bluuebunny/crossref_metadata_2025_split huggingface dataset:
Instrumentation of an Unsaturated Residual Soil Slope
Authors: Gasmo J , Hritzuk KJ , Rahardjo H , Leong EC 
Published: February 2009

Abstract
The stability of slopes has become a major concern in areas that experience frequent periods of heavy rainfall such as the tropical areas of Southeast Asia. Previous research has indicated that rainfall has a detrimental effect on the stability of residual soil slopes. The reason for this is that the additional shear strength that exists in unsaturated soils due to negative pore-water pressures is lost as a result of rainwater infiltration into the soil.
To study the infiltration characteristics in slopes, a residual soil slope in Singapore was instrumented. The instruments were used to determine the changes in the pore-water pressure distribution throughout the slope in response to evaporation and infiltration. Tensiometers were used to measure negative pore-water pressures, piezometers were used to measure the groundwater level, and a rain gage was used to measure rainfall intensities on the slope. An automated data acquisition system was used to collect the data from the slope. This paper describes the instrumentation program and the procedures associated with the installation of the instruments into the slope. Typical measurement data collected from the slope are presented, and their interpretations are discussed.
Preparation of Epoxy Impregnated Sand Coupons for Image Analysis
Authors: Jang D-J , Frost JD , Park J-Y 
Published: February 2009

Abstract
The study of sand structure using image analysis is an emerging area in soil mechanics research. Quantification of parameters such as the local void ratio distribution or the orientation of sand known to directly affect the behavior of sand masses is possible. However, accurate quantitative measurement requires high-quality specimen coupon surfaces for imaging. A comprehensive procedure for preserving sand specimens with epoxy resin and preparing specimen coupon surfaces for image analysis using a variety of grinding and polishing procedures is presented. Factors affecting the accuracy of subsequent image analysis measurements are discussed. Example images obtained using the proposed procedures are presented to demonstrate their effectiveness and potential.
Interaction Between Hexagonal Wire Mesh Reinforcement and Silty Sand Backfill
Authors: Bergado DT , Teerawattanasuk C , Wongsawanon T , Voottipruex P 
Published: February 2009

Abstract
Pullout tests were conducted on hexagonal wire mesh embedded in silty sand locally known as Ayuttaya sand to investigate the soil reinforcement interaction. Two types of hexagonal wire mesh were tested, namely: (a) galvanized (zinc-coated) which has smaller aperture (cell) dimension of 60 by 80 mm and (b) PVC-coated which has larger aperture (cell) dimension of 80 by 100 mm. The tests were conducted under normal pressures ranging from 35 to 91 kPa and the specimens were pulled at a rate of 1 mm/min. The total pullout resistance of hexagonal wire mesh reinforcement consists of two components, namely; friction and bearing resistance. The bearing resistance is higher than the friction resistance for both types of reinforcement. Higher friction and bearing resistances were obtained with increasing normal pressures. The friction and bearing resistances mobilized on the galvanized wire mesh were greater than the PVC-coated wire mesh, due to higher friction coefficient as well as greater number of transverse and longitudinal members (elements) per unit width in the former than the latter. The proposed analytical method of predicting the pullout resistance and displacement relation using the basic soil and reinforcement properties agreed with the test results reasonably well.
Evaluation of Initial Specimen Condition and Its Effect on Consolidation Properties of Saturated Clay
Authors: Chang M-F 
Published: February 2009

Abstract
The reliability of results of laboratory tests on soils depends on the specimen quality or the initial specimen condition. The quality of specimens prepared using different methods, from clay samples extracted using different techniques and subjected to different periods of storage, can be evaluated based on the measurement of residual porewater pressure. For a laboratory-fabricated normally consolidated clay, the residual porewater pressure decreases when using an inferior sampling technique or preparation method and when the storage time increases, with the effect from the method of specimen preparation dominating. Results of oedometer tests indicate that consolidation properties are noticeably affected by the initial specimen condition, and reasonably strong correlations exist between the preconsolidation pressure and the coefficient of volume compressibility of the clay and the residual porewater pressures in the test specimens. These corrections can be potentially applied to natural clays, although prior verification is necessary.
Quick and Reliable Procedure for Liquid Limit Determination of Fine-Grained Soils
Authors: Mendoza MJ , Orozco M 
Published: February 2009

Abstract
This paper describes comparative results of liquid limits for fine-grained soils, determined by the percussion-cup standard procedure and alternative techniques with penetrating cones. Microwave oven drying is used as a complement to fall-cone tests. In this way, the liquid limit for a soil sample can be accurate and reliably obtained in about 45 min. The studied cones were the pioneer Swedish cone with 60° angle and 60 g mass, and the English cone with 30° and 80 g. Percussion liquid limits differ from those obtained with the cones; however, results of a comprehensive experimental program evince that there exist linear correlations between their liquid limits.
Laboratory Testing of Concrete-rock Joints in Constant Normal Stiffness Direct Shear
Authors: Seidel JP , Haberfield CM 
Published: February 2009

Abstract
This paper describes the experimental component of an extensive investigation into the shear behavior of joints formed between concrete or cement grout and soft, weak or weathered rock. Understanding the behavior of such joints is important for the prediction of performance of a diverse range of structural elements, such as drilled piers socketed into rock, rock anchors, and dam foundations. The particular tests described in this paper were carried out on joints formed between concrete and an artificial silstone called Johnstone, under conditions of constant normal stiffness, and involved a range of boundary conditions and interface profiles. Interfaces included a series of regular triangular asperities and irregular profiles based on fractal geometry concepts. The authors have included the complete suite of test results in the belief that it will be a significant addition to the literature, which currently contains very few results of constant normal stiffness tests. It also demonstrates the importance of realistically modelling interface roughness. Careful observations made during testing using time-lapse photography have aided in the development of a number of simple theoretical models of behavior, which are published elsewhere.
Permeability of Two-Layer Soils
Authors: Sridharan A , Prakash K 
Published: February 2009

Abstract
The equivalent coefficient of permeability of a stratified soil system calculated theoretically has been observed to be not the same as that directly measured, when the flow is normal to the orientation of the bedding planes. A hypothesis has been proposed in this investigation to explain this deviation according to which the permeability of the exit layer controls whether the measured permeability is greater or lesser than the theoretically calculated value. The proposed hypothesis has been used to successfully and satisfactorily explain the experimental observations made with the two-layer systems. It has been shown that the coefficient of permeability of a soil in a layered system cannot be considered as its property and that it depends upon the permeabilities of adjoining layers, their thicknesses, and the flow direction.
Development of RECP Performance Test Methods
Authors: Joel Sprague C , Carver CA , Allen S 
Published: February 2009

Abstract
The recent growth and development of the Rolled Erosion Control Products (RECP) industry have created the need for a way to compare the wide array of products now available.
The Erosion Control Technology Council (ECTC) identified the need for standardized performance testing for RECPs and initiated a project to develop performance tests that provide economical and efficient product evaluation and which are suitable for the ASTM approval process. The resulting new performance test protocols have been developed:
• “Determination of RECP Performance in Protecting Soil from Rainsplash”
• “Determination of RECP Performance under Shear Stress”
• “Determination of the Biodegradability of RECPs by CO2 Release”
• “Determination of RECP Performance in Encouraging Seed Germination and Vegetation Growth”
This paper documents the developmental process including the design bases for erosion control tests, a review of existing performance test practices, and details the new performance test protocols for RECPs in both slope and channel lining applications. Initial testing using the new test standards has indicated that the tests are practical, cost-efficient, and reproducible.
Stress-Strain Strength Characteristics of a Marine Soil with Different Clay Contents
Authors: Yin J-H 
Published: February 2009

Abstract
It is commonly believed that the clay content has a major influence on the behavior of a soil, among other factors. This technical note presents main results of a series of consolidated undrained (CU) triaxial tests on re-consolidated soft Hong Kong marine deposits (HKMD) with different clay contents. The focus is placed on the influence of the clay content on the stress-strain strength characteristics of the HKMD, including the stress-strain curves, effective stress paths, friction angles, and Young's modulus. The results are discussed and interpreted. New understanding and useful correlations are presented.
Anisotropic Consolidation Behavior of Soft Bangkok Clay
Authors: Seah TH , Koslanant S 
Published: February 2009

Abstract
The anisotropic consolidation behavior of soft Bangkok clay is investigated by means of constant rate of strain consolidation tests with vertical and radial drainage conditions. Conventional oedometer tests were performed to verify the results of constant rate of strain consolidation tests in the vertical flow condition. Better-defined compression curves were obtained from the CRS tests, resulting in better estimation of preconsolidation pressure. A new method of determining the preconsolidation pressure based on the pore pressure ratio gave values close to those obtained from the Casagrande construction of compression curves. The results of CRS tests under different drainage conditions indicated that soft Bangkok clay is slightly anisotropic, with the ratio of coefficients of consolidation and permeability in the horizontal to vertical directions of about unity at in-situ stress. The difference increases with increasing stress due to stress-induced anisotropy of the soil.
Performing Undrained Shear Tests on Saturated Sands in a New Intelligent Type of Ring Shear Apparatus
Authors: Sassa K , Wang G , Fukuoka H 
Published: February 2009

Abstract
The design and construction of an undrained ring shear apparatus, which was newly developed at Disaster Prevention Research Institute, Kyoto University, are presented in detail. This apparatus is suited for undrained shear tests under all types of loading, and enables observing the undrained shear behavior of soils in high-speed motion (maximum rotating speed 2.24 m/s) to an endless displacement level. Using rubber edges and a gap control system, leakage of pore water was effectively prevented, and the friction of rubber edges was controlled with high credibility during shearing. For undrained shearing tests on sand, the related experimental procedures are introduced and the undrained shear behavior of sand in ring shear test is presented. Test results showed that high pore water pressures could be built up in both loose and dense sands, given the shear displacement is great enough.
A Double Cell Triaxial System for Continuous Measurement of Volume Changes of an Unsaturated or Saturated Soil Specimen in Triaxial Testing
Authors: Yin J-H 
Published: February 2009

Abstract
This paper presents an improved Double Cell Triaxial System (DCTS) for continuous measurement of the volume change of an unsaturated or saturated soil specimen in triaxial testing. The DCTS developed by the author overcomes the two critical shortcomings of the conventional triaxial system and has advantages over the existing modified triaxial cells for measuring the volume changes of unsaturated/saturated soils during water flushing, consolidation, and compression. The calibration of the DCTS has been done using both a dummy solid copper specimen and a fully saturated marine clay specimen. The water volume changes of the inner cell and the outer cell are measured and compared on the copper specimen under compression of the inner/outer cell pressure up to 400 kPa. It is found that the volume changes of the outer cell are significant, while the volume changes of the inner cell are negligible. On the saturated marine clay, volume changes of the clay specimen under isotropic consolidation and drained axial compression are measured using two methods: the conventional method (Method A) by measuring the volume of water coming out from inside the specimen and the method (Method B) by using the DCTS to measure the internal cell water volume changes. The volume changes using the two methods are compared. It is found that the differences of the volume changes using the two methods are within 5.6%. The calibration results using both the solid copper specimen and the saturated marine clay specimen show that the DCTS is accurate and reliable for continuously measuring the volume changes of unsaturated or saturated soil specimens during consolidation and compression.
Interface Behavior of Sands from Constant Normal Stiffness Direct Shear Tests
Authors: Porcino D , Fioravante V , Ghionna VN , Pedroni S 
Published: February 2009

Abstract
This paper reports an experimental study concerning the frictional behavior of sand-solid structure interfaces. The study was performed using a constant normal stiffness (CNS) direct shear box. Three natural silica sands and four aluminium plates with different roughnesses were investigated. A comparison between constant normal load (CNL) and CNS tests is reported. The influence of the main factors controlling the frictional behavior of the investigated materials such as constant normal stiffness, roughness of solid surface, particle size, and relative density, and initial effective normal stress are analyzed and discussed.
Compression Tests of Ultra-Soft Soil Using an Hydraulic Consolidation Cell
Authors: Bo MW , Sin WK , Choa V , Ing TC 
Published: February 2009

Abstract
Compression behavior and compression parameters in the ultra-soft soil stage are still not well understood. In ultra-soft soil stage, the process of compression does not follow Terzaghi's unique relationship of deformation and effective stress gain principle, and the large deformation with little or no effective stress gain occurred in this stage. One-step loading compression tests were conducted, using a large diameter hydraulic consolidation cell (Rowe Cell). Vertical displacement and pore pressure behavior were measured during the deformation process. The transition point between slurry and soil stage determined from various methods are discussed. Approximate determination of compression indices in slurry stage from one-step high pressure loading was described in the paper. Step loading compression tests were also carried out with hydraulic consolidation cells on an ultra-soft soil with radial drainage conditions. Based on these test results, new compression parameters C*c1, C*c2, and C*c3 are introduced in this paper. The correlation between e*10 and void ratio at liquid limit eL is proposed. With this information, the total settlement at various loadings can be determined using the proposed equations. The prediction of time-rate of settlement could even be made using the coefficient of large strain consolidation CF estimated from the void ratio-permeability relationship. The computed magnitude and time rate of settlement agreed well with measured data. The dimensionless time factor curves for various radial drainage conditions are also proposed.
Changes in Interface Stresses During Pullout Tests on Geogrid Strip Reinforcement
Authors: Hayashi S , Shahu JT , Watanabe K 
Published: February 2009

Abstract
For a strip geogrid reinforcement, pullout resistance per unit width is known to increase with decreasing specimen width at low applied normal stresses. This phenomenon can be explained by a conceptualized model for a pullout interaction mechanism consisting of combined 2-D and 3-D interaction mechanisms, and the results obtained from laboratory pullout tests can be extended to the field. In this paper, a series of pullout tests on stiff extruded geogrid specimens embedded in dense sandy gravel was carried out and the normal stresses at the soil-reinforcement interface were measured by small-diameter earth pressure cells. On the basis of these tests, the fundamental behavior of soil-geogrid reinforcement interaction is explained and the conceptualized pullout interaction model is corroborated. It is shown that restrained positive dilatancy, observed at low applied normal stresses, results in an increase in actual normal stresses at the soil-reinforcement interface at the edges of the geogrid, thereby increasing the pullout resistance of the reinforcement.
Automated Humidity System for Measuring Total Suction Characteristics of Clay
Authors: Likos WJ , Lu N 
Published: February 2009

Abstract
A computer-automated experimental system for determining total suction characteristic curves using relative humidity control is described. The system is applicable in the relatively high suction range important for fine-grained materials (7000 to 700 000 kPa). The new system has several advantages over existing suction measurement techniques; most notably, it is fully automated, has a much broader measurement range, is capable of determining both wetting and drying characteristics in significantly less time, and requires only one undisturbed sample for testing. Tests are conducted to evaluate the system response and illustrate its use in practice. Total suction characteristic curves are determined for four types of clay, ranging from highly expansive smectite to non-expansive kaolinite. Concurrent characteristic curves are determined using the filter paper method for comparison. Practical applications are demonstrated in two ways. First, select results are analyzed to assess the swelling potential of the four clays using an existing methodology based on total suction testing. Second, aspects related to the adsorption kinetics of expansive soils are evaluated by analyzing the results with a first-order kinetic model.
An Evaluation of Geometric Factors Used in the Two-Stage Borehole Test (ASTM D6391-99) Using the Finite Element Method
Authors: Ratnam S , Soga K 
Published: February 2009

Abstract
Geometric or shape factors are constants used in the interpretation of in-situ hydraulic conductivity tests, such as the Two-Stage Borehole (TSB) test in ASTM D6391-99. The finite boundary condition shape factors used with the TSB test are an extension of those derived by Hvorslev (1951) for infinite boundary conditions. The accuracy of this extrapolation is investigated here, using the finite element method (FEM) as a tool for deriving shape factors for finite boundary conditions. The utilized FEM has been validated against closed-form solutions for other test geometries. The resulting errors from the incorrect use of shape factors with the TSB test are discussed, and new shape factors derived from the FEM are presented in the form of a chart.
Experimental Investigation of Dynamic Response of Compacted Clayey Soils
Authors: Inci G , Yesiller N , Kagawa T 
Published: February 2009

Abstract
A study was conducted to determine the dynamic properties of compacted clayey soils subjected to low amplitude vibration. A fast and simple ultrasonic pulse transmission method was used. Tests were conducted on three clayey soils with low to high plasticity compacted using standard and modified Proctor effort over a range of water contents. The samples were allowed to dry after compaction and P-wave velocity, S-wave velocity, Poisson's ratio, and shear modulus were determined. The effects of soil type, compaction conditions, and degree of saturation on the dynamic response of the soils were investigated. The elastic wave velocities and the dynamic shear modulus increased as the soil plasticity decreased. The velocities and the modulus increased and the Poisson's ratio decreased as the degree of saturation decreased due to drying. Generally, the velocities and moduli increased significantly at the early stages of drying with the changes becoming more gradual as drying progressed. Variations were high for soils compacted with low energy and high water content. The shear moduli of the soils were also estimated using a common empirical equation. Suction values obtained for the test soils in a different study were used as effective stresses in the estimation. The estimated shear moduli agreed well with the measured values.
Horizontally Mounted Bender Elements for Measuring Anisotropic Shear Moduli in Triaxial Clay Specimens
Authors: Pennington DS , Nash DFT , Lings ML 
Published: February 2009

AbstractNovel horizontally mounted bender element devices capable of high-quality transmission and reception of horizontally propagated shear waves polarized in orthogonal planes across the mid-height of a triaxial clay specimen are described. Mounting of these mini benders, in a T-shaped configuration, is in the pads of a radial strain belt on 100 mm diameter triaxial samples, or alternatively as bender probes (similar in concept to mid-height pore pressure probes) suitable for use on triaxial samples down to 38 mm diameter. This latter type may also be used in bench-top tests or on site. The effective fabrication procedures that have been developed are described. The instrumentation systems used to drive and receive signals are outlined, and estimates of the magnitude of the shear strains developed by the bender elements and the accuracy with which shear wave velocities can be determined are discussed. These new bender elements enable both anisotropic shear moduli to be measured over the same path length on a single triaxial specimen that can be taken to a wide variety of anisotropic stress states. Comparison with measurements using conventional platen-mounted bender elements suggests these may underestimate the shear modulus by up to 20%.