Plug Resistance Research Articles

Numerical investigation of soil plugging effect inside sleeve of cast-in-place piles driven by vibratory hammers in clays.

During driving sleeve of cast-in-place piles by vibratory hammers, soils were squeezed into sleeve and then soil plugging was formed. The physic-mechanical properties of the soil plug have direct influence on the load transmission between the sleeve wall and soil plug. Nevertheless, the researches on this issue are insufficient. In this study, finite element and infinite element coupling model was introduced, through the commercial code ABAQUS, to simulate the full penetration process of the sleeve driven from the ground surface to the desired depth by applying vibratory hammers. The research results indicated that the cyclic shearing action decreases both in soil shear strength and in granular cementation force when the sleeve is driven by vibratory hammers, which leads to a partially plugged mode of the soil plug inside the sleeve. Accordingly, the penetration resistance of sleeve driven by vibratory hammers is the smallest compared to those by other installation methods. When driving the sleeve, the annular soil arches forming in the soil plug at sleeve end induce a significant rise in the internal shaft resistance. Moreover, the influence of vibration frequencies, sleeve diameters, and soil layer properties on the soil plug was investigated in detail, and at the same time improved formulas were brought forward to describe the soil plug resistance inside vibratory driven sleeve.

Design and analyses of open-ended pipe piles in cohesionless soils

Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized different design methods for open-ended pipe piles in sandy soils. A major factor for all the design codes is to properly account for the formation and effects of soil plug. The comparison indicates that there is a large variation in the base capacity evaluation among different methods due to the complex behaviors of soil plug. To close the knowledge gap, discrete element method (DEM) was used to simulate the soil plugging process and provide insight on the plugging mechanism. The simulation results show that the arching effect significantly increases the internal unit shear resistance along pipe piles. The porosity distribution and particle contact force distribution from DEM model indicate a large stress concentration occurs at the bottom of the soil plug. Besides, nearly 90% of the plug resistance is provided by the bottom half portion of the soil column. The soil-pile friction coefficient has a significant effect on the magnitude of plug resistance, with the major transition occurred for friction coefficient between 0.3 and 0.4.

Carbon Nanotube Contact Plug on Silicide for CMOS Compatible Interconnect

Carbon nanotube (CNT) filled contact plugs with silicide as the bottom electrode have been demonstrated in this letter. Nickel has been used as the main catalyst to achieve CMOS compatibility. By modifying the catalyst from a pure Ni single layer structure to a Ni/Al/Ni multilayer composite, uniform selective CNT growth on Ti silicide substrate has been achieved. At a low temperature of 450 °C, the vertically aligned CNTs with a density of 1.1×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> tubes/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> inside the silicon dioxide contact plug are formed without the need of catalyst patterning. Four-point Kelvin structures are designed to measure the resistance of the CNT filled contact plugs. Measurement results show that an ohmic contact plug resistance of 216 Ω·μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is obtained.

Algorithm development for quality monitoring on end plug resistance weldment of nuclear fuel rods

The welded area of nuclear fuel rods has the highest possibility of leakage during the combustion of nuclear fuel. The welded area therefore must have integrity and strength. Burst tests and metallographic tests are currently performed via sampling for the quality evaluation of the welded area of fuel rods. Due to the significance of the welded area, extensive research has been conducted on non-destructive testing methods, such as radiography and ultrasonography, to enable real-time inspection as well as full quantity inspection. Applying these testing methods to the actual site, however, is quite challenging.

Development of new hybrid ultrafiltration membranes by entanglement of macromolecular PPSU‐SO3H chains: Preparation, morphologies, mechanical strength, and fouling resistant properties

ABSTRACTThe present work focuses on the preparation of Polyphenylsulfone (PPSU) membranes with enhanced antifouling surfaces through an incorporation of sulfonated Polyphenylsulfone (PPSU‐SO3H), which acts as both, surface modifying agent and macromolecular additive. Initially, Sulfonated polyphenylsulfone (PPSU‐SO3H) was synthesized by using chlosulfonic acid via bulk modification method. The degree of sulfonation (DS, %) of PPSU‐SO3H was calculated by using NMR (nuclear magnetic resonance).The phase inversion technique was used to prepare all asymmetric membranes by allowing the PPSU‐SO3H (different wt %) to entangle with the PPSU membrane matrix. All prepared membranes were characterized by using scanning electron microscope (SEM), X‐ray diffraction analysis (XRD), contact angle analysis (CA), mechanical strength analysis, molecular weight cut off (MWCO), porosity (%), mean pore size, and BSA adsorption studies. The performance efficiency of the membranes was evaluated by using BSA protein as a model foulant in terms of permeability, rejection (SR %), Rm (hydraulic resistance), Rc (cake layer resistance), Rp (pore plugging resistance), Rr (reversible fouling), Rir (irreversible fouling), and FRR (flux recovery ratio). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41986.

Fouling behavior of urban sewage on binary blend PVDF UF membrane

Polyvinylidene fluoride (PVDF) ultrafiltration membranes with better performance were prepared by blending with PVA, polyvinylpyrrolidone, polyethylene glycol, and polymethylmethacrylate through phase inversion via immersion precipitation method. Phase inversion progress of membranes was investigated though light transmittance experiment. Membrane components and morphologies were analyzed by FTIR, scanning electron microscopy, and atomic force microscopy, respectively. Membrane performance was evaluated in terms of pure water permeation, BSA rejection, and water contact angle. Membranes fouling behavior was evaluated according to dynamic fouling resistance analysis, using secondary effluent of urban sewage as separation object. The results showed that PVDF UF membranes with high hydrophilicity, dense surface, and through macrovoids in cross-section had small sewage flux decline and low fouling during filtration, and the main fouling resistance was due to concentration polarization and cake layer resistance, and membrane fouling was reversible. While the UF membranes with porous surface, not through internal macrovoids, and loose sponge-like structure were trend to bring about pore plugging resistance, and membrane fouling was irreversible. The surface roughness had certain influence on the antifouling performance of PVDF UF membranes.

Resistance in Series Model for Ultrafiltration Betacyanin from Hylocereus polyrhizus Peels

This study investigates the fouling mechanism in ultrafiltration membrane during separation of betacyanin from Hylocereus Polyrhizus extract. The Resistance-In-Series Model was used to identify the responsible hydraulic resistance. The resistance against the flux was assumed to be comprised as membrane hydraulic, adsorption, pore plugging and fouling resistance. The profile of total resistance and corresponding flux decline were calculated and compared with the experimental data. The result showed that the adsorption resistance (Rad) was the main contributed the rate of flux decline. Moreover the significant organic fouling that contribute during betacyanin separation revealed that the fouling potential was Rad >Rpp > RF. the measured flux recovery of filtration betacyanin production was 65%.

Evaluación de la fuerza de anclajes de andamios de fachada

The resistance of the anchors to the facade of collective protection (CP) or building aids (MAE) is an essential point of the stability of these elements, which in many cases is unknown. There have been numerous studies on resistance and behavior of the braces to concrete structures. But hardly any studies analyzing the strength of masonry anchors, much less masonry with decades of service in real situations: buildings that have to intervene and must anchor CP and MAE to its factories. In this study we have evaluated the pullout resistance of cancer plastic plugs inserted into staying in masonry building already built. The results were compared with those of other investigators and allowed to assess the requirements of the standard UNE-EN 12810-1 regarding the disposition and removal of scaffolding anchors to the facade.

Highly effective antifouling performance of PVDF/graphene oxide composite membrane in membrane bioreactor (MBR) system

A composite microfiltration membrane, prepared by blending polyvinylidene fluoride (PVDF) and hydrophilic graphene oxide (GO) nanosheets, was successfully used in a submerged membrane bioreactor system. Scanning electron microscopy (SEM), contact angle measurements, and X-ray photoelectron spectroscopy were used to determine the surface properties of GO modified PVDF membrane. To compare the composite membrane with a commercial PVDF membrane, the critical flux, fouling behavior, membrane resistance, and anti-fouling properties against extracellular polymeric substances (EPS) were studied. Higher critical flux was obtained by PVDF/GO composite membrane due to the change of surface characteristics. The PVDF/GO composite membrane demonstrated sustained permeability, lower cleaning frequency, and filtration time that was three times longer than that of the PVDF membrane. In terms of anti-EPS accumulation, the PVDF/GO composite membrane showed lower membrane resistance, particularly, lower pore plugging resistance than the PVDF membrane. Fewer amounts of EPS, specifically polysaccharide accumulated on the composite membrane surface due to the introduction of GO nanosheets. The SEM and confocal laser scanning microscope images showed that the cake layer on composite membrane was looser and thinner than that of commercial PVDF membrane. Consequently, membrane surface was exposed, resulting in the maintenance of high permeability over a long period of time.

Material characterization of a novel new armour steel

The material characterization of a novel new armour steel with comparison to a leading commercial benchmark alloy is presented. Direct ballistic and experimental comparison is drawn. The 5.56 × 45 mm [M193] and 7.62 × 51 mm [NATO Ball] projectiles were used in a cartridge type high pressure barrel configuration to evaluate the superior plugging resistance of the new steel over a range of plate thicknesses. To characterize the dynamic plasticity of the materials, quasi-static, notched and high temperature tensile tests as well as Split Hopkinson Pressure Bar tests in tension and compression were performed. The open source explicit solver, IMPACT (sourceforge.net) is used in an ongoing numerical and sensitivity analysis of ballistic impact. A simultaneous multi variable fitting algorithm is planned to evaluate several selected numerical material models and show their relative correlation to experimental data. This study as well as micro-metallurgical investigation of adiabatic shear bands and localized deformation zones should result in new insights in to the underlying metallurgical and physical behavior of armour plate steels during ballistic perforation.

Two-fluid model for blood flow in stenosed arteries under periodic body acceleration: a mathematical model

This study analyses the pulsatile flow of blood through narrow arteries with mild asymmetric stenosis. Blood is modeled as a two-fluid model with the suspension of all the erythrocytes in the core region being treated as Casson fluid and the plasma in the peripheral layer being assumed as Newtonian fluid. Perturbation method is used to solve the resulting coupled implicit system of non-linear partial differential equations. The expressions for shear stress, velocity, wall shear stress, plug core radius, flow rate and resistance to flow are obtained. The effects of pulsatility, stenosis shape parameter, stenosis depth, peripheral layer thickness, body acceleration and non-Newtonian behavior of blood on these flow quantities are discussed. It is noted that the plug core radius and resistance to flow decrease with the increase of the body acceleration and pressure gradient. It is observed that the velocity and flow rate increase with the increase of the peripheral layer thickness and they decrease with the increase of the stenosis shape parameter. It is recorded that the estimates of the mean flow rate of the two-fluid blood flow model are considerably higher than that of the single-fluid blood flow model. It is also noticed that the presence of body acceleration and peripheral layer influences the mean flow rate by increasing their magnitude significantly in the arteries with different radii.

Base Capacity of Open-Ended Steel Pipe Piles in Sand

This paper presents a new method for estimating the base capacity of open-ended steel pipe piles in sand, a difficult problem involving great uncertainty in pile foundation design. The method, referred to as the Hong Kong University (HKU) method, is based on the cone penetration test (CPT), and takes into consideration the mechanisms of annulus and plug resistance mobilization. In this method the annulus resistance is properly linked to the ratio of the pile length to the diameter—a key factor reflecting the influence of pile embedment—whereas the plug resistance is related to the plug length ratio, which reflects the degree of soil plugging in a practical yet rational way. The cone tip resistance is averaged over a zone in the vicinity of the pile base by taking into account the failure mechanism of the piles in sand, the condition of pile embedment (i.e., full or partial embedment), and the effect of soil compressibility. The predictive performance of the new method is assessed against a number of well-documented field tests including two fully instrumented large-diameter offshore piles, and through comparisons with major CPT-based methods in current engineering practice. The assessment indicates that the HKU method has attractive capabilities and advantages that render it a promising option.

Motion effect on the dynamic contact angles in a capillary tube

A mathematical model is developed to predict the effect of motion of a liquid plug in a capillary tube on the dynamic contact angles including the effects of driving pressure, liquid plug length, tube diameter, and operating temperature. Results show that the advancing contact angle significantly affects the flow resistance of the liquid plug occurring in a capillary tube. For a given driving pressure difference, the pressure difference due to the increase of the advancing contact angle is the primary contribution to the flow resistance of capillary flow in a capillary tube. For example, when the liquid plug length is equal to 5 mm at a driving pressure difference of 10 Pa and a tube radius of 500 μm, the flow resistance caused by the dynamic contact angle can be 92% of the total flow resistance at an operating temperature of 60°C. It can be concluded that the effect of the dynamic contact angle on the fluid flow of a liquid plug in a capillary tube must be considered.

Key Technology of Refined Cotton Centrifuge Unloading

On the basis of studying the principle of centrifugal dewatering technology applied to refined cotton, the paper analyzes the key technologies of screen plugging and pushing resistance concerning problems of cotton fiber blocking screen stencil and impracticality of pushing when refined cotton is tested on P-60 centrifuge, in combination with refined cotton’s properties. Besides, measures of improvement are proposed as to the design of the centrifuge’s main components’ structures, which lays a good foundation for further development of refined cotton centrifuge.

Physics-based models of ground deformation and extrusion rate at effusively erupting volcanoes

[1] We present a model of effusive silicic volcanic eruptions which relates magma chamber and conduit physics to time-dependent data sets, including ground deformation and extrusion rate. The model involves a deflating chamber which supplies Newtonian magma through a cylindrical conduit. Solidification is approximated as occurring at fixed depth, producing a solid plug that slips along its margins with rate-dependent friction. Changes in tractions acting on the chamber and conduit walls are used to compute surface deformations. Given appropriate material properties and initial conditions, the model predicts the full evolution of an eruption, allowing us to examine the dependence of observables on initial chamber volume, overpressure, and volatile content. Employing multiple data sets in combination with a physics-based model allows for better constraints on these parameters than is possible using kinematic idealizations. Modeling posteruptive deformation provides an improved constraint on the rate of influx into the magma chamber from deeper sources. We compare numerical results to analytical approximations and to data from the 2004–2008 eruption of Mount St. Helens. For nominal parameters the balance between magma chamber pressure and frictional resistance of the solid plug controls the evolution of the eruption, with little contribution from the fluid magma below the idealized crystallization depth. While rate-dependent plug friction influences the time-dependent evolution of the eruption, it has no control on the final chamber pressure or extruded volume.

Research on Performance Characteristic of Novel Fomichev Plug Used in Julong-Type Piercer

The novel Fomichev plug described in this paper is of characteristic producing equal unit-reduction of wall thickness along its perforation section during seamless tube piercing, which designed on the base of the roll opening of Julong piercer, taking into account for both feed angle and toe angle of a cone type piercer. Then a 3-D thermal-mechanical coupled numerical simulation on performance characteristic of novel Fomichev plug is presented with the aid of commercial FE code MSC.SuperForm, according to practical process parameters of piercing and rolling for steel grade P91 on Julong piercer in Yangzhou Chengde Steel Pipe Co., Ltd. By comparison with conventional plugs, as FE simulation result shows that the new plug reduces the damage value of the workpiece, thus decreases the tendency of lamination defects. What’s more, the axial resistance of novel Fomichev plug is smaller than the conventional, which is in favor of biting condition and increases piercing efficiency. Furthermore, the newly-designed plug’s temperature field is more uniform, which can alleviate failure of piercing plug caused by overtop local temperature, prolong its working life, and improve the quality of hollow shells.

Passive Inflow-Control Device Maximizes Productivity Through Every Phase of a Well's Life

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper IPTC 13863, ’The First Passive Inflow-Control Device That Maximizes Productivity During Every Phase of a Well's Life,’ by Luis A. Garcia, SPE, Martin P. Coronado, SPE, Ronnie D. Russell, Gonzalo A. Garcia, SPE, and Elmer R. Peterson, SPE, Baker Hughes, prepared for the 2009 International Petroleum Technology Conference, Doha, Qatar, 7-9 December. The paper has not been peer reviewed. In long horizontal wells, production rate typically is higher at the heel than it is at the toe. This imbalanced production profile may cause early water or gas breakthrough into the wellbore. To eliminate this imbalance, inflow-control devices (ICDs) are placed in each screen joint to balance the production-influx profile across the entire lateral length to compensate for permeability variations. Passive ICDs (PICDs) could control the influx without the need for intervention. Introduction The primary purpose of ICDs is balancing well production throughout the operational life of the completion to optimize hydrocarbon recovery. Because a typical well with ICDs can produce for 5 to 20 years or longer, the long-term reliability of such a device is crucial to the well’s overall success. If an ICD cannot maintain a uniform flux rate, increased localized production rates will occur and the well will become unbalanced. Thereby, the ICD becomes ineffective, leading to premature water and/or gas breakthrough and possible loss of sand control. Water can reach the wellbore in certain sections because of formation heterogeneities and/or vertical fractures. Ideally, once breakthrough occurs, flow contribution from these water-producing zones should be less than that of the oil-producing sections. The ICD device should increase the flow restriction at the onset of water production, thus allowing other oil-producing zones to continue flowing effectively. In wells with oil viscosity &amp;gt;10 cp, ICD-type selection becomes more critical because of the large difference in viscosity between the oil and produced water. To maintain an even flow profile across the entire wellbore lateral, the pressure-reduction mechanism in the ICD situation must have the lowest sensitivity to viscosity. A restrictive-type ICD can provide desirable results in this regard with its lower sensitivity to viscosity. However, this type of ICD requires a very small flow area to generate the pressure drop (restriction) required in ICD applications. This small flow area has a greater potential for erosion and a low plugging resistance. Another solution is to enable lower viscosity sensitivity in the restrictive device with the low erosion and high plugging-resistance level of the frictional design. The restrictive-pressure-loss mechanism can be used while limiting the fluid velocity through the device below the critical level, which will minimize erosion potential.

Subsidence Control of Construction on Soft Soils with “Akar Foundation”

Good quality soils are always preferred in development projects, where the bearing capacity of the grounds is sufficiently high and the resulting subsidence is non-excessive. However these sites may not be as readily available with increased population and land use, making it inevitable to construct on less favourable soils, like soft organic materials. To ensure long term stability of structures erected on such soft soils, elaborate and extensive foundation systems are generally required. Alternatively, pre-treatment with ground improvement techniques is necessary. Both these methods tend to incur high costs and labour as well as require prolonged construction period, while making a rather negative impact on the environment in terms of raw material sourcing, heavy machinery mobilization and exposure to the risk of groundwater contamination. This paper describes an exploratory study on a simple shallow foundation system for construction on soft soils, which can be a potentially cheaper and more sustainable approach. The foundation system, termed the “Akar Foundation”, literally translates as “Root Foundation”, is essentially a lightweight platform supported by a group of hollow stumps (i.e. PVC pipes). The ‘root’ base served dual functions: 1. to collectively assert a stronger grip of the soft soils, hence giving higher bearing capacity; 2. to spread the imposed structural load evenly into the subsoil, thus avoiding excessive and non-uniform settlements. The effects of the end condition of the pipes (i.e. open or close) as well as the spacing between the pipes on the foundation settlement mechanism were examined, with static load tests conducted using a lab-scale simulation chamber. The findings showed that the effectiveness of the “Akar Foundation” depends on the compatibility of the pipe spacing and individual pipe lengths, highlighting the inter-relationship between the mobilisation of end resistance, skin friction and formation of soil plug in the open-end system. In a promising light, the reduced subsidence suggest the potential of the “Akar Foundation” as an economical yet effective foundation system in economically challenged soft soil areas.

Characterization of protein–polysaccharide ratios on membrane fouling

The dominant problem associated with membrane bioreactors is membrane fouling, for which protein (PN) and polysaccharides (PS) are primarily responsible. However, little is currently known about these foulants. In the present study, combined influences of PN and PS on microfiltration (MF) have been investigated in terms of dead-end filtration mode. It revealed that the initial fouling rate of polyvinylidene fluoride (PVDF) was lower than that of track-etched polycarbonate (PC), except when the PN/PS had a ratio of 500:100 mg/L. Flux decline could be divided into two stages and a faster decline rate was assigned to a higher fouling rate. Resistance-in-series model was applied and the results showed that cake resistance rather than pore adsorption was the main fouling mechanism for both membranes during filtration with all combined ratios, and it would be easier caused at the lower ratios of PN/PS than the higher ratios. Moreover, pore plugging resistance increased in proportion to the increment of PN/PS ratio while maintaining constant PS concentrations. Backwashing removable fouling resistance was 69–97% and 85–97% for PVDF and PC membranes, respectively. Furthermore, adsorption resistance was higher for PC membranes, and both membrane materials showed better PS rejection than PN rejection.

Field investigation of base resistance of pipe piles in clay

This paper presents the results of a series of field tests performed to study the effect of soil plugging during installation on the base resistance developed by an open-ended (pipe) pile in clay. Three instrumented pipe piles were installed in soft clay, and the installation resistance and soil plug development were recorded. The tests revealed that the annular base resistance was equal to the cone penetration test qc resistance and was independent of the soil plug development. In contrast, the soil plug resistance increased from a minimum when the pile was fully coring to a maximum when the pile was fully plugged. A simple expression is proposed that links the plug resistance to the cone penetration test qc value at the specified depth and the incremental filling ratio value developed during installation. This expression is shown to provide reasonable estimates of the plug resistance developed by a large-diameter pipe pile driven into stiff to hard clay in the North Sea. The proposed relationship will be particularly useful for modelling the installation resistance of monopile foundations.