bluuebunny/crossref_metadata_2025_split huggingface dataset:
Specimen Size and Scale Effects of Direct Shear Box Tests of Sands
Authors: Cerato AB , Lutenegger AJ 
Published: March 2009

Abstract
The direct shear test has survived over the past 50 years in geotechnical engineering applications because of its simplicity and repeatability. Many laboratories perform direct shear box tests on sands to determine the friction angle φ′, or shear strength of the sand for engineering design purposes. However, there are different size shear boxes in use today and the effect of the varying specimen size on the resulting friction angle used in foundation deign has never before been investigated thoroughly. Five sands with different properties were tested in three square shear boxes of varying sizes (60 mm, 101.6 mm, and 304.8 mm), each at three relative densities (dense, medium, and loose). Results of the direct shear tests show that the friction angle φ′ can be dependent on specimen size and that the influence of specimen size is also a function of sand type and relative density. The tests indicate that for well-graded, angular sands, φ′ decreases as box size increases and that the influence of box size is dependent on relative density. The paper provides a description of the test methods and presents the test results.
Analysis of Installation of FDR Sensors in a Hard Soil
Authors: Navarro V , Candel M , Yustres A , Merlo O , Mena M 
Published: March 2009

Abstract
Success using capacitance sensors is critically dependent upon the proper installation of access tubes to maximize soil contact. In this paper we present the technique followed in the installation of 11 access tubes in a hard soil from Alcazar de San Juan (central Spain) to optimize this contact.
Investigations on Sand Reinforced with Different Geosynthetics
Authors: Latha MG , Murthy VS 
Published: March 2009

Abstract
This paper presents results of triaxial compression tests on sand reinforced with different types of geosynthetics in different layer configurations to study the effect of quantity of reinforcement and tensile strength of the geosynthetic material on the mechanical behavior of geosynthetic-reinforced sand. The reinforcement types used are woven geotextile, geogrid, and polyester film. The layer configurations used are two, three, four, and eight horizontal reinforcing layers in a triaxial test sample. From the triaxial tests, it is found that the geosynthetic reinforcement imparts cohesive strength to otherwise cohesionless sand. The effect of reinforcement on the friction angle was found to be insignificant. The magnitude of imparted apparent cohesion is found to depend not only on the tensile strength of the geosynthetic material but also the surface roughness changes during loading. Special triaxial tests using rice flour as the reinforced medium, microscopic images, and surface roughness studies revealed the effect of indent formation on the surface of polyester film, which was the reason for the unusually high strength exhibited by the sand reinforced with polyester film.
Digitally Controlled Simple Shear Apparatus for Dynamic Soil Testing
Authors: Duku P. M. , Stewart J. P. , Whang D. H. , Venugopal R. 
Published: March 2009

Abstract
We describe the characteristics of a simple shear apparatus capable of applying realistic multidirectional earthquake loading to soil specimens. This device, herein termed the Digitally Controlled Simple Shear (DC-SS) apparatus, incorporates features such as servohydraulic actuation and true digital control to overcome control limitations of some previous dynamic soil testing machines. The device is shown to be capable of reproducing sinusoidal and broadband command signals across a wide range of frequencies and amplitudes, although the device has limited control capabilities for very small command displacements (less than approximately 0.005 mm). The small deformation limitation results from noise introduced to the control system from analog-to-digital conversion of feedback signals. We demonstrate that bidirectional command signals can be accurately imparted with minimal cross coupling, which results from an innovative multiple-input, multiple-output digital control system. The capabilities of the device are demonstrated with a series of broadband tests on unsaturated soil specimens subjected to uni- and bidirectional excitation.
A Novel Trimming Technique for Frozen Sand Specimens
Authors: Sanzeni Alex , Germaine John T. , Whittle Andrew J. , Colleselli Francesco 
Published: March 2009

Abstract
A trimming technique is described for the preparation of specimens of frozen sand for one-dimensional thawing and consolidation tests. Specimens are trimmed directly into the apparatus’ confining ring using its cylindrical cutting edge; a heated metal blade is employed to remove the excess soil, while dry ice is used as coolant. The technique is performed at room temperature and is particularly suitable for 1-D thaw-consolidation tests where dimensional tolerances are critical. The technique was applied for preparing specimens of frozen sand from the Venice Lagoon deposits for 1-D compression tests in the Constant Rate of Strain (CRS) apparatus (Wissa et al. 1971). Specimen handling and test setup are described in detail; testing procedure included measurement of axial strain during thawing.
Probabilistic CPT Method for Estimating the Ultimate Capacity of Friction Piles
Authors: Abu-Farsakh Murad Y. , Titi Hani H. 
Published: March 2009

AbstractThis paper presents a probabilistic CPT method to estimate the ultimate capacity of driven friction piles utilizing CPT data. A database of 35 square PPC piles that were loaded to failure and their adjacent CPT were used to develop this method. Backcalculation was carried out to calibrate the correlation factors needed to determine the unit end bearing (qb) and unit skin friction (f) of the pile from CPT data (qc, fs) based on the probability of having each soil type. The ultimate pile capacities (QP) of the investigated piles estimated by the proposed method, three other CPT methods, and static α and β methods were compared with the measured pile capacities obtained from pile load tests. Statistical analyses were carried out to evaluate the reliability of the probabilistic CPT method and the results showed that the proposed method can predict the ultimate capacity of the piles with good accuracy. The capability of the proposed method was further verified by predicting the capacities of an additional 17 pile load tests. The probabilistic CPT method, in addition to Schmertmann, α, and β methods were calibrated to evaluate the resistance factors needed for the design of single driven piles based on the LRFD method.
A New Isotropic Cell for Studying the Thermo-Mechanical Behavior of Unsaturated Expansive Clays
Authors: Tang Anh-Minh , Cui Yu-Jun , Barnel Nathalie 
Published: March 2009

Abstract
This paper presents a new suction-temperature controlled isotropic cell that can be used to study the thermo-mechanical behavior of unsaturated expansive clays. The vapor equilibrium technique is used to control the soil suction; the temperature of the cell is controlled using a thermostat bath. The isotropic pressure is applied using a volume/pressure controller that is also used to monitor the volume change of soil specimen. Preliminary experimental results showed good performance of the cell.
A Laboratory Model to Study Arching within a Hydraulic Fill Stope
Authors: Pirapakaran Kandiah , Sivakugan Nagaratnam 
Published: March 2009

Abstract
A simple laboratory apparatus, to study the effects of arching within a hydraulic fill mine stope, was developed. Four different model stopes, two circular and two square, made from Perspex, were used in the study. A dry hydraulic fill obtained from a local mine was used in the study. The model was filled in 100-mm layers, and the fractions of the fill weight, carried by the bottom and the wall of the stope, were separately measured. From these measurements, the variation of average vertical stress with depth could be computed. These experimental values were compared against those obtained from numerical modeling using FLAC and FLAC3D, and the agreement was excellent, thus validating the numerical model.
Centrifuge Modeling of Surface Blast Effects on Underground Structures
Authors: De Anirban , Zimmie Thomas F. 
Published: March 2009

Abstract
The effects of surface blasts on underground structures were studied through centrifuge model tests. Centrifuge scaling relationships make it possible to model the effects of large explosions, using a relatively small quantity of explosives under a high g-level. Centrifuge tests, conducted at 70 g, using 2.6 mg of TNT equivalent of explosives, resulted in explosions equivalent to those using 8.7 kN (0.9 tons) of TNT equivalent under normal (1 g) gravity. Strains induced at different locations of the model structure due to the explosion were measured using strain gages. Results indicated that the strains depend on the thickness and nature of the intervening medium. The presence of a polyurethane geofoam compressible inclusion barrier appeared to mitigate the impact of the explosion. Centrifuge model testing is useful in determining the effectiveness of different design alternatives, in studying the mitigating effects of different barrier systems, and in verifying and calibrating results of numerical models related to explosions and underground structures.
An Alternative Test Method for Assessing Consistency Limits
Authors: Lee Landris T. , Freeman Reed B. 
Published: March 2009

Abstract
Experiments were conducted to assess simpler alternatives for estimating the Atterberg (liquid and plastic) limits as needed during military field reconnaissance and combat engineering exercises. Eight non-ASTM test methods were compared to the Casagrande cup liquid limit method and ten non-ASTM alternatives were compared to the rolled-bead plastic limit method for three cohesive soils having wide plasticity index ranges. Only one non-ASTM method yielded results within 10 % of the ASTM liquid and plastic limit values. This unique test method was created from a unified (dual-weight) fall cone apparatus and procedure to enable simple assessment of soil consistency limits.
A Numerical View into Direct Shear Specimen Size Effects
Authors: Jacobson Douglas E. , Valdes Julio R. , Evans T. Matthew 
Published: March 2009

Abstract
The ASTM D 3080-04 standard, Standard Test Method for Direct Shear Test of Soils under Consolidated Drained Conditions, indicates that the direct shear test specimen width L must be at least ten times larger than the largest particle in the specimen, L/d ≥ 10. The results documented in this note provide visual insight into specimen size and boundary effects through discrete element simulations conducted with numerical specimens ranging in size from L/d = 6.5 to L/d = 177. Particle translation data indicate that in the tested configuration, localized shear zones located far from the specimen boundaries develop only when the specimen size is L/d &gt; 58. The results provide a description of the microstructure evolution during shearing and suggest that the ASTM specimen size criterion may be inappropriate when localized shear banding in uniform granular materials is sought.
Uplift Behavior of Horizontal Anchor Plates Buried in Geosynthetic Reinforced Slopes
Authors: El Sawwaf Mostafa A. 
Published: March 2009

Abstract
Uplift behavior of horizontal anchor plates located near sandy earth slopes with and without geosynthetic reinforcement has been investigated in model tests. Several configurations of reinforcement layers were used to reinforce the sandy soil over anchor plates. Many factors, such as relative density of sand, embedment depths, and the location of the plate relative to the slope crest, along with geosynthetic parameters including size, type, number of layers, and the proximity of the layer to the plate have been studied in a scale model. The failure mechanism and the associated rupture surface were observed and discussed. Test results showed that using geosynthetic reinforcement has a significant effect in improving the uplift capacity of the anchorage plate. However, it was found that inclusion of one layer that is placed resting directly on top of the anchor plate was more effective in enhancing the anchor capacity than reinforcing the slope itself. Based on test results, critical values were discussed and recommended, but should be validated in full-scale or centrifugal model tests.
An Empirical Relationship between Rock Structure Rating and Rock Mass Rating
Authors: Sarsby RW , Rama Sarma K 
Published: March 2009

AbstractPrediction of support pressures for underground openings is one of the most difficult tasks in rock engineering. The difficulties associated with the selection of reliable material properties, laws of material behavior, stress environment, etc. (which are essential for satisfactory application of analytical methods and numerical techniques) and the simplicity of the classification systems have collectively contributed to the popularity of empirical approaches for support design. The unpredictable nature of weathering enhances the complexity of the assessment of rock masses. In this study an attempt has been made to derive a simple relationship between rock structure rating and rock mass rating, which will permit accurate estimation of engineering properties of rock using easily measured parameters. The data used to formulate the empirical relationships came from tests conducted on rock samples collected from 45 boreholes at various locations between Visakhapatnam and Koraput (India).
Centrifuge Modeling of Solid Waste Landfill Systems—Part 1: Development of a Model Municipal Solid Waste
Authors: Indrasenan Thusyanthan N , Gopal Madabhushi SP , Singh S 
Published: March 2009

Abstract
This paper presents the development of a model waste that has physical properties similar to those reported by investigators for municipal solid waste (MSW). The model waste was developed using a mixture of peat, E-grade kaolin clay and fraction-E fine sand. Unit weight, compressibility, and shear strength characteristics of the model waste were experimentally determined and shown to match well with those reported for MSW.
An Improved Oedometer Apparatus to Measure Lateral Stress During Testing
Authors: Gareau LF , Molenkamp F , Sharma J 
Published: March 2009

Abstract
Soils which have been subjected to complex geological stress histories (such as glaciation) exhibit incongruent geotechnical properties when tested in the oedometer. A new oedometer apparatus has been developed to permit measurement of anisotropic horizontal stress reactions during vertical loading. The objective of the apparatus is to assess how different geological stresses relate to present state properties. The apparatus has been tested using laboratory prepared samples of kaolin and thin tube core samples of Pot Clay from the north Netherlands. These results indicate that the new apparatus can measure isotropic and anisotropic lateral stresses with reasonable repeatability. Also, the orientation of maximum and minimum horizontal stresses can be calculated if oriented core samples are used. Results from the Pot Clay indicate anisotropic horizontal stresses which are related to the known glacial stress history.
Development of a Direct Shear Apparatus with Rock Joints and Its Verification Tests
Authors: Kim D-Y , Chun B-S , Yang J-S 
Published: March 2009

Abstract
A new direct shear apparatus for natural rock joints and artificial joints has been developed that can achieve constant normal stress (CNS), constant normal load (CNL), and infinite normal stiffness (INS). The CNS condition during shear is maintained by changing the normal load corresponding to a reduced contact area with shear displacements. The deformation of the apparatus due to normal loading is excluded in order to obtain the pure displacement of the specimen. The deformation of the apparatus due to shear loading included in the total displacement is also minimized by measuring the relative displacement between the upper and lower shear boxes. Four degrees of freedom are employed in this study: two transitional motions of the upper and lower shear boxes and two rotational motions of the upper shear box. A series of tests for CNS, CNL, and INS conditions have been performed to verify the accuracy of the control system for the same roughness. Other tests have also been performed on saw-tooth joints with asperities having inclinations of 16.7° and 26.6°, and JRC values of 10 and 15 were obtained from the tests, respectively. The maximum dilation angle occurs at peak shear strength, which shows a good agreement with Barton's model.
Constant Flow Method for Concurrently Measuring Soil-Water Characteristic Curve and Hydraulic Conductivity Function
Authors: Lu N , Wayllace A , Carrera J , Likos WJ 
Published: March 2009

Abstract
A constant-flow laboratory testing method (CFM) is presented for concurrently measuring the soil-water characteristic curve (SWCC) and hydraulic conductivity function (HCF) of unsaturated coarse-grained soils. Two computer-automated syringe pumps are employed to control the volumetric water content of a specimen and to periodically impose constant volumetric flow rates through the specimen, respectively. Hydraulic conductivity (k) corresponding to each water content increment is determined from Darcy's law by measuring the steady-state gradient induced by the applied constant flow. Matric suction is maintained by axis translation using elevated pore air pressure and high-air-entry ceramic disks. Diffused air bubbles are removed using unique passive bubble traps. SWCCs and HCFs are obtained for three sandy soil specimens, requiring about 25–35 days to obtain both functions for each soil. The range of the system is demonstrated for k from about 10−4 cm/s to 10−9 cm/s at corresponding matric suction between about 0 kPa (saturated) and 40 kPa. Results are validated by comparison with independent SWCC measurements obtained using Tempe cells and HCFs estimated using a statistical model.
Triaxial Compression of Clay Reinforced with Sand-Coir Fiber Core
Authors: Vinod P. , Bhaskar Ajitha , Lekshmi C. S. 
Published: March 2009

Abstract
This paper describes the results of a study into the undrained response of clay specimens reinforced with sand-coir fiber cores in triaxial tests. Coir, used to reinforce sand, is the processed fiber from the husk of coconuts. Coir combines the properties of biodegradability and fiber strength, and remains an under-utilized material of great potential value for ground improvement in parts of the world where such materials are available in abundance. A thin PVC pipe kept centrally inside a split mold is used to form the core in the triaxial tests. The clay is placed inside the mold around the PVC pipe at maximum dry unit weight—optimum moisture content condition while the sand-coir mixture is placed inside the pipe at the same bulk unit weight as that of clay. Influence of variables such as replacement area ratio (ratio of cross-sectional area of sand-coir fiber core to that of the triaxial test specimen), confining pressure, fiber content, and fiber aspect ratio on the behavior of the composite soil specimen is identified and isolated. It is found that stress-strain strength properties of clay specimens reinforced with sand-coir fiber core is appreciably better not only when compared with untreated clay specimens but with sand core reinforced clay specimens as well. Such an improvement is of importance to allow reduced requirement of sand and increased use of natural fiber. An optimum fiber content of 1 % (by weight) was identified for strengthening of the sand core. The reinforcement effect is found to increase appreciably with increase in replacement area ratio and to a smaller extent with increase in fiber aspect ratio. The larger reinforcement effect observed at higher confining pressures suggests that the proposed method is more effective at greater depths.
Drip Injection of Chemical Grouts: A New Apparatus
Authors: Hayashi S , Chai XJ , Matsunaga K , Toki A 
Published: March 2009

Abstract
The tip structure of conventionally used drip injection apparatus for chemical grouting has the defect that the chemical grouts flow upwards to the ground surface frequently, which reduces the accuracy and efficiency of injection significantly. Normally, cement and bentonite are used for sealing the gap between injection tube and drill hole, the performance of which is not satisfactory. In this study, a balloon cover injection tip (called BCIT) has been developed. The special tip structure of the injection tube prohibits the chemical grout flowing upward to the ground surface. In particular, BCIT can implement down-to-up chemical grouting due to its soft and tight attachment with the drill hole sides. The main advantage of the BCIT is its simplicity, portability, adaptability, and accurate injection quantity management. Further, this can be used effectively for small-scale strengthening and preservation of historical remains with complicated geographic features without spoiling their appearance. In the laboratory, the feasibility of BCIT apparatus has been verified by chemical grouting in model ground, which simulates the practical condition of Funasako kiln sites. A soil hardness tester was used to evaluate the strength of the solidified body.
Shear Strength and Stress-Strain behavior of Contaminated Soils
Authors: Ratnaweera P , Meegoda JN 
Published: March 2009

Abstract
A series of unconfined compression tests performed on fine-grained soils contaminated with varying amounts of chemicals showed a decrease in shear strength and stress-strain behavior. These observations were attributed to changes in dielectric constant and pore fluid viscosity. Consolidated drained triaxial tests performed on a granular soil showed a similar behavior, even though granular soils do not show a physicochemical interaction between soil and pore fluid. This is attributed to mechanical interactions at particle contacts, caused by enhanced lubrication by viscous pore fluids. For fine-grained soils, the observed reduction in shear strength is attributed to physicochemical effects caused by a reduction in dielectric constant and mechanical interactions caused by high pore fluid viscosities. Observations show that the reduced physicochemical interactions seem to have been overshadowed by mechanical interactions. The clayey silt tested showed a marginal reduction in shear strength, indicating that the net effect is insignificant.
A Convenient Graphical Representation of Compaction Data
Authors: Chapuis RP , Mbonimpa M , Aubertin M , Dagenais A-M 
Published: March 2009

Abstract
The results of compaction tests are usually presented as dry density versus molding water content. In the corresponding graph, the curves of levels of saturation appear as hyperbolas. A new graphical presentation is proposed where the inverse of the dry density is plotted against the molding water content. In this convenient representation, all curves of equal degree of saturation become straight lines, which facilitates plotting and interpolation. It appears also more practical to establish a linkage with other graphs, such as those relating mechanical or hydraulic properties, to void ratio.