purposes pose important questions for the groundwater management of alluvial aquifers facing the northern Italian Apennines. The large groundwater withdrawals, coupled with an overall worsening of the water quality, requires a detailed knowledge of the recharge mechanisms of these aquifers that can be useful for further adaptation measures. Concerning the recharge area of the alluvial aquifers (i.e., apices made up of gravelly materials), the present study investigates a dataset made up of 282 water samples for which stable isotopes oxygen-18 (18O) and deuterium (2H) are available. The latter involves precipitations (three rain gauges), surface water (five rivers) and groundwater (twenty wells) from five selected alluvial fans. The study confirms that the different isotopic signatures characterizing rain and river water from this area can be exploited for preliminary characterization of their significance on groundwater recharge. These results lay the foundations for the further use of a suite of environmental tracers (in which a primary role is that of water stable isotopes) at the event-scale (i.e., that of rainfall and/or flood) for eventually estimating the effective quota of recharge linked to precipitation and surface water.

Assessment of groundwater potential using geophysical data: a case study in parts of Cross River State, south-eastern Nigeria

Groundwater potential of some parts of Cross River State, Nigeria, was assessed involving vertical electrical sounding (VES) and high-resolution aeromagnetic methods (HRAM). The VES and HRAM dataset were used to delineate the hydro-lithostratigraphic units and map the spatial distributions of geologic structures, respectively. The electro-stratigraphic sections revealed the various hydro-lithostratigraphic units composed of fractured/weathered crystalline basement, sandstones, siltstones, sandy shales, and highly baked and fractured shales occurring at different depths. Generally, the unsaturated top layer is composed of shales, marl, clay, silt, gravel and lateritic materials with resistivity ranging from ~ 3.0 to ~ 550 Ω m. This layer is underlain by various aquifer units like sandstones, siltstones, fractured shales and limestone/marl, and fractured/weathered basement occurring at different depths (~ 30 to ≤ 100 m) as revealed by the electro-stratigraphic sections obtained in the study area. In the Calabar Flank (CF), Oban Massif (OM) and Ikom-Mamfe Embayment (IME), the apparent resistivity for these hydro-lithostratigraphic units varied between ~ 8.50 and ~ 59.50 Ω m, ~ 120.2 and ~ 1562.6 Ω m and ~ 30.8 and ~ 277.2 Ω m, respectively. The enhanced total magnetic intensity maps and source parameter imaging result showed that the OM and IME are characterized by high concentration of short-wavelength anomalies, while the CF is dominated by relatively undisturbed thick sedimentation (~ 6217 m). HRAM results show that such areas are predominated by geologic structures like faults, fractures, fissure, dyke swamps, etc. caused by tectonics. Such geologic structures create secondary porosity and enhance permeability. From all the results obtained, OM and IME represent areas with moderate groundwater potential. The CF dominated by argillites with no significant tectonic activity is observed to have low groundwater potential.

Effects of unit cement content and aggregate maximum particle size on compressive strength of cemented sand and gravel materials

Cement Sand and Gravel (CSG) is a new type of construction material between RCC and ordinary concrete. At present, there are few research theories on cemented sand and gravel in China. Therefore, this paper analyses the influence of unit cement content and aggregate maximum particle size on the compressive strength of cemented sand and gravel through experimental research. The test results show that the compressive strength has increased with the increase of unit cement content; the compressive strength of the material has a decreasing trend as the maximum particle size of the aggregate increases from 20mm to 80mm. The analysis of the test results shows that when the maximum particle size of the aggregate is 40mm and the unit cement content is above 80kg / m3, the compressive strength of the material can be guaranteed and the material can be used reasonably.