Dynamic Compaction Method Research Articles

Dynamic compaction treatment technology research of red clay soil embankment in southern mountains

High liquid limit soil generally adopted in expressway embankment construction of southern mountains, which often expresses some characteristics including high moisture content, high porosity ratio, low permeability, high compressibility, certain disintegration, and so on. Spring soil phenomenon and inhomogeneous compaction have effects on the quality of embankment construction, just because the water in soil is difficult to evaporate. Based on the study of reinforcement mechanism for high liquid limit soil, in situ tests for dynamic compaction treatment in Yizhang—Fengtouling expressway embankment were developed. The reliable and economical dynamic compaction treatment methods and the construction technology for large range high liquid limit soil embankment in southern mountains expressway were discussed. In the process, convenient measurement methods were adopted to evaluate the treatment effects. The test results show that the dynamic compaction method has good treatment effects on the local red clay embankment. The embankment compaction degree is improved with compactness coming to 90% around tamping pits and compactness over 95% in tamping pits interior after tamping. The bearing capacity, the physical mechanic-property and the shear strength for soil are obviously improved, which are enhanced with cohesive strength increasing over 10 kPa and compression modulus increasing over 3 MPa.

Studying The Influence Of Compacting Method On The Engineering Properties Of Expansive Clayey Soil

This study deals with the effect of two methods of compaction (static compaction (S.C.) and dynamic compaction (D.C.)), on the engineering properties of high plasticity clayey soil (CH) selected from Mosul city. Results showed that maximum dry density of soil compacted by static method is higher than that compacted by dynamic method. But the inverse was obtained for optimum moisture content. Unconfined compressive strength, effective shear strength parameters (ć, ǿ), splitting and California Bearing Ratio (CBR) for soil compacted by dynamic method has higher values than that compacted by static method. Swelling pressure and free swell tests gave higher values under static compaction method. But the values of compression index and coefficient of consolidation using dynamic compaction method gave higher values. On the other hand, the results of crumb, slackening and pinhole tests showed that the internal erosion of soil compacted by dynamic method are less than that compacted by static method. From filter paper method and soil water characteristic curves showed that compaction methods had no effect on soil suction. Finally, statistical models between engineering properties for soil compacting by two methods were obtained.

Soil improvement effects of coal ash reclaimed ground by dynamic compaction method

海面に埋め立てられた石炭灰は，細粒分含有率が80%～90%を占め，含水比も高く軟弱地盤を形成する。そのため石炭灰埋立地の地盤改良工法は，粘性土系の工法が選定される傾向が強い。通常は砂質地盤に適用される動圧密工法を石炭灰埋立地の地盤改良工法に使用した事例は，これまでほとんどなかった。本研究ではこのような背景の下，石炭灰埋立地盤において動圧密工法による地盤改良の試験施工を実施した。施工中の間隙水圧の挙動，改良前後の静的コーン貫入試験（CPT）などの原位置試験結果により，石炭灰への動圧密工法の適用性を検討した。その結果，同工法により石炭灰の強度増加が図れることを示した。さらに，これらの試験結果を踏まえて，動圧密工法による改良地盤の物性評価法を提案した。

Use of WEDM in the Characterization Process of Al/2-Phase Systems Consolidated by Multilayer Cylindrical Dynamic Compaction Method

The aim of this paper is to present an exploratory process to characterize fabricated 2-phase aluminum metal-matrix systems (2-phase systems) by using a dynamic consolidation technique, with an arrangement of multilayer mixings in steel cylinders. Aluminum powder (~150mm) was mechanically mixed with different fractions of multi-wall carbon nano-tubes (MWCNTs, 2 and 5 percent), with ~30 nm and ~30 μm diameter SiC and Al 2 O 3 powders (in volume fractions of 2, 4, and 21 percent), then, were green compacted uniaxially to ~80 % density, to be finally explosively consolidated with ammonium nitrate-fuel oil (ANFO) and C3. After compaction, WEDM (wire electrical discharge machining) was used to prepare tensile and hardness testing samples, also TEM, light microscopy and SEM characterization samples, all by using ~25 % of the obtained material , this represents less than 10cc , preserving ~60 % of the obtained monoliths. Densities of the consolidated monoliths achieve an average of ~98 % compaction (measured by Archimedes technique). Observations and measured hardness (HRE) reveal well compacted systems with a hardness consistent along the composites. Using light microscope imaging different zones were identified showing different grain behaviors.

Influence of tamper weight shape on dynamic compaction

This paper presents the effect of tamper weight shape on the dynamic compaction method in granular soils. Although the dynamic compaction method appears to be very simple, it requires careful design of the compaction process. The aim of this study is to improve the efficiency and decrease the cost of deep compaction by using cylinder-shaped tamper weights. The influence of the shape of the bottom of the tamper weight on dynamic compaction efficiency was evaluated experimentally on sandy soils. Sands of three different densities were used to evaluate the compaction efficiency. Conical-bottom tamper weights were studied with the conic angle approximately the same values as the internal friction angles of the three different densities of soil. Also, in order to compare results, a flat-bottom tamper was used with the same weight. The results indicated significant increases of the amount of ground improvement by using a conical rather than a flat-bottom load. Cet article traite de l'effet de la forme du poids de dameuse sur la méthode de compactage dynamique sur les sols granulaires. Bien que cette méthode apparaisse très simple, elle demande une conception soignée du processus de compactage. Cette étude a pour objectif d'améliorer l'efficacité et de réduire le coût du compactage profond en utilisant des poids de dameuse de forme cylindrique. Elle évalue expérimentalement l'influence de la forme de la base du poids de dameuse sur l'efficacité du compactage dynamique pour des sols sablonneux. Des sables de trois densités différentes ont été utilisés pour déterminer l'efficacité du compactage. L'étude porte sur des poids de dameuse de forme conique avec un angle conique correspondant approximativement aux mêmes valeurs que les angles de frottement interne des trois différentes densités de sable. Une dameuse de base plate, de même poids, a également été utilisée en vue d'établir une comparaison. Les résultats indiquent une augmentation significative de l'amélioration du sol lorsque l'on utilise une charge à base conique plutôt que plate.

Using dynamic methods for compaction of particulate composite materials

This paper is about development of new method of producing metal matrix composites with small size reinforcements. The method is based on combination of mechanical alloying and dynamic compaction methods. Mechanical alloying was implemented in planetary mills; dynamic methods included magnetic-impulse pressurizing and explosive treatment. Optical microscopy and transmission electron microscopy were main methods for investigating structure of obtained composite materials. Research shows that developed method allow obtaining high quality material without any defects at interface between components.

Test sequence compaction methods for acyclic sequential circuits using a time expansion model

AbstractTest sequences for acyclic sequential circuits can be generated by using a time expansion model. In this paper, static and dynamic test sequence compaction techniques are proposed in which the test sequence generated by the time expansion model has two characteristics: (1) The test sequence length is constant, and (2) The location of an undefined value (X) for all primary inputs can be determined independently of test generation faults. First, a static test sequence compaction method is proposed that uses a template which is independent of the value of the test sequence. Then a dynamic test sequence compaction method is presented using reverse transform fault simulation, performing fault simulation for the time expansion model of the test pattern in which the test sequence after compaction is reverse‐transformed. As a result of application of the proposed method to acyclic sequential circuits made by using partial scan design, the test sequence length was reduced by 19 to 34%. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 105–115, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1162

Effective Method for Dynamic Compaction of Slightly Cohesive Saturated Soils

Results of theoretical and experimental investigations under laboratory conditions are cited for a method of dynamic compaction of slightly cohesive saturated soils subject to aeration around the perimeter of the zone of compaction. The method described makes it possible to improve the compactive effect as a result of amplification of oscillations in the compaction zone, and attenuate them appreciably beyond the limits of the aerated wall; this considerably reduces dynamic effects on nearby structures.

電磁力を利用した動的粉末成形法の研究

Hollow cylinder product has been made from aluminum powder by a dynamic compaction method that electromagnetic force shrinks an aluminum tube named as a sheath and utilises deformation of the sheath to compact the aluminum powder. A female screw and a taper can be formed inside of the product by this method. The electromagnetic force appears between the sheath and a solenoid coil according to Flemming's left hand law and can be controlled by discharge energy of a power supply. By using a cylindrical core with high stiffness the sheath shrinks uniformly without wrinkles and the aluminum powder can be compacted uniformly. The compacted powder compact, which was sintered at 893 K for 1 hour in a vacuum furnace, has shown about 2.0g/cm3 of density and 50MPa of compression failure strength. The density and strength increase with an increase in the discharge energy. However, the strength has decreased due to applying the same electromagnetic force on the sheath repeatedly.

Reducing liquefaction potential using dynamic compaction and construction of stone columns

In-place soils in the floodplains of major rivers are frequently stabilized to reduce the liquefaction potential when sites are located in earthquake prone areas. A site in the floodplain of the Missouri River in the United States of America was recently remediated to reduce liquefaction potential using the Deep Dynamic Compaction method of densification of in-place soils. Modifications were made to the conventional method in the form of construction of stone columns to densify the in-place soils to deeper depths. Results are presented to show that the modified procedure used at the site satisfactorily remediated the site. Construction of stone columns not only densified the soils to the required depths, but also helped support a five-story office building on conventional strip and spread shallow foundations. Site remediation and an alternative foundation scheme resulted in substantial cost savings without any delay in the construction schedule.

Compact Test Generation Using a Frozen Clock Testing Strategy

Test application time is an important factor in the overall cost of VLSI chip testing. We present a new ATPG approach to generating compact test sequences for sequential circuits. Our approach combines a conventional ATPG algorithm, a technique based on the frozen clock testing strategy, and a dynamic compaction method based on a genetic algorithm. The frozen clock strategy temporarily suspends the sequential behavior of the circuit by stopping its clock and applying several vectors to increase the number of faults detected without changing the circuit state. Results show that test sets generated using the new approach are more compact than those generated by previous approaches for many circuits.

Evaluation and Reduction of Liquefaction Potential at a Site in St. Louis, Missouri

This paper presents results of seismic ground response and liquefaction analyses performed for a site located in the floodplain of the Missouri River in St. Louis, Missouri. Synthetic earthquake time histories and recorded ground motions from two earthquakes in Canada were used to perform the analyses. Synthetic time histories were generated using attenuation relationships for Central United States. The ground response analyses indicated that the ground motions at the site are likely to amplify by a factor between 1.4 and 2.25. From the liquefaction analysis it was concluded that the site had significant liquefaction potential. The site was remediated to reduce liquefaction potential using deep dynamic compaction. Modifications, in the form of construction of stone columns, were made to the conventional method of deep dynamic compaction to densify the soils to required depths. Results presented show that site remediation procedure used at the site successfully densified the site soils to desired densities. Construction of stone columns not only densified the in-place soils to deeper depths, but also helped to support relatively heavily loaded columns on spread footings. The project was completed on schedule with significant cost savings.

Ｍａｌｖｅｒｎ型構成方程式を用いた金属粉末の動的圧粉解析

In powder Metallurgy process, some dynamic powder compaction methods have been proposed because they have advantages of giving uniform density distribution even for high-aspect-ratio parts and breaking surface oxides of powders, comparing with static powder compaction methods.Constitutive equations considering strain-rate effect are usually used to analyze the dynamic deformation of solid materials. One-dimensional dynamic analyses using static stress-strain relations were carried out so far. However, in case of powder materials, constitutive equation considering the strain-rate effect has not been applied.In this paper a Malvern-Type constitutive equation, Ee=σ+K(σ-f(e)) for powder materials is employed to analyze dynamic behavior of powder materials. A constant, K, in the equation is obtained by comparing the experimental and analytical results in terms of plastic strain distribution at longitudinal in a container. In the case of rapidly solidified Al-Li powder, K=2×105 is obtained.This method can widely be applicable to get dynamic constitutive equations for powders.

Biological activities of sustained polymyxin B release from calcium phosphate biomaterial prepared by dynamic compaction: Anin vitro study

Calcium phosphate ceramics (CaP) have recently been proposed as a potential matrix for a bioactive drug delivery system (DDS) in which the effect in situ of a released therapeutic agent is favored by the biocompatibility, osteoconductivity, and bioresorption of the ceramic material. Polymyxin B (PMB) is a polypeptidic antibiotic which undergoes thermodamage above 60 degrees C. The dynamic compaction method was developed to consolidate the drug load on CaP powder without external heating. Two projectile velocities (50 and 25 m/s) were used here to achieve powder consolidation. Among the different techniques used to associate therapeutic agents with CaP, wet adsorption was performed before the dynamic compaction process. The PMB release profile was measured by a capillary electrophoresis technique, CaP crystallography was studied by x-ray diffraction, and CaP physicochemical analysis was performed by infrared spectroscopy. The biological activities of PMB-loaded compacted CaP were determined by the effect of the antibiotic and monocyte/macrophage degradation on compact surfaces. PMB release began after 2-3 days of incubation for blocks compacted at 25 m/s velocity and on day 5 for those compacted at 50 m/s velocity. A discrepancy was noted between the amounts of PMB released (0.5-2.1 mg) and the amounts initially compacted (2-8 mg) with CaP powder. The biological activities (antibacterial activity and inhibited lipopolysaccharide effects on monocyte/macrophage CaP degradation) of PMB released from compacted calcium-deficient apatite were unaltered. Thus, dynamic compaction allows PMB to be used with CaP ceramics without any loss in its integrity and biological effects.

動的圧粉体に及ぼすパンチ形状の影響

In the present study, the thin film forming of pure aluminum powders is carried out by a dynamic compaction method. The influence of processing parameters on the density, mechanical properties and microstructures of compacted powders is investigated. The control of stress wave is also attempted in order to obtain a high compacting stress due to the superimpose of stress waves. The dynamic powder compaction is carried out by an electromagnetic induction method. This method allows easy control of stress pulse. Two kinds of punches with a straight shape and a sudden increase in cross section are used for the dynamic powder compaction. Pure aluminum powders of 37, μm in average are used as a raw material for the compaction. The compactions are carried out at room temperature in air. A density measurement shows that the compacted Al powders have a relative density of 0.90-0.97. As the stress has increased with a superimpose of the incidence stress wave and reflection stress wave in using the punch with the sudden increase in cross section, the bending strength of the compacted powders is stronger than the one in using the punch with a straight shape.

Lithium Ion Conductivity of a Statically and Dynamically Compacted Nano-structured Ceramic Electrolyte for Li-Ion Batteries

The densification of a ceramic electrolyte for rechargeable lithium ion batteries by using different compaction methods is described. The ceramic electrolyte for lithium ions, BPO4- Li2O, is compacted using either static or dynamic compaction methods. A difference in peak width in the X-ray diffraction spectra and a difference in lithium ion conductivity is observed. The dynamically compacted BPO4-Li2O shows an increase of up to three orders of magnitude in total ionic conductivity as compared with statically compacted samples. The total lithium ion conductivity is up to 2.10-4 S/cm at room temperature, which can compete with polymer electrolytes.

Association of human growth hormone and calcium phosphate by dynamic compaction: In vitro biocompatibility and bioactivity

The association of therapeutic agents with biomaterials has been achieved through various techniques, such as coating of the ceramic block surface or drug incorporation into ceramics. The dynamic compaction method recently was developed to consolidate drug-loaded calcium phosphate powder without a sintering step. In the present work, human recombinant growth hormone was loaded on biphasic calcium phosphate powder and consolidated by a specific process of cold sintering (dynamic compaction). Analyses of the biocompatibility of compacted pellets (mouse L929 fibroblastic cell culture) and the bioactivity of the drugs released by them (growth hormone bioassay) were performed. This report demonstrates the biocompatibility of the compacts prepared by dynamic compaction. L929 cell proliferation was maintained and the capacity to secrete fibronectin was conserved in the presence of compacted materials. Comparison of released growth hormone integrity, revealed by radioimmunoassay and eluted stain bioassay, has shown that the biological activity of growth hormone was totally preserved after dynamic compaction. However, 35% of loaded growth hormone was not released in our experimental conditions, probably because of the inaccessibility of growth hormone within the granulated compacts. Dynamic compaction shows good potential for the production of biomaterials capable of releasing therapeutic agents in situ. © 1997 John Wiley & Sons, Inc. J. Biomed Mater Res, 36, 258–264, 1997.

Association of human growth hormone and calcium phosphate by dynamic compaction: in vitro biocompatibility and bioactivity.

The association of therapeutic agents with biomaterials has been achieved through various techniques, such as coating of the ceramic block surface or drug incorporation into ceramics. The dynamic compaction method recently was developed to consolidate drug-loaded calcium phosphate powder without a sintering step. In the present work, human recombinant growth hormone was loaded on biphasic calcium phosphate powder and consolidated by a specific process of cold sintering (dynamic compaction). Analyses of the biocompatibility of compacted pellets (mouse L929 fibroblastic cell culture) and the bioactivity of the drugs released by them (growth hormone bioassay) were performed. This report demonstrates the biocompatibility of the compacts prepared by dynamic compaction. L929 cell proliferation was maintained and the capacity to secrete fibronectin was conserved in the presence of compacted materials. Comparison of released growth hormone integrity, revealed by radioimmunoassay and eluted stain bioassay, has shown that the biological activity of growth hormone was totally preserved after dynamic compaction. However, 35% of loaded growth hormone was not released in our experimental conditions, probably because of the inaccessibility of growth hormone within the granulated compacts. Dynamic compaction shows good potential for the production of biomaterials capable of releasing therapeutic agents in situ.

Sintering enhancement in dynamically compacted commercial iron powders

Powder metallurgy compacts of near theoretical density have been made from commercial sponge iron and atomized iron powders, the latter with and without admixed lubricant. Equivalent compacts were made by conventional quasi-static die pressing and by the dynamic powder compaction method to allow for comparative testing of mechanical properties. The compacts were sintered over a range of temperatures from 700 to 1120°C. Test specimens were cut from the compacts and tested to produce data on tensile strength, ductility (area reduction) and cantilever beam (Izod) impact strength. Compacts made dynamically from both the sponge iron and atomized iron powders exhibited higher tensile strengths and ductilities than those made quasi-statically and sintered to the same temperature. However, there were marked differences in the impact strength. With the sponge iron powder, dynamic compacts had lower impact strength than equivalent quasi-static compacts, but the reverse result was obtained with the atomized powder. The atomized powder was of much higher purity than the sponge iron and the microstructural evidence indicated that the inferior impact strength of the dynamically compacted sponge iron was due to interaction between the shock waves used for compaction and the numerous brittle inclusions present in this material. The results with the lubricated powder showed no sintering enhancement attributable to dynamic powder compaction. This suggests that the mechanism for the sintering enhancement that can be achieved with this consolidation technique is related to the friction processes at the particle boundaries, possibly coupled with the elevated temperatures present at these boundaries during dynamic compaction.