Sand Penetration Research Articles

Coupled 3D discrete-continuum numerical modeling of pile penetration in sand

A coupled discrete-continuum simulation incorporating a 3D aspect and non-circular particles was performed to analyze soil-pile interactions during pile penetration in sand. A self-developed non-circular particle numerical simulation program was used which considered sand near the pile as interacted particles using a discrete element method; the sand away from the pile was simulated as a continuous medium exhibiting linear elastic behaviors. The domain analyzed was divided into two zones. Contact forces at the interface between the two zones were obtained from a discrete zone and applied to the continuum boundaries as nodal forces, while the interface velocities were obtained from the continuum zone and applied to the discrete boundaries. We show that the coupled discrete-continuum simulation can give a microscopic description of the pile penetration process without losing the discrete nature of the zone concerned, and may significantly improve computational efficiency.

The effect of rod nose shape on the internal flow fields during the ballistic penetration of sand

This paper discusses the technique of Digital Speckle Radiography (DSR) and its application to the measurement of the internal flow fields in penetration of sand by long-rod projectiles at velocities up to 200 m/s. Three different rod nose shapes were studied: flat-ended, ogive-2, and hemispherical. Impacts performed on gelatine and concrete gave significantly different displacement fields to sand. Sand, therefore, cannot either be modelled as a fluid or as a conventional solid. Simulations performed using a code written by two of the authors (Bobaru and Promratana) showed that the velocity distribution has a very different appearance to the force distribution. This suggests that processes such as reorganisation, sliding and void filling take place, allowing the grains to move in directions other than the applied force. The resulting velocity distribution bears a strong resemblance to the experimentally measured displacement fields.

Simulation of Suction Caisson Penetration in Seabed Using an Adaptive Mesh Technique

This paper reports results of a numerical investigation into the suction caissons penetration in sand. A 3D finite element model is used for this purpose. The water saturated soil domain is modelled as a two-phase medium, consisting of soil skeleton and pore-water phases. Nonlinear behavior of the solid phase is described by means of a bounding-surface plasticity model. The caisson itself is modelled by solid elements and non-porous linear elastic properties. The soil-soil and soil-caisson interactions along the penetration path are modelled with a master/slave contact algorithm using contact surfaces and a frictional contact interface. A re-meshing technique is also used to avoid excessive distortion of the finite elements along the caisson-soil penetration path.The model was first substantiated against laboratory test data. The numerical model was found to present acceptable agreements with the experimental measurements. The verified model was then used to study the influence of parameters such as soil internal friction, penetration speed and adaptive mesh schemes on the installation behavior of suction caissons in sands.

Centrifuge model study of spudcan penetration in sand overlying clay

A series of centrifuge model tests has been conducted to investigate the bearing resistance of spudcan foundations of offshore jack-up rigs in sand overlying normally consolidated clay. The spudcan bearing-resistance profiles measured in most of the tests recorded a peak resistance at a shallow depth within the upper sand layer, followed by an abrupt post-peak reduction in resistance causing the spudcan to plunge into the underlying soft clay. This phenomenon is commonly termed as ‘spudcan punch-through hazard', which potentially leads to severe structural damage of jack-up rigs in the field. The centrifuge test results revealed that the ratio of upper sand layer thickness over spudcan diameter and the ratio of bearing resistance between the upper sand and underlying clay affect the development of spudcan bearing resistance. The limitations of existing design methods, which were derived for the ultimate bearing capacity of pre-embedded shallow foundation to assess the spudcan bearing resistance-depth profile, are also identified. It is proposed that the profile may be assessed by focusing on three key characteristic bearing resistances.

Distribution, Chemical Speciation, and Mobility of Lead and Antimony Originating from Small Arms Ammunition in a Coarse‐Grained Unsaturated Surface Sand

This study quantified the heavy metal contamination caused by firing 500 high-velocity 7.62-mm jacketed Swedish military rounds. Contamination of solid and aqueous phases was studied, with Pb and Sb being the two contaminants of primary interest. The distribution of the Pb and Sb were measured in terms of depth of penetration in sand and grain size distribution of the bullet particles. The Pb- and Sb-contaminated sand was then used as a source material in two bench-scale unsaturated lysimeters to measure the transport of Pb and Sb through two coarse-grained sands, which were taken from the berms on two Swedish military small arms ranges. The lysimeters were subjected to an infiltration cycle that reproduced spring snowmelt, which is the most significant infiltration event of the year in northern climates. The levels of mobile Pb and Sb were monitored in the effluent from the lysimeters. Extended X-ray absorption fine-structure spectroscopy analysis was performed on the contaminated sands to determine Pb speciation before and after leaching. Ninety-three percent of the mass of bullets was found in the top 30 cm of sand. Lead oxide was the predominant species of Pb before and after leaching. Transport of Pb was small, with aqueous concentrations remaining stable at <2 microg L(-1). Antimony was far more mobile, with solute breakthrough occurring between 5 and 14 d and concentrations rising to over 125 microg L(-1) within 1 month.

Two dimensional mesoscale simulations of projectile instability during penetration in dry sand

To gain insight into the instability and trajectory change in projectiles penetrating dry sand at high velocities, two dimensional plane strain mesoscale simulations were carried out using representative models of a particulate system and of a small projectile. A program, ISP-SAND, was developed and used to generate the representative particulate system with mean grain sizes of 60 and 120 μm as well as ±30% uniform size distribution from the mean. Target porosities ranged from 30% to 40%. The penetration of ogive nose steel projectiles with caliber radius head of 3.5 and length-to-diameter (l/d) ratio of 3.85 was simulated using the updated Lagrangian explicit parallel finite element code ISP-TROTP. Deformation of the projectile and individual sand grains was analyzed using a nonlinear elastic-inelastic model for these materials. Grain-grain and grain-projectile interactions were analyzed using a contact algorithm with and without friction. Projectile instability was quantified and compared using the lateral displacement of the center of mass, lateral force acting on the projectile, and its rotational momentum about the center of mass. The main source of projectile instability and the ensuing trajectory change in the penetration simulations was found to be the inhomogeneous loading of the projectile due to the heterogeneities and randomness inherent in a particulate media like sand. The granularity of the media has not been considered explicitly in previous work. Projectile instability increased with impact velocity, as expected. However, it also increased for the case of elastic impactor that preserved the nose shape, with an increase in grain size, and for uniform grain sizes. Moreover, friction, inherently present in geologic materials, was found to be a major contributor to instability. Conclusions derived from one projectile depth simulations were confirmed by two deeper penetration simulations considering up to three full lengths of penetration (requiring a larger sand target). The deep penetration simulation predicted considerable instability with a trajectory change of approximately 45° when friction was considered in the dry sand medium. An overall conclusion of this work is that projectile penetration studies in geologic materials need to explicitly consider the heterogeneous or particulate nature of these materials.

Penetration Resistance of Offshore Skirted Foundations and Anchors in Dense Sand

Penetration of skirts is an essential design issue for offshore skirted foundations and anchors in sand. Skirts may not penetrate far enough into dense sand by the available submerged weight alone. It may therefore be necessary to apply underpressure inside the skirt compartment to produce an increased driving force and to reduce the penetration resistance. This paper recommends procedures to calculate penetration resistance and required underpressure for skirts penetrated in dense sand with and without interbedded clay layers. The recommendations are based on interpretation of skirt penetration data from prototypes, field model tests, and laboratory model tests in dense sand. The paper first presents a model to calculate the penetration resistance of skirts penetrated by weight, or other external vertical load that does not cause flow of water in the sand. Two models are considered; one based on bearing capacity equations with friction angles from laboratory tests, and the other one based on empirical correlations with CPT tip resistance. The bearing capacity model gives more consistent correlations with the empirical data than the CPT model. Thereafter, a model to account for the effect of underpressure applied inside the skirt compartment is proposed. This model is developed based on interpretation of available prototype and model test data from skirts penetrated by underpressure. The results show that underpressure facilitates skirt penetration in sand considerably by providing both an additional penetration force and a reduced penetration resistance. It is also shown that interbedded clay layers can prevent flow of water through the sand and eliminate the beneficial reduction in penetration resistance.

Influence of Water-Cement Ratio and Cover Thickness on Chloride Extraction of Reinforced Concrete

Chloride ions can infiltrate concrete by a variety of ways, including admixtures, contaminated sand, or external penetration. When the concentration of chloride ions reaches a critical level, the corrosion begins. This article reports on a study that evaluated the method of electrochemical extraction of chloride ions for the rehabilitation of concrete structures with reinforcement corrosion. The authors investigated the influence of the concrete cover and the water-cement ratio (w/c) in the efficiency of the method by determining the initial and the final chloride content. Electrochemical impedance spectroscopy and the corrosion potential were used to monitor the reinforcement electrochemical behavior during the chloride extraction. The test results verified that the method successfully extracted chloride ions. On average, 77% of the content of initial chloride ions at a distance of 0.5 cm from the surface (depth where the slices had been extracted) were removed. The study used tap water as the electrolyte, which caused high polarization of the reinforcing bars during the extraction; the authors recommend an alkaline solution for future studies. The porosity of the concrete was not affected by the electrochemical chloride extraction.

The geo-dscm system and its application to the deformation measurement of rock materials

Sand is a granular, porous material with high compressibility, which influences the penetration process. According to the sand responses at different penetration velocities, the P-alpha equation of state and Mohr-Coulomb Tresca-limit yield criterion are used to describe the constitutive behavior. In the plastic region, the spherical cavity-expansion model is applied, and in the fluid-like region the hydrodynamic model with compressibility considered is applied based on the Alekseevskii-Tate model. Comparison with experimental results shows that the model is suitable for calculating sand penetration depths for rigid and erosive projectiles. Initial sand density affects penetration dissimilarly for different striking velocities, and a critical striking velocity exists. The compressibility should be considered with P-alpha equation of state below this critical striking velocity, and otherwise the fully compacted density can directly be used to calculate the penetration depth. Projectile dynamic yield strength influences penetration strongly. For an erosive projectile, the penetration depth and change in residual projectile length vary with the projectile dynamic yield strength.

SAR Studies in the Yuma Desert, Arizona: Sand Penetration, Geology, and the Detection of Military Ordnance Debris

Synthetic Aperture Radar (SAR) images acquired over part of the Yuma Desert in southwestern Arizona demonstrate the ability of C-band (5.7-cm wavelength), L-band (24.5 cm), and P-band (68 cm) AIRSAR signals to backscatter from increasingly greater depths reaching several meters in blow sand and sandy alluvium. AIRSAR images obtained within the Barry M. Goldwater Bombing and Gunnery Range near Yuma, Arizona, show a total reversal of C- and P-band backscatter contrast (image tone) for three distinct geologic units. This phenomenon results from an increasingly greater depth of radar imaging with increasing radar wavelength. In the case of sandy- and small pebble-alluvium surfaces mantled by up to several meters of blow sand, backscatter increases directly with SAR wavelength as a result of volume scattering from a calcic soil horizon at shallow depth and by volume scattering from the root mounds of healthy desert vegetation that locally stabilize blow sand. AIRSAR images obtained within the military range are also shown to be useful for detecting metallic military ordnance debris that is located either at the surface or covered by tens of centimeters to several meters of blow sand. The degree of detectability of this ordnance increases with SAR wavelength and is clearly maximized on P-band images that are processed in the cross-polarized mode (HV). This effect is attributed to maximum signal penetration at P-band and the enhanced PHV image contrast between the radar-bright ordnance debris and the radar-dark sandy desert. This article focuses on the interpretation of high resolution AIRSAR images but also compares these airborne SAR images with those acquired from spacecraft sensors such as ERS-SAR and Space Radar Laboratory (SIR-C/X-SAR).

The use of multifrequency and polarimetric SIR-C/X-SAR data in geologic studies of Bir Safsaf, Egypt

Bir Safsaf, within the hyperarid “core” of the Sahara in the Western Desert of Egypt, was recognized following the SIR-A and SIR-B missions in the 1980s as one of the key localities in northeast Africa, where penetration of dry sand by radar signals delineates previously unknown, sand-buried paleodrainage valleys (“radar-rivers”) of middle Tertiary to Quaternary age. The Bir Safsaf area was targeted as a focal point for further research in sand penetration and geologic mapping using the multifrequency and polarimetric SIR-C/X-SAR sensors. Analysis of the SIR-C/X-SAR data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and structures mostly hidden from view on the ground and on Landsat TM images by a relatively thin, but extensive blanket of blow sand. Basement rock units (granitoids and gneisses) and the fractures associated with them at Bir Safsaf are shown here for the first time to be clearly delineated using C- and L-band SAR images. The detectability of most geologic features is dependent primarily on radar frequency, as shown for wind erosion patterns in bedrock at X-band (3 cm wavelength), and for geologic units and sand and clay-filled fractures in weathered crystalline basement rocks at C-band (6 cm) and L-band (24 cm). By contrast, Quaternary paleodrainage channels are detectable at all three radar frequencies owing, among other things, to an usually thin cover of blow sand. The SIR-C/X-SAR data investigated to date enable us to make specific recommendations about the utility of certain radar sensor configurations for geologic and paleoenvironmental reconnaissance in desert regions.

The Role of Jute Geotextile/Slurry Interface Friction on the Bearing Capacity of Clay Slurry

Abstract The layered clay-sand scheme of land reclamation depends on the successful formation of sand seams sandwiched between hydraulically placed layers of marine clay slurry to provide shorter drainage paths for rapid clay consolidation during surcharge application. It is anticipated that a low-cost jute geotextile placed on a clay slurry surface without anchorage will expedite construction of sand seams by providing support for the thin sand layers and preventing penetration of sand into the clay slurry. In this application, the interface friction between the very soft clay slurry and the jute geotextile plays a major role in determining the support for the thin sand seam. This paper discusses measurement of the jute/slurry interface friction by incremental vertical penetration of a thin, end-weighted jute sheet under an incremental load to obtain the interface stress value under a quasistatic condition. The effects of sheet width and sheet type were investigated and found to be negligible on the measured interface friction for the clay slurry water content range tested. The results of the interface friction for the 500 g/m2 jute geotextile is then applied to a rectangular loaded area with a jute base on clay slurries of 150 to 300% water content. These water contents are the likely range of values to be encountered in field applications. The load test results indicate that the measured bearing capacity for the jute on clay slurry is about 5.5 to 6.5 times the interface friction, which is in close agreement with typical bearing-capacity factors used in a shallow foundation on clays.

Sand Penetration into Clay Slurry Through Jute Interlayer

The layered clay-sand scheme of land reclamation involves the formation of thin sand seams sandwiched in between hydraulically placed marine clays to provide shorter drainage paths for the rapid consolidation of the clay layers during surcharge application. In a situation of scarce and expensive sand supply, it is desirable to minimize the losses of sand through penetration into the very soft clay slurry during the process of forming the horizontal sand seams. This study provides some insights as to the nature of sand penetration into a clay slurry through a jute interlayer. The factors that affect the efficacy of the jute layer in minimizing sand losses into a clay slurry are the height of drop of the sand through still water before hitting the jute interlayer, the intensity of sand spreading, the relative sizes of sand particles to the opening size of the jute fabric, and the clay slurry strength. Experiments are conducted to examine the effects of each of these factors, and the results are verified by gamma-ray density profiling of the clay column before and after sand spreading. Results indicate that the key factors that control sand penetration are the relative sizes of sand particles to jute opening, the intensity of spreading, and the slurry strength.

Sand penetration into clay slurry : Inoue, T; Tan, T S; Lee, S L Proc International Conference on Geotechnical Engineering for Coastal Development, GEO-COAST'91, Yokohama, 3–6 September 1991P317–322. Publ Japan: Coastal Development Institute of Technology, 1991

Sand penetration into clay slurry : Inoue, T; Tan, T S; Lee, S L Proc International Conference on Geotechnical Engineering for Coastal Development, GEO-COAST'91, Yokohama, 3–6 September 1991P317–322. Publ Japan: Coastal Development Institute of Technology, 1991

The measurement of interface friction between a jute geotextile and a clay slurry

The layered clay-sand scheme proposed by Lee et al. has been shown to be feasible for land reclamation in sand-scarce country. Although the layered clay-sand scheme has great potential as a means of saving sand fill in replacing scarce sand by cheap marine clay available in the surrounding seabed, practical problems exist in its implementation. The most difficult part of the scheme is to form thin sand-drainage layers on top of a very soft clay slurry without losing too much sand material into the clay. This can only be accomplished by careful spreading of thin sand layers (of less than 5 cm) on the clay slurry when it has reached a water content below 200%. From the process of self-weight sedimentation and consolidation above, it takes a very long time to achieve such consistency from an initial deposition water content of 500–600%. It is therefore necessary to investigate the use of a low-cost geotextile (such as a jute fabric, which can support the formation of thin sand layers on top of the clay slurry at higher water content, to shorten the waiting period before sand-spreading, as well as to save sand fill by reducing sand penetration into the clay slurry. It is proposed that the jute fabric is placed on top of the clay slurry before careful sand-spreading. To aid the use of jute fabric for this purpose, an investigation is carried out to determine the interface friction between a jute geotextile and a clay slurry at various water contents by means of a vertical-plate-penetration test that is described in this paper.

Numerical simulation of penetration in sand based on FEM : Sikora, Z; Gudehus, G Comput GeotechV9, N1/2, 1990, P73–86

Numerical simulation of penetration in sand based on FEM : Sikora, Z; Gudehus, G Comput GeotechV9, N1/2, 1990, P73–86

Numerical simulation of penetration in sand based on FEM

This article presents the application of the Finite Element Method (FEM) for estimating the penerration resistance and the stress and strain state in the soil around a penetrating rod. Numerical solutions are obtained assuming Lagrangian formulation with finite deformations. The Jauman terms are incorporated in the analysis. A constitutive law by Kolymbas is used. A condition representing skin friction has been defined for the surfce of the penetrometer, and subsequently the unknown stress state on its surface is determined with an iterative method. The method is closely connected with the localization of deformation. Some numerical problems due to time-integration and convergence criteria for incrementally nonlinear constitutive laws are also discussed. In numerical computations, the friction coefficient parameter is varied. The influence of this parameter on the penetration resistance is discussed.

Interpretation of CPTs and CPTUs. Part 2: drained penetration of sands: Baldi, G; Bellotti, R; Ghionna, N; Jamiolkowski, M; Pasqualini, E Proc 4th International Geotechnical Seminar, Field Instrumentation and In-situ Measurements, Singapore, 25–27 November 1986P143–156. Publ Singapore: NT1, 1986

Interpretation of CPTs and CPTUs. Part 2: drained penetration of sands: Baldi, G; Bellotti, R; Ghionna, N; Jamiolkowski, M; Pasqualini, E Proc 4th International Geotechnical Seminar, Field Instrumentation and In-situ Measurements, Singapore, 25–27 November 1986P143–156. Publ Singapore: NT1, 1986

Zum Erstickungstode beim Verschlu� der Atem�ffnungen durch Sand

Eleven cases are reported in which death occurred because of suffocation as a result of occlusion of the respiratory tract by sand (without thoracic compression: 3 cases) or being buried alive (8 cases). Two tables demonstrate the findings and circumstances in the events. Three cases are described in detail. A 22-year-old woman was manhandled by blows and kicks to the head and neck. She became unconscious and her head and neck were covered by a layer of sand so that she suffocated. A 42-year-old man was smothered, while unconscious, in a prone position with his face in the sand, after hard blows to the head by two culprits. A 17-year-old girl finally died by chocking. Previously the culprit had pressed her face into the ground, so that she aspirated particles of soil. The question of vital reactions during aspiration of sand was investigated by microscopic examination of the content of the air passage and by destroying parts of the lungs by sulphuric acid. Minimal aspiration of sand occurred in all cases. Although the postmortal remains were left in the ground, there was no postmortem penetration of sand into the air passage. Histological examinations were carried out to support the diagnosis of violent suffocation. In some cases, there were remarkable findings (mobilization of alveolar cells, hepatocelullar hydropic degeneration), but there were no typical or unanimous findings that pertained to all cases.

The Outlook for Geopressured/Geothermal Energy and Associated Natural Gas

Distinguished Author Series articles are general, descriptiverepresentations that summarize the state of the art in an area of technology bydescribing recent developments for readers who are not specialists in thetopics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and presentspecific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleumengineering. Introduction Worldwide energy shortages over the past decade have focusedattention on alternative past decade have focused attention on alternativeenergy sources that might reduce dependence on imported petroleum. Geothermalenergy in the form of dry steam or hot water has become a significantalternative energy source in many countries for electric power generation andvarious process heat applications. power generation and various process heatapplications. Intensive exploration for geothermal reservoirs is under way bymajor energy producer worldwide. Since the early 1970's, an unconventional formof geothermal energy-geopressured/geothermal energy-has been underinvestigation by the U.S. DOE and its predecessor agencies, in cooperation withindustry and various research units and universities. This effort has beenconcentrated in Tertiary deposits of the northern Gulf of Mexico basin alone, the Texas and Louisiana coastal region. This basin, one of several geopressuredbasins within the U.S., has given us the most information from the manythousands of wells drilled for hydrocarbons over the past 80 years, othergeopressured basins of similar type are found throughout the world. It has beenestimated that more than 60 such basins are known and others may exist. Thus, these investigations may have applicability not only in the U.S. gulf coastarea, but also in similar geologic environments worldwide. Geology and Fluid Characteristics of the Gulf Coast Basin In the northernGulf Coast basin. sedimentary deposits exhibit a maximum thickness of 50,000 ft(15 240 m), with the upper 25,000 ft (7620 m) composed primarily of alternatingseries of rock layers broadly classified as sandstones and shales. The lowerlayers consist almost entirely of shales, believed to be the origin of methanein the geopressured formations. The geopressure phenomenon in this regionresulted from rapid sediment loading from riverborne systems and their deltas, ending as a "leapfrogged" sediment distribution that has extended the coastlinefrom about 100 miles (160 km) inland to its present location, The penetrationof sands into underlying muds resulted in isolation of large sand members fromthe overlying strata. Above the isolated intervals, pressures throughout thebasin are approximately 0.465 psi/ft (10.5 kPa/m), which is considered normalhydrostatic pressure based on the fluid pressure of a column of saline water.However, beneath these normally pressured zones, the isolated units of sandsand muds contain pressures far greater than normal, and approach lithostaticpressure of 1.0 psi/ft (22.6 kPa/m). This is the result of compaction psi/ft(22.6 kPa/m). This is the result of compaction of sediments. As the overburdenon locked-in sands increases, the fluid within the sands must support a portionof the overburden, resulting in dramatic portion of the overburden, resultingin dramatic increases in pressure. In addition, temperatures at the top ofgeopressure [approximately 200 to 225F (93 to 107C)] cause conversion ofmontmorillonite shales to illite or chlorite, resulting in expulsion of anadditional 15% of the water contained in the shales into overlying and adjacentgeopressured sands. The additional free water forced into the sands causesadditional overpressure and decreases salinity within the zones withfine-grained mud particles acting as semipermeable membranes, permittingselective water escape and concentrating dissolved components in the remainingpore fluids. p. 1915