Influence Of Gravel Research Articles

Study of experimental and numerical simulation on the influence of gravel on the interflow of slope land.

The formation of interflow is of great significance for the stability of mountain slopes and soil erosion. Hillsides are often covered with a certain amount of gravel, and research on interflow of slope land with different gravel ratios needs to be carried out. This article is based on indoor experiments and numerical models to study the formation law of interflow in hillside soil under different gravel coverage ratios. It was found that the interflow in the soil rapidly increased in the early stage and began to decrease after briefly reaching equilibrium. The formation of interflow is a complex process that is related to slope, soil characteristics, and rainfall intensity, but the correlation is not high when viewed separately. The lattice Boltzmann model can effectively simulate such problems and achieve high simulation accuracy. The [Formula: see text] of the simulated data and measured data ranged from 0.5217 to 0.7403, and [Formula: see text] of the simulated data and measured data ranged from 0.4051 to 0.5711.

Influence of Gravel as Protection Layer on the Filter Run Time

Abstract: Since the beginning of the usage of slow sand filter (SSF) as one of the water treat-ment technologies, studies on how to enhance the performance have been conducted to date. One of the limitations in the current knowledge is regarding the method to increase the filter run time. The addition of protection layer may extend the filter run time. This paper focuses on the influence of gravel as the protection layer to the filter run time and turbidity removal. Gravel was chosen as the material of protection layer because of its low-cost and availability. A system-atic investigation by comparing only one different factor within the filter, which was protection layer, was conducted under the laboratory scale. The experimentconsisted of two filter columns namely K1 and K2. Both filters were constructed using the same filter depth, type of sand, and grain size distribution. The protection layer was added to filter K1, but not to filter K2. The sol-ids penetration and the increase of filter head loss wasused to evaluate the filter run time. A sta-tistical analysis was also carried out to examine the difference on the turbidity removal from both filters. The findings showed that by adding the protection layer, the filter run time could be extended up to 70%. Regarding to the turbidityremoval, there was insignificant difference between two filters.

Study on the law of artificial crack propagation and fracturing technology in strong heterogeneous conglomerate strata: a case study of the Mahu glutenite in Xinjiang Oilfield

The glutenite reservoir of the Triassic Baikouquan Formation in the Mahu sag with a large amount of resources, is the main block for Xinjiang oilfields and even domestic oil production in recent years. The reservoir is characterized by deeper burial, fewer natural cracks, low fluidity, high pressure coefficient, high horizontal stress difference and special lithology. For these geological problems, researches on fracture extension law, proppant placement law and fracturing technology have been developed to form an integrated volume fracturing technology of heterogeneous glutenite geological engineering. The contributions are as follows:(1) The lithofacies reservoir in Mahu includes matrix support, particle support and mixed support, which makes the conglomerate reservoir have large differences in many respects. The mechanical parameters of granular-supported conglomerate are higher than those of complex-base-supported conglomerate, and the brittleness index is higher.(2) Fracture regularity of glutenite varies greatly at different scales. As the ratio of fracture size to gravel size enlarges gradually, the influence of gravel on fracture extension weakens.(3) The fracture roughness of glutenite has great influence on fluid flow and proppant migration. The sand-laden fluid flows by fingering in small fracture. The crack with larger width is the dominant flow channel and will influence proppant placement.

Influence of gravel and adjuvant on the compressive strength and water absorption of concrete

Concrete is the most commonly used material in civil engineering, given its economic cost and ease of manufacture. Its strength depends on the characteristics of its constituents. A good mix makes it possible to build solid, durable and economical structures. The present work aims to characterize the gravel of the Eastern region (quarry of eastern Morocco) by granulometric analysis and water absorption. Then, the studied gravel is used to produce three types of concrete (B20, B25 and B30), which were assessed in terms of water absorption and compressive strength. The last step is to study the effect of an adjuvant, more specifically a water reducer, on mechanical characteristics of local concrete. B25 concrete was chosen for the last step since it is the most used type in the region. Results show that adding a water reducer adjuvant, in this case ‘Chrysoplast’, can improve the compressive strength of concrete if the percentage added is accurately determined.

Influence of gravel on the propagation pattern of hydraulic fracture in the glutenite reservoir

The clear mechanism of hydraulic fracture propagation in glutenite reservoirs with high heterogeneity is still not obtained, thus it is difficult to carry out the design of fracturing plan effectively. Based on the characteristics of the glutenite reservoirs, a coupled flow-stress-damage (FSD) model of hydraulic fracture propagation with gravels is established. This model is experimentally verified and the research on the influence of rock physical parameters and gravel property on the hydraulic fracture propagation is conducted. It is shown that as the gravel tensile strength increases, the hydraulic fracture is prone to propagate around the gravel, where the fracture deflection always occurs; as the gravel Young's modulus increases, there is high probability that hydraulic fracture propagates around the gravel, with more obvious fracture deflection; the matrix permeability influences fracture propagating morphology when encountering gravel and total fracture length; the horizontal geostress difference seriously impacts the fracture deflection; as the fracturing fluids injection displacement increases, the fracture is prone to deflect when encountering gravel; the low viscosity fracturing fluids result in the shorter fracture; the larger gravel increases the possibility of fracture deflection; in case of smaller gravel sizes, the increasing gravel content has a big influence on fracture deflection, and the increasing content of large gravel complicates the fracture morphology, resulting in the fine branched fractures; for the well rounded gravel, the fracture propagation around the gravel is prone to occur, and the fracture is not prone to deflect. Compared with the conventional sandstone reservoir, the glutenite reservoirs have higher breakdown and extension pressures, which fluctuate due to the gravel; the larger gravel size results in higher extension pressure. In this paper, a simulation method of hydraulic fracture propagation in the glutenite reservoirs is introduced, and the result provides the theoretical support for prediction of fracture propagation morphology and plan design of hydraulic fracturing in the glutenite reservoirs.

EFFECT OF GRAVEL CONTENT ON SOIL SUCTION

: This paper seeks to a) investigate the effect of gravel on soil suction and b) establish whether results of standard suction tests using filter paper can accurately represent the value of suction that would be expected in the field. Eight natural soils with different soil gradation and plasticity were used to prepare two types of specimens: a) the “original” specimens (no change compared to the field soil), and b) “sieved” specimens – when the “original” soil was passed through a 2-mm sieve to meet the standard requirement. Comparisons of soil-water characteristics curves (SWCC) obtained for both types of specimens were made to better understand the effect of gravel content on total and matric suction. The obtained data indicated that the results of standard tests can significantly overestimate the soil suction. In particularly, it was found that as the gravel content increased from 4.8 to 19.6%, the difference in suction between the “original” and “sieved” specimens increased to 14% (total suction) and almost 20% (matric suction). The experimental data showed that the effect of gravel was more pronounced for low plasticity soils, compared to high and very high plasticity soils, in which the influence of gravel on suction was found to be insignificant. Although the “sieved” specimens tended to produce higher values of suction, this tendency might reverse for high and very high plasticity soils when their liquidity index (LI) became positive.

Analysis of Cracking Risk in Early Age Mass Concrete with Different Aggregate Types

The main cause of early age cracks often observed in massive concrete structures is inhomogeneous volume changes associated with thermal and moisture gradients occurring in these structures due to the hydration process. Significant impact on a temperature rise which is the main reason of significant changes in concrete volume, and as a consequence, on the cracking risk in the massive foundation slab has the type of aggregate, which forms the thermal properties of concrete. In the paper, thermal properties of concretes made with different aggregate types and their impact on the cracking risk in a massive concrete slab are discussed. Thermal conductivity and heat capacity of concrete with different aggregate types have been experimentally measured and next used in the numerical study. The influence of gravel (consisting mainly of quartz), basalt, granite and limestone aggregate on the temperature development, stress level and the cracking risk has been studied in the numerical tests. The presented numerical analyses are conducted for a massive foundation slab with use of the original numerical model and computer programs TEMWIL and MAFEM. It has been shown that the use of the aggregate with the appropriate thermal properties may result in the reduction of thermal stresses and the cracking risk in early age concrete slabs.

The influence of gravel on the ambient temperature of power substations

This paper examines the role of gravel in the heating process of substation environments. The choice of the material applied to the electric energy substation surface level can influence temperature changes in equipment. Ambient temperature is an important parameter used to define how many years a transformer will last when subjected to a load curve, under normal and emergency operation conditions. This paper shows that the ambient temperature of 30°C, suggested in IEEE C 57.91 standard for calculating transformer's loading depending on the desired equipment life span is underestimated. There are differences in ambient temperature on surfaces when applying different rocks on the soil surface substations. In terms of the resistivity, some rocks have higher values than others when the drain systems fail to drain all the rainwater to the soil. Two field tests were performed, one in the 345kV/138kV Jacarepagua Substation in Rio de Janeiro, and the other in the Substation of Foz do Iguaçu in the state of Paraná, where measurements were performed at three locations: switchyard of 600kV direct current – DC, 500kV and 750kV alternating current – AC. Laboratory tests of thermal and electrical properties of rocks typically used to cover the ground of substations were also performed. This paper presents some consideration of drainage properties.

Closure to “Influence of Gravel on the Compression Characteristics of Decomposed Granite Soil” by Tae-Gew Ham, Yukio Nakata, Rolando P. Orense, and Masayuki Hyodo

Closure to “Influence of Gravel on the Compression Characteristics of Decomposed Granite Soil” by Tae-Gew Ham, Yukio Nakata, Rolando P. Orense, and Masayuki Hyodo

Discussion of “Influence of Gravel on the Compression Characteristics of Decomposed Granite Soil” by Tae-Gew Ham, Yukio Nakata, Rolando P. Orense, and Masayuki Hyodo

Discussion of “Influence of Gravel on the Compression Characteristics of Decomposed Granite Soil” by Tae-Gew Ham, Yukio Nakata, Rolando P. Orense, and Masayuki Hyodo

Influence of Gravel on the Accumulationof Pedogenic Gypsum in Kuwait

In hot arid regions, \\hbox{per descendum} action of meteoric water on airborne salts is often invoked to explain the distribution of pedogenic gypsum and calcite. In northern Kuwait, such differentiation is readily associated with salt laden dust blown from the north and patterns of infiltration. However, the degrees of partitioning, accumulation, and crystalline forms of the pedogenic salts are not simply related to uniform infiltration and drying. Soil survey data from Northern Kuwait provide evidence that physical properties influencing the geometry of descending wetting fronts, such as texture, surface sealing, and gravel size and quantity, also influence the nature and degree of gypsum accumulation. Profile features, including wetting front fingering and fibrous, vertically orientated gypsum on the underside of large gravels in sand, betray this geometry. The concentration of gravity driven, gypsum laden solutions below large stones also partly explains linkages between gypsum abundance and its crystalline forms and profile inflation.