bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Danish Rigid Boundary True Triaxial Apparatus for Soil Testing
Authors: Bo Ibsen L , Prasstrup U 
Published: February 2009

Abstract
The intermediate principal stress plays an important role for the stress-strain behavior of soils. The effect of the intermediate stress cannot be examined in the conventional triaxial apparatus since axisymmetric stress states are prescribed in it. Thus, other testing devices capable of producing asymmetric stress states are necessary for more accurate determination of the stress-strain behavior. This paper describes the Danish rigid boundary true triaxial apparatus developed at Aalborg University and the techniques employed to prepare and test specimens of clay and sand for effects of the intermediate stress. Three series of true triaxial tests are presented together with various conventional triaxial tests to illustrate the capabilities of the apparatus. The first series of tests was carried out on cross-anisotropic specimens from a natural clay deposit. The other two series were carried out on air-pluviated (frozen and unfrozen) specimens of sand that also showed cross-anisotropic behavior.
A Cyclic Gradient Ratio Test Device
Authors: Hameiri A , Fannin RJ 
Published: February 2009

Abstract
Gradient ratio test results are reported from the commissioning of a device that was modified to impose dynamic cyclic flow. The flow conditions, using head control, are similar to those in marine protection works. Each test included a stage of unidirectional flow, followed by stages of cyclic flow at a frequency of 0.2 Hz and 0.02 Hz. Flow reversal invokes an initial transient state of water head distribution in the sample, attributed to changes in hydraulic gradient to accommodate the new values of constant head at the inflow and outflow. Consequently, tests at the higher frequency yielded unsteady flow in the sample, while tests at the lower frequency resulted in steady flow during each half cycle. In unsteady flow, the transient state of water head distribution (and hence gradient ratio) cannot serve as an index of soil-geotextile compatibility. Therefore, a recommendation is made that testing of filtration compatibility in dynamic cyclic flow include a stage of slow flow reversal (or alternatively unidirectional flow) to permit a quantification of water head distribution under steady flow.
One-Dimensional Shock-Induced Pore Pressure Response in Saturated Carbonate Sand
Authors: Veyera GE , Charlie WA , Hubert ME 
Published: February 2009

AbstractExperiments were performed to investigate the transient undrained pore water pressure response of a shock-loaded saturated carbonate sand (Enewetak coral sand). Specimens were dynamically loaded using an experimental laboratory facility capable of generating compressive shock pulses with millisecond rise times to peak stress. Boundary conditions were for one-dimensional confined compressive loadings without drainage. Pore water pressure increases of 50% or more were observed at compressive strains above about 0.01%. For most tests, liquefaction was observed at peak compressive strains in excess of about 0.10%. An empirical equation for estimating pore water pressure increases from transient compressional shock loadings was developed from a statistical analysis of the data. A silica sand, Monterey No. 0/30, has also been previously tested in this apparatus and a comparison is made. The residual excess pore water pressure equations for Enewetak coral and Monterey No. 0/30 sands are presented. Test results indicate that the response of these two sands is markedly different. Residual excess pore water pressures are proportional to approximately the square root of peak compressive strain for Enewetak coral sand and approximately the cube root of peak compressive strain for Monterey No. 0/30 silica sand. Measured static C parameter values were consistently less than unity for all saturated specimens of Enewetak coral sand tested. The C parameter decreased with increasing specimen density and effective stress.
Polymer Capacitance Sensors for Measuring Soil Gas Humidity in Drier Soils
Authors: Albrecht BA , Benson CH , Beuermann S 
Published: February 2009

Abstract
Polymer capacitance sensors were assessed in this study for measuring soil gas relative humidity and total suction in soils that are too dry for thermocouple psychrometers. Capacitance of the sensors varies as the relative humidity of the gas surrounding the sensor is varied. Soil gas relative humidity is inferred through a calibration curve relating soil gas relative humidity and capacitance. Tests conducted with six finer textured soils and three sands showed that the capacitance sensors can be used to obtain unbiased estimates of relative humidity for a broad variety of soils with a precision of approximately ±3%. Tests also showed that the sensors are non-hysteretic and relatively insensitive to temperature, except when the temperature approaches the freezing point of water. An example is provided illustrating how capacitance sensors can be used to monitor soil gas relative humidities in alternative earthen final covers that employ passive flow of atmospheric air to remove water.
New Wave Equation Technique for High Strain Impact Testing of Driven Piles
Authors: Liang RY 
Published: February 2009

Abstract
The real time records of force and velocity measured at the pile head during each hammer impact constitute the so-called high strain test (HST) data in the modern wave equation technology in connection with pile-driving activities. Currently, the Case method and the CAPWAP match procedure represent the state-of-art in interpreting HST data to obtain useful information, such as bearing capacity of a pile, soil-pile interaction model parameters, and the hammer performance, etc. A new HST data interpretation procedure based on wave equation theories is developed in this paper. For the case where only toe resistance exists, the new method utilizes both force and velocity records to analytically compute the corresponding dynamic soil resistance at the toe of an impact-driven pile. An inverse optimization scheme is developed to use these analytically computed quantities to determine the pertinent soil-pile interaction model parameters. Examples are given to illustrate the use of the new method to determine the pertinent Smith model constants commonly used in modeling the dynamic soil-pile interactions. The developed algorithm is also successfully extended to the case in which both shaft and toe resistances are involved during pile driving.
Shear and Interface Strength of Clay at Very Low Effective Stress
Authors: Pedersen RC , Olson RE , Rauch AF 
Published: February 2009

Abstract
Thin-specimen direct shear (TSDS) tests were conducted to measure the shearing strength of kaolinite, and interface strengths between kaolinite and acrylic plastic and anodized aluminum, at normal effective stresses from 1 to 2400 Pa (0.02 to 50 lb/ft2). At the lowest effective normal stresses, curved strength envelopes fitted through the data exhibited no cohesion and high secant friction angles. Accurate information on the behavior of soil in this low-pressure range is needed to properly interpret the behavior of prototype foundations in laboratory-scale model tests.
Method for Determining the Coefficient of Permeability of Clays
Authors: Moriwaki T , Umehara K 
Published: February 2009

Abstract
A new method for directly determining the coefficient of permeability of clays from the constant rate of strain consolidation tests was proposed by Yoshikuni et al. (1995). In order to confirm the reliability of this method, the constant rate of strain consolidation tests under three kinds of strain rates were carried out on four kinds of clays in this study. The permeability tests using a flow pump and the conventional consolidation tests were also carried out on the same clays for comparing the coefficient of permeability obtained from each test. As the results, it was found that the coefficient of permeability obtained by the proposed method from the constant rate of strain consolidation tests agreed with the coefficient of permeability obtained from the permeability tests.
A Substitute Pore Fluid for Seismic Centrifuge Modeling
Authors: Dewoolkar MM , Ko H-Y , Stadler AT , Astaneh SMF 
Published: February 2009

Abstract
In seismic centrifuge modeling, a time-scaling conflict exists between dynamic and dissipative phenomena. To help alleviate this fundamental problem, a substitute pore fluid consisting of powdered methylcellulose (known commercially as Metolose) dissolved in water was studied. The methylcellulose-water mixtures are referred to as “metolose” in general from here on. To examine the suitability of this substitute pore fluid, an experimental program was conducted using water- and metolose-saturated sand specimens. The program included triaxial compression tests, permeability tests, and a seismic centrifuge experiment on level ground models. In addition, modeling of models type experiments were conducted on metolose-saturated embankment and retaining wall models. Results from the triaxial tests indicated that the constitutive behavior of the saturated sand specimens was not significantly altered with metolose as the pore fluid. Results from the permeability tests showed that the scaling requirements of the centrifuge environment were satisfied. The centrifuge experiments demonstrated clearly that the conflict between the dynamic and consolidation time scales exists and reinforced the need for a substitute pore fluid in tests designed to model prototype behavior. Based on this experimental program, metolose was found to be an acceptable substitute pore fluid.
The Use of Miniature Pore Pressure Transducers in Measuring Matric Suction in Unsaturated Soils
Authors: Muraleetharan KK , Granger KK 
Published: February 2009

Abstract
Matric suction (pore air pressure minus pore water pressure) is an important stress state variable in unsaturated soil mechanics. Currently available devices to measure matric suction suffer from one or more of the following: bulky construction, long time to reach equilibrium, high sensitivity to temperature, and inability to produce continuous output. Tests were conducted using a miniature pore pressure transducer (PDCR81), traditionally used to measure positive pore water pressures in saturated soils, to measure matric suction in unsaturated soils. The results were compared with measurements from a conventional Bourdon-type tensiometer. Due to the small volume of fluid in the measuring chamber, the PDCR81 reached equilibrium much faster than the tensiometer and is more responsive to changes in pore water pressure. However, incomplete saturation produced greater errors in PDCR81 measurements. An increase in the saturation fluid viscosity of the PDCR81 increased the time to reach and maintain equilibrium.
The Effects of Varying Centerline Tube Sampling Disturbance on the Behavior of Reconstituted Clay
Authors: Siddique A , Clayton CRI , Hopper RJ 
Published: February 2009

Abstract
In order to simulate varying degrees of disturbance of soil at the centerline of a tube sampler, triaxial stress and strain path tests have been carried out on normally consolidated and overconsolidated reconstituted London clay specimens. The tests were carried out using an automated system capable of controlling both stresses and deformations imposed on specimens. The specimens were instrumented with local axial and radial strain and mid-plane pore pressure measuring devices.
Test results indicate that the most pronounced effects due to imposed tube sampling strains in reconstituted normally consolidated London clay are significant reductions of mean effective stress and undrained small-strain stiffness, which are accompanied by reductions in the excess pore pressure generated during shearing. The higher the magnitudes of tube sampling strains, the greater the change in behavior. In over-consolidated reconstituted London clay, however, laboratory simulation of tube sampling strains together with deviatoric stress relief (i.e., “ideal” sampling) causes little change in effective stress, stiffness, and strength.
Shrinkage Limit of Soil Mixtures
Authors: Sridharan A , Prakash K 
Published: February 2009

Abstract
Shrinkage limit, one of the Atterberg limits, is widely linked with many plasticity-based soil behaviors. However, in a great majority of these cases, such correlations have been found to exhibit poor performance. Recently, it has been brought out that the shrinkage limit of a natural soil does not depend upon plasticity characteristics, and it is primarily governed by the relative grain size distribution of the soil. The present study confirms this mechanism with the results obtained using clay-clay, clay-non-cohesive soil, and non-cohesive soil mix systems. The present study gains importance from the point of view of criteria with respect to the design of back fill materials to be used in various applications, such as nuclear waste disposal projects.
Cyclic Response of Axially Loaded Tapered Piles
Authors: El Naggar MH , Wei JQ 
Published: February 2009

Abstract
Tapered piles have a substantial advantage over straight-sided wall piles with regard to their load-carrying capacity in the downward frictional mode; however, their behavior under cyclic axial loading has not been investigated. In this study, the characteristics of the cyclic response of tapered piles were established from experimental investigation. A large laboratory facility for testing model piles was developed. In this facility, the soil was contained in a steel chamber and pressurized using an air bladder to model the confining pressure. Three instrumented steel model piles with different degrees of taper were installed in loose sand and subjected to two-way cyclic axial load tests. The results of this study indicated that the pile stiffness under cyclic loading increased with an increase in the confining pressure for all piles examined in this study. Moreover, the pile stiffness increased through cyclic loading due to the densification of the sand surrounding the pile. The amplitude of the cyclic load had a significant effect on the performance of the piles. As a result, it is recommended that the amplitude of the cyclic load be limited to 25% of the static axial capacity and 75% of the static uplift capacity to ensure satisfactory performance of tapered piles. This requirement is readily satisfied in the design of most piles. In this case, the performance of tapered piles under cyclic axial load was found to be superior to that of straight-sided wall piles.
Particle Motion Tracking Utilizing a High-Resolution Digital CCD Camera
Authors: Paikowsky SG , Xi F 
Published: February 2009

Abstract
Digital imaging acquisition and processing is applied for the tracking of a two-dimensional assembly of disks. The disks are used to assemble models for studying granular material behavior for which the kinematics of the individual particles, and hence the disks' trajectory during motion, are of cardinal importance. Large particle size is dictated by photoelastic interparticle interaction analysis. Therefore, a sufficiently large representative number of particles results in a large physical model.
The system requirements of a sizable physical model comprised of a large number of particles, and simultaneous precise tracking of all particles, are achieved through the use of high-resolution digital CCD camera and semi-automatic image processing and analysis algorithms.
The physical system setup, image acquisition procedure, calibration, accuracy, and algorithms of analysis are described. The system's performance is demonstrated through test results describing the displacement field along with the motion and interaction of individual particles.
The system's advantages in providing detailed tracking of a large number of particles with minimal labor are unmatched by any other technique. The data obtained by such systems allow a better understanding of particulate media behavior with the ability to examine and calibrate numerical models on an individual grain basis.
Modified Triaxial Apparatus for Shearing-Infiltration Test
Authors: Wong J-C , Rahardjo H , Toll DG , Leong E-C 
Published: February 2009

Abstract
A triaxial apparatus was modified and developed for performing shearing-infiltration tests under saturated and unsaturated conditions. Miniature pore-water pressure transducers were installed at different heights of the soil specimen for pore-water pressure measurement. Two different types of miniature pressure transducers were used, and problems associated with the transducers are discussed. Ancillary works and equipment to install the miniature transducers onto the soil specimen are also discussed. The measurement of air entry value of the small disk in the transducer was found to be very difficult. The results show that the soil specimen failed during infiltration due to increase in pore-water pressure or decrease in matric suction.
Retaining Wall Model Test with Waste Foundry Sand Mixture Backfill
Authors: Lee K , Cho J , Salgado R , Lee I 
Published: February 2009

Abstract
This paper presents experimental data concerning the lateral earth pressures acting against a small-scale retaining wall, with a backfill consisting of waste foundry sand (WFS) mixtures. The instrumented retaining-wall facility at Dongeui College in Korea was used in the testing. Two different testing methods were employed in this study: the controlled-strain method and the natural-strain method. The lateral earth pressures on the wall depend on the backfilling sequence, the type and drainage characteristic of the WFS mixture, and the shear strength of the mixtures. The mixtures of Green WFS performed best, showing a decrease in the lateral earth pressures and an increase in cohesion with curing time. The measured thrust lateral earth pressure of WFS mixtures was less than that observed for common residual soils in Korea. The stability of the retaining wall with respect to overturning and sliding, calculated using the measured lateral earth pressures, increased substantially with curing time. Judging from the retaining wall model test, the backfilling of a 6-m high retaining wall can be completed in two days with two backfilling stages.
Investigation of Resonant Frequency and Amplitude of Vibrating Footing Resting on a Layered Soil System
Authors: Baidya DK , Krishna GM 
Published: February 2009

Abstract
Influence of layering and presence of rigid boundary in the soil mass on natural frequency and resonant amplitude are studied experimentally by conducting model block vibration tests in vertical mode. Tests are conducted on different layered beds prepared in a tank using a model footing. A Lazan type mechanical oscillator is used for inducing vibration and two different materials (sand and sawdust) are used to form a layered system. In total, 180 tests are conducted in different layering combinations and different static and dynamic loading combinations, and several important observations are reported. Damping factors are found to be within 6.5% for the entire test series, which indicates that radiation damping is insignificant in the test system. It is also found that layering including layer position and thickness has significant effect on natural frequency. Observed natural frequencies are also compared with the predicted one based on static equivalent stiffness; encouraging agreement between observed and predicted values are found.
Effect of Compaction Duration on the Induced Stress Levels in a Laboratory Prepared Sand Bed
Authors: Hanna AM , Soliman-Saad N 
Published: February 2009

Abstract
In foundation engineering, due to the complexity of the problems investigated, the need for laboratory testing of prototype models arises. The results of these tests are usually utilized to validate theories, or to develop empirical formulae for design purposes. The success in obtaining good predictions from these theories and empirical formulae lies heavily on the reliability of the experimental test results, and accordingly, on the test setup used and the procedure followed.
In literature, a wide range of discrepancies can be found among various design theories for shallow and deep foundations in cohesionless soils. These discrepancies can be explained by the fact that the in situ stress levels in the prototype model have not been evaluated but rather ignored, in developing design theories. Accordingly, different theories may generate different results, depending on the techniques and procedures followed in developing the experimental results used to validate the theory.
This paper presents the results of an experimental investigation on the effect of compaction duration in a prototype model on the mechanical properties, and the induced stress levels in the sand mass. The results of this investigation should develop some awareness of the validity of using the results of model testing as a guide in developing design theories. Furthermore, attempts should be made to measure and incorporate the in situ stress level as a governing parameter in design theories.
Shear Strength Characterization of Geosynthetic Interfaces on Inclined Planes
Authors: Lalarakotoson S , Villard P , Gourc JP 
Published: February 2009

Abstract
Tests to characterize the shear strength of geosynthetic interfaces under low confinement pressure were carried out on an instrumented inclined plane apparatus designed at Lirigm. The apparatus was validated through repeatability and reproducibility tests carried out as part of the European project to standardize geosynthetic interface tests. Typical results obtained for geosynthetics of different textures are presented and discussed. Finally, interface test results obtained using the direct shear box under normal confinement pressure and on an inclined plane under low confinement pressure were compared and assessed.
Fast and Accurate Techniques for Determination of Water Content in Soils
Authors: Mendoza MJ , Orozco M 
Published: February 2009

AbstractThis paper describes expeditious and reliable procedures for determining the water content of soils that are alternative to the traditional convection oven technique. There exist linear relationships between the results of the conventional procedure and those obtained by the use of the microwave oven, direct heating of soils on a stove, distilling toluene, or burning alcohol to induce the evaporation of water; proportionality coefficients linking these results vary between 0.96 and 1.02. Microwave ovens are a much faster and cheaper means than convection ovens and are as reliable; for this technique, the mass of water that must be removed and the output power of the oven play the most important roles in defining the drying time for a soil.
Mechanical Durability of Expanded Shale Lightweight Aggregate
Authors: Valsangkar AJ , Holm TA 
Published: February 2009

Abstract
The paper presents results of a laboratory study that investigated mechanical durability of expanded shale lightweight aggregate. Large-size, one-dimensional cyclic compression and direct shear tests were performed to investigate particle breakage under these loading conditions. The results obtained are compared with the data reported by other researchers. The results indicate that the expanded shale lightweight aggregate experiences only a minor amount of particle breakage under one-dimensional compression and direct shear type of loadings.