bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantity of Fines Produced During Crushing, Handling, and Placement of Roadway Aggregates
Authors: Pintner RM , Vinson TS , Johnson EG
Published: February 2009

A three part test procedure was developed to determine the quantity of fines produced during crushing, handling, and placement of aggregates used as base course in roadway construction. The first test simulates crushing at the aggregate source. It involves processing an aggregate sample of specified gradation through a small laboratory jaw crusher. The second test simulates handling by agitating an aggregate sample of specified gradation at 10% moisture content for 20 min. The modified American Association of State Highway and Transportation Officials (AASHTO) compaction test is used to simulate placement. Following the conduct of each test in the procedure, the fines are measured by washing the aggregate over a 75-µm (No. 200) sieve. At the conclusion of the three part test procedure the fines produced during crushing, handling, and placement are determined by summing the fines determined from each test in the series. The maximum fines produced with the procedure developed were correlated to with the Washington Degradation Test results for samples obtained from six aggregate sources in Alaska. In all cases, a poor correlation was found. Owing to the lack of a large body of well-documented field data, the three part test procedure can only be used at this time to determine the maximum quantity of fines that is likely to be produced for a given crushing, handling, and placement history.
The Dimethyl Sulfoxide (DMSO) Accelerated Weathering Test for Aggregates
Authors: Szymoniak T , Vinson TS , Wilson JE , Walker N
Published: February 2009

A standard accelerated weathering test using dimethyl sulfoxide (DMSO) was developed to simulate the chemical degradation of basaltic rock. The final development of the standard test involved a study of the interaction of DMSO with clay standards and an investigation of the test condition parameters affecting an existing DMSO test procedure. The weighted loss reported under the existing test procedure (similar to the sodium sulfate soundness test) was affected by the aggregate particle size, specimen mass, immersion time, and container geometry. In the recommended standard DMSO accelerated weathering test, aggregates in the particle size range of 2.4 to 4.8 mm are immersed in a container of DMSO for a period of five days. The mass loss determined by re-sieving the material on a 2.4-mm (No. 8) sieve after five days immersion provides a measure of durability. Immersion of basaltic aggregates in DMSO results in a greater breakdown owing to the type and concentration of ions contained in the rock matrix. Specifically, it was found that DMSO reacts with the cations held to the swelling clay minerals in the aggregate. The results from Atterberg limits tests indicate that DMSO substantially reduces the liquid limit for clays with high activities and increases the liquid limit for clays with low activities. The changes in the liquid limits were influenced by the interaction of DMSO with cations held on the surface of the clay mineral and the ability of DMSO to donate hydrogen ions.
Instrumentation for Torsional Shear/Resonant Column Measurements Under Anisotropic Stresses
Authors: Isenhower WM , Stokoe KH , Allen JC
Published: February 2009

Instrumentation for torsional shear/resonant column testing under anisotropic stresses has been developed. The test apparatus discussed is capable of torsional shear and resonant column testing with anisotropic states of stress applied to the soil specimen. Low-frequency torsional shear measurements are made using proximity probes to measure the angle of twist of the soil specimen. High-frequency measurements are made using conventional resonant column techniques adapted for use with an anisotropic loading system. Methods used for reduction of test data and calibration procedures are described.
Effective Stress Hyperbolic Stress-Strain Parameters for Clay
Authors: Stark TD , Vettel JJ
Published: February 2009

This paper presents a procedure for estimating the effective stress hyperbolic stress-strain parameters for normally consolidated clays from the results of consolidation and direct shear tests. The procedure for calculating Young's modulus and the modulus number includes: (1) estimating the failure ratio from the shear stress-horizontal displacement curve obtained from a direct shear test; (2) using a tangent modulus at the end of each normally consolidated load increment in the consolidation test and the void ratio at the beginning of each load increment to calculate Young's modulus; and (3) multiplying the resulting modulus number by 1.9 to obtain a reasonable estimate of the isotropically consolidated-drained triaxial (CID) modulus number. The modulus exponent was approximately unity for both the consolidation and CID triaxial tests. A procedure for estimating the bulk modulus number, the bulk modulus exponent, and the unload-reload modulus number is also presented.
Testing Techniques for Evaluating the Shear Strength of Lime/Fly Ash Slurry Stabilized Soil
Authors: Borden RH , Baez JI
Published: February 2009

Lime slurry pressure injections have been successfully used to stabilize and control swelling and expansive soils and low-strength clay soils to depths of up to 40 ft (12 m). When the activity of soils is somewhat lower, or when soils have large void ratios, lime/fly ash (L/FA) slurry mixtures have been injected to fill voids. It has been postulated that this action creates stronger seams, helps to mend possible failure surfaces, and at the same time increases the overall stability of a slope by decreasing water infiltration. The investigation reported herein was undertaken to develop laboratory testing techniques suitable for evaluating the strength improvement realized by introducing L/FA into a soil mass in the form of seams. To accomplish this goal, six specimen configurations were conceived, and a total of 45 direct shear specimens, including 35 containing vertical and/or horizontal seams of L/FA, were tested. In addition to demonstrating the viability of testing techniques developed, the testing program resulted in a small data base on one soil stabilized with an L/FA slurry having a lime-to-fly ash weight ratio of 1:3.75 and a solids-to-water ratio of 7.6 lb to 1 gal (0.9 kg to 1 L).
Quantification of Particle Shape and Angularity Using the Image Analyzer
Authors: Yudhbir  , Abedinzadeh R
Published: February 2009

The image analyzer commonly used by the powder metallurgists has been successfully employed to quantify angularity and shape characteristics of granular materials. In this paper a detailed procedure has been outlined. Results of investigation of different natural sands are presented in the form of a distribution of tangent count taken as a measure of angularity. Powers' roundness index has been calibrated against the tangent count. Mechanical properties of different sands have been shown to be correlated with angularity.
Elastic-Wave Velocities and Liquefaction Potential
Authors: Alba PD , Baldwin K , Janoo V , Roe G , Celikkol B
Published: February 2009

Cyclic triaxial liquefaction tests are used to establish a direct relationship between liquefaction resistance and shear- or compressive-wave velocities in saturated sand. Transducers for generating and receiving elastic waves have been built into the end caps of a triaxial specimen, producing a 3500-Hz shear wave and a 150-kHz compressive wave. Both the fluid-wave and the shear-wave velocities are found to be sensitive to sand type as well as to differences in fabric and stress history for the same sand. Results for six sands of different origins and gradations show that characteristic relationships between elastic-wave velocities and liquefaction resistance can be established for each material. This conclusion suggests that field measurements of elastic-wave velocities may be used to reconstitute laboratory specimens to their in-place liquefaction resistance. On the other hand, velocity measurements alone will not quantify liquefaction resistance, since the resistance-velocity relationship is material dependent.
The Use of Electrical Conductivity for Evaluation of Strain Distribution in the Simple Shear Device
Authors: Yong RN , Sadana ML , Li R , Chen SY
Published: February 2009

This study examines the use of the electrical conductivity method for assessment of internal strain distribution in a simple shear specimen as a result of the shearing process. In this proposed technique, which enables one to assess the strain distribution pattern in the specimen, it is shown from a limited study that the strains developed in the simple shear test are not uniformly distributed, as has been suggested by some researchers.
A Study of Membrane-Permeant Compatibility
Authors: Rad NS , Acar YB
Published: February 2009

Triaxial cells are often used to conduct permeability tests on soil specimens. The specimen inside a flexible membrane, is placed in the triaxial cell. The permeant is then percolated through the specimen, and the hydraulic conductivity is measured. However, the incompatibility of the available latex membranes to some permeants is a major drawback for this procedure. In some cases the membrane experiences excessive deformations resulting in wrinkles and inaccurate measurements caused by possible side leakages. This paper describes a test procedure and testing equipment that can readily be used to predict the membrane-permeant compatibility. Test results for different membranes and various organic fluids are also provided.
Gelation of Chemical Grouts While in Motion
Authors: Daniele P , Hutchinson J , Karol RH , Ospitia L , Reim B
Published: February 2009

A procedure is described for a laboratory test to determine if a chemical grout will gel while in motion through a soil mass. An experiment is detailed, using sodium silicate grout catalyzed with glyoxal, to demonstrate the use of the test method and the extrapolation of laboratory scale to field scale parameters.
Development of an Erosion Test for Soil Cement
Authors: Oswell JM , Joshi RC
Published: February 2009

The development and initial testing of an erosion test apparatus for soil cement mixtures is described. The device differs from other test apparatuses in that it combines the impacting forces of waves and debris. The apparatus consists of a water jet that impacts the sample causing erosion and also a number of small stones that are activated by the water jet, resulting in further erosion of the test specimen.

Samples of plastic soil cement cured for different periods of time were tested in the apparatus. The pressure of the water jet was varied between 70 and 280 kPa (10 and 40 psi) to simulate impact of 1.5- to 6.5-m (5- to 21-ft) high waves of varying periods.

Preliminary test results (and regression equations for the data) obtained from testing of various mixes are presented. Test data suggest a strong correlation between compressive strength and erosion resistance. The data indicate that to minimize soil cement erosion caused by waves of even 1.5 m (5 ft) in height, soil cement should attain a compressive strength of 16 MPa (2300 psi) or higher.
Development of an Index to Quantify Rock Texture for Qualitative Assessment of Intact Rock Properties
Authors: Howarth DF , Rowlands JC
Published: February 2009

A dimensionless quantitative measure of rock texture, describing grain shape, orientation, degree of grain interlocking, and relative proportions of grains and matrix (packing density) has been developed. Data required for the model are obtained by image analysis of thin sections and concern percentage areas of grains and matrix, length, breadth, perimeter, orientation, and area of each grain in the viewing window. The results of intact mechanical property tests in eleven sedimentary and crystalline rocks are reported and correlated with the developed texture coefficient. The texture coefficient returns highly statistically significant correlations with mechanical property data and is superior to the Schmidt hammer rebound test number in this regard. Observational and correlated data are supportive of the suggestion that the texture coefficient is a qualitative measure of the resistance of the microstructure of a rock to crack propagation, whether it be integranular or intragranular. The texture coefficient can be used as a predictive tool for the assessment of mechanical rock performance. On a fundamental level it provides an insight into texture-crack propagation mechanical performance relationships.
Influence of Borehole Stabilization Techniques on Standard Penetration Test Results
Authors: Whited GC , Edil TB
Published: February 2009

The standard penetration test (SPT) is an extensively used and generally accepted field test for determining engineering characteristics of soils. However, there are many variables inherent in the performance of the test. The influence of some of the major variables on SPT results are examined under methods of borehole stabilization (drilling fluid, hollow stem augers, and driven casing); methods of raising and lowering the drive weight (cathead and rope and a mechanically released free-fall hammer); and nine different soil sites. Soil profiles at these locations were reasonably uniform with depth, and included sands, silts, and clays. Borehole depths ranged from 16 to 30 m, with ground-water levels varying from near surface to very deep. Standard penetration tests were performed by experienced drilling crews, using standard procedures as outlined in ASTM Method for Penetration Test and Split-Barrel Sampling of Soils (D 1586), at intervals of 1.5 m. Results were analyzed using standard statistical procedures and presented in both graphical and tabular summaries. Results indicate that use of casing gives SPT values different (higher above the ground-water level, lower below) than those obtained using drilling fluid or hollow stem augers in sands; whereas no significant difference was observed among the three methods in fine-grained soils. SPT values obtained using a mechanically released free-fall hammer were comparable to values obtained with the cathead and rope method using a level of care no higher than that routinely exercised in the field.
Evaluation of the Gamma and Neutron Radiation Scattering and Transmission Methods for Soil Density and Moisture Determination
Authors: Ruygrok PA
Published: February 2009

In order to warrant the accuracy of soil density and moisture data from measurements by means of the gamma and neutron radiation attenuation methods several influencing factors have to be taken into account, for example, the soil hydrogen content, the soil inhomogeneity, the resolution characteristics of the measuring device and the probe travel velocity. Some interpretation concepts, related to the total hydrogen content in soil, are discussed in view of a calibration protocol. An iterative calculation procedure is proposed for the case of saturated soil, especially for the case that local organic content information is lacking. Further, a probe-travel velocity criterion and a possible approach to increase the resolution of a measured density profile are presented. Interpretation problems associated with data from inhomogeneous soil, measured with different devices, are discussed in relation with the difference in spatial averaging characteristics, which influence the significance of the measured quantity.
Stress Path and Permanent Deformations in Sand Subjected to Repeated Load
Authors: Leshchinsky D , Rawlings DL
Published: February 2009

The development of permanent deformations in soil has been studied by a number of researchers using triaxial systems. In most cases soil specimens were subjected to a pulsating axial stress while the confining pressure was maintained constant. This loading path simulates a very limited number of practical cases. Thus, there is a question as to the generality of the results obtained from conventional laboratory studies.

Presented is a study of the effect of stress path on the development of permanent deformations in sand. Using a pneumatic servo-controlled triaxial system, the confining pressure was varied simultaneously with the axial load. Six different straight line stress paths were investigated; three under compression and three under extension conditions. Dry Ottawa sand was subjected to 100 000 sinusoidal loading cycles at a frequency of 1 Hz. Several loading intensities were used in each stress path.

A linear relationship was observed between the permanent axial strain and the logarithm of the number of loading cycles, for constant repeated stress magnitude and constant stress path. Furthermore, based on the results presented here, one can utilize the conventional constant confining pressure triaxial tests to estimate the effect of stress path. Consequently, the results of the conventional tests can be generalized.
Stabilization of Liquefiable Samples During Transport
Authors: Ho CL , Sarmiento JS , Kavazanjian E
Published: February 2009

This technical note presents a new method to transport liquefiable soils from the investigation site to the laboratory. The development of this method resulted from research on liquefiable soils from the Imperial Valley, CA. This method is based upon the application of a slight vacuum on the pore water of the soil. The vacuum decreases the pore pressure, and therefore increases the effective confining stress. Sample recovery and integrity were compared with experiences of others. Comparisons were made in the sample quality after extrusion and sample preparation, as well as the variability of the test results. This method proved to be an improvement over previous techniques.
Consolidation Behavior of Clayey Soils Under Radial Drainage
Authors: Sridharan A , Prakash K , Asha SR
Published: February 2009

For Barron's degree of consolidation, Ur, versus the time factor, Tr, relationship for soils undergoing consolidation with radial drainage for the equal vertical strain condition, a simple method has been developed to determine the value of the coefficient of consolidation with radial drainage, cr. Theoretical log10(d2e/t) versus Ur curves where de is the diameter of influence and t is the real time for the different known value of cr have been generated. A method has been developed wherein both the theoretical and experimental behaviors of soils undergoing consolidation with radial drainage can be simultaneously compared and studied on the same plot. The experimental log10(d2e/t) versus Ur curves have been compared with the theoretical curves. Effects of initial compression, secondary compression, and duration of load increment are studied. Simple procedures are presented for calculating the values of cr using the experimental log10(d2e/t) versus Ur curves. A comparative study of the coefficient of consolidation and the coefficient of permeability between the cases of vertical and radial drainage has been done.
Cylindrical Expansion Test for Tensile Properties of Geotextiles
Authors: Salman AG , Juran I , Potnis A
Published: February 2009

This technical note describes a new apparatus and testing procedure to perform rapid quality control and assessment of the design parameters of geosynthetic materials. The cylindrical expansion test (CET) is based on the principles of the extension of a geosynthetic specimen wrapped around the surface of an expanding thin-wall cylinder. The parametric study conducted on two nonwoven polyolefin geotextiles showed that the diameter of the cell and the geometry of the specimen have a statistically insignificant effect on the tension-strain behavior of the tested materials. Design parameters such as initial and secant tensile moduli were determined, and it appeared that the values obtained for these parameters are comparable within the margin of experimental errors with those derived from the results of the wide width strip test.
A Centrifuge-Modeled Rigid Structure to Investigate Dynamic Soil-Structure Interaction
Authors: Andersen GR , Todorovski L , Likos W , Whitman RV
Published: February 2009

A centrifuge-modeled rigid structure (CMRS) has been developed to study fundamental aspects of dynamic soil-structure interaction. It has been configured to simulate a gravity retaining wall and consists of a central core and multiple load-sensing panels called F-MAP transducers (force-magnitude, angle, and position) that can directly measure interaction forces between the wall and the surrounding soils (backfill, foundation, and toe). Dimensions and inertial properties of the CMRS can be varied to conduct parametric studies. The F-MAP transducers incorporate load-sensing reaction supports. Calibration coefficients for each of these reaction supports have been determined from 1-g static loading tests. Measured bending moments on the reaction supports are used to estimate the magnitude, angle, and position of the interaction forces. Verification tests have included the static normal gravity loading and the dynamic normal and high-gravity loading of each assembled F-MAP transducer, and the dynamic normal and high-gravity loading of the CMRS in a geotechnical centrifuge without sand. Acceleration measurements on the F-MAP transducers and the CMRS during the dynamic tests are used in conjunction with the interaction force measurements from the F-MAP transducers in a D'Alembert-type dynamic equilibrium analysis to demonstrate the combined accuracy and precision of the F-MAP measurements.
Performance Evaluation of LDTs for Use in Triaxial Tests
Authors: Hoque E , Sato T , Tatsuoka F
Published: February 2009

The performance of local deformation transducers (LDTs) is described in the light of obtaining reliable data on the stiffness of geomaterial in a small-strain range. The components of LDTs and their functions are described, including recent modifications aimed at improving performance. Resolution, working range, and performance were critically examined with special reference to the evaluation of small strain elastic behavior of soil. LDTs in a lateral direction (or simply lateral LDTs) that are able to measure lateral strains precisely are also described. LDTs can underestimate the maximum elastic modulus measured during a small unload/reload cycle of a given geomaterial for no more than 2%, while they can measure strains less than 0.0005% without amplification. LDTs also function satisfactorily under submerged conditions in pressurized water for a long duration (at least 41 days).
The Effect of In-Plane Tensile Loads on the Retention Characteristics of Geotextiles
Authors: Fourie AB , Addis P
Published: February 2009

The results of hydrodynamic sieving tests in which pretensioned geotextile specimens were tested using glass beads as the suspended particles are reported. Biaxial as well as uniaxial tensile loads were used. Two types of geotextile were tested, a woven slit-film polypropylene geotextile and a nonwoven needle-punched polyester geotextile. In all but one of the tests reported, the effect of a tensile load was to reduce the filtration opening size. The effect was most pronounced with the woven geotextile, where an equal biaxial load of only 8% of the minimum tensile strength of the geotextile resulted in a 28% decrease in the filtration opening size. Since all the tests resulted in a decrease in the filtration opening size, it appears unlikely that inplane tensile loads will exacerbate problems of loss of particles through a geotextile. However, it is suggested that increased problems associated with geotextile clogging and blinding can be expected. Preliminary tests in a modified permeameter on uniaxially loaded geotextile specimens in contact with a fine sand confirmed this hypothesis.
Calibration and Use of Grid-Based Tactile Pressure Sensors in Granular Material
Authors: Paikowsky SG , Hajduk EL
Published: February 2009

A revolutionary technology is introduced enabling the measurement and presentation of normal stress distribution over an area in real time. A flexible, grid-based, tactile pressure sensor allows pressure to be measured in up to 2288 (52 × 44) sensing locations. The overall shape and size of the measured area can vary with sensors up to 427 by 488 mm in size. Pressure ranges are possible up to 172 MPa (25 ksi). The system was originally developed for dental purposes and has been used in other medical and mechanical applications as well.

The implementation of the system is complex due to three factors: (a) the measurements are relative and hence absolute calibration is required; (b) the measurements are carried out simultaneously at a large number of points, and a calibration system calls for the development of “known” conditions at each point; and (c) the novel technology makes use of new principles and materials that can be influenced by loadrate, post-loading effects, creep, and hysteresis in addition to unfamiliar problems like trapped air.

The preliminary examination of the technology for geotechnical applications is introduced through tests with ideal granular material. A calibration system was developed, and the sensors were examined through various loading and unloading rates as well as unchanging pressure conditions. The mean stress measurement depends on the pressure application sequence (stress history) with overall high accuracy compared to existing intruding soil pressure measurement techniques. The ability to examine stress variations over an area in real time is unmatched by any other existing means. The measurements of stresses developed along the front boundary of an interfacial shear device are used for demonstrating the system's application.
Comparative Study on Physical Tests of Dispersibility of Soils Used for Earthfill Dams in Turkey
Authors: Tosun H
Published: February 2009

Use of dispersive clays in earthfill dams causes serious problems that may be difficult to solve later unless this type of soil is adequately defined and properly used. The problems may occur suddenly and cause catastrophic failures. In many countries, such problems have resulted in dam incidents or failures attributed to dispersive soils. This paper briefly presents tests to determine the dispersibility properties of soils and discusses their limitations as shown by the comparative study on crumb and pinhole tests. The study was based on test results of 352 samples belonging to 29 different projects currently under planning and design stages in Turkey. As a result of this study, it can be stated that the results of pinhole tests mainly confirm those of crumb tests, while some index tests do not provide a more reliable way to identify dispersive soils.
Operation of a Geotechnical Centrifuge from 1970 to 1979
Authors: Craig WH , Rowe PW
Published: February 2009

A review is provided of the experience gained in operating a large purpose-built geotechnical centrifuge over a period of eight-and-a-half years from its commissioning in 1971. The physical development of the centrifuge and its associated equipment are reported together with details of the arrangements for operating and staffing the laboratory. Safety considerations are outlined. Some broad conclusions are drawn from the accumulated experience gained in almost 500 centrifuge runs.
Feasibility of Drag Bit Tunneling in Limestone
Authors: Rad PF
Published: February 2009

A series of experiments were performed to assess the values of performance indicators of drag bits in limestone. The experiments were done with a constant normal thrust linear cutter. The results show that for sharp drag bits, productivity and efficiency of drag bits are superior to that of disk cutters. However, the high values of cutting coefficient point to high torque requirements for drag bit machines.
Modern Electronics for Geotechnical Engineers 8. Microprocessor Applications
Authors: Moore CA
Published: February 2009

A typical application using a microprocessor to control the consolidation of a pair of triaxial samples to determine the coefficient of earth pressure at rest K0 is presented. The details of the microprocessor program are explained and improvements to be implemented by the reader are suggested.
The Effect of Elastic Tube Strength on the Pressuremeter Modulus
Authors: Elton DJ
Published: February 2009

A study of the effect of elastic tube strength on the pressuremeter modulus is presented. By using probes with different strength tubes in adjacent boreholes, a comparison of pressuremeter moduli was made. While the tubes varied in their resistance to inflation, the effect on the modulus was negligible. It is suspected that the effect might be more significant in very soft soils. The sensitivity of the pressuremeter was not affected by the changing elasticity of the tubes. The unusual shape of the inflated probe was noted.
Experiments in Geotechnical Fabric-Reinforced Soil Behavior
Authors: Haliburton TA , Lawmaster JD
Published: February 2009

Four different geotechnical fabrics were evaluated for use in lateral restraint reinforcement of a cohesionless soil mass. Though considerable increases in strength and load-deformation modulus were obtained for the fabric-reinforced soil systems, no significant difference in behavior was noted among the four fabrics tested, despite variations of an order of magnitude or more in their physical properties. Fabric prestressing had essentially no effect on lateral restraint reinforcement behavior.

Lateral restraint reinforcement was determined to occur as a result of fabric interference with development of soil mass zones of radial shear, underneath and adjacent to the loaded area. The net effect of fabric interference is to produce horizontal restraint and confinement in the zones of radial shear, increasing the deformation modulus and ultimate load capacity of the fabric-reinforced soil.

After initial shear failure and soil yielding, loaded area sinkage again brings the radial shear zones into contact with the fabric and reinitiates soil strength gain. The secondary strength gain phenomenon caused by reinterference of the fabric with radial shear zone development was termed soil strain-hardening.

An optimum depth of placement for fabric was found to occur, and is related to the width of the loaded contact area and frictional properties of the reinforced soil. If fabric is placed at a depth greater than optimum, initial load-deformation behavior is reduced to that of the unreinforced soil system and considerably more soil strain is required to develop the strain-hardening phenomenon.
Triaxial Testing at the Norwegian Geotechnical Institute
Authors: Berre T
Published: February 2009

The equipment and the procedures for triaxial tests used at the Norwegian Geotechnical Institute today are described in detail. The use of the test results in connection with the stress path method for stability analysis is briefly outlined. Cyclic loading procedures are also included.
A Multistage Triaxial Test for Unsaturated Soils
Authors: Ho DYF , Fredlund DG
Published: February 2009

A triaxial testing procedure is presented for measuring the increase in shear strength resulting from soil suction in an unsaturated soil. Necessary modifications on a conventional triaxial cell are described. A simple graphical method is presented to interpret the test data in accordance with the shear strength equation for unsaturated soils.
A Probe to Measure Friction Coefficient of Cohesionless Soils
Authors: Kolbe E , Corell RW , Nielsen JP
Published: February 2009

A probe is designed to measure the in-place value of internal friction angle for cohesionless soils. The behavior of the blunt probe is similar to that of a rough footing forced into the soil. The face of the probe is split and capable of measuring shear forces which vary with the internal friction angle of the soil. A series of static penetration tests in dry sand show the variation of the ratio of shear and normal forces on the probe face (R/N) with soil friction angle φ.
Vertical Soil Extensometer
Authors: Selig ET , Reinig IG
Published: February 2009

A vertical soil extensometer was developed to measure differential soil movement between two reference points. The extensometer incorporates telescoping casing sections installed in a bore hole with the aid of a section spacing device. The length of the casing can thus expand and contract with the soil. Connecting pipes inside the casing transfer upper and lower anchor movements to an electrical sensor, without interference from the soil around the casing. The extensometer is easily fabricated from standard materials and purchased components. This paper is intended to provide enough details to enable the reader to construct the device. Installation procedures are also presented.
Methods of Studying Clay Microstructure
Authors: Osipov VI
Published: February 2009

This paper is concerned with some methods used for evaluation of clay soil microstructure: optical, scanning electron microscopy (SEM), transmission, electron microscopy (TEM), X-ray, and magnetic methods. A brief description is given of the physical principles of the methods, their advantages and disadvantages, specific methods used for the preparation of specimens for the analysis, and methods of qualitative and quantitative interpretation of the obtained results. Special attention is given to methods not widely used yet in investigations, such as X-ray and magnetic methods.
The Modified Borehole Shear Device
Authors: Demartinecourt JP , Bauer GE
Published: February 2009

The standard borehole shear device (BHSD) as developed by Handy and Fox (1976) was modified to include pore-water pressure and load transducers, a motorized pulling mechanism, and different types of shear plates. With the modified device it is possible to monitor the drainage conditions during both the consolidation and shear phases of the test. Undrained and drained shear strength parameters have been measured within boreholes augered into a soft sensitive clay deposit.
Influence of Stress History on the Experimental Flow Rule
Authors: Rao NBS , Yudhbir  , Madhav MR
Published: February 2009

The influence of stress history on the flow rule exhibited by anisotropically and normally consolidated clay samples has been investigated. Based on the experimental results a general equation for the flow rule, incorporating the effects of stress history, has been formulated. The flow rule suggested by Burland is shown to be a special case of the general equation formulated.
Permeability Test for Unsaturated Soil
Authors: Daniel DE
Published: February 2009

A method has been developed for measuring the hydraulic conductivity of unsaturated soil using the instantaneous profile method and a combination of thermocouple psychrometers and tensiometers. Soil samples are first compacted or trimmed into tubes. The tubes are instrumented with psychrometers, and the soil is slowly moistened from one end. When the unsaturated soil becomes too moist for psychrometers to function properly, the psychrometers are removed and tensiometers are inserted. Equipment, procedures, and results for two soils are described. The method has broad range and good versatility, but testing times are long and equipment costs are significant.
Measurement of Underground Corrosion of Steel
Authors: Roy SK , Ramaswamy SD
Published: February 2009

Underground corrosion of steel was studied from a measurement of the soil resistance and the degree of soil depolarization. This technique is capable of giving an instantaneous corrosion rate of steel in soil. A cell consisting of magnesium and steel as electrodes with the soil in between them was used as a probe. The current passing between the electrodes is chiefly controlled by the degree of soil depolarization. A resistance bridge operating on an alternating current determines the pure resistance between the electrodes. Various soils were studied with the instrument. Organic soils were found to be highly corrosive (corrosion rate of as high as 0.096 mm/year). Since the corrosion rate varies considerably for different types of soils, the soil resistance and degree of depolarization measurements could be useful in soil profiling.
Regression Analysis of Experimental Data Using Desktop Computers
Authors: Frink D , Sundaram PN
Published: February 2009

This paper describes regression analysis of certain types of experimental data obtained from geotechnical testing. By suitable transformation, nonlinear equations may be converted into linear equations if appropriate weighting factors are applied to the data before performing the regression analysis. Sample problems in BASIC, which can be used with desktop computers, are described. Typical examples from soil mechanics and rock mechanics are included.
Alternative Test Method for Ensuring Full Saturation in Triaxial Samples
Authors: Strachan P
Published: February 2009

Under certain circumstances, the measurement of the B value does not prove a reliable guide for ensuring that a triaxial sample is fully saturated. In such cases, an alternative method, that of monitoring compressional-wave signals, is suggested. The amount of instrumentation required is modest, and the method has proven dependable over a large number of tests on sand.
Reproducible SPT Hammer Impact Force with an Automatic Free Fall SPT Hammer System
Authors: Riggs CO , Schmidt NO , Rassieur CL
Published: February 2009

Stress wave energy measurements were made to compare the performance of an automatic standard penetration test (SPT) hammer system with the free fall performance of a safety type hammer. It was found that the automatic free fall hammer and the safety hammer tested in free fall provide practically the same mean peak force at impact and the same mean driving energy. The coefficient of variation of measured stress wave energy during any test series of the automatic hammer system is relatively small and usually in the range of 1 to 2%.
Investigation of Boundary Friction Effects in Polyaxial Tests
Authors: Demiris CA
Published: February 2009

Development of boundary friction forces is a common problem in testing of materials, such as rock and concrete. This article reports on experimentations with different friction reducing pads, aiming at diminishing the side friction effects in polyaxial tests. This appears technically possible by using special Teflon®-grease pads, with optimum lubrication achieved at high pressures. Ineffective lubrication can cause an apparent increase of strength and Young's modulus. The volumetric changes under polyaxial stress states appear relatively little affected by boundary friction, contrary to the partial volume changes of ΔV2 and ΔV3.
Evaluation of Shear Strength in Cohesive Soils with Special Reference to Swedish Practice and Experience
Authors: Larsson R , Bergdahl U , Eriksson L
Published: February 2009

The paper describes how the Swedish Geotechnical Institute (SGI) currently proceeds in the evaluation of shear strength in cohesive soils. Information is given on how different test results and empirical experience can be weighted and combined to give the best possible estimation of the shear strength properties in cohesive soils. The procedure described has evolved during the continuing work at SGI as research results and practical experience from the Institute as well as others have been obtained and taken into consideration.
Resonant Column Testing of Frozen Ottawa Sand
Authors: Bosscher PJ , Nelson DL
Published: February 2009

The unique properties of frozen soils have posed special problems for engineers seeking to install stable structures in cold climates. Foundations, pipelines, and other structures subjected to high-frequency low-amplitude vibrations present special problems to the designer even when construction occurs in nonfrozen ground. When these dynamically loaded structures must be founded in frozen soil, the design problems become more complex. To produce a satisfactory design, reliable values of dynamic soil properties, such as soil stiffness, and damping, are required.

This paper presents the results of an investigation into the influence of confining pressure on the dynamic response of frozen Ottawa sand. In addition, the stiffness and damping ratio values obtained from a specimen of pure ice are reported herein.
A Method for Estimating the Excavatability of Caliche
Authors: Nowatzki EA , Almasmoum AA
Published: February 2009

A simple method for classifying caliche with respect to excavatability is presented. The method is based on the results of a laboratory testing program from which two empirical equations were derived, one relating seismic velocity to size-corrected point load strength index, the other relating seismic velocity to a newly proposed parameter, the comminuted uniformity coefficient. The effect of carbonate content also was investigated, but no correlation between carbonate content and either point load strength or comminuted uniformity coefficient could be established. The excavatability of the caliche is determined from the seismic velocity by the empirical correlations between seismic velocity and ease of excavation established by excavation equipment manufacturers. The results of this study were applied successfully to a number of excavations in caliche in Tucson, AZ.
Collapse Behavior of an Artificially Cemented Clayey Silt
Authors: Rao SM , Sridharan A , Ramanath KP
Published: February 2009

The present study examines the role of interparticle cementation in the collapse behavior of two partly saturated (Sr = 4 to 12%) and very highly porous (initial void ratio = 1.5 to 2) laboratory-desiccated clayey silt specimens containing varying amounts (5 and 15% by dry weight of the respective specimens) of the cementitious iron oxides hematite and goethite, which are generally encountered in tropical residual soils. Kaolinite is the representative clay mineral of the soil matrix used for this research.

Interparticle cementation by the crystalline iron oxides was generated in the laboratory by repeated (six times) wetting and drying of the iron-hydroxide-admixed clayey silt specimens under ambient conditions of temperature and humidity. Results showed that, for a given laboratory-desiccated clayey silt specimen (i.e., a specimen containing 5 or 15% of iron oxide on a dry weight basis), the amount of collapse (represented by Δϵ, the change in vertical strain upon wetting under constant pressure) increases with an increase in the experimental loading under which the specimen is inundated. The laboratory results also show that the desiccated specimen with a higher iron oxide content (containing 15% iron oxide by dry weight of the desiccated specimen) in spite of a lower dry unit weight (γd = 8.8 kN/m3) undergoes a lesser amount of collapse on soaking under a constant external stress (50 or 100 kPa) than the desiccated specimen with a lower iron oxide content (i.e., containing 5% iron oxide by dry weight of the desiccated specimen, γd = 10.4 kN/m3).

Based on the X-ray diffraction results and the stress-strain relationships obtained from isotropically consolidated undrained triaxial tests, it is suggested that the laboratory-desiccated specimens are characterized by a metastable bonding provided by capillary suction and the crystalline iron oxides. On soaking under load owing to the loss of the metastable bonding, collapse of the laboratory-desiccated specimens occurs. Also, in the case of the laboratory-desiccated specimen with a higher iron oxide content, the presence of a stronger interparticle cementation (due to a greater abundance of crystalline iron oxides) and a higher initial moisture content are considered responsible for the specimen exhibiting a lower amount of collapse in comparison to that exhibited by the desiccated specimen with a lesser iron oxide content.
Strain Rate Effects on Shear Modulus and Damping of Normally Consolidated Clay
Authors: Shibuya S , Mitachi T , Fukuda F , Degoshi T
Published: February 2009

A laboratory investigation into the effects of shear strain rate on shear modulus and hysteretic damping of normally consolidated clays was carried out. The effects of shear strain rate were examined at cyclic shear strain amplitudes between 10−6 and 10−3 in undrained cyclic torsion shear tests. When the frequency of loading was changed between 0.005 and 0.1 Hz, the equivalent shear modulus was insensitive to the rate of shear straining. On the other hand, the hysteretic damping increased according to the decrease in the shear strain rate. Furthermore, for shear strains less than about 2 × 10−5, the maximum stiffness was hardly influenced by the shear strain rate, type of loading, number of cycles, and the cyclic prestraining; it can therefore be characterized as pseudoelastic shear modulus. On the basis of the test results, it is concluded that when applying the results of laboratory cyclic loading tests to the analysis of in situ cyclic loading problems, the effects of shear strain rate on hysteretic damping should be properly evaluated to match the frequency of loading expected in the field.
Bearing Capacity of Highly Frictional Material
Authors: Perkins SW
Published: February 2009

Highly angular dense soils are known to possess secant friction angles well in excess of commonly encountered sands. These soils also exhibit a significant variation of the friction angle over a common range of mean normal stress confinement. These characteristics raise questions regarding the ability of conventional solutions to predict bearing capacity and how linear strength parameters are to be determined for a nonlinear material. To examine these issues, centrifuge experiments were performed on shallow foundations at three embedment depths. Linear strength parameters required for three conventional solutions were obtained from the nonlinear envelope first by a simple averaging technique. To indirectly account for the material nonlinearity, tangent and secant linear strength parameters were estimated once an appropriate level of mean normal stress was determined. A relationship between mean normal stress and the resulting footing bearing capacity was developed using classical plasticity theory. The latter approach offered significantly better predictions than the averaging method, yet the results indicate the inability of conventional theories to model experimentally observed behavior.
Determination of Ice Forces with Centrifuge Models
Authors: Clough HF , Wurst PL , Vinson TS
Published: February 2009

A test system and procedures were developed to investigate ice forces on offshore structures with the technique of centrifugal modeling. The development progressed through four design stages associated with (1) the model container strong box, (2) the ice sheet formation system, (3) the model structure drive system, and (4) the instrumentation. The components were developed separately before incorporation into the final system. The test apparatus developed included an aluminum strong box with a motor driven model structure. The ice sheets were formed by prolonged application of vaporized liquid nitrogen. Temperatures, loads, and displacements were measured with thermistors, strain gages, and a linear variable differential transformer (LVDT), respectively. The test results indicate a relationship between ice thickness, temperature, and time may be used to create an ice sheet of predetermined thickness on the centrifuge. The test results from ice lateral load pile tests conducted with the system developed compare favorably with the results obtained by other investigators.