Piston Sampler Research Articles

EVALUATION OF THE EFFECT OF AIR ON THE HYDRATION SYSTEM OF THE AXIAL PISTONS

This study investigates the effect of air exposure on the hydration system of axial pistons, critical components in various hydraulic systems. The hydration process, which is integral to the functionality and longevity of axial pistons, is potentially sensitive to environmental factors such as air. This research aims to elucidate the effect of air on the hydration kinetics, surface properties and performance of axial pistons. Experimental studies were conducted using controlled environments to analyze the hydration behavior of piston samples under varying degrees of air exposure. Techniques such as surface microscopy, chemical analysis and mechanical testing were used to comprehensively evaluate the effects. Preliminary findings indicate that exposure to air significantly affects the hydration kinetics of axial pistons, affecting the rate and extent of hydration. Surface analysis reveals changes in surface morphology and chemical composition indicating changes in the air-induced hydration process. Moreover, mechanical testing reveals notable differences in the performance characteristics, including wear resistance and friction properties, of pistons exposed to varying weather environments. Overall, this study underlines the importance of considering air exposure in understanding and optimizing the hydration system of axial pistons and provides valuable information for improving hydraulic system efficiency and reliability. Keywords: axial pistons, hydration system, piston, hydraulic machine, rotor.

Assessing the impact of sample size and geology on earthen embankment design and construction

This technical paper investigates the influence of sample size and geologic characteristics on the geotechnical design of levee embankments. Sample quality plays a vital role in quantifying engineering properties for levee embankment projects, and numerous studies have highlighted the impact of sample disturbance on such engineering properties. Despite this evidence, conventional tube and piston samplers of different diameters continue to be widely used, potentially leading to underestimation of shear strength. The paper focuses on comparing 7.6 cm and 12.7 cm diameter undisturbed Shelby tube samples and CPT data collected from three levee sites in the Greater New Orleans Area, Louisiana, USA, which encompass diverse geologic histories. The study aims to assess the effect of industry used samples size and geology on levee construction costs. The findings provide valuable insights into optimizing sample collection methods and improving geotechnical design for earthen embankments.

Disturbance of sand samples obtained by piston samplers and ground freezing

High quality sampling of sand and silty sands is extremely challenging. Undisturbed samples of sand can be obtained by means of very expensive and time-consuming techniques such as ground freezing. Given the high costs and expertise required to obtain undisturbed sand samples through ground freezing, piston sampling techniques are usually used in engineering practice. This paper summarises the experiences, technical difficulties, disturbance analyses and issues encountered during sand sampling at the Norwegian Research Site at Øysand using piston sampling and ground freezing technology. Two state-of-the-art piston samplers were used (NGI-Geonor composite piston sampler and Geonor K-200 thin-wall push piston sampler) along with the state-of-the-art Japanese gel push piston sampler. Ground freezing was successfully achieved also both on sands and silty sands at Øysand. Sample disturbance was assessed qualitatively and quantitatively through analysis of micro-computed tomography images. Results from these analyses provide an overview of the strengths and weaknesses of the three piston samplers in comparison with ground freezing, together with recommendations for sampling of sands using piston techniques.

Laboratory evaluation of sampling quality of a new A+ sampler for natural fine soils

This paper presents a comparison of sampling disturbance measured by consolidation tests between two high quality samplers and stationary piston samplers. University G. Eiffel and Cerema have used their université Laval sampler and a new sampler on a soft organic clayey soil experimental site. This paper present first the new sampler designed to sample almost undisturbed soil specimens. The objectives of this sampler are to collect natural fine soils such as clay or silt, normally to medium overconsolidated for depths up to 10 m. This sampler is designed to preserve the saturation state of the specimen. An inner diameter of 150mm core barrel allow to keep the sampler relatively compact, even with the size of a ball valve used to close the sampler. Tests on Pont de Cran clayey site are presented and laboratory tests results on specimen sampled using both samplers show the quality of the specimen and the efficiency of the samplers using void ratio criteria.

Palynological Characteristics and Volcanic Ash from Sediments of Chistoye Lake, Northern Priokhotye

Chistoye Lake (59° 32' N, 151° 48' E) is located 10 km from the northern coast of Taui Bay (Okhotsk Sea) in the central part of a tectonic depression that has been infilled with Paleogene and Neogene deposits. The lake originated as the result of glacial activity during the latest Pleistocene (MIS2). A 550-cm-long lacustrine sediment core was raised from Chistoye Lake using a piston sampler. The core is dominated by silt with layers of peat and sand at its base. The silt includes two tephra layers at 360-364 cm and 77-80 cm. The tephra layers have different geochemical, magnetic, and mineralogical properties. Volcanic ash like the lower tephra in the Chistoye core has been found in other lacustrine sites from the Upper Kolyma, Upper Indigirka, and Northern Priokhotye regions. Radiocarbon dating of organic remains that bracket this second tephra, corresponding to the lower tephra in Chistoye Lake, indicates an age of 7 650 ± 50 years ago, which is comparable with the age of the Kurile Lake - Iliyinskaya caldera forming eruption in Kamchatka. The younger tephra also has been noted in cores from other lakes in Northern Priokhotye and dated to 2 745 ± 10 years ago. A distinctive feature of this Late Holocene tephra is its high magnetic susceptibility. Extrapolation of a sedimentation rate based on the tephra ages suggests that the Chistoye record is approximately 11 700 years old. Palynological analysis of the Chistoye Lake material showed that all samples contain pollen redeposited from Neogene sediments (Picea sect. Eupicea, Tsuga, Tilia, Corylus, Juglans, Ulmus). These taxa can be easily discounted as contaminant, but other pollen types (e. g., Pinus subgen. Haploxylon, Betula, Alnus, Cyperaceae, Poaceae) are more problematic for interpreting the paleovegetation, because they represent plants that were present during the Holocene and/or the Late Pleistocene and during the Neogene. Nonetheless, the changes in the percentages of Sphagnum spores suggest a gradual increase in effective moisture during the Younger Dryas and Holocene. A multiproxy study of the sediments from Chistoye Lake, in conjunction with their palynological characteristics, shows the importance of analyzing magnetic properties to help determine the presence of tephra in the sediments. Volcanic ash layers in the lake sediments from northeastern Siberia are reliable chronostratigraphic markers that can supplement radiocarbon dates and improve the regional understanding of climate and vegetation changes during the Holocene.

Failure analysis of the piston used in a pneumatic down the hole impactor

In this paper, the failure mechanism of the piston in the pneumatic down the hole (DTH) impactor has been studied. Failed piston microstructure has been analyzed using the light optical microscopy (OM) and scanning electron microscope (SEM). Impact toughness test and the Rockwell hardness test were conducted. Results showed the following: a) The carburizing layer of IQCT failed piston is mainly composed of acicular martensite and lower bainite after the carburizing-tempering-isothermal quenching-cryogenic treatment-tempering (IQCT), and there are collapses on the impact side and outer surface of the piston, mainly fatigue failure. b) IQT failed piston samples are subject to carburizing-tempering-isothermal quenching-tempering treatment (IQT). The carburized layer is mainly composed of high-carbon martensite, carbide and retained austenite. The transition layer is still composed of lower bainite and acicular martensite, but the volume fraction of lower bainite increases significantly and the core is mainly composed of lower bainite. It has the best impact toughness, up to 61.5 J/cm2, which is mainly fatigue failure. c) OQT failed piston sample is subject to carburizing-tempering-oil quenching-tempering (OQT). The carburized layer is mainly composed of acicular martensite, the transition layer is composed of acicular martensite (AM) and lath martensite (LM), and the core is mainly composed of LM. The impact toughness of the sample is the worst. Therefore, fatigue fracture failure is caused.

Physical properties of Quaternary sediments from the western South Korea Plateau, East Sea

Sediment samples were collected with a piston sampler (114 samples) and a box core sampler (266 samples) during research cruises on the R/V Tamhae 2 of the Korea Institute of Geoscience and Mineral Resources (KIGAM) from 2015 to 2019, to examine the characteristics of seafloor sediments from the western South Korea Plateau of East Sea. The in situ velocity was measured at four sites using a seafloor acoustic probe developed by KIGAM (KISAP). The samples were analyzed for their physical properties and the resulting data were examined to gain insights into the distribution patterns of the sediments and how the physical properties varied by burial depth. The actual velocity of the seafloor sediments was investigated by comparing the velocities in the laboratory and in situ velocity measurements at four sites. Overall, the physical properties agree well with the expected characteristics of marine sediments but there is considerable variation in the mean grain sizes. The sediment distributions either increases or decreases gradually with depth, reflecting transport from topographically high areas (e.g., possible source and/or shelf areas). The relationships between the physical properties of samples from two transects, one east-west and the other south-north, are different, and reflect the presence of tephra with a low grain density at the specified depth intervals. The laboratory velocity is higher (approximately 20–40 m/s) than the in situ velocity measured by the KISAP because of differences in the temperature (approximately 22 °C) and pressure (∼100 atmospheric pressure). However, the corrected laboratory velocity agrees well with the in situ velocity. Inconsistencies in the data, such as the measurement frequency and condition of each system, measurement interval, and sediment grain size, are probably responsible for some of the variations in the physical property data.

Using a Machine Learning Method to Predict the Penetration Depth of a Gravity Corer

The study of penetration depth of gravity piston samplers has an essential impact on sampling efficiency and instrument safety. This study focuses on predicting penetration depth based on the characteristic parameters of the sampled seafloor sediments and the sampler parameters. Although numerous studies of gravity corer penetration depth have been carried out, most have been based on the energy conservation equation, which considers a varying number of influencing factors. Furthermore, most research has focused on the same research idea of finding analytical solutions. The present study proposes a new approach to predicting gravity corer penetration depth based on a machine learning method that uses real sampling data from the sea and experimental data from a gravity sampling physical model for training and testing. Experimental results indicate that the machine learning model can accurately predict gravity corer penetration depth. Moreover, predictions were made for the same penetration conditions using the machine learning model and three other analytical solution models. Results show that the prediction accuracy of machine learning outperforms that of the analytical prediction model under various statistical rubrics. This study demonstrates the capacity of the proposed machine learning model and provides civil engineers with an effective tool to predict the penetration depth of gravity corers.

An experimental and thermodynamic study of sphalerite solubility in chloride-bearing fluids at 300–450 °C, 500 bar: implications for zinc transport in seafloor hydrothermal systems

The solubility and speciation of zinc (Zn) in chloride-bearing aqueous fluids at high temperature and pressure are important for understanding Zn transport in natural hydrothermal systems and associated mineralizing processes. Here, we measured sphalerite solubility in NaCl-HCl-H2O fluids using a fixed-volume titanium alloy hydrothermal reactor equipped with a newly designed gas-tight titanium piston sampler. This novel reactor-sampling system is capable of acquiring internally filtered fluids at high temperature and pressure. The experiments were conducted at 300–450 °C, 500 bar, in fluid with 0.5 m and 1 m NaCl, respectively. The measured sphalerite solubilities are consistent with predicted values using previous thermodynamic data at 300–400 °C, but diverge significantly above 400 °C. To resolve this discrepancy, we adjusted the solubility product of Zn minerals by modifying the heat capacity and Born coefficients that describe the Gibbs Free Energy of formation from the elements of the Zn2+ aqua ion based on the new solubility data. The refined Helgeson-Kirkham-Flowers (HKF) equation of state (EoS) of Zn2+ empirically reproduces the solubility data of Zn minerals from previous experimental studies well over the covered T-P range (25–600 °C, Psat to 2 kbar), but extends accurate predictions to conditions typical of deep sea hydrothermal systems, down to fluid densities of 0.35 g/cm3. Thermodynamic modelling using the revised EoS of Zn2+ shows that higher temperatures, chlorinity and lower pH increase Zn solubility, and that Zn chloride complexes are the predominant species. The influence from salinity on Zn solubility is less significant in fluids with low pH. Applied to seafloor hydrothermal systems, our results suggest that in addition to temperature, pH and total dissolved chloride, fluid/rock ratio may be an important factor contributing to Zn concentrations in vent fluids at Mid Ocean Ridges.

Collection sediment from Mariana Trench with a novel pressure-retaining sampler

Sediments in the hadal trenches have been proved to contain a large number of specific microorganisms. In this study, we developed a pressure-retaining sampler for the hadal trenches. A novel piston sampling mechanism was designed, the weight of which is light enough to be mounted on a lander for field tests. Furthermore, laboratory tests validated its high-pressure resistance and pressure-retaining performance. We tested the penetration force and the sampling performance in different clays. Moreover, a pressure compensator was designed based on the actual gas state under high pressure. Finally, a prototype of the sampler was built and field tested in the Mariana Trench. The results indicated that the sampler has an excellent pressure-retaining capacity and can collect sediment samples at the deepest point of the in the world's ocean.

Settlement and pore pressure behaviour and predictions of test embankments on an organic clay

ABSTRACT Two test embankments were built on an organic clay at the Lampen test site in Sweden and movements and pore pressures were measured over a period of six years. Well-established 2D and 1D constitutive models, were used to predict the settlement and pore pressures. The predictions suggest, with model parameters based on laboratory test results for carefully taken and handled standard piston samples, that creep should be included to provide better agreement with the in situ measured settlements and pore pressures. A comparison between the predictions and the measured settlements and pore pressures showed that it is important to study the trend over time and at different depths, and not just settlements at a few times at the ground surface. The 2D model including creep agreed relatively well with the measured total settlements and with pore pressures at different depths, but the settlement-time relationship was not qualitatively well described.

Experimental Investigation on Tribological Behaviour of Various Processes of Anodized Coated Piston for Engine Application

In the automobile sector, pistons are anodized on the crown, on ring grooves, and also on skirts to improve its wear resistance and corrosion resistance properties. In this work, we have carried out crown anodizing along with skirt anodizing simultaneously to study the wear resistance of anodized samples. The surfaces are anodized with three different processes such as soft anodizing, hard anodizing, and microarc oxidation (MAO) or well known as plasma arc oxidation (PAO). All the three processes differ in their respective procedures. The hardness value and microstructure of all the samples were tested to find wear resistance values and the effect of coatings on the samples. In wear testing, piston samples are rubbed on cast iron to denote its wear resistance based on weight loss per unit time. Reciprocating wear testing is also carried out on every sample for testing their wear resistance value.

Application of Constant Rate of Strain Tests in Consolidation Analysis of the Band-Shaped Prefabricated Vertical Drains for Vietnam Clays: The Validation Analysis

Band-shaped prefabricated vertical drains in the combination of surcharge preloading have been widely applied in the soft ground improvement cases in Vietnam to eliminate the post-construction settlement of the ground. However, the method of the settlement prediction has remained incorrect on the comparison between the field and calculation. A new procedure for consolidation analysis is proposed to determine the ground settlement more accurately in the routine design of the soft ground improvement. Two case studies are presented to study the ground performance under consolidation with surcharge preloading. The consolidation analysis of the soft ground deposits with the application of the constant rate of strain (CRS) consolidation tests is performed. In addition to that, the input parameters as the coefficient of consolidation and compression indices of the soft ground are characterized based on the CRS tests under the strain rate of 0.02%/min. on undisturbed soil samples that are taken at the two sites by stationary piston sampler. On the comparison of calculated and field monitored data of surface settlement, layered settlement, dissipation of the excess pore water pressure, and undrained strength gain, this analysis is also to confirm the appropriate strain rate for CRS tests, which are utilized in the determination of consolidation parameters.

One dimensional formulae for time-dependent compression characteristics of over-consolidated clays

The time-dependent compression characteristics of clay exhibit apparent differences when loaded from the over-consolidated and normally consolidated states. Based on the Nishihara model, this paper presents one dimensional isotache-based formulae for over-consolidated clays which consists of elastic, visco-elastic and visco-plastic deformation components. The newly constructed constitutive model is used to interpret the visco-elastoplastic compression characteristics of over-consolidated clays and incorporates effects including long-term compression, strain rate dependency and stress relaxation. Corresponding analytical solutions are obtained and the methodology to determine the model parameters is then introduced. New data from a series of oedometer, constant rate of strain (CRS) tests and stress relaxation tests on piston samples of marine, lightly over-consolidated, carbonate clay from the Australian North West Shelf (NWS) are presented. These test data are used to verify the predictive capability of the proposed constitutive model, reasonable agreements between the computing and experimental results were found.

A importância da amostragem de solo de perfil completo (ASPC) para a investigação de alta resolução em áreas contaminadas

A metodologia tradicional de investigação de áreas contaminadas no Brasil se baseia na instalação de poços de monitoramento não afogados com 3 m de seção filtrante e amostragem de solo somente na zona não saturada, realizada na mesma sondagem e com o mesmo equipamento utilizado para fazer a perfuração para a instalação do poço (normalmente trado manual ou helicoidal mecanizado). Essa metodologia não é capaz de fornecer informações suficientes para a elaboração de um modelo conceitual adequado para a área e é incompatível com as normas: NBR 16.434, NBR 15.495-1, ASTM D6282 e com a Decisão de Diretoria 038 (DD-038) da CETESB. Para que esses dispositivos sejam integralmente atingidos, é necessário que, durante a investigação, seja dada prioridade à execução de amostragens de solo de perfil completo (ASPC) que coletem amostras representativas de todo o perfil, inclusive na zona saturada. A ASPC deve permitir: a aquisição de amostras para análises químicas e físicas em laboratório; a realização de uma varredura vertical de contaminantes; e a identificação e caracterização das UH. Para isso, é preciso utilizar a técnica Direct Push, e dentro dessa técnica, as modalidades Dual Tube, Piston Sampler, ou em casos especiais, Single Tube revestida. Dessas, a que se mostrou mais eficiente para a execução da ASPC foi a Dual Tube.

Consolidation Analysis with Application of Constant Rate of Strain Consolidation Tests for Vietnam Clays

Constant rate of strain (CRS) consolidation testing has specific advantages over the standard incremental loading (IL) consolidation testing. The first advantage is shortening testing period of 1–2 days compared to 7–10 days for the standard; the second one is that testing data are recorded automatically and continuously for the ease of determination of consolidation yield stress. Moreover, pre-consolidation pressure from CRS is larger than that resulted from IL, so many researchers have not recognized the application of CRS into the routine design of consolidation problems. Therefore, there has been little effort and application of CRS in the consolidation analysis into the soft ground improvement especially in Vietnam. There has been no standard for CRS applicable in the soft ground improvement design in Vietnam. The paper is focused on characterization of Vietnam soft clay deposit with application of the results of constant rate of strain consolidation tests in order to achieve the input parameters for consolidation analyses. Total 4 PVD and surcharge construction sites with the undisturbed samples taken by stationary hydraulic piston sampler are investigated in this study. The characterized input data are utilized in consolidation analyses by finite difference method (FDM) in order to determine the behavior of Vietnam soft clay deposit. A comparison of the monitored data to the calculated data from a new finite difference code which has been developed by the author is presented.

Evaluation of sample quality from different sampling methods in Finnish soft sensitive clays

The determination of reliable geotechnical parameters from laboratory testing is highly dependent on sample quality. Over the past decades, undisturbed sampling of soft sensitive clays has been performed using various apparatuses and procedures. This paper outlines details of the design and performance of a new Laval-type tube sampler employed for the investigation of five soft clay sites located in Finland. The investigation was conducted using the new tube sampler and two different piston samplers. The sample quality was evaluated based on the recompression volume during reconsolidation to the in situ effective stress in constant-rate-of-strain oedometer tests. Test results show that tube samples are generally characterized by higher quality, especially in low-plasticity clays. In particular, the quality of piston samples is highly affected by the apparatus condition and sampling operations. Furthermore, the influence of storage time on tube samples was investigated. To guarantee a proper confinement, and thus reduce swelling, a pressurized system was applied to the tube samples obtained in two soft clay sites. Results demonstrate that the sample quality is not significantly affected by storage time as long as the soil is properly stored in the tube.

Cyclic resistance ratio of pleistocene-age sands from the South Carolina coastal plain

Field and laboratory tests were performed on sandy soils from three Pleistocene-age sites in the South Carolina Coastal Plain to investigate the age–related resistance to liquefaction. Reported research indicates that liquefaction resistance of sands increases with the age of the deposit, and that liquefaction may reset the aging clock. The stress-controlled cyclic triaxial test was used to determine the cyclic strength of soil deposits with geologic ages of approximately 200,000, 450,000, and 1,400,000 years and evidence of sand blows that are 467 to 4185 years old. Specimens were obtained using a fixed piston sampler frozen ex situ and include naturally occurring differences in fabric. Cyclic stress ratios ranging from 0.135 to 0.225 were used to determine the peak deviator stress applied during the cyclic triaxial test and were initially estimated from two age-based methods, which were found to over-estimate the laboratory cyclic stress ratio. Estimates of the at-rest earth pressure coefficient were applied to the laboratory cyclic resistance ratio, which resulted in field cyclic resistance ratios that ranged from 0.100 for the oldest deposit (1,400,000 years) to 0.131 for the mid-aged deposit (450,000 years) for initial liquefaction occurring when the generated excess pore pressure was equal to the effective confining stress of 100 kPa (ru = 1.0) at N equal to 15 cycles. The carbon-dated age of the sand blow events correlated with the field cyclic resistance ratios; the geologic ages of the soil deposits did not. A correlation between the clay content, not the fines content, was observed.

Characterization and engineering properties of the NGTS Onsøy soft clay site

In the 1960s, NGI investigated numerous potential research sites and established the first Onsoy soft clay site in 1968. In 2016, the NGTS project established five research sites, one of which is the NGTS Onsoy soft clay site. The purpose of this paper is to provide a reference for further in-situ and laboratory testing at the site and easy access to high-quality soil investigation data. The paper interprets the soil conditions providing engineering soil properties, comments on data reliability and quality, and correlations between different soil parameters where appropriate. The lightly overconsolidated soft clay site has been characterized based on extensive in-situ and laboratory testing. In-situ methods include electrical resistivity tomography, multichannel analysis of surface waves, total soundings, rotary pressure soundings, cone penetration testing with and without seismic and electrical resistivity measurements, dilatometer with seismic measurements, self-boring pressuremeter, electric piezometers, thermistor string, hydraulic fracture testing and earth pressure cells. Soil samples were obtained using Sherbrook block sampler, Geonor ϕ 72 mm piston sampler, Geonor ϕ 54 mm composite piston sampler and hydraulic piston and push samplers with liners. Laboratory tests include multi-sensor core logging, index testing, cyclic and monotonic, consolidated and unconsolidated triaxial tests, bender element tests, oedometer tests with constant rate of strain and incremental loading and direct simple shear tests.

Investigation and geotechnical characterization of Perniö clay, Finland

Understanding the behavior of soft sensitive clays is a key aspect of geotechnical design, especially in those regions where constructions are planned in marine clay areas. In Finland, one of the major geotechnical issues is the stability and deformation of the railway embankments located on soft soil deposits. The Tampere University of Technology (TUT) and the Finnish Transport Agency (FTA) have been carrying out a research project aiming to a better understanding of strength and deformation properties of Finnish soft clays. As a part of this project, a detailed site investigation was conducted at Pernio site in Western Finland. This paper presents the details of the geotechnical investigation, including field testing, sampling operations, and the laboratory testing program. In particular, an open drive tube sampler with 132 mm diameter, designed at TUT, was used to collect high quality samples. For comparison, samples were also taken using the conventional piston samplers and Sherbrooke Mini-block sampler. Field testing included piezocone, vane shear, and seismic piezocone. Laboratory testing consisted of index, consolidation, triaxial and simple shear tests. A comprehensive study of all these data is presented in a framework to describe Pernio soft clay.