bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibration and Use of Grid-Based Tactile Pressure Sensors in Granular Material
Authors: Paikowsky SG , Hajduk EL 
Published: February 2009

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
The Effect of Elastic Tube Strength on the Pressuremeter Modulus
Authors: Elton DJ 
Published: February 2009

Abstract
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

Abstract
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.
A Multistage Triaxial Test for Unsaturated Soils
Authors: Ho DYF , Fredlund DG 
Published: February 2009

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.