bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Multidirectional Direct Simple Shear Apparatus
Authors: DeGroot DJ , Germaine JT , Ladd CC 
Published: February 2009

AbstractThe paper describes a new simple shear testing device, the multidirectional direct simple shear (MDSS) apparatus, for testing soil specimens under conditions that simulate, at the element level, the state of stress acting within the foundation soil of an offshore Arctic gravity structure. The MDSS uses a circular specimen that is consolidated under both a vertical effective stress (σ′vc) and a horizontal shear stress (τ1). The specimen is subsequently sheared undrained by applying a second independent horizontal shear stress (τ2) at an angle ϑ relative to the horizontal consolidation shear stress τ1. Evaluation of the MDSS first compares conventional K0-consolidated undrained direct simple shear (CK0UDSS) test data (τ1 = 0) on normally consolidated Boston blue clay (BBC) with results obtained in the Geonor DSS device. The MDSS gives lower secant Young's modulus values and on average 8% lower strengths, but produces remarkably less scatter in the test results than the Geonor DSS. Kinematic proof tests with an elastic material (rubber) confirm that the setup procedure, application of forces, and strain measurement systems in the MDSS work properly and produce repeatable results.Results from a MDSS test program on BBC wherein specimens were first normally consolidated with σ′vc and τ1 = 0.2σ′vc and then sheared undrained at ϑ varing in 30° increments from zero (shear in same direction) to 150° show dramatic differences in the response of the soil as a function of θ. The peak undrained strength varies almost twofold from θ = 0 to 120°, while the deformation behavior varies from very brittle at low θ angles to becoming ductile at higher angles. The experimental results indicate that dramatic changes in foundation response at different θ angles will be an important design issue.
Behavior of Fiber-Reinforced Cemented Sand Under Static and Cyclic Loads
Authors: Maher MH , Ho YC 
Published: February 2009

Abstract
Triaxial static compression, cyclic compression, and splitting tension tests were performed to evaluate the effect of randomly distributed fiber reinforcement on the response of cemented sand to load. Test results indicated that fiber reinforcement significantly increases the compressive and splitting tensile strength of cemented sand. An increase in the compressive and tensile strength was found to be more pronounced at higher fiber contents and longer fiber lengths. Peak strength envelopes in compression indicated that both the friction angle and cohesion intercept of cemented sand were increased as a result of fiber inclusion. Inclusion of fibers also contributed to increased brittleness index of cemented sand while increasing its total energy absorption capacity. Fiber reinforcement also affected the response of cemented sand to cyclic load by significantly increasing the number of cycles, and the magnitude of cyclic strain needed to reach failure.
Strain Measurement in HDPE Geomembrane Tensile Tests
Authors: Giroud JP , Monroe M , Charron R 
Published: February 2009

Abstract
According to ASTM D 638, the tensile strain in an HDPE geomembrane dumbbell specimen subjected to a tensile test should be evaluated using an extensometer that records the elongation of a defined length of the central portion of the specimen. However, the current practice in the United States for HDPE geomembrane quality control and conformance testing consists of following the 1991 NSF standard that recommends to conventionally evaluate the tensile strain by dividing the change in grip separation by an arbitrary gauge length. A theoretical analysis and test results presented in this paper show that the strain derived from grip separation using the gauge length specified by the 1991 NSF standard is significantly different from the actual strain, which is obtained using an extensometer as recommended by ASTM D 638. The discrepancy between the conventionally calculated strain and the actual strain may lead to unconservative design of HDPE geomembrane applications. A modification to the NSF standard is proposed to obtain a strain derived from grip separation that is close to the actual strain.
Determination of P-Y Curves Using Inclinometer Data
Authors: Brown DA , Hidden SA , Zhang S 
Published: February 2009

Abstract
Derivation of p-y curves from lateral load tests on deep foundations is a tedious and expensive task, requiring large numbers of strain gages along the length of the pile to develop bending moment versus depth relationships. A method is proposed which allows derivation of p-y curves from simple inclinometer data using a least-squares regression technique. Inclinometer measurements can and have been routinely made on lateral load tests of piles and drilled shafts. The method outlined in this paper provides a means of “calibrating” p-y curves using data from tests where only inclinometer data are available and promises to allow a substantial improvement in the database of load tests from which the empirical p-y curves used in design are based.
Laboratory Filter Paper Suction Measurements
Authors: Houston SL , Houston WN , Wagner A-M 
Published: February 2009

Abstract
Results of filter paper measurements for both matric and total suction values are reported for a sand, silt, and clay. Calibration curves for the matric and total suction are given for the filter paper used in this study, and comparisons with the results of several other researchers are made. For low suction values, the matric suction is more easily measured than the total suction using the filter paper method. This difference is due primarily to the insensitivity of the water content of the noncontact filter paper to changes in suction when the suction is low. A pressure membrane, saturated salt solutions, and tensiometers were used in developing the filter paper calibration curves. Potential pitfalls in making filter paper measurements and limitations of the method are discussed. A procedure for obtaining filter paper suction measurements is given.
Suggested Modifications to ASTM Standard Methods When Testing Arid, Saline Soils
Authors: Al-Amoudi OSB , Abduljauwad SN 
Published: February 2009

Abstract
Arid, saline soils are residual in nature, highly cemented, and formed in hot, arid environments. The presence of soluble and insoluble salts affects the geotechnical properties of these soils. Techniques used to determine the properties of these soils should take into consideration the presence of diagenetic minerals that are considered part of these soils. In this investigation, a typical arid, saline, evaporitic soil, known locally as sabkha, was tested to determine its grain-size characteristics, hydraulic conductivity, compressibility, and collapse potential using standard ASTM methods and nonstandard techniques. The presence of soluble salts necessitates modifications to these standard test methods to properly assess the properties of these soils. Erratum to this paper appears in 17(3).
A Study of an Anisotropically Overconsolidated Silt by the Resonant Column Method
Authors: Macari EJ , Ko H-Y 
Published: February 2009

Abstract
This paper presents the results of a study of the anisotropic characteristics of the shear modulus and damping ratio of a remolded silt that has been uniaxially consolidated. Resonant column tests were conducted on specimens trimmed vertically and horizontally from bulk samples previously subjected to various uniaxial preconsolidation pressures. The tests were performed under various confining pressures, hence resulting in a range of overconsolidation ratios. The degree of anisotropy was defined as the percent difference between the shear modulus of the vertically trimmed specimens and the horizontally trimmed specimens. Empirical relations were found to represent the degree of anisotropy as functions of the overconsolidation ratio and the effective confining pressure.
Investigation of the Strain-Softening Behavior of Granular Soils with a New Multiaxial Cell
Authors: Lo S-CR , Chu J , Lee IK 
Published: February 2009

Abstract
The special considerations leading to the design of a new multiaxial cell used for strain-softening studies are presented. This cell has the special features of being able to accommodate large strain without introducing boundary imperfections, allowing observation of shear band formation, and permitting strain path control. The observed strain-softening behavior of a quartz sand under multiaxial stress condition, i.e., σ'1 ≠ σ'2 ≠ σ'3, are presented. Both stress path tests and strain path tests were conducted. In a stress path test, the specimen was loaded in the major principal direction in a deformation-controlled mode but with the stress response constrained along a prescribed path using computer control. Hence strain-softening response can still be observed in a controlled way. Two types of softening, prefailure and postfailure softening, are identified. Prefailure softening will occur along certain strain paths, and the associated deformation is homogeneous. In postfailure softening under a multiaxial stress condition, only limited homogeneous deformation can be sustained, and eventually there will be shear band formation. However, this shear band is not triggered by boundary imperfections but is an inevitable response of the specimen to shearing in the postfailure domain under a multiaxial stress condition.
Prediction Models of Resilient Modulus for Nongranular Materials
Authors: Pezo R , Hudson WR 
Published: February 2009

AbstractThis paper describes an experimental program and the analyses performed for the purpose of developing prediction models of resilient modulus for nongranular materials. Two models were developed and are presented herein. The first model provides a quick estimation of the resilient modulus based on basic characteristics of the specimens, while the second model includes a family of curves that relate a normalized modulus to the resilient axial strains and the plasticity index of the specimens. The significance of the second model is corroborated particularly now that moduli measurements obtained from field and laboratory tests can be easily related.
A Modified Commercial Triaxial Testing System for Small Strain Measurements: Preliminary Results on Pisa Clay
Authors: Lo Presti DCF , Pallara O , Puci I 
Published: February 2009

AbstractA computer-controlled hydraulic triaxial cell was modified with the aim of obtaining (1) a better measuring accuracy of soil stiffness at small strains, (2) a reliable automatic procedure for K0 consolidation, and (3) a minimum disturbance during system saturation and specimen consolidation. To obtain the above objectives, many modifications were introduced. The cell structure and loading piston were modified and many transducers were introduced, including the LDTs for local radial and axial strain measurement. Finally, control software was developed to achieve the following testing procedures: (1) dry setting, (2) system saturation by flushing with stress control to avoid any swelling and back pressurization, and (3) K0 consolidation with control of nil radial strain by means of local measurement. The paper will benefit those interested in upgrading an existing hydraulic triaxial system in-house in an economical manner.
A Direct Simple Shear Device for Measuring Small-Strain Behavior
Authors: Doroudian M , Vucetic M 
Published: February 2009

Abstract
A simple shear device named the double specimen direct simple shear (DSDSS) device was designed to investigate static and cyclic properties of soils at small strains, such as cyclic stress-strain loops, maximum shear modulus, Gmax, secant shear modulus, Gs, and the equivalent viscous damping ratio, λ. Cyclic shear strains between 5 × 10−4 and 2 × 10−2% were successfully applied and measured. Such measurements of very small strains were achieved by completely eliminating the friction of the load-transfer mechanism and by reducing the effects of the mechanical compliance of the device to practically zero. This was facilitated by using a special configuration of two parallel specimens. The performance of the DSDSS device was examined first by testing rubber dummy specimens of different stiffnesses and then by conducting a series of tests on kaolinite clay consolidated under different vertical consolidation stresses and over-consolidation ratios. The results produced by the new device show very consistent trends and are in good agreement with equivalent data obtained by others using other types of tests and equipment.
Permeability and Compressibility Behavior of Bentonite-Sand/Soil Mixes
Authors: Pandian NS , Nagaraj TS , Raju PSRN 
Published: February 2009

Abstract
As a seepage barrier, slurry trench material should have a relatively low coefficient of permeability, in the range of 10−7 cm/s, and at the same time should be compatible with surrounding material with regard to compressibility. Although bentonite-sand/soil mixes are used widely, there is no specific engineering approach to proportion these mixes that satisfies the above practical requirements. In this paper, a generalized approach is presented for predicting the permeability and compressibility characteristics of mixes with minimum input parameters. This approach will be helpful in proportioning mixes and predicting corresponding changes in engineering behavior. It is possible to proportion a mix to arrive at the required compressibility without affecting the permeability. This is explained using an illustrative example.
A New Filter Material for Measuring Soil Suction
Authors: Sibley JW , Williams DJ 
Published: February 2009

Abstract
The filter paper method for determining soil suction has been in use for many years and owes its attraction to its simplicity. A major drawback of the method is that the suction range over which it can be applied is limited by the moisture sensitivity of the filter paper or absorbent used. By convention, filter paper has been adopted for use in the method, but other absorbents may well be more suitable, increasing the sensitivity of the method and extending the suction range over which the method may usefully be applied. In this paper the desirable attributes of absorbents for use in determining soil suctions are outlined, and the suitability of a nonconventional absorbent material is assessed. It was found that this material had enhanced sensitivity over the middle suction range.
Laboratory and Field Calibration of a Neutron Depth Moisture Gauge for Use in High Water Content Soils
Authors: Silvestri V , Sarkis G , Bekkouche N , Soulie M , Tabib C 
Published: February 2009

AbstractIn recent years radioisotopes have been increasingly used for determining site values of the density and the water content of soils. Since field measurements obtained by neutron moisture gauges are relative, these instruments must be calibrated. Calibration is usually carried out in the laboratory by plotting neutron counting rates versus known water content values of several soil media, homogeneous as well as heterogeneous.The accuracy of the factory calibration curve of a widely used, commercial neutron depth moisture gauge was evaluated both in the field and in the laboratory by comparing probe readings to measured volumetric water contents of several soil mixtures. The analyses of the laboratory results indicate that the factory linear calibration curve is satisfactory for volumetric water contents not exceeding 40%. However, for volumetric water contents in the range from 40 to 100%, the relationship between probe readings and volumetric water contents is nonlinear. This nonlinear curve was found to be quite different from that obtained in the field calibration campaign carried out in a deposit of sensitive Champlain clay having volumetric water contents which compare well with those of the laboratory-prepared clay mixtures.
Determination of Clay Size Fraction of Marine Clays
Authors: Sridharan A , Jose BT , Abraham BM 
Published: February 2009

Abstract
This technical note describes a study on the effect of different dispersing agents and the quantity of same on the grain-size distribution and in particular the percentage of clay size. The results confirm that the existing practice of using 100 mL of standard dispersing agent, viz. sodium hexametaphosphate and sodium carbonate solution, is suitable for marine clays also. The clay size fraction in a marine soil exists in the form of flocs, and hence a dispersing agent is imperative in determining the percentage of clay size fraction. This paper shows that the clay size fraction can vary significantly (4 to 45%) for the marine clays depending upon the dispersing agent used. It also brings out the importance of the need for using an initially moist sample for grain-size analysis in the case of marine clays. Initial air/oven drying before testing induces irreversible aggregation.
Design and Performance of the Imperial College Instrumented Pile
Authors: Bond AJ , Jardine RJ , Dalton JCP 
Published: February 2009

Abstract
This paper describes the design, calibration, and field performance of a number of new instruments that have been used for research into the behavior of displacement piles in clays and sand. The instruments include axial load cells, surface stress transducers, and pore pressure probes. The special features of the surface stress transducers and pore pressure probes are described in detail, and problems associated with measuring pore pressures in strongly dilating soils are discussed. Data recorded at a stiff clay site are used to demonstrate the reliability of measurements obtained with the new instruments.
Tensiometers—Theory, Construction, and Use
Authors: Stannard DI 
Published: February 2009

Abstract
Standard tensiometers are used to measure matric potential as low as −870 cm of water in the unsaturated zone by creating a saturated hydraulic link between the soil water and a pressure sensor. The direction and, in some cases, quantity of water flux can be determined using multiple installations.
A variety of commercial and fabricated tensiometers are commonly used. Saturated porous ceramic materials, which form an interface between the soil water and the bulk water inside the instrument, are available in many shapes, sizes, and pore diameters. A gage, manometer, or electronic pressure transducer is connected to the porous material with small- or large-diameter tubing. Selection of these components allows the user to optimize one or more characteristics, such as accuracy, versatility, response time, durability, maintenance, extent of data collection, and cost.
Special designs have extended the normal capabilities of tensiometers, allowing measurement in cold or remote areas, measurement of matric potential as low as −153 m of water (−15 bars), measurement at depths as deep as 6 m (recorded at land surface), and automatic measurement using as many as 22 tensiometers connected to a single pressure transducer.
Continuous hydraulic connection between the porous material and soil, and minimal disturbance of the natural infiltration pattern are necessary for successful installation. Avoidance of errors caused by air invasion, nonequilibrium of the instrument, or pressure-sensor inaccuracy will produce reliable values of matric potential, a first step in characterizing unsaturated flow.
The Bending of a Screw Plate
Authors: Brown PT 
Published: February 2009

Abstract
The bending of a screw plate may have a considerable influence on the value of soil modulus derived from test results. This paper presents the dimensionless results of a study in which the plate is analyzed by finite elements and the soil is analyzed by integrated Boussinesq theory corrected for embedment in the medium. These results enable correction for the effect of plate bending for a range of screw plates. Such corrections may increase the derived value of modulus by 40% or more above the value obtained when a rigid plate is assumed. A correction based on the assumption that the plate is a disc is shown to be somewhat unsatisfactory.
Development of a True Triaxial Testing Apparatus
Authors: Reddy KR , Saxena SK , Budiman JS 
Published: February 2009

Abstract
A stress-controlled, flexible boundary, true (or cubical) triaxial apparatus has been developed to investigate the behavior of cemented sand under various stress paths which are not achievable using conventional axisymmetric triaxial apparatus. The apparatus components, specimen preparation, and test procedure are described. Tests were performed on cemented sand along different stress paths which included hydrostatic compression, conventional triaxial compression, and along different directions on octahedral planes. The test results indicate that stress-strain and volumetric response of cemented sand depends on stress path.
Leach Tests on Lime-Treated Clays
Authors: McCallister LD , Petry TM 
Published: February 2009

Abstract
This paper describes the design, use, and results of a multiple leach-cell operation to test the changes in permeability and calcium removal of a lime-treated expansive clay under continuous water leaching. Seventy laboratory-prepared lime-treated clay specimens were subjected to continuous accelerated leaching for periods of 45 and 90 days with varying lime contents and compactive moisture contents. Permeability, leachate pH, and leachate cation changes were continuously recorded during the leach process.
Results indicate that lime dramatically increased the soil's permeability, with maximum permeability occurring at the lime modification optimum (LMO). Leachate pH increased as the lime content of the soil increased but decreased linearly during the leach cycle. Calcium concentration in the leachate was lowest in specimens prepared at their LMO but increased as the lime content increased. There is strong evidence to suggest that calcium removal and permeability are in direct correlation to the complex ion interaction within the soil-lime mixture, and therefore the LMO is central in determining leaching effects on lime-treated soils.
Static and Cyclic Direct Shear Tests on Carbonate Sands
Authors: Al-Douri RH , Poulos HG 
Published: February 2009

AbstractThis paper examines the static and cyclic behavior of different types of carbonate sediments and one type of silica sand under direct shear test conditions. For both static and cyclic loading, the effects of interface surface roughness, overburden pressure, void ratio, size and shape of grains, and saturation are studied. It is found that the static shear resistance is influenced by most of these factors and that the cyclic behavior depends significantly on the number of cycles and the cyclic displacement amplitude. The amount of crushing caused by cyclic loading is found to depend strongly on particle shape and grading characteristics.The results of the static tests can supply useful information about the strength parameters (δ and ϕ), which are important in assessing skin friction for the design of pile foundations. The cyclic test results provide useful indications of the likelihood of degradation of pile skin friction under cyclic loading. The larger the volume change under cyclic loading, the greater is the likely amount of degradation.