bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Thickness Equation for Nonwoven, Needle-Punched Geotextiles under Normal Loading
Authors: Weggel JR , Gontar WA 
Published: February 2009

Abstract
An equation to predict the thickness of nonwoven, needle-punched geotextiles under normal compressive loading is proposed. The equation is t=(t0−t∞)e−ασ+t∞ in which, t0 is the initial thickness, t∞ is a limiting thickness, σ is the normal stress, and α is an empirical coefficient. Comparison with thickness data obtained in multiple tests on eight different geotextiles using an in-plane, radial flow device results in excellent agreement for normal stresses up to about 372 kPa. Mean square errors are typically less than 0.017 mm. An equation for the limiting thickness, t∞, is developed based on the observation that under compressive loads at the limiting thickness, nonwoven, needle-punched geotextiles have their porosity reduced to about 91% of the initial value.
Monotonic and Cyclic Loading Behavior of Two Sands at Small Strains
Authors: Lo Presti DCF , Pallara O , Lancellotta R , Armandi M , Maniscalco R 
Published: February 2009

Abstract
The shear modulus of freshly deposited specimens of two different sands was measured in a resonant column (RC)-torsional shear (TOS) apparatus. The soil specimens studied included a calcareous, crushable, well-graded, coarse-to-medium sand containing about 2% fines (Quiou sand) and a silica, uniform, coarse-to-medium sand without fines (Ticino sand).
A brief description of the apparatus, with particular attention to the facilities used for the monotonic loading condition, is given together with a concise literature review.
The shear moduli of the two sands in cyclic dynamic tests (RC) were compared with those measured in static monotonic loading torsional shear tests. It is shown that at small strains of less than about 0.001%, the shear moduli of the Ticino sand obtained from the dynamic tests and the static monotonic loading tests are the same, which means that the behavior of the sand at these very small strain levels is strain-rate independent and recoverable, namely elastic. In the case of Quiou sand, the shear moduli at small strains obtained from the dynamic tests are 20% greater than those from the static monotonic loading tests. The authors believe this difference is due to the sand crushability. It is also shown that the strain level dependency of shear modulus at larger strain levels is smaller under cyclic loading conditions than in monotonic loading conditions. The effects of precompression and cyclic prestraining are also examined.
The Continuous Abrasion Index for the Assessment of Rock Abrasion
Authors: Al-Ameen SI , Waller MD 
Published: February 2009

Abstract
The continuous abrasion test is a new and simple test for evaluating the abrasive potential of rock material where attrition or low-stress sliding wear problems exist. The test is sensitive to the abrasive mineral content in the host rock and was found to be very suitable in comparing the degree of abrasiveness of various sedimentary rocks and in particular coal measures rocks. The wear area generated on a tested ball bearing is used as the Continuous Abrasive Index value for the tested rock. Several types of abrasive wear pattern were recognized on the tested steel ball; these can be used as a guide for the assessment of the abrasive potential of the rock. The exploitation of this new test has led to a new rock classification index according to the abrasive potential of the rock.
Numerical Modeling of a Thermal Conductivity Matric Suction Sensor
Authors: Xing A , Fredlund DG 
Published: February 2009

Abstract
Thermal conductivity matric suction sensors appear to be a promising device for the measurement of suction in soil. The technique indirectly measures matric suction by measuring the thermal conductivity of a ceramic block. This paper uses both a spherical and a cylindrical porous medium to simulate the heat flow in a thermal conductivity matric suction sensor. It is found that, although the transient temperature at the center of the sensor is heavily dependent on the material of the thermocouple and the heating device, the steadystate temperature is primarily determined by the thermal conductivity of the ceramic block. Therefore, accurate measurements can be obtained by using a longer heating period or by selecting a lower-heat-capacity material for the thermocouple and the heating device. Optimal sizes of the sensor for given heating rates and heating periods are calculated using a finite difference method. A multilayered sphere was also used to simulate the situation where the size of the sensor is not sufficiently large and an error occurs due to the influence of the surrounding soil. The numerical model is verified by comparison with the theoretical solution of a special case.
Development of a Transparent Material to Model the Geotechnical Properties of Soils
Authors: Iskander MG , Lai J , Oswald CJ , Mannheimer RJ 
Published: February 2009

Abstract
Measurement of three-dimensional deformation patterns and flow characteristics within a soil continuum are usually limited by the fact that soil sensors do not provide a continuous image of the measured continuum. Additionally, soil sensors exhibit static and dynamic characteristics that are different from those of the surrounding soils and therefore can change the response of the measured continuum. Tests conducted with a transparent material which has properties that closely model the geotechnical properties of natural soils can potentially circumvent these experimental problems if the response of a model transparent continuum can be measured using nonintrusive optical visualization techniques.
This paper demonstrates the feasibility of producing transparent materials which exhibit macroscopic properties representative of the geotechnical properties of natural soils. The transparent “soils” discussed in this paper were made by consolidating suspensions of amorphous silica in liquids with matching optical refractive indices. The measured shear strengths and permeabilities of the transparent soils are characteristic of natural clays and silts. The stress-strain response of transparent soils is characterized by large strains during consolidation and shear.
Effect of Preparation Technique on Permeability and Strength of Cement-Grouted Sand
Authors: Schwarz LG , Krizek RJ 
Published: February 2009

Abstract
The effectiveness of cement grouting is generally evaluated in terms of the improvement attained in the engineering properties of the grouted soil. Although this degree of improvement should logically be related to the amount of cementitious particles present in the pore spaces of the grouted sand, and indeed is to some extent, the method of preparing the specimens can exert an even stronger influence. Two significantly different preparation procedures—injection and hand mixing—were used to combine sand with a microfine cement grout at three different water-to-cement ratios. In the hand-mixing technique, a measured volume of grout (relative to the total void volume of the sand) was mixed mechanically with the sand, whereas in the injection method the grout permeated the sand through interconnected pore channels. Immediately after preparing the injected specimens, they were disassembled and an elutriation and filtration procedure was used to quantify the mass of cement particles deposited in the voids of the sand. For grouts with corresponding water-to-cement ratios, the injected specimens manifested higher cement contents than their hand-mixed counterparts with voids completely filled with grout. However, permeability and strength tests on companion specimens cured for 7 or 48 days indicated that injected specimens were generally somewhat stronger, but considerably more permeable, than hand-mixed specimens; this is attributed to the vastly differing mechanisms that govern the distribution and packing arrangement of the cement particles within the void spaces and on the sand grains.
Effect of Short Duration of Load increment on the Compressibility of Soils
Authors: Sridharan A , Sivapullaiah PV , Stalin VK 
Published: February 2009

AbstractThis study concerns the effect of duration of load increment (up to 24 h) on the consolidation properties of expansive black cotton soil (liquid limit = 81%) and nonexpansive kaolinite (liquid limit = 49%). It indicates that the amount and rate of compression are not noticeably affected by the duration of loading for a standard sample of 25 mm in height and 76.2 mm in diameter with double drainage. Hence, the compression index and coefficient of consolidation can be obtained with reasonable accuracy even if the duration of each load increment is as short as 4 h.The secondary compression coefficient (Cαε) for kaolinite can be obtained for any pressure range with 1/2 h of loading, which, however, requires 4 h for black cotton soil. This is because primary consolidation is completed early in the case of kaolinite. The paper proves that the conventional consolidation test can be carried out with much shorter duration of loading (less than 4 h) than the standard specification of 24 h or more even for remolded fine-grained soils.
Soil-Geogrid Reinforcement Interaction by Pullout and Direct Shear Tests
Authors: Alfaro MC , Miura N , Bergado DT 
Published: February 2009

Abstract
Pullout and direct shear tests have been conducted to investigate the soil-reinforcement interaction behavior in pullout and direct shear mechanisms. An apparatus—discussed in this paper—has been developed that is capable of performing both pullout and direct shear tests. Displacement measurements to monitor dilatancy on the backfill soil during pullout tests are incorporated in the apparatus. Test results for the geogrid type of reinforcement embedded in dense granular soil are discussed. The devised testing program provides valuable information on the appropriate interaction models and parameters that will be employed in the design and analysis of reinforced soil structures. The dilatancy measured in the laboratory may also provide useful information on the increase of interface shear resistance when dilatancy is restrained under field conditions.
External Measurement of Axial Strain in the Triaxial Test
Authors: Bressani LA 
Published: February 2009

Abstract
The errors involved in measuring axial strains in the triaxial test are reviewed based on previously published results. A technique is described to allow more reliable external measurements to be obtained and used for strain calculations. The technique is simple, inexpensive, and can be implemented in any soils laboratory. Comparisons are made between the strains obtained by this method and those using local transducers (connected to the specimen); satisfactory results are obtained. Triaxial tests were made on specimens of an artificially bonded soil, Corinth marl, and remolded London clay. Errors involved in previous tests are explained, and the “bedding error” is defined in a more precise way. In some tests, this error was eliminated due to a combination of factors such as soil grading, the finishing quality of the specimen surfaces, and the ratio of confining pressure to soil strength.
Geosynthetic/Soil Interface Friction Angles Using a Rotation Shear Device
Authors: Evans MD , Fennick TJ 
Published: February 2009

Abstract
A modified rotation shear device was used for measuring interface friction angles between soils and geosynthetics. The device was modified so that a geosynthetic specimen can be attached to the upper platen. A reliable method for cutting and attaching geosynthetic specimens to the device is described. The geosynthetic mounting system is simple, strong, and easy to remove. Interface friction angles and interface efficiencies for two ash samples and Boston Blue Clay with three geosynthetics are reported and compared. A range of strength increase is reported for a given soil with change from a smooth geomembrane to a textured geomembrane or nonwoven geotextile. Shear displacements up to 300 mm are quantified in the paper, showing that large, unidirectional displacements may accumulate in the rotation shear device.
Effect of Rib Spacing on Deformation of Profile-Wall Plastic Pipes Buried in Coarse Granular Backfill
Authors: Sargand S , Masada T , Hurd JO 
Published: February 2009

Abstract
Several different types of plastic pipe products were instrumented, buried in coarse granular backfill, and subjected to monotonic, distributed load in the field. During each field test, data were recorded from strain gages, linear variable differential transformers, and earth pressure cells by computerized data acquisition units.
Review of the deflection data from 14 tests revealed a pattern on the initial deflection that can be explained by considering a dimensional ratio between the rib spacing, S, and maximum particle size, dmax. Earth pressure cell readings taken in the springline region appeared to support this. Based on this observation, a recommendation was made that the S/dmax ratio should be either less than 0.6 or larger than 2.6 to prevent excessive initial deflection under relatively low levels of loading.
A Flexible Strain Gage for Soil Testing
Authors: Li XS 
Published: February 2009

Abstract
A novel strain gage for the measurement of soil deformation is introduced. The gage is based on the principle that the change in the length of a coil is linearly related to the change in its inductance. The gage measures a wide range of strains and can be easily installed on a soil specimen in any direction; therefore, it is particularly suitable for the measurement of deformations of in situ subsurface soil. This paper reports the principle and the characteristics of the gage. A discussion on further improvements is also given.
Determination of Coefficient of Consolidation from Early Stage of LogtPlot
Authors: Robinson RG , Allam MM 
Published: February 2009

AbstractThe standard curve-fitting methods, Casagrande's log t method and Taylor's root t method, for the determination of the coefficient of consolidation use the later part of the consolidation curve and are influenced by secondary compression effects. Literature shows that secondary compression is concurrent with primary consolidation and that its effect is to decrease the value of the coefficient of consolidation. If the early part of the time-compression data is used, the values obtained will be less influenced by secondary compression effects. A method that uses the early part of the log t plot is proposed in this technical note. As the influence of secondary compression is reduced, the value obtained by this method is greater than that yielded by both the standard methods. The permeability values computed from Cv (obtained from the proposed method) are more in agreement with the measured values than the standard methods showing that the effects of secondary compression are minimized. Time-compression data for a shorter duration is sufficient for the determination of Cv if the coefficient of secondary compression is not required.
Determining a Pavement Modulus from Portable FWD Testing
Authors: Livneh M , Livneh NA , Elhadad E 
Published: February 2009

Abstract
This paper assumes that there is room for an additional measuring device that, on the one hand, will serve mainly as an in situ device not requiring complicated back-calculation procedures and, on the other hand, will not involve large volumes of in situ materials as presently required by the falling weight deflectometer (FWD). Such a device is the new portable FWD (PFWD). Comparative tests with this device show no significant correlation between the central deflection measurements taken on the asphalt surface and the corresponding Benkelman-beam-measured deflections. This is due to the fact that the PFWD device “senses” only the upper layers of the pavement, down to no more than a small thickness, whereas the two other devices “sense” all pavement layers down to the subgrade medium, as well. A composite-pavement modulus of elasticity (Ep) can still be derived from the PFWD measurements, but only with the performance of additional measurements on the asphalt surface, followed by coring of the asphalt layers down to their far bottom. In this way, the above Ep value is calculated for the full structural thickness and for the standard radius of the contact area obtained from the PFWD testing, i.e., the modulus of elasticity (EA) of the asphalt layers and the modulus of elasticity (EG) of the granular layers. A comparison of the above Ep values calculated from the PFWD outputs, with the values derived from the conventional FWD measurements, led to the introduction of a correction factor that varies with the ratio of the thickness of the asphalt layers to their elastic modulus. The lower the ratio, the closer the correction factor approaches the value of 1.0.
Upgrading Equipment and Procedures for Stress Path Triaxial Testing of Coarse-Grained Materials
Authors: Flora A , Modoni G 
Published: February 2009

Abstract
Advanced laboratory testing is often the only way to gain an insight into the mechanical behavior of soils in the whole range from small strains to failure, which in some cases is required for the engineering modeling of complex structures. When such structures are rockfill dams, the use of a large apparatus in-laboratory is virtually unavoidable because of particle size, even though testing becomes far more difficult than usual. This paper presents problems arising from the upgrading of an existing large triaxial cell in order to provide fully automated stress-path control. Because of the large dimensions of the apparatus, implementation of both stress rate and strain rate controls posed a number of unusual problems. Even though the control had to be carefully tuned in order to consider strain-softening behavior, the adopted procedure proved successful. The new cell produced good results for different kinds of stress paths, with satisfactory control in all stages.
Grain-Size Analysis by Buoyancy Method
Authors: Bardet J-P , Young J 
Published: February 2009

Abstract
A new routine experiment referred to as buoyancy analysis is proposed to determine the grain-size distribution of fine-grained soils. The buoyancy analysis is based on the sedimentation principles of the hydrometer and pipette analyses. It determines the percent by weight finer than a given grain size by measuring the buoyant weight of a 2.5-cm-diameter sphere immersed in the soil suspension. The buoyancy analysis is slightly more accurate than the hydrometer analysis, has a shorter duration, and its readings can be fed directly into a computer. It yields results identical to those of the hydrometer analysis when the sphere is immersed within the depth range of the hydrometer bulb.
Microcomputer Based Data Acquisition Systems for Centrifuge Modeling
Authors: Shen C-K , Li X-S , Kim Y-S 
Published: February 2009

Abstract
A general discussion is given as to how microcomputer based data acquisition systems can be used in centrifuge model testing. Special attention is paid to the transmission of signals from the rotating section to the stationary section of the system. Both the direct and indirect methods of signal transmission are illustrated. Examples of applications are cited. It is concluded that the adoption of a computerized system can greatly enhance the accuracy and speed of the data acquisition process for centrifuge model studies of geotechnical structures.
Measurement of Volumetric and Linear Shrinkage on Black Cotton Soil
Authors: Subba Rao KS , Satyadas GC 
Published: February 2009

Abstract
Experimental investigations on the shrinkage of expansive black cotton soil have been made to study the process of shrinkage. Tests have been conducted on compacted soil specimens with different water contents under controlled conditions of temperature and humidity. The changes that take place in the air and water phases of specimens have been analyzed, and shrinkage paths have been examined both for volumetric and linear shrinkage. Volumetric shrinkage is shown to take a unique shrinkage path in terms of water loss, independent of water content or rate of shrinking. In contrast, the linear shrinkage paths are shown to be dependent on conditions under which shrinkage takes place.
Effect of Grain Characteristics on Liquefaction Potential—In Search of Standard Sand for Cyclic Strength
Authors: Ishibashi I 
Published: February 2009

Abstract
Since the original Monterey 0 sand, which had been used for cyclic triaxial testing system calibration, is not available any more, the search for an alternative sand was started. In order to provide useful information for the above purpose, liquefaction potentials were evaluated for Monterey 0 and 0/30 sands and for ASTM Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or 50-mm Cube) (C 109) Ottawa sands from various sources. The results clearly indicated that the liquefaction potential was very sensitive to slight changes in material properties (mean grain size, coefficient of uniformity, sphericity, and volume decrease potential).
Geotextile Filters for a Large Liquefaction Tank
Authors: Hryciw RD , Cornet J-M , Dowding CH 
Published: February 2009

Abstract
A large liquefaction tank used to prepare sand for laboratory testing required a 107-cm (42-in.) diameter filter. The filter was needed to separate the sand from water diffusers below, to facilitate a uniform upward flow of water, and to filter out undersired fines. The chosen design consisted of two geotextile fabrics sandwiched between a perforated plexiglass sheet and a steel grating. Selection of the geotextiles was based on the fabrics' porosities, permeabilities, and pore sizes. The system has been a success and has required no maintenance in over four years of usage.
Use of Time Series in Geotechnical Data Analysis
Authors: Wu TH , El-Jandali A 
Published: February 2009

Abstract
Methods of time series analysis based on the Box-Jenkins method were used to analyze random variations and inherent variability in geotechnical test data. The paper presents a summary of the time series models and their application to the analysis of data from unconfined compression tests, field vane tests, and cone penetration tests. The integrated-moving-average-autoregressive model was found to be a versatile tool and served this purpose well. The model permits the determination of the autocavariance function and the random testing error that best fit the test data.
Electro-Servo Control System for Thermomechanical Properties Testing
Authors: Myer LR 
Published: February 2009

Abstract
The main features of a system for pseudo-static thermomechanical triaxial rock testing systems are discussed. The system emphasizes ease of control and versatility in performing complex load/deformation paths required in many testing applications in the temperature-pressure range of 20 to 200°C and atmospheric pressure to 70 MPa. The pressurization system, utilizing electric motor-driven pumps and a computer-aided data acquisition/motor control system is described in detail. Example results are given of the application of the test system in determination of thermoelastic properties of a quartz monzonite rock.
A New Automatic Volume Change Monitoring Device
Authors: Rad NS , Clough GW 
Published: February 2009

Abstract
Automated testing systems are presently widely used in soil laboratory strength testings to monitor load, displacement, and pressure. A new device is introduced here for automatic measurements of the volume change of soil specimens during drained triaxial tests. The device is versatile and capable of monitoring volumetric changes of soil specimens with various dimensions, volume change characteristics, and degrees of saturation. It can also be used to measure the pore pressure inside a soil specimen during an undrained test.