Uncompacted Sand Research Articles

A model tank investigation of the electrical resistivity response over a simulated forensic target

The electrical resistivity response of a simulated clandestine buried weapon box-laden ammunition tank was carried out. This was with the aim of determining the adoptability of the resistivity method in search for similar forensic targets. The experiment was carried out in a model tank of dimension 207x160x50 cm3. The model tank was filled with compacted and un-compacted sand and a weapon box-laden ammunition tank was buried within the compacted sand. The ammunition tank was made of stainless steel while the weapon box was metallic. Resistivity measurements were taken on the crest of the tank along five (5) traverses before and after the burial of the ammunition tank. The Electrical Resistivity Imaging (ERI) technique in conjunction with the dipole-dipole array was adopted for the measurements. The data were quantitatively interpreted by inversion and the results were presented as 2-D resistivity structures, maps and stacked profiles. During the pre-burial measurements, resistivity values generally increased with increasing depth and three (3) resistivity classes (101–266, 275–835 and 2113–23,944 Ω-m) resulting from the variation in compaction and/or degree of water saturation were observed. The resistivity classes were present within the depth ranges of 0–8 cm, 8–16 cm and 16–40 cm respectively. A drastically reduced resistivity regime, however characterized the post-burial measurements. The post-burial images of the traverses straddled by the region of burial had their resistivity values decreasing with increasing depth as against the pre-burial pattern. The presence of the stainless steel ammunition tank was attributed to the resulting higher resistivity values introduced within the overburden after its burial. A major low resistivity anomaly coincident on the position of burial of the metallic weapon box indicated its presence. The study demonstrated the potential of the electrical resistivity method in the delineation of similar targets that may have forensic implications.

Effect of racetrack surface on glycolytic activity of trained endurance horses

ABSTRACT No study has analysed the effects of wet and dry racetrack surface on the glycolytic activity of Arabian horses. The aim of the present study was to investigate the effects of wet and dry racetrack surfaces during a riding test in an Arabian endurance horse. Using a counterbalanced design, nine healthy and trained mixed-bred Arabian horses performed a single-step riding test on a wet (compacted sand) or dry (uncompacted sand) racetrack surface. The wet racetrack received a daily wetting and was compacted using a tractor, while the dry racetrack was upturned by a tractor daily. Both racetracks were elliptical with straight lines of 600 m and total length around 900 metres. Blood samples were drawn from the jugular vein, immediately after the end of the test, and used for the analysis of blood lactate concentration. Mean blood lactate concentration was significantly higher after the riding test on the dry racetrack (2.6 ± 1.6 mmol/L) compared with wet racetrack (0.9 ± 0.3 mmol/L) surface (p = 0.007; d = 1.48, [large]; 95%CI = 0.37–2.44). In conclusion, dry racetrack surface increases lactic anaerobic contribution in trained Arabian horses during a single-step riding test in the field.

EXPERIMENTAL INVESTIGATION ON MONOTONIC BEHAVIOR OF CIRCULAR STEEL STIFFENED COMPOSITE COLUMN UNDER COMPRESSION

Concrete-filled square or rectangular thin-walled steel tubular columns are becoming increasingly attractive to be used in engineering practice. However, local buckling is more likely to occur for thin-walled tubes, and thus has adverse effects on strength and ductility for the composite columns. In order to improve their overall performance, one of the most effective stiffening measures is to provide longitudinal stiffeners for the steel tubes. In this experiment, Monotonic Behavior of Circular Steel Stiffened Composite Column under Compression is studied. In this study typical Fifty Four specimens of variable thickness t1&t2 and variable dia d1&d2 with piercing and also 54 specimens of thickness t1&t2, and variable dia d1&d2 without piercing is considered. For each Thickness combination of stiffeners at different position are selected that is for single stiffeners at mid span, from top h/3,from bottom h/3 and also for double stiffeners equispaced ,from top h/2&from bottom h/3,from top h/3&from bottom h/2. Experiments were carried out for four different cases : Hollow , Uncompacted Sand, Compacted Sand & Dry Cement & Dry Sand in order to know the behavior and buckling load of above said columns and tests were conducted under Monotonic loading. Major conclusion from this study are: Load carrying capacity of tubes with single stiffener with piercing at mid height found to decrease by 8-10% than hollow tubes of same diameter and thickness , but for with single stiffener without piercing at mid height found to increase by 2% than hollow tubes of same diameter and thickness . Also, Load carrying capacity of tubes with single stiffener without piercing at mid height was found to increase by 10-15% than pierced stiffener at mid height of same diameter and thickness.

The survey and mapping of sand-boil landforms related to the Emilia 2012 earthquakes: preliminary results

<p>Sand boils, which are also known as sand blows or sand volcanoes, are among the most common superficial effects induced by high-magnitude earthquakes. These generally occur in or close to alluvial plains when a strong earthquake (M >5) strikes on a lens of saturated and unconsolidated sand deposits that are constrained between silt-clay layers [Ambraseys 1988, Carter and Seed 1988, Galli 2000, Tuttle 2001, Obermeier et al. 2005], where the sediments are converted into a fluid suspension. The liquefaction phenomena requires the presence of saturated and uncompacted sand, and a groundwater table near the ground surface. This geological–geomorphological setting is common and widespread for the Po Plain (Italy) [Castiglioni et al. 1997]. The Po Plain (ca. 46,000 km2) represents 15% of the Italian territory. It hosts a population of about 20 million people (mean density of 450 people/km2) and many infrastructures. Thus, the Po Plain is an area of high vulnerability when considering the liquefaction potential in the case of a strong earthquake. Despite the potential, such phenomena are rarely observed in northern Italy [Cavallin et al. 1977, Galli 2000], because strong earthquakes are not frequent in this region; e.g., historical data report soil liquefaction near Ferrara in 1570 (M 5.3) and in Argenta 1624 (M 5.5) [Prestininzi and Romeo 2000, Galli 2000]. In the Emilia quakes of May 20 and 29, 2012, the most widespread coseismic effects were soil liquefaction and ground cracks, which occurred over wide areas in the Provinces of Modena, Ferrara, Bologna, Reggio Emilia and Mantova (Figure 1). […]</p>

Microalgal species variation at different successional stages in biological soil crusts of the Gurbantunggut Desert, Northwestern China

Biological soil crusts (BSC), most notably lichen crusts, develop and diversify in the Gurbantunggut Desert, the largest fixed and semi-fixed desert in China. Four different successional stages of BSC, including bare sand, microalgal crusts, lichen crusts, and moss crusts, were selected to determine successional changes in microalgal species composition and biomass and formation of BSC. A 10 × 10-m observation plot was established in an interdune region of the Gurbantunggut Desert and data were collected over an 8-year study period. The main results were: (1) different successional stages of BSC significantly affected the content of soil organic C and total and available N but not the total and available P and K content of soil; (2) composition of microalgal communities differed among the four successional stages; (3) significant differences in microalgal biomass were observed among the four successional stages; (4) bare sand was mainly uncompacted sand gains; (5) filamentous cyanobacteria, particularly Microcoleus vaginatus, were the dominant species in the early phase of crust succession. The presence of fungal mycelium and moss rhizoids prevented water and wind erosion.

Compaction effects on strains within profiled thermoplastic pipes

Results from laboratory tests are reported to establish how pipe deflections, strains and local bending are influenced by the selection of backfill soil and its placement for two profiled thermoplastic culverts. Lined-corrugated high-density polyethylene (HDPE) and poly vinyl chloride (PVC) pipes with a nominal inside diameter of 600 mm were tested in poorly graded sand and well-graded gravel backfills. The backfill was compacted using real compaction equipment and procedures, and then subjected to a maximum increase in vertical pressure of 200 kPa in a test cell that simulates deep burial. For the specific conditions tested, the largest deflections and strains were for the HDPE pipe when placed just above a rigid base and with uncompacted sand backfill placed below the springline, while local bending was greatest for the PVC pipe with well-compacted gravel backfill. A procedure is presented to account for the maximum local bending strain within a simplified design approach for profiled thermoplastic pipes using an empirical strain factor inferred from the measured results.

Applying Radial Acoustic Amplitude Signals To Predict Intervals of Sand-Stuck Tubing

Summary The reuse of existing well bores is a cost-saving technique used by oil and gas producers in mature fields. This process usually requires the removal of tubing and packers to allow the well to be deepened or sidetracked. The tubing removal process is often made difficult when the tubing is stuck inside the casing because of mechanical binding or binding caused by dehydrated mud or sand in the annulus between the tubing and casing. Conventional direct and indirect methods of finding the stuck point(s) along an interval of tubing, such as free-point indicator tools or acoustic attenuation measurements, have proved themselves useful in finding the point(s) where the tubing is stuck. However, when the sticking is caused by uncompacted sand that has entered the annular space between the tubing and casing, these conventional stuck-pipe indication methods are often inconclusive or misleading. Technological advancements in the design and development of slim, 11116-in. outside diameter (OD), radial cement bond tools allow the application of a new measurement to find sand-stuck tubing intervals. These tools provide up to six independent, closely spaced acoustic attenuation measurements distributed radially around the tool body. When the recording operation is performed inside the tubing, the increased sensitivity of these tools to sound attenuation, as compared with conventional omnidirectional amplitude signals, allows sand intervals along the outside of the tubing to be distinguished from intervals where little or no sand is present. This information is used to select the best depth to sever or back-off the free tubing in order to reduce the interval length and expense associated with the washover process required to remove the remaining tubing from the wellbore. An overview of conventional stuck-pipe recovery techniques is provided here, along with a brief explanation of applicable acoustic technology. A case study of a South Louisiana well is presented to demonstrate the application and illustrate the cost savings which can be gained by use of this very new technology.

Delineation of a collapse feature in a noisy environment using a multichannel surface wave technique

A collapse developed at Calvert Cliffs Nuclear Power Plant, Maryland, in early 2001. The location of the collapse was over a groundwater drainage system pipe buried at an elevation of +0·9 m (reference is to Chesapeake Bay level). The cause of the collapse was a subsurface drain pipe that collapsed because of saltwater corrosion of the corrugated metal pipe. The inflow/outflow of sea water and groundwater flow caused soil to be removed from the area where the pipe collapsed. To prevent damage to nearby structures, the collapse was quickly filled with uncompacted sand and gravel (∼36 000 kg). However, the plant had an immediate need to determine whether more underground voids existed. A high-frequency multichannel surface-wave survey technique was conducted to define the zone affected by the collapse. Although the surface-wave survey at Calvert Cliffs Nuclear Power Plant was conducted at a noise level 50–100 times higher than the normal environment for a shallow seismic survey, the shear (S)-wave velocity field calculated from surface-wave data delineated a possible zone affected by the collapse. The S-wave velocity field showed chimney-shaped low-velocity anomalies that were directly related to the collapse. Based on S-wave velocity field maps, a potential zone affected by the collapse was tentatively defined.

Delineation of a collapse feature in a noisy environment using a multichannel surface wave technique

A collapse developed at Calvert Cliffs Nuclear Power Plant, Maryland, in early 2001. The location of the collapse was over a groundwater drainage system pipe buried at an elevation of +0·9 m (reference is to Chesapeake Bay level). The cause of the collapse was a subsurface drain pipe that collapsed because of saltwater corrosion of the corrugated metal pipe. The inflow/outflow of sea water and groundwater flow caused soil to be removed from the area where the pipe collapsed. To prevent damage to nearby structures, the collapse was quickly filled with uncompacted sand and gravel (∼36 000 kg). However, the plant had an immediate need to determine whether more underground voids existed. A high-frequency multichannel surface-wave survey technique was conducted to define the zone affected by the collapse. Although the surface-wave survey at Calvert Cliffs Nuclear Power Plant was conducted at a noise level 50–100 times higher than the normal environment for a shallow seismic survey, the shear (S)-wave velocity field calculated from surface-wave data delineated a possible zone affected by the collapse. The S-wave velocity field showed chimney-shaped low-velocity anomalies that were directly related to the collapse. Based on S-wave velocity field maps, a potential zone affected by the collapse was tentatively defined.

The dynamic loading response of surfaces encountered in beach running

The purpose of this study was to measure the response to dynamic loading of sand surfaces typically encountered in beach running. An instrumented drop test rig was constructed and used to guide a drop mass through impact with two surfaces (i) dry, uncompacted sand; and (ii) wet, compacted sand. Four drop masses (3.86, 7.24, 10.62 and 14.0 kg) were chosen and dropped from four different drop heights (100, 200, 300 and 400 mm) to represent the kinetic energies typically experienced during heelstrike in running. Accelerations were measured using a piezoelectric accelerometer and the trajectory of the drop head was measured using a displacement transducer. The following response variable were calculated for each trial: (i) peak impact force, (ii) mean impact force, (iii) impulse, (iv) total impact time, (v) rise time, (vi) fall time, (vii) maximum penetration, (viii) energy absorbed by the surface, and (ix) surface stiffness. Mean and peak impact forces were approximately 4 times greater for the wet surface while penetration, impact time and rise time were approximately 3-4 times greater for the uncompacted surface condition. The wet surface was also found to be 6 times stiffer than the uncompacted surface indicating the presence of water substantially altered surface compliance. Results are discussed in terms of their implications for performance and the potential for injury to athletes who run on these surfaces.

Umbonium vestiarium, a filter‐feeding trochid

U. vestiarium, a dominant species on the seaward side of sand flats at the mouth of the River Vellar, S. India, collects food by filtering the palliai stream of water as it glides over the surface of the sand or is buried except for its tentacles, eye stalks and siphons. It may remain stationary or creep when buried, but feeds only when conditions are quiet. Inhalant and exhalant siphons are formed by folding of the neck lobes of the epipodium; elsewhere the entrance to the mantle cavity is blocked by the head. The inhalant current is filtered by siphonal tentacles and then passes over the osphradium which encircles the base of the siphon. The gill is monopectinate with the axis, which is fused to the mantle throughout its length, shifted to the right so that the prebranchial chamber of the mantle cavity is large; it can be reduced by muscles in the mantle skirt and the gill displaced from the feeding position. The gill filaments are filiform and elongated and their tips overarch a food groove, except anteriorly. Secretion for trapping food is produced by an endostyle and hypobranchial glands. The food cord, formed by the combined action of cilia on the tips of the filaments and dorsal body wall, is directed to the lateral margin of the right eye stalk. It passes beneath the stalk towards the mouth which is at the end of a very small tubular snout hidden between the bases of the siphons. When food in suspension is scarce, organic matter is collected from the substratum, its supply to the vicinity of the mouth being regulated by the activity of the right tentacle and the foot. Odontophore, salivary and oesophageal glands are reduced. There is no crystalline style; the stomach has large sorting areas and a small gastric shield. A valve prevents entry of paniculate matter to the single duct of the digestive gland. Modifications of shell and foot facilitate burrowing in the uncompacted sand and enable the snail to resist displacement when conditions are adverse. The animal moves easily through soft substrata, but with difficulty over a hard one.

The Role and Fate of the Connate Water in Oil and Gas Sands

Published in Petroleum Transactions, AIME, Volume 52, 1916, pages 587–610. What becomes of the water which must have filled the oil and gas sands at the time of deposition, has long puzzled students of oil and gas and has found expression in Munn's well-known article on the hydraulic theory. Both Munn and Clapp have pointed out that in the Appalachian field the deeper sands carry increasingly less proportionate amounts of water. It seems to me probable that the principal source of oil and gas has been in the shales in proximity to the sands which now contain these products. The sand spits which mark off the lagoons from the sea comply particularly with the requirements of a limited sand imbedded in shales rich in organic matter. Cunningham Craig has objected to this view that the rich organic muds of lagoons are found only at the surface. That such muds do extend to considerable depth I am assured by Prof. Douglas W. Johnson, who has made an extensive study of the Atlantic Coast marshes. As any particular sand body becomes weighted by a heavier and heavier overburden, the result of increasing deposition, a part of the very large percentage of water in the uncompacted sand and mud is forced out. The water percentage of freshly settled mud is vastly higher than that of the resultant shales, or even of a very porous sand. If beds of less compressible material meet or underlie the shales in question, there will frequently be a lateral motion along such beds to some point where the upward movement will be resumed. We find in our laboratory work here that oil, gas, and water have extremely slight capacity for gravitational sorting while in a state of rest, but when moving the gravitational sorting is readily accomplished. As the oil, gas, and water pass a body of larger pores, the gas, owing to its lack of capillary attraction, is retained in the large pores. This has been predicted by Washburne, Blatchley and others on the ground that the water has a higher capillarity and grips the finer pores in such a way that there will be a greater proportion of oil and gas in the large pores. T.P. 051–39