bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamically Loaded Pile in Overconsolidated Clay
Authors: Muster GL , O'Neill MW
Published: February 2009

A series of dynamic axial loading tests were conducted on a 273-mm-diameter steel pipe pile driven 13.4 m into a layered deposit of overconsolidated clay. A linear inertial mass vibrator was used to provide frequency sweep loadings from frequencies above to frequencies below the fundamental frequency of the pile-soil-cap system at three magnitudes of dynamic load. Superposition of a dynamic component of load of about 5% of the static capacity of the pile on a static biased compressive load resulted in slight nonlinear behavior and induced some residual increase in flexibility of the system. Two existing analytical models were studied in light of the measured performance of the pile and were found to yield appropriate solutions provided the soil parameters were selected properly.
A New Apparatus for Investigating the Stress-Strain Characteristics of Sands
Authors: Alarcon A , Chameau JL , Leonards GA
Published: February 2009

A new hybrid resonant column/torsional shear apparatus has been developed, which permits the determination of dynamic soil properties on a single solid or hollow cylinder specimen over the entire range of shear strain amplitudes of engineering interest, that is, from 10−4 to 10%. The main characteristics of both the resonant column and torsional shear tests are presented with emphasis on those factors that influenced the design of the new apparatus. The new apparatus is described in detail, and representative test results to demonstrate its capabilities are presented.
On the Importance of Rate of Strain in the Consolidation Test
Authors: Crawford CB
Published: February 2009

In many consolidation tests the imposed rate of strain is several orders of magnitude faster than field rates even though it is well known that some of the parameters derived from laboratory tests are strain rate dependent. For this reason it is essential that the standard test procedure provides adequate guidance on the acceptable rate of strain for various classes of natural soils. This paper reviews the problem, describes the approach taken by several authors, and suggests further research that will lead to improvements in consolidation technology.
Methylene Blue Adsorption as a Rapid and Economical Method of Detecting Smectite
Authors: Higgs NB
Published: February 2009

Methylene blue adsorption (MBA) is found to be an effective method of indicating when smectite (group name for the mont-morillonite minerals) is present in major amounts in mudrocks or along discontinuities. The basic relationship is that MBA values greater than 15 indicate that smectite is present as 15 is the maximum value found for illite, the next most adsorptive mineral as compared with smectite. For example, the Pierre shale, which typically contains 30 to 40% smectite along with 25 to 45% mixed-layered smectite-illite has a MBA value of 48.5; whereas, the Palastine shale, which has illite rather than smectite as its chief component has a MBA value of only 7.0. The abundant smectite constituted samples are of materials involved either in slope stability or slaking in foundations, or both. MBA requires only a 2-g specimen, and thus clays along discontinuities and clays along thin slip zones of slides can also be analyzed as to type of clay. The method is less expensive than X-ray diffraction analyzes but also can supplement X-ray diffraction investigations.
Determination of Consolidation Properties for Very Soft Clay
Authors: Tan S-A , Tan T-S , Ting LC , Yong K-Y , Karunaratne G-P , Lee S-L
Published: February 2009

A finite strain consolidation test with a constant surcharge to determine the compressibility (e − σ′) and permeability (e − k) relationships of very soft clay is proposed. The method uses Gammarays and pore pressure transducers to measure density and pore pressure profiles, respectively, at various times of the test without hindering the consolidation process. The constant surcharge applied accentuates the changes in density and pore pressure profiles enabling them to be measured reliably. These profiles are then used to determine the compressibility and permeability of the soft clay. A test is carried out to extract these properties, which are used in a finite strain consolidation theory to predict the settlement, void ratio, and pore-pressure distributions of other tests done under different initial and boundary conditions. The predictions are found to agree well with the experimental data, thus suggesting that the properties determined are accurate.
Laboratory Investigation of Earth Walls Simultaneously Reinforced by Strips and Random Reinforcement
Authors: Arenicz RM , Chowdhury RN
Published: February 2009

The performance of reinforced earth structures depends, among other factors, on the shear strength of the backfill material used in construction. The shear strength can be enhanced by the use of random reinforcement. This paper presents the result of laboratory investigations concerning the effects of several types of random reinforcement on soil strength and, in particular, on the performance of reinforced earth model walls.

Six series of experiments were conducted, in which a medium sand randomly reinforced by various metal particles was used as a backfill material for construction of 32 model walls. In construction of the walls standard reinforcement (horizontal metal strips attached to facing units) was used as well. The results obtained from shear box tests and from observation of model wall failures indicate that the presence of random reinforcement could lead to a significant increase in the critical height of model walls. An increase of up to 13% was observed as a result of adding only 0.5% of random reinforcement to the sand used for the construction of model walls. It was also found that fiber-like shapes of random reinforcement particles give a more significant increase in the soil strength and critical height of walls than other shapes tested. It might be reasonably expected that a small quantity of similar random reinforcement used in full-scale constructions could lead to a significant increase of their design height or, alternatively, to a decrease in volume of standard reinforcement needed.
A Device for Evaluating One-Dimensional Compressive Loading Rate Effects
Authors: Farr JV , Woods RD
Published: February 2009

It has long been suggested that the one-dimensional or uniaxial strain response of most soils subjected to high-intensity transient loads differs from the response measured under static conditions. As the time to peak pressure decreases, most soils exhibit a stiffening of the loading stress-strain response. That stiffening is usually referred to as a time or loading rate effect. Some researchers have suggested that, as the time to peak pressure approaches the submillisecond range, a drastic increase (up to tenfold) in the loading constrained modulus occurs for partially saturated granular soils under unconsolidated-undrained conditions. The existence of this effect has been the subject of debate.

A test device was developed at the U.S. Army Engineer Waterways Experiment Station using explosives to obtain submillisecond loading times to peak pressures of approximately 138 MPa (20 000 psi). By using state-of-the-art measurement and acquisition systems, an accurate measurement of the uniaxial stress-strain response to submillisecond loadings was obtained. This paper presents the details of that device and the associated electronic measurement and acquisition systems, testing techniques, data interpretation, and typical test results used in assessing loading rate effects of a partially saturated carbonate sand. Results showed that a drastic stiffening did not occur for this material as the time to peak pressure approached the submillisecond range. Instead, a gradual stiffening occurred and the basic shape of the stress-strain curve was maintained.
Strain-Rate Influence on the Interpretation of Plate Bearing Tests
Authors: Georgiadis M
Published: February 2009

The effect of the rate of load application (or settlement application) during a plate bearing test, on the load-settlement relationships is examined. A series of plate bearing tests on clay demonstrated that when the loading rate increases the bearing capacity and the stiffness also increase. To quantify this increase, an exponential foundation model was proposed, which considers the clay as a viscous material. This model proved very satisfactory in determining the load-settlement response of a bearing plate at any loading rate, provided that the response of the same plate at a different loading rate and the basic geotechnical properties of the clay are known. The importance of the loading rate depends on the viscosity of the clay, which is affected by the plasticity, the water content, and the undrained shear strength.
Automatic Back-Pressure Saturation Device for Triaxial Testing
Authors: Brandon TL , Duncan JD , Cadden AW
Published: February 2009

If back pressures are applied to unsaturated triaxial specimens too rapidly, the specimens may be overconsolidated by the temporary application of effective stresses that are higher than intended. This is dangerous because the strengths of the specimens will be higher than they would be without this inadvertent overconsolidation. An automated device has been developed to ensure that the specimen will not be overconsolidated during saturation. This device continuously monitors the maximum effective stress in the specimen and optimizes the rate at which the cell pressure and back pressure can be increased without exceeding an allowable effective stress at any point in the specimen. Tests were performed on three soils with different grain sizes and degrees of saturation to investigate the effectiveness of the device under varying test conditions. The tests show that the device is capable of applying back pressures with a minimum of operator attention, and that it eliminates the possibility of inadvertently overconsolidating specimens during back-pressure application.
Transition from Maximum Tension Line to Actual Failure Surface in Reinforced Soil Model Walls
Authors: Arenicz RM
Published: February 2009

This paper presents the results of laboratory tests conducted on reinforced soil model walls. The effect of model height on distribution of tensile stress in an instrumented reinforcement strip was investigated. It was found that, with increasing height of wall, a continuous redistribution of tensile stress had occurred with the point of maximum tension moving towards the actual failure surface of the model. On that basis, a correlation between the position of maximum tension in reinforcement and the overall safety factor of model walls was investigated. General and specific equations of maximum tension line in terms of wall height and safety factor were suggested.
Effects of Oversize Particles on the Density of Clean Granular Soils
Authors: Fragaszy RJ , Su W , Siddiqi FH
Published: February 2009

Fill material often contains particles too large to be tested in conventional testing equipment. In order to evaluate the compaction, strength, and deformation characteristics of soil containing such oversize particles, a modeling criterion is required which specifies how the soil minus the oversize particles (the soil matrix) should be tested. Questions such as whether or not to replace oversize particles with particles just large enough to be tested and at what density should the model material be prepared must be addressed by such a modeling criterion. To develop modeling criteria it is necessary to know how the oversize particles affect the density of the total material. This paper presents the results of a study which shows that oversize particles increase the void ratio of the soil matrix in a manner which is affected by the relative density of the soil. Both theoretical and experimental work are described which lead to the development of a method for predicting the density of the soil surrounding oversize particles as a function of the relative density of the entire soil sample and the percentage of oversize particles.
Physical and Statistical Models for Bulking of Sand
Authors: Neema DL , Patel AN , Sharda BL
Published: February 2009

Four physical models and one statistical model are proposed to provide quantitative estimates of the extent of the contribution of water film, entrapped water vapor, and particle aggregates to the process of bulking of sand. The limiting conditions of each model are also discussed. A new concept of void-to-aggregate-volume-index (VAVI) is proposed. The experimental study, performed on two fractions of Narmada sand, suggests that VAVI is larger for finer sand. The dependence of VAVI on moisture is complex. It is confirmed that the porosity of sand is maximum when the moisture content is 5 to 7%. This observation is duly explained on the basis of a new concept of moisture per contact per particle due to the disappearance of apparent cohesive forces. The models and concepts developed in this study may be extended to other granular media.
Geotomography in Site Investigation: Simulation Study
Authors: Tallin AG , Santamarina C
Published: February 2009

Tomography is the reconstruction of images from measurements of line integrals. It is used in a variety of scientific and technical applications. Advances in electronics and computers make the technique accessible to geotechnical engineering. The combination of penetration testing and tomographic reconstruction would result in a powerful site investigation tool.

A tomographic software was developed in this research. This paper discusses the fundamentals of the procedure and presents the results of a simulation study using the algebraic reconstruction technique (ART). The parametric study involves field set-up conditions, number of instruments per side, and the size of the grid used in the reconstruction.
Microwave Drying of Highly Plastic and Organic Soils
Authors: Hagerty DJ , Ullrich CR , Callan CA
Published: February 2009

Microwave ovens offer a means of drying soil specimens more quickly than standard drying in convection ovens. Doubt exists, however, about the suitability of microwave drying of highly plastic soils and soils containing organic material. A study of microwave drying was done on highly plastic clays and clays mixed with peat. Comparison of microwave oven drying results with corresponding data obtained in conventional ovens showed that careful use of a microwave oven produced moisture content values very close to those obtained using a conventional oven.
Consolidation Apparatus for Testing Unsaturated Soils
Authors: Rahardjo H , Fredlund DG
Published: February 2009

An apparatus for performing consolidation tests under K0 conditions was designed and constructed for testing unsaturated soils. Three types of consolidation tests are of interest in unsaturated soils. These are: (1) constant water content loading tests, (2) consolidation under a net total stress, and (3) consolidation under a matric suction. The apparatus had been used for simultaneous and separate measurements of pore-air and pore-water pressures for all three types of consolidation tests. The experimental results demonstrate the pore pressure and volume change behavior of an unsaturated soil during these tests.
A Multi-Sensor Piezometer for Shallow Marine Sediments in Coastal Environments
Authors: Andersen GR , Bennett RH , Barber ME , Todorovski L , Maynard GL
Published: February 2009

A multi-sensor piezometer has been developed to measure dynamic excess and ambient pore pressures in shallow marine sediments under the effect of surface waves, tides, and currents. The probe consists of a shaft (1.5 m long with five porous stones at subseafloor depths ranging from 0.10 to 0.93 m) and two upper chambers (one that is hermetically sealed for the transducer electronics and another that is hydraulically connected to the free water column). Pore pressures in the sediments under the effect of surface waves are measured with differential pressure transducers referenced to the mean water column pressure (cyclic component removed by a specially designed cyclic damping system). Field deployments of the probe follow a calibration and verification sequence to assure the proper function of all necessary components. This sequence involves laboratory and dockside calibrations using a static fluid reservoir technique and the measurement of differential pressures in the free water column prior to insertion. Calibration and pore pressure data from one deployment in 9.4 m of water off the Gulf of Mexico Coast near Biloxi, Mississippi show excellent precision and cyclic response.
Measurement of Shear Waves in Laboratory Specimens by Means of Piezoelectric Transducers
Authors: Brignoli EGM , Gotti M , Stokoe KH
Published: February 2009

The use of piezoelectric ceramics to measure shear wave velocity in laboratory soil specimens is discussed. The experimental technique and interpretative methodology are described. Both bender and flat-plate ceramic elements were employed, and each performed well. Interpretation of the shear waveforms generated with each transducer improved as the number of wavelengths between the source and receiver increased, with four or five wavelengths being optimum. Shear wave velocities measured using both types of transducers compared closely with the results of a parallel program performed with the torsional resonant column. Based on this work, flat-plate shear transducers show significant potential for future laboratory use because of their robustness and noninvasive nature.
Effects of Shear Band Formation in Triaxial Extension Tests
Authors: Lade PV , Yamamuro JA , Skyers BD
Published: February 2009

The stress-strain and strength behavior from conventional triaxial extension tests is usually erratic due to excessive influence of necking in the hardening regime followed by shear banding. Two techniques have been attempted to impede the onset and gross development of strain localization. These resulted in macroscopically more uniform strains in the hardening regime and therefore more reliable stress-strain and strength behavior in triaxial extension. The results of tests on three different sands are compared with those from conventional extension tests in which strain localization can progress due to the soft rubber membrane. The effectiveness of each of the techniques is evaluated in view of its ability to maintain uniform strains and in view of the resulting sand behavior. The influence of the type of results on the choice of 3-D failure criterion is discussed.
Method of Rapid Determination of the Plasticity Index of Calcareous Materials Used in Road Construction
Authors: Melachrinos B
Published: February 2009

The plasticity index (PI) of calcareous materials is determined rapidly by drawing a quarry diagram representing the calcium carbonate percentages and plasticity indices of representative samples predetermined by AASHTO T89 and T90 standard procedures for Atterberg limits.

These samples are taken from the quarry producing the calcareous materials and are mixtures of stone and 10, 15, 20, 25, and 30% clay to be used to prepare the quarry diagram.

The plasticity index of further samples from this quarry is determined by analyzing the samples for calcium carbonate content by titration and reading the corresponding plasticity index on the quarry diagram.
Round Three—Repeatability and Reproducibility of RQD Values for Selected Sedimentary Rocks
Authors: Pincus HJ , Clift SJ
Published: February 2009

A third round of study of the Interlaboratory Testing Program for Rock Properties (ITP/RP) of the Institute for Standards Research has produced precision measures for the Rock Quality Designation (RQD) index. Eight experienced participants determined the RQD index of four types of sedimentary rock (anhydrite/calcite, calcareous shale, limestone, and anhydrite) with four replications per rock type. The mean RQD indexes for the four rock types ranged from 60 to 92%. The normalized repeatability and reproducibility (r/¯x and R/¯x) for the four rock types range from 0.15 to 0.53 and from 0.15 to 0.66, respectively. The magnitudes of the repeatability r and the reproducibility R decrease with the increasing mean value ¯x of the RQD index. For three of the four rock types, the reproducibility R is equal to the repeatability r, that is, the variability among participants' results is no greater than the variability among replicate results from the same participant. The fourth rock type, for which R/¯x > r, is the calcareous shale; this is also the rock type with the smallest mean RQD index, ¯x, and the largest normalized repeatability and reproducibility, r/¯x and R/¯x. Because this study's range of mean RQD indexes is small, all of the rocks studied are sedimentary, and the number of participants making measurements is only slightly greater than the required minimum, the results of this work should be regarded as a first step in estimating the precision measures of the RQD index. Appended is a proposed precision statement suitable for inclusion in an ASTM standard on the determination of the RQD index.
Methods for Broad-Band Dielectric Permittivity Measurements (Soil-Water Mixtures, 5 Hz to 1.3 GHz)
Authors: Klein K , Santamarina JC
Published: February 2009

Broad-band permittivity data enable the determination of micro- and macro-scale material characteristics and the monitoring of geo-processes. While high-frequency (> ≈ 100 MHz) permittivity measurements can be performed readily in the laboratory, low-frequency (< ≈ 10 MHz) measurements are more difficult to conduct. This paper describes two low-frequency techniques and presents broadband permittivity data for various soil-water mixtures.

Low-frequency data were gathered with an impedance analyzer in conjunction with two-terminal and four-terminal measurement systems. The two-terminal cell consisted of two copper electrodes; its range was restricted at low frequencies due to electrode polarization. The four-terminal system used separate current and voltage electrodes; its accuracy at low frequencies was limited by the ability of the equipment to resolve small phase angles.

High-frequency data obtained with a coaxial termination probe and low-frequency data obtained with these two cells are presented. Soils of very different specific surface were tested at water contents ranging from air-dry to saturated. It is shown that the conductivity of the specimen controls not only the low-frequency measurement limit (i.e., electrode polarization and phase resolution), but also the high-frequency limit due to stray inductances.
Design and Performance of a Portable Piezocone Driver for High Resolution Profiling of Wetland Sediments
Authors: Zeeb PJ , Hemond HF , Germaine JT
Published: February 2009

A portable piezocone driver was designed and built for use on wetland deposits that cannot support the weight of conventional truck-mounted equipment. The driver has successfully pushed a standard piezocone to the bottom of a wetland deposit at depths ranging from 2 to 8 m, including thick sand lenses. Records of penetration pore pressure and point resistance from these explorations distinguish several different types of peat, an underlying organic deposit, and sand strata. These results demonstrate that a piezocone can be driven through thick wetland deposits without a truck-mounted rig and that the data collected can be used to map deposit-scale heterogeneities in the wetland soil type.
Design, Fabrication, and Assembly of an Apparatus for Electrokinetic Remediation Studies
Authors: Yeung AT , Scott TB , Gopinath S , Menon RM , Hsu C
Published: February 2009

This paper presents the design, fabrication, and assembly of a new geo-environmental engineering apparatus specifically made to experimentally evaluate the viability, feasibility, practicality, and economics of electrokinetic extraction of conservative and reactive contaminants from fine-grained soils and to develop a better understanding of the various complex transport processes, electrochemical reactions, and physicochemical soil-contaminant interactions during the process. The design criteria and details of each component of the new apparatus are presented. The distinct advantages of the apparatus developed are discussed. Typical experimental results obtained by the apparatus are presented to demonstrate its simplicity of operation and versatility of measuring various parameters at different spatial and temporal intervals.
Effects of Test Duration and Specimen Length on Diffusion Testing of Unconfined Specimens
Authors: Cotten TE , Davis MM , Shackelford CD
Published: February 2009

Effective diffusion coefficients, D*, of chloride and zinc diffusing in saturated, unconfined specimens of a compacted sandclay mixture are measured for three specimen lengths, L (2.91, 5.83, and 11.60 cm) and three test durations (7, 14, and 21 days). For a specimen length of 2.91 cm, both the chloride and zinc D* values tend to decrease with increasing test duration, possibly due to the measurement of concentration-dependent D* values. For a 14-day test duration, no consistent trend in D* with specimen length is observed, but the overall effect of specimen length on D* is minor relative to the range of measured D* values. A 21-day test duration provides the best correlation between the D* values based on reservoir concentrations, D*Res, and the D* values based on soil concentrations, D*Soil, for chloride for a given test regardless of the specimen length. The effect of test duration on the correlation between D*Res and D*Soil for zinc is minor based on the relatively narrow range of measured zinc D* values. The observed effects of specimen length on the correlation between D*Res and D*Soil for a given test are consistent with the more uniform final porosity distributions in the shorter specimens and the contrasting effects of the non-linear distributions in porosity and dry density that become less significant as the specimen length increases.
Generation of Progressive Fluid Waves in a Geo-Centrifuge
Authors: Sekiguchi H , Kita K , Sassa S , Shimamura T
Published: February 2009

This paper describes a practical way of generating progressive fluid waves in a wave tank of limited length that may be readily mounted on a geo-centrifuge. The wave tank developed features a quasi-flap-type wavemaker, a sediment trench, and a slotted vertical partition that was placed in the wave channel for wave absorption purposes. A comprehensive series of centrifugal wave tests with either water or silicone oil of scaled viscosity showed that, for a slotted-area ratio of 0.3, the reflection coefficient of the slotted partition became as low as 0.13, thereby giving rise to essentially progressive waves. The optimal distance behind the partition to the far end of the wave channel was found to be equal to approximately a quarter wave length of the incident waves.

This led to the second stage of experimentation in which fine-grained sand beds were subjected to a range of essentially progressive waves, with viscous scaling introduced. The results of the centrifugal wave tests showed that, when subjected to severe waves, the sand beds underwent liquefaction, resulting in a complete loss of effective stress due to the buildup of residual pore pressures.
Analysis of Consolidation Data by a Non-Graphical Matching Method
Authors: Robinson RG , Allam MM
Published: February 2009

Conventionally the laboratory time-compression data from an odometer test are analyzed by graphical methods. This involves the determination of initial compression, δi, total primary consolidation, δ100, and coefficient of consolidation, Cv. The advent of computer-controlled data-logging systems calls for adoption of non-graphical techniques for analysis of consolidation test data. In this Technical Note a non-graphical matching method is proposed for analyzing the time-compression data. The values of δi, δ100, and Cv can be obtained by direct matching with the theory. The computed time-compression curve for this Cv value matches very well with the experimental data in the primary consolidation phase. The proposed method is also applicable to consolidation under conditions of radial drainage. The method will be very useful if the data are collected through computer-driven data-logging systems.
Survey of Laboratory Devices for Measuring Soil Volume Change
Authors: Alva-Hurtado JE , Selig ET
Published: February 2009

A review of devices for measuring soil volume change in triaxial testing was made. Emphasis was placed on those devices with electrical transducers to permit recording or automatic data logging. The devices are classified according to type, and the advantages and limitations of each are presented. An indication of the sensitivity and capacity is also given when this information was available.
Controlled Extrusion of Thin-Walled Tube Samples
Authors: Eischens GR
Published: February 2009

An ongoing concern that geotechnical engineers must deal with continually is the indeterminable amount of disturbance that thin-walled tube samples are subjected to during sampling, handling, and transporting. The effects of the extrusion process should be of equal or greater concern. The monitoring and limiting of forces (loads) to which the sample is subjected during extrusion provides for some control of the degree of disturbance. This control is most critical for soft, loose, unsaturated, and sensitive soils. A simple method for calibrating an extruder is given.
A Hydrogeologic View of Waste Disposal in the Shallow Subsurface
Authors:   ASTM Subcommittee D18.14 on Soil and Rock Pollution
Published: February 2009

This paper discusses waste disposal in the shallow subsurface, that is, landfills. Emphasis is placed on the soil and groundwater regime. The paper can be considered to be a position paper and, therefore, general guidelines and principles are presented, as opposed to specific technical details or design procedures.
The Expansion Index Test
Authors: Anderson JN , Lade PV
Published: February 2009

The Expansion Index Test was developed a decade ago for laboratory determination of the expansion potential of soils. The initial conditions in this test are specified to provide a specimen that will produce a measurable amount of expansion with a fairly wide range and sensitivity in a 24 h period. Thus, the test provides an index to the expansion potential of soils. Thirteen soils were used in a correlation study between the expansion index and other indices of soil expansion potential. Five of these soils were used in a detailed study of the influence of the initial degree of saturation. Three of the soils were sent to geotechnical engineering firms to determine the reproducibility of test results. This study showed a good deal of scatter but on the order of similar studies for other tests. Respondents to a survey generally agreed that the Expansion Index Test produces a reliable index to soil expansion potential.
Determination of Permeability Coefficients for Geotextiles
Authors: Carroll RG
Published: February 2009

This paper recommends the use of the ASTM Test for Air Permeability of Textile Fabrics (D 737) in determining the coefficient of water permeability for geotextiles (that is, civil engineering filter fabrics). The article explains the theory and experimental data that result in this determination.
Properties of Asphalt-Stabilized Aggregates from Evaluation of Laboratory Prepared Specimens
Authors: Mamlouk MS , Wood LE
Published: February 2009

The tensile and resilient characteristics of the cold-mixed asphalt-stabilized aggregates were investigated in the laboratory using the indirect tensile and resilient modulus techniques. The mixture was also characterized by using the Marshall equipment that is frequently used in asphalt concrete mix design. Specimens were fabricated with emulsified asphalt, two aggregate types, two emulsion contents, and two initial added moisture contents. The properties of the mixture were evaluated at different curing conditions and test temperatures. Comparisons were made between dry and vacuum saturated specimens to evaluate the moisture resistance of the mixture. It was found that the mixture properties were largely affected by temperature. In addition, curing increased the tensile resistance and the resilient modulus values. Aggregate type, asphalt content, and initial added moisture content altered the properties of the mixture at different degrees. Vacuum saturation affected the mixture characteristics to some extent. Other properties such as density, moisture content, and air voids were evaluated.
Testing of a Field Dielectric Soil Moisture Meter
Authors: Kuráž V
Published: February 2009

The functional relationship between dielectric constant and soil content has been applied to the development of a dielectric soil water moisture meter based on converter capacitance-frequency. A measured capacitance forms part of the tuning capacitance of an oscillator and causes a definite frequency deviation. A cylindrical probe fitted with an oscillator is used to measure the electrical field. The author has determined the basic characteristics of the instrument—center of sensitivity, radius of the electrical field, and influence of soil properties, particularly changes in bulk density, chemical composition, and temperature. The device is applicable for either continuous use, with the probe permanently built in to the soil layer, or use with the probe sliding inside an access tube, in which case the vertical distribution of soil moisture is measured. Field calibration of the meter is required.
Constant-Volume Triaxial Tests to Study the Effects of Membrane Penetration
Authors: Ramana KV , Raju VS
Published: February 2009

In conventional undrained triaxial tests a rubber membrane is used to confine soil samples. This rubber membrane penetrates the peripheral voids of the sand sample and causes volume changes under varying effective confining pressures during shear. These volume changes invalidate the no-volume-change condition of an undrained test and lead to considerable and even unsafe errors in pore pressure measurements and thus in measurements of static undrained strength and liquefaction resistance. In order to make a qualitative study of the influence of membrane penetration on pore pressure development in static and cyclic tests, constant-volume triaxial tests were performed on saturated sand samples. Resulting pore pressure response and stress path behavior are discussed.
A Note on the Conductivity of Electrolytes for Analog Models
Authors: Brand EW , Premchitt J
Published: February 2009

During the measurement of piezometer shape factors with an electrolytic tank, it was found that the electrolyte resistance was temperature-dependent to an appreciable extent. A study of temperature effects showed that the conductivity of ordinary tap water varied by only 1.9% per °C, compared to almost twice as much for copper sulfate solutions. It was concluded that tap water was the more suitable electrolyte where extremely accurate measurements are to be made in an electric analog model.
Results and Interpretation of SPT Practice Study
Authors: Kovacs WD
Published: February 2009

Geotechnical engineers in the United States commonly use the results of the ASTM Penetration Test and Split-Barrel Sampling of Soils (D 1586) in subsurface investigations for routine foundation design. Wide variations occur in standard penetration test (SPT) results because the present standard does not address some of the variables that control the energy delivered to the sampler. Current methods of performing the SPT in the United States were surveyed and the results are reported and interpreted. The purpose of the survey was to aid in bringing current practice to a more uniform state and to provide information for the next revision of ASTM D 1586.
Nondestructive Soil Bulk Density Measurements by X-ray Attenuation
Authors: Been K
Published: February 2009

Nondestructive density measurement of soil samples in the laboratory has a number of important applications. It can be used to monitor the progress of soil settlement through water and subsequent consolidation to a final equilibrium state, with or without an additional applied load. It can provide information on moisture content distribution in laboratory samples, in both static and changing conditions, and on soil structure in undisturbed cores. This paper describes a nondestructive technique for density measurement that can achieve accuracies in measured soil density of the order of ± 0.005 g/cm3 and a spatial resolution of ± 1 mm. The technique uses an X-ray system with a scintillation detector and counter assembly to record the radiation transmitted through the soil sample. This is converted to a density value by empirical calibration. The principles of the method are described with consideration given to the variables of the measuring system, the beam collimation, and the sample geometry. The method is shown to be reliable and versatile.
Laboratory Instrument for Measuring Lateral Soil Pressure and Swelling Pressure
Authors: Ofer Z
Published: February 2009

A new instrument which allows the measurement of lateral pressure and lateral swelling pressure of a soil sample in the laboratory, either with or without lateral strain, is presented. Results of tests carried out with this apparatus are discussed and compared with results of similar tests using other instruments.
Linearizing Triaxial Test Failure Envelopes
Authors: Handy RL
Published: February 2009

Soil variability biases both the best-fit-by-eye and linear regression of p-q triaxial test data plots (where p represents the abscissa of the center of a Mohr circle and q is the radius) to substantially over-estimate the friction angle ø. This is because linear regression of q on p assumes that variability lies in the y-axis direction, whereas if lateral stress σ3' is constant, variability is 45° to the y-axis. A correct regression is quickly performed by converting p-q data points to polar coor-dinates, adding 45° or another angle indicated by the mean stress paths to the coordinate angle, converting back to rectangular coordinates, and performing the linear regression. The correlation coefficient thus obtained is lowered because it correctly assesses data variability. Without correction the error in ø may be as much as 10°.
Determination of Elastic Modulus of Stress Relief Cores of Shale
Authors: Szwilski AB
Published: February 2009

The overcoring procedure for the determination of the magnitude and direction of underground in situ stresses, in a coal mine entry roof, is reviewed. For an isotropic rock, the direction of the principal lateral stresses can be computed directly from the stress-relief measurements of diametral deformation for the three axes of the borehole in the roof. However the computation of the magnitude of the in situ principal stresses requires that the Young's modulus of the host rock be determined. The degree of influence of anisotropy of the rock on the orientation of the principal lateral in situ stresses is also examined.
A Low Cost Stressmeter for Measuring Complete Stress Changes in Underground Mining
Authors: Peng SS , Su WH , Okubo S
Published: February 2009

A stressmeter consisting of a thick steel pipe with a central partition on which a wire-resistance strain rosette gage is mounted was proposed and examined. Linear relations between applied stresses and the induced strains at the center of the partition were obtained under different loading conditions. The linear relationship is a practical necessity in monitoring stress changes. Results of three-dimensional finite element simulation compared favorably with those of laboratory calibration. Ratios of the Young's modulus of steel to the Young's modulus of rock or resin or both were found to be the dominating factor in determining the sensitivity of the stressmeter. The stressmeter is more sensitive in soft rock, such as coal, than in hard rock, such as sandstone.
Proposed Standard Specification for Standard Sizes of Quarried Stone for Erosion Control
Authors: Marek CR
Published: February 2009

The Proposed Standard Specification for Standard Sizes of Quarried Stone for Erosion Control is a new specification currently being developed by ASTM Subcommittee D18.17 on Rock for Erosion Control. The proposed specification contains standard size designations and maximum permissible ranges in weight or mechanical analyses for standard sizes of (1) graded quarry stone or riprap and (2) filter bedding stone for use in erosion control structures. A total of seven standard sizes are included for graded quarry stone, and three standard sizes are included for filter bedding stone. The proposed standard sizes were developed to provide the designer, the consumer, and the producer with a common reference in connection with the sizing of quarried stone materials used to control erosion. Use of standard gradations versus nonstandard gradations should be evaluated for each major project, and standard gradations should be utilized whenever cost-effective.
The Rapid Carbonate Analyzer
Authors: Demars KR , Chaney RC , Richter JA
Published: February 2009

A gasometric method is proposed for measuring soil carbonate content. The device consists of an enclosed acrylic cylinder in which soil carbonate reacts with acid to produce carbon dioxide gas. For a constant volume reactor, the carbon dioxide gas pressure is directly related to the soil carbonate content at completion of the reaction. The effect of several variables, including particle size, acid concentration, and carbonate mineralogy, on the reaction time is considered. This method has the advantages of accuracy to within ±5%, high analytical speed, low cost, and minimal operator skill. It is well suited for both laboratory and field use.
Interpreting the Physical Properties of a Clay Using Microanalysis Techniques
Authors: McManis KL , Ferrell RE , Arman A
Published: February 2009

A microanalysis with the scanning electron microscope and energy dispersive X-ray microprobe (SEM-EDS) is used to explain the apparent brittle failure and sensitivity of a clay soil. The electron micrographs produced show concentrations of pyrite crystals interrupting the parallel bedding of the clay particles. These fabric modifiers significantly influence the failure mechanisms of the soil. The SEM-EDS microanalysis provides details of the fabric configuration and distribution of chemical species and their association with the soil fabric.
A Laboratory Investigation of Grid Reinforcements in Clay
Authors: Ingold TS
Published: February 2009

The governing criteria for internal stability of reinforced soil require that the soil reinforcement should have adequate factors of safety against tensile fracture and pullout. In terms of total stress the pull-out resistance will be some function of the area of reinforcement embedded in the restraint zone and the soil-reinforcement adhesion that may be related to the undrained shear strength of the soil by an adhesion factor. This factor has been assessed for several types of reinforcement using a direct shear box with the reinforcement inclined across the two halves of the box. These tests showed grid reinforcement to be the most efficient, consequently, subsequent testing, in the form of pull-out and shear box tests with horizontal reinforcement, was restricted to grids. The adhesion factors were found to be markedly dependent on test method with the pull-out test giving the lowest values. An analytical assessment of the results suggests that grid pull-out resistance is a function of the area of grid members normal and parallel to the direction of applied load rather than embedded plan area.
Measurement of Axial Strains in Triaxial Tests on London Clay
Authors: Costa Filho LDM
Published: February 2009

Equipment for measuring axial strains directly on the center part of triaxial test specimens is described. The accuracy to which axial strains can be computed using this equipment is determined. The results of a series of tests on London clay provide a comparison between the axial strains computed using this equipment and conventional techniques. It is concluded that bedding problems can introduce significant errors in the determination of deformation moduli at small strains for stiff clays.
A Direct Shear Machine for Testing Rock Joints
Authors: Franklin JA
Published: February 2009

Most direct shear machines are designed for soil testing or research and have serious limitations when used for rock joint testing by commercial testing laboratories. To overcome some of these limitations, a machine has been designed that uses split cylindrical specimen holders to encapsulate rock specimens in the field, protecting them against drying, swelling, and mechanical damage in transit to the laboratory and in storage. Molten sulfur is used as an encapsulating material. Field encapsulation saves “downtime” during laboratory testing and virtually eliminates specimen disturbance. The holders are uncoupled only when in the test machine and after a normal load has been applied.

Further features designed to make the machine more versatile and less expensive include pumps, pressure and displacement pages that are demountable so that they can be easily calibrated and used in other testing applications. Two opposing jacks allow reversals of shear direction. Testing procedures are outlined for reversed shearing at increasing increments of normal load.
A Low-Cost Ring Dynamometer for Monitoring the Performance of Roof Bolts
Authors: Cyrul T
Published: February 2009

A steel ring dynamometer, which is placed at the end of a roof bolt, was evaluated. The diametral loading causes deformation of the ring caused by the change in loading of the bolt. This deformation is measured in the normal direction of loading with a high sensitivity dial gage. The steel that the ring is made of exhibits linear load-deformation characteristics and makes the ring appropriate for long-term monitoring.

The dynamometer can, without additional steps, be applied to an ordinary roof bolt. Its small dimensions do not affect the mining operations in the area of monitoring. Low cost and simple methods of measurement allow the dynamometer in the area of monitoring to be widely applied for monitoring of roof behavior.
Experimental Modeling of the Shaft Capacity of Grouted Driven Piles
Authors: Joer HA , Randolph MF , Gunasena U
Published: February 2009

Pile foundations are widely used in compressible soils such as calcareous sediments. However, the friction capacity of driven piles in such soils tends to be very low, owing to severe reduction of the normal effective stresses at the pile-soil interface during installation of the pile, caused by densification of the soil. The shaft capacity may be increased by injection of grout along the pile-soil interface, referred to as “grouted driven pile” construction. A new apparatus for testing such a type of pile has been developed at the University of Western Australia. In this paper, the design of the apparatus and associated model piles are described, along with the grouting technique. Limitations of early versions of the apparatus and difficulties with grouting at small scale are discussed, and recommended solutions are presented. Results of tests performed on specimens of calcareous soils that were artificially cemented in order to reproduce typical in situ strengths are also presented.