bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Comparative Study of Suction-Induced Seepage Consolidation Versus Centrifuge Consolidation
Authors: Robinson RG , Tan TS , Lee FH 
Published: February 2009

Abstract
The time required for the preparation of a normally consolidated clay sample, by self-weight consolidation in the centrifuge, is often very long and the process may take up to several days. To save centrifuge time, a hydraulic consolidation method of preparation of normally consolidated clay beds, using seepage forces, is often used prior to final consolidation in the centrifuge. At present, the required hydraulic gradient is usually generated by high-pressure water at the top of the clay bed. This method tends to cause hydraulic fracturing at comers when rectangular containers are used. A simple method of using vacuum suction to induce seepage forces to clay samples is proposed and discussed in this paper. Experience with this method shows practically no incidence of hydraulic fracturing. Comparison of the variation of water content and shear strength with depth of samples prepared by the present method and those prepared exclusively by self-weight consolidation in the centrifuge lends support to the validity and effectiveness of the proposed method. The method can be used to prepare clay samples for prototype depth less than about 17 m. A procedure for estimating the final height, water content, and shear strength profiles of the soil model prepared is also presented.
Laboratory and Field Shear Wave Measurement at a Reclaimed Site in West Taiwan
Authors: Chien L-K , Oh Y-N 
Published: February 2009

Abstract
Land reclamation using hydraulic sand fills is a method adopted widely in West Taiwan. In this paper, the influence of fines content, void ratio, and effective confining pressure on the measurement of shear wave velocity of reclaimed soil obtained from the reclaimed soil in the Yun-Lin area of West Taiwan is discussed. A “critical s-wave void ratio” (ef.c.) is defined. As shown in the results, for critical s-wave void ratio (ef.c.) with 10% of fines content, there exists a maximum shear wave velocity. As the fines content exceeds 10%, the shear wave velocity decreases. Based on the laboratory and in-situ test, a modification factor (M) is defined. From the results, the modifications factor (M) increases as the soil depth increases. The results presented can be a reference for soil property evaluation in land reclamation and coastal area.
Oxygen Diffusion Coefficient of Soils at High Degrees of Saturation
Authors: Shelp Lin M , Yanful EK 
Published: February 2009

AbstractThe oxygen diffusion coefficient is an essential parameter for design of soil covers over mine waste. This study presents a method for measuring the oxygen diffusion coefficient of soils at high degrees of saturation. The method eliminates measurement errors caused by soil microbial activity, high humidity, and stagnant air in laboratory diffusion cells. Results show that microbial activity is an important factor that causes errors in O2 measurements. Sterilization of soil, utilization of a silica gel-membrane system with oxygen sensors, and minimal stirring in the cell headspace greatly reduce the variability in O2 diffusion coefficient measurements. The variations in estimated O2 diffusion coefficients for the same soil at the same degree of saturation were ±31% about the mean for clayey soil samples and ±10% about the mean for silty soil samples.
Model Studies on Geocell Supported Embankments Constructed Over a Soft Clay Foundation
Authors: Krishnaswamy NR , Rajagopal K , Madhavi Latha G 
Published: February 2009

Abstract
This paper describes the results of laboratory model tests on geocell-supported earth embankments constructed over a soft clay foundation. The soft clay foundation was prepared in a large test tank to a depth of 600 mm. A single geocell layer was formed on this clay foundation with different thicknesses, and embankments were constructed above this layer. Four different types of geogrids were used for the formation of the geocell layer. The embankments were subjected to uniform surcharge pressure on the crest until failure. The vertical and horizontal deformations and the strains developed within the geocell layer were measured during the test. The influence of various parameters such as tensile stiffness of geogrids used to fabricate the geocell material, height, and pocket-size of the geocell layer, length of the geocell layer, and type of fill material inside the geocell on the behavior of the embankments was investigated through a series of laboratory tests.
Evaluation and Application of the Transient-Pulse Technique for Determining the Hydraulic Properties of Low-Permeability Rocks—Part 1: Theoretical Evaluation
Authors: Zhang M , Takahashi M , Morin RH , Esaki T 
Published: February 2009

Abstract
The transient-pulse technique is a well-established laboratory method for determining the permeability of hydraulically tight rocks. Although graphical solutions to this test make it possible to evaluate both the permeability and the specific storage of a rock specimen, the attendant procedures are relatively complicated. Often, the expression introduced by Brace et al. (1968) is typically used to interpret the experimental results and arrive at a value for permeability only. In Part 1 of this study, the general solution for the transient-pulse test is extended to consider quantitatively the transient distributions of hydraulic head and hydraulic gradient within the specimen and to examine the validity of using the solution presented by Brace et al. (1968) under these conditions. Based on a series of parametric studies, some theoretical and practical considerations related to the design of a transient-pulse test are also provided. In Part 2, a relatively convenient and general approach to calculating the specific storage of a specimen from a transient-pulse test is presented and its efficiency is demonstrated through the application of this approach to experimental investigations.
Evaluation and Application of the Transient-Pulse Technique for Determining the Hydraulic Properties of Low-Permeability Rocks—Part 2: Experimental Application
Authors: Zhang M , Takahashi M , Morin RH , Esaki T 
Published: February 2009

Abstract
In Part 1 of this study, the general solution to the transient-pulse test (Hsieh et al. 1981) was extended to evaluate quantitatively the transient variations in hydraulic head and the corresponding distributions of hydraulic gradient within a test specimen. In addition, the conditions and the validity of using the expression proposed by Brace et al. (1968) to compute the low permeability of a rock specimen from a transient-pulse test were examined. Some theoretical considerations related to the optimal design of a transient-pulse test were also discussed. Part 2 presents a relatively general and convenient approach for determining not only the hydraulic conductivity and specific storage of a specimen directly from a transient-pulse test, but also the compressive storage of the fluid reservoirs. The accuracy and efficiency of this method are demonstrated through (1) the comparison of the compressibility of the fluid-reservoir (permeating) system back-calculated from the transient-pulse tests with the value obtained from calibration tests, and (2) its application to a series of experimental studies designed to investigate the effects of confining pressure on the hydraulic properties of Shirahama sandstone and Inada granite, two rock types available widely in Japan.
A New Technique for Simulation of Tunnel Excavation in a Centrifuge
Authors: Sharma JS , Bolton MD , Boyle RE 
Published: February 2009

Abstract
A new technique is presented for the simulation in a centrifuge of the excavation and lining of a model tunnel. It involves the use of a polystyrene foam core that is placed tightly inside the tunnel lining and that can be dissolved using an organic solvent. This technique is an improvement over other contemporary methods of modeling tunnel construction, such as reduction of air pressure supporting the tunnel lining or gradually draining zinc chloride solution (or some other heavy liquid) from within the lining. The stiffness of the filled tunnel can, approximately, be made to simulate the parent soil. The stiffness of the lining is correctly left in place when the foam core has been dissolved. Since there is no air or fluid pressure involved, there is also no need to seal the ends of the tunnel segment. Results from the first few trials of this technique in a 2 m diameter drum centrifuge are presented. These results demonstrate the usefulness of the technique in modeling progressive collapse of a tunnel and show ample promise of its use in the modeling of the construction of a tunnel using the NATM (New Austrian Tunneling Method).
Simultaneous Measurement of Surface Wave Dispersion and Attenuation Curves
Authors: Rix GJ , Lai CG , Foti S 
Published: February 2009

Abstract
In existing surface wave test procedures, experimental dispersion and attenuation curves are determined separately (i.e., uncoupled) using different source-receiver configurations and different interpretation methods. A new procedure based on displacement transfer functions is proposed in which dispersion and attenuation data are derived simultaneously (i.e., coupled) from a single set of measurements using the same source-receiver array. The new approach is motivated by the recognition that in dissipative media, Rayleigh phase velocity and attenuation are not independent as a result of material dispersion. Therefore, a coupled analysis of dispersion and attenuation is a more robust, fundamentally correct approach. The new approach is also more consistent with coupled inversion techniques to obtain the shear wave velocity and shear damping ratio profiles. The proposed approach is illustrated using data measured at a site in Atlanta, Georgia.
Influence of Peripheral Velocity on Vane Shear Strength of an Artificial Clay
Authors: Biscontin G , Pestana JM 
Published: February 2009

AbstractShearing rate is among the most important factors affecting the undrained shear strength of clays. In particular, for seismic or storm-wave loading conditions, the shearing rate is much higher than that used in many common laboratory or field tests. The testing program described here evaluates the effect of peripheral velocity on the undrained strength inferred from the shear vane test. The study was conducted on a lightly cemented bentonite-kaolinite mixture manufactured in the laboratory, which possesses many characteristics similar to those of natural materials. Results show that the shear strength increases with increasing peripheral velocity, while the residual shear strength seems to be nearly independent of rotation rate.
Determining the Maximum Density of Sands by Pluviation
Authors: Cresswell A , Barton ME , Brown R 
Published: February 2009

Abstract
Experiments have been carried out to find the maximum dry density taken up by sands during pluviation. These experiments were facilitated by use of a flow divider that permitted very low depositional intensities. It was found that the maximum dry density occurred at an optimum pluviation time. Careful observation of the pluviating sand reveals that compaction takes place within an “energetic layer” of 3 to 4 grains in thickness and that maximum dry density requires the full and continuous development of this layer. Further experiments were conducted to compare simple pouring without diffuser meshes with pluviation: it is shown that at very slow rates of pour, pouring gives the same density as pluviation.
Mechanical Behavior of a Pulverized Fly Ash Grouted Sand
Authors: Markou IN , Atmatzidis DK 
Published: February 2009

Abstract
A laboratory investigation was conducted in order to develop a new grout based on pulverized fly ash. Pulverization of a selected Greek fly ash yielded a gradation with D15 = 1.3 µm, D50 = 6 µm, and D85 = 20 µm and Blaine specific surface approximately equal to 8300 cm2/g. Suspensions of this pulverized fly ash, improved with additives, have comparable properties to ordinary and microfine cement suspensions. Suspensions were injected into clean sands. Permeability, UU, and CU-PP triaxial compression tests were conducted on the grouted specimens. The coefficient of permeability of the sands is reduced by 4 to 7 orders of magnitude. Grouting increases the stiffness and reduces the deformability of the sands. The Mohr-Coulomb failure criterion represents adequately the behavior of the grouted sands, yielding cohesion values ranging from 290 to 450 kPa and angle of internal friction values up to 5° higher than those of the clean sands. The shear strength parameters vary with axial strain, attaining their final values well before failure.
The Use Of Embedded Stress Cells For Monitoring Pavement Performance
Authors: Gonçalves PF , Ceratti JAP , Damiani Bica AV 
Published: February 2009

Abstract
This paper discusses factors that influence the performance of stress cells embedded in pavement test sections. Accelerated testing of two instrumented flexible pavement sections was carried out using a linear traffic simulator. Interesting data were obtained from stress cells embedded in the clayey subgrade. For both sections, the vertical stress inside this layer was shown to increase with axle load repetition. It also appeared to correlate well with the corresponding increase of surface rutting. The interpretation of these data required a previous investigation of stress cell performance using both laboratory and in situ calibration tests. Details of pavement testing and cell calibration procedures are also described in this paper.
Consolidation and Permeability of Transparent Amorphous Silica
Authors: Liu J , Iskander MG , Sadek S 
Published: February 2009

Abstract
The consolidation and permeability of transparent amorphous silica are studied in this paper. Transparency is achieved by matching the refractive indices of the amorphous silica particles and the pore fluid. The fundamental premise of this research is that transparent synthetic soils made of amorphous silica can be used in model tests to study three-dimensional deformation and flow problems, using nonintrusive optical visualization techniques, if amorphous silica can be produced with geotechnical properties similar to natural soils. The amorphous silicas studied in this paper exhibit consolidation behavior similar to that of organic clays and peat. The permeability of the material falls within the range typically reported for clays and peats.
Design Criteria for Geotomographic Field Studies
Authors: Fernandez A , Santamarina JC 
Published: February 2009

Abstract
The tomographic inversion of boundary measurements permits determining the spatial distribution of a material property within a soil mass. The most common geotomographic setup for wave-based measurements (mechanical or electromagnetic) consists of two arrays of transducers, one with sources and the other with receivers. The separation between the arrays and the number of sources and receivers have to be determined for every new field condition in order to satisfy resolution requirements in view of physical processes and mathematical constraints. The adequate design of a geotomographic study maximizes the amount of information gathered in the field, renders the maximum possible resolution within the physical constrains associated with field conditions and the available instruments, and prevents unnecessary measurement duplication.
Absorption Water Content and Liquid Limit of Soils
Authors: Sridharan A , Nagaraj HB 
Published: February 2009

Abstract
Consistency limits are extensively used in geotechnical engineering practice. Besides the consistency limits, the plasticity index, liquidity index, and consistency index have been used to correlate with engineering properties. The test procedures that have been developed to determine liquid limit are based on the strength criterion, and the liquid limit corresponds to a shearing resistance of 1.7 to 2.0 kPa. However, the mechanisms controlling the test procedures do not simulate the mechanisms controlling the water-holding capacity of soils that the liquid limit is supposed to represent. In this paper an attempt has been made to devise a test procedure, known as the absorption test, which simulates the mechanisms controlling the water holding-capacity of soils. The equilibrium water content reached by the dry soil pats starting at shrinkage limit void ratio is found to have a good correlation with the conventional liquid limit obtained from the cone penetrometer method.
Unsaturated Hydraulic Conductivity of Mine Tailings Under Wetting and Drying Conditions
Authors: Rassam DW , Williams DJ 
Published: February 2009

Abstract
The unsaturated hydraulic conductivity of a soil-like material required in flow models is usually quantified with the aid of predictive models. In this study, an optimum set of input parameters for Campbell's hydraulic conductivity function was estimated. The resulting hydraulic conductivity relationship was compared to that obtained using the van Genuchten model. A flow cell was developed in which transient water contents and matric suctions were monitored while the soil underwent drying and wetting cycles. A one-dimensional numerical model was used to simulate the experimental flow problem for a wide range of input parameters. The sum of the square of the differences (SSD) between the observed and simulated water contents was calculated. The parameters corresponding to the minimum SSD were used to establish three hydraulic conductivity relationships for drying, wetting, and redrying conditions. For wetting conditions, the relative hydraulic conductivity function calibrated against the estimated optimum saturated hydraulic conductivity compared well with the measured unsaturated hydraulic conductivity. A lower-saturated hydraulic conductivity was required to calibrate the hydraulic conductivity function for drying conditions.
A Complex Permittivity Measurement System for Undisturbed/Compacted Soils
Authors: Shang JQ , Rowe RK , Umana JA , Scholte JW 
Published: February 2009

Abstract
The design and calibration of a complex permittivity measurement device for undisturbed and compacted soils is presented. The system consists of an automatic network analyzer, a sample holder, coaxial cables, and software to process data. The design of the sample holder and the limitations and sources of errors in the measurement system are discussed. The complex permittivities of two natural clayey soils were measured over the frequency range of 0.3 MHz to 1.3 GHz. For the soils tested, the dielectric constants and volumetric water contents showed a linear trend that was independent of the soil type. It was found that when performing the complex permittivity measurements the soil specimen length should be kept constant and as short as possible while ensuring that the sample is representative of the in-situ soil fabric and grain-size distribution.
Determination of the Plasticity Index from Flow Index
Authors: Sridharan A , Nagaraj HB , Prakash K 
Published: February 2009

Abstract
The flow index (If), which is the slope of the water content versus log10 (number of blows) plot in the percussion cup method or the slope of the water content versus log10 (depth of penetration) plot of the cone penetration method of determining the liquid limit of soils is a measure of soil plasticity. Hence, the plasticity index of a soil that represents the soil plasticity can be correlated with the flow index.
Analysis of test data pertaining to soils of widely varying plasticity characteristics and geological origin indicates that there is an excellent correlation between the plasticity index and the flow index, particularly in the cone penetration method. In this paper, a simple equation has been suggested to obtain the plasticity index of a soil from the flow index, thereby eliminating the dependence of the plasticity index determination on the time-consuming and unrefined plastic limit test.
Development of a Stress/Suction-Controlled True Triaxial Testing Device for Unsaturated Soils
Authors: Hoyos LR , Macari EJ 
Published: February 2009

AbstractA servo-controlled, true triaxial (cubical) testing apparatus has been modified to test 10-cm cubical specimens of unsaturated soil under suction-controlled conditions and for a wide range of stress paths. The equipment is a mixed-boundary type of device, with the specimen seated on top of a saturated high-air-entry disk and between five flexible membranes on the remaining sides of the cube. This paper describes the development of the device, including details of main apparatus components, specimen preparation, step-by-step assembling procedure, and the corresponding validation of its suitability for testing unsaturated soils. The device features two independent pore-air pressure and pore-water pressure control/monitoring systems. Matric suction states in the specimens are induced and maintained constant during testing by using the axis-translation technique. A companion paper (Macari and Hoyos Jr. 2001) presents the results from a comprehensive experimental study of the stress-strain response of a recompacted silty sand following simple-to-complex stress paths under suction-controlled conditions.
A Flat Dilatometer to Operate in Glacial Tills
Authors: Akbar A , Clarke BG 
Published: February 2009

Abstract
The Marchetti flat dilatometer is a simple to operate in-situ testing device that was designed for use in clays, silts, and sands. A new dilatometer has been developed for use in a greater variety of soil types, in particular glacial tills. This probe is more robust than the Marchetti dilatometer because it uses a rigid piston instead of a flexible membrane to load the soil. The new dilatometer is also a research dilatometer incorporating a displacement transducer and pressure transducer. This allows an applied pressure displacement curve to be produced. Tests have been carried out at several sites to compare results from the two dilatometers, check the robustness of the new dilatometer, and produce data to establish new correlations.
Determining Hydraulic Conductivity of Soil-Bentonite Using the API Filter Press
Authors: Filz GM , Henry LB , Heslin GM , Davidson RR 
Published: February 2009

AbstractThe American Petroleum Institute (API) filter press is commonly used to measure the hydraulic conductivity of soil-bentonite, both during mix design and as a part of construction quality assurance and quality control. However, interpretation of the test results is complicated by the fact that, during the test, the soil-bentonite specimen is consolidated by seepage forces, which produce a variation in effective consolidation stress from the top of the specimen to the bottom. This paper presents the results of a laboratory investigation undertaken to illustrate that seepage consolidation theory provides a logical way to interpret filter press test results. A description of seepage consolidation theory, which relates stress, compressibility, and hydraulic conductivity in soil consolidated by seepage forces, is presented. Following this is a description of the laboratory testing program that involved comparing the hydraulic conductivity of two soil-bentonite mixes, as measured in rigid wall consolidometer permeameter cells, a flexible wall permeameter, and an API filter press. Using seepage consolidation theory to interpret the filter press tests produces hydraulic conductivities consistent with those obtained from the other tests. The filter press test results are used to illustrate a method for estimating the hydraulic conductivity of soil-bentonite in a cutoff wall by taking backfill consolidation pressures into account.