bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relative Moisture and Moisture Deficiency of Desiccated Expansive Cohesive Soil Deposits
Authors: Hanafy EADE 
Published: February 2009

Abstract
The concept of relative moisture in soil mechanics is introduced for assessing the in-situ moisture deficiency and moisture change potential of desiccated expansive clay layers. This paper introduces the terms moisture change potential (MCP), relative moisture (RM), and moisture deficiency (MD) in order to relate the in-situ moisture content to the corresponding equilibrium moisture content at saturation under the same applied pressure. This concept has been developed for sites having variations in moisture content to identify the desiccated zones and to correlate the moisture deficiency to the swelling potential. The paper also defines the saturation coefficient, Sv, as a new term that is numerically equal to the product of void ratio and percent saturation to correlate the initial and final moisture values. Furthermore, it emphasizes that the “relative moisture” term is different from the well-known terms of “degree of saturation” and “relative humidity.”
The suggested terms are found relevant for assessment of field monitoring records of heave-related movements when evaluating long-term stability of foundations, slabs-on-grade, and pavement as a result of moisture increase and when making recommendations of necessary precautionary measures. In addition, the relative moisture term, defined here, is found to be the more appropriate term to be adopted for soil deposits instead of the relative humidity term commonly borrowed and used.
Numerical examples and typical applications are included to illustrate the versatility and validity of the concept introduced. Selected laboratory data of a highly expansive clay are also included. For the application considered, zones of the clay layer showed relative moisture (RM) values of less than 50%, and moisture deficiency (MD) values of more than 100% were classified as highly desiccated. The concept of the relative moisture adopted in this study is concluded to offer a practical means of identifying and evaluating the degree of desiccation of expansive soils for nonuniform sites with varying layer depths and moisture conditions.
Constant Rate of Strain Consolidation with Radial Drainage
Authors: Seah TH , Juirnarongrit T 
Published: February 2009

Abstract
This paper describes a method of determining the consolidation characteristics of soft Bangkok clay under the radial drainage condition by using a newly developed constant rate of strain (CRS) consolidometer. A new formulation for this type of test was proposed. A series of constant rate-of-strain consolidation tests were compared to the results of oedometer tests. The pore water pressure distribution across the specimen in the CRS tests was estimated from measurements made at two locations. The results agreed well with the theoretical solution. A simple method of estimating the preconsolidation pressure by means of the pore water pressure ratio is also proposed. Because the tests conducted at different strain rates indicate that apparent preconsolidation pressure increases with strain rate, it is believed that secondary compression occurred during primary consolidation for this clay. The consolidation characteristics, including coefficient of consolidation and coefficient of permeability, in the vertical and horizontal directions were also compared.
Instrumentation of Anchored Segmental Retaining Wall
Authors: Yoo C , Lee KM 
Published: February 2009

Abstract
This paper presents the measured behavior of an anchored segmental retaining wall. In an attempt to understand the overall mechanical behavior of the anchored segmental retaining wall and to confirm the applicability of the design assumptions, an extensive monitoring program was implemented for a 7-m-high anchored segmental retaining wall. The measured horizontal earth pressures and the inferred tensile loads in the reinforcements indicated that the state of stress within the reinforced soil mass is higher than the Rankine active state of stress and that by Coulomb wedge analysis, approaching to that based on the FHWA design approach for inextensible reinforcements. The measured performance satisfied the minimum performance requirements for the internal stability with a maximum wall movement comparable to that reported for walls with inextensible reinforcements. The wall survived severe rainfalls during and after the wall construction, exhibiting an excellent performance in terms of drainage. Implications and findings from this study are discussed.
Performance Evaluation of Automated Machines for Measuring Gradation of Aggregates
Authors: Browne C , Rauch AF , Haas CT , Kim H 
Published: February 2009

Abstract
Several automated devices are commercially available for measuring the gradation of stone aggregates. These computerized machines, which provide a rapid alternative to manual sieving, capture and process two-dimensional digital images of aggregate particles to determine grain size distribution. Five of these automated gradation devices were evaluated for accuracy using fifteen aggregate test samples. To quantify how well the machine results compare with data from standard sieve analyses, the CANWE (Cumulative And Normalized Weighted Error) statistic was developed and used. While the machine data did not match the sieve data exactly, the evaluated devices were found to provide good measures of particle gradation for most samples. These tests also indicate that some machines will give more repeatable results in multiple tests of a given material, while others yield better results when testing different materials. The methodology used in this study is suitable for objectively evaluating the accuracy of other rapid gradation machines for various applications.
Design and Performance of a 1m Diameter Ring Shear Apparatus
Authors: Kelly R , Airey DW , Tabucanon JT 
Published: February 2009

Abstract
Constant Normal Stiffness (CNS) testing has evolved over the last 15 years in order to study the effects of soil deformations on the capacity of axially loaded piles. The majority of CNS testing in the laboratory has been carried out using modified shear box apparatus. However, results obtained from these apparatus may not accurately represent real behavior due to effects associated with the modifications to the shear box apparatus. The use of ring shear apparatus for CNS testing avoids many of the difficulties associated with modifying shear box apparatus. A large ring shear was constructed at the University of Sydney. This paper provides a description of the ring shear apparatus and some shakedown results to assess its performance.
Alternative Encasement Materials for Clod Test
Authors: Krosley L , Likos WJ , Lu N 
Published: February 2009

Abstract
The Clod test has been often used in the United States for obtaining the relationship between soil volume or volumetric strain and water content for expansive soils. Alternative encasement materials non-toxic to humans and non-hazardous to the environment were examined for the Clod test. It is shown that Elmer's craft glue is superior to the commonly used solution of Dow saran resin and methyl ethyl ketone (MEK) for its non-hazardous nature, low cost, and fast testing time. For several different expansive soils, nearly identical volumetric strain-water content curves were obtained using the traditional solution of Dow saran resin and MEK and Elmer's craft glue. 3M adhesive spray was shown to be not suitable for encasement material. It is concluded that Elmer's craft glue can be reliably used as an excellent alternative encasement material for the clod test.
Measurement of Quasi-Elastic Stiffness Parameters of Dense Toyoura Sand in Hollow Cylinder Apparatus and Triaxial Apparatus with Bender Elements
Authors: Chaudhary SK , Kuwano J , Hayano Y 
Published: February 2009

Abstract
Quasi-elastic stiffness parameters of dense Toyoura sand were measured at various stress states during similar consolidation and p′-constant shear tests in a hollow cylinder apparatus and a triaxial apparatus equipped with local deformation transducers and bender elements. Test results from these two test setups were compared. Although the Young's moduli from the triaxial apparatus were slightly lower than those from the hollow cylinder apparatus, they followed approximately the same power laws with the effective normal stresses. The shear modulus Gvh from the hollow cylinder apparatus was almost the same as that from the shear wave velocity measurement in the triaxial apparatus. The Poisson's ratios were also similar from both test setups. The vertical Young's modulus was found to be smaller than the horizontal Young's modulus. The anisotropy in Young's moduli followed a power law with the effective stress ratio. However, the Poisson's ratios were not dependent on the mean effective pressure or the shear stress level. The symmetry of the stiffness matrix was also examined.
Mechanical Behavior of an Unsaturated Soil Under Multi-Axial Stress States
Authors: Macari EJ , Hoyos LR 
Published: February 2009

Abstract
A series of drained (constant suction) true triaxial tests has been conducted on several identically prepared, 10-cm side, cubical specimens of recompacted silty sand to study the stress-strain-strength behavior of an unsaturated soil under multiaxial stress states and suction-controlled conditions. The experiments were conducted in a stress/suction-controlled true triaxial (cubical) setup following a multi-stage testing scheme. Matric suction states in the specimens were induced and maintained constant during testing by using the axis-translation technique. Imposed stress paths included an initial hydrostatic compression followed by conventional traxial compression, triaxial compression, or simple shear in the first octant of the octahedral stress plane. Test results are used to evaluate the nature of principal strain response of an unsaturated soil along multi-axial stress paths, and to observe the influence of matric suction on the shape, size, and position of the failure envelopes in the octahedral stress plane.
Design and Performance of an Electro-Pneumatic Pile Hammer for Laboratory Applications
Authors: Iskander MG , Olson RE , Bay JA 
Published: February 2009

Abstract
Small piles used in research programs have generally been installed by pushing or driving using slow mechanical drop hammers, because of the expense and technical difficulties associated with manufacture of realistic small-scale pile driving hammers. However, pushing does not model inertial effects and slow driving does not model diffusive effects in the soil. It remains to be demonstrated whether these effects are important or not. To help clarify this issue, an electronically controlled, single-acting air hammer, with a rated energy of 211 J (156 ft · lb), and an operating frequency of up to 1.2 Hz, was designed and built. The hammer was used successfully to drive 90 mm (3.5 in.) diameter piles into dense sand under a confining pressure of 138 kPa (20 psi). The behavior of the hammer was documented using detailed measurements of time-dependent ram movements, accelerations, and chamber pressures. This paper is concerned with the design and performance of the hammer.
Consolidation and Permeability Behavior of Segregated and Homogeneous Sediments
Authors: Sridharan A , Prakash K 
Published: February 2009

Abstract
The ever-increasing demand for the use of marginal lands for various human activities necessitates the need to understand the behavior of soft sediments under the action of external forces. As the segregated sediments are of common occurrence in a freshwater depositional environment, it is essential to understand the compressibility and permeability characteristics of segregated sediments, in addition to those of homogeneous sediments. The present paper discusses the compressibility and permeability behaviors of soft segregated and homogeneous sediments, making use of a simplified seepage consolidation testing procedure developed by the authors. The other variables included in the study are the clay mineralogy of the soil and the stress history of the sediments. The study clearly brings out the significant effect of clay mineralogy on the compressibility characteristics of segregated, normally consolidated sediments. The compressibility behavior of homogeneous soil sediments formed under a given depositional environment, having different clay mineralogy, appears to be similar. It is shown that the coefficient of permeability of any soil is a function of stress history in addition to void ratio and soil type.
Measuring the Effect of Mixed Grading on the Maximum Dry Density of Sands
Authors: Barton ME , Cresswell A , Brown R 
Published: February 2009

Abstract
During cut and fill operations, compaction using sands from different sources may be carried out. The resulting mixed sand will have different compaction characteristics than those of the parent sands. An increase in dry density will result as the grading moves towards more ideal characteristics for dense packing. Laboratory compaction tests using pluviation and the vibrating hammer method have been carried out to measure this increase in dry density. The resulting value is generally significantly greater than the result predicted by taking the mean value of dry density given by the parent sands.
Comparison of Young's Moduli of Dense Sand and Gravel Measured by Dynamic and Static Methods
Authors: AnhDan LQ , Koseki J , Sato T 
Published: February 2009

Abstract
The stiffness of soil at very small strain is a useful parameter for characterizing the non-linear stress-strain behavior of soil, which has been evaluated by both dynamic and static methods based on different principles. A new technique for measuring dynamic wave velocities of coarse material is introduced in large-scale triaxial tests on rectangular specimens with dimensions of 58 cm high and 23 × 23 cm in cross section. At the same time, static deformation properties during small-amplitude unloading and reloading cycles are measured with local deformation transducers. Young's moduli of dense sand and gravel evaluated based on the static and dynamic measurements are compared, and some discussions on anisotropy and inhomogeneities are made taking advantage of the movable feature of the new technique.
Properties of Singapore Marine Clays Improved by Cement Mixing
Authors: Tan T-S , Goh T-L , Yong KY 
Published: February 2009

Abstract
Stabilization of soft ground by the deep cement mixing (DCM) method has become an increasingly popular method to improve stability in an excavation in soft clay and to limit movement in adjacent sub-structures. The desired increase in strength and stiffness to fulfil the intended functions can be achieved provided that the right mix proportion is adopted. To proceed with this kind of soil improvement, prediction of the strength and stiffness of the improved soil is necessary. Due to a short history of the DCM method in Singapore, there is limited data on the improved properties of local clays. This study is conducted to bridge that gap and also extends its usefulness to clays elsewhere. In the paper, the influences of three main constituents of the mixture, namely clay, water, and cement on the strength development of Singapore marine clays improved by cement mixing are investigated. Based on the experimental results, it is shown that a convenient normalization can produce a consistent pattern for evaluation of improved strength of clays from different parts of Singapore. This normalization is also shown to work for one Japanese clay. Correlations between strength and stiffness of the improved clay are also obtained. Lastly, it is shown that for a cement mixed clay there is a continual increase in strength and stiffness with time. This will help to reduce ground movement, and it will also increase the bending moment in the retaining wall. Both aspects must be considered in a design.
An Experimental Study of the Mechanics of Two Weakly Cemented Soils
Authors: Lo S-CR , Lade PV , Wardani SPR 
Published: February 2009

Abstract
The effects of a cementing agent on the mechanical behavior of a quartz sand and a natural silt were studied with drained triaxial tests. The cementing agent was a cement fly ash slurry, and the specimens so formed were weakly cemented. The higher stiffness of the cemented specimens can be explained by the presence of structure, but it may not be always valid to equate structure to the contribution of a cementing agent. Special zero effective confinement tests were conducted to directly measure the contribution of bonding between grains to the strength and stiffness of the two cemented soils. Test results unambiguously indicated the occurrence of progressive bond breakage prior to failure. At a stress state remote from failure, a cemented soil has lower dilatancy relative to the parent soil because of the presence of significant bonding. However, bond breakage occurring at higher shear stress led to a more dilatant soil fabric. The shear strength data followed a curved failure surface that merged back, at high stress, to that of the parent soil. This feature can be captured by a failure function that models the contribution of a cementing agent to strength as two parts, true bonding between soil grains and increase in dilatancy at failure. Both parts degrade with increasing effective confining pressure, but at different rates.
Design of an Instrumented Flat Dilatometer
Authors: Stetson KP , Benoît J , Carter MJ 
Published: February 2009

Abstract
To better understand the mechanics of the flat plate dilatometer expansion, a probe has been developed to measure the continuous pressure-displacement soil response during the test. This paper presents details of a specially designed Marchetti dilatometer with sensors to record the continuous displacement of the membrane, unload-reload cycles, the pore water pressure, the total pressure, and the penetration thrust. With minimal impact on the original blade design, the resulting instrumented dilatometer was tested at the University of Massachusetts-Amherst National Geotechnical Experimentation Site.
Development of a Spreadsheet for Modeling SPT Stress Wave Data
Authors: Daniel CR , Jackson RS , Howie JA , Walker B 
Published: February 2009

Abstract
The advantages of measuring and correcting for variations of Standard Penetration Test (SPT) stress wave energy are well documented. Despite this fact, geotechnical engineers are often hesitant to measure SPT energy, due to high cost and uncertainty about data quality or the reliability of energy calculation methods. Two spreadsheets that model the propagation of stress waves through simple and safety hammers (and attached rod strings) were developed to address the issue of data quality. This paper describes the development of the spreadsheets, including critical aspects of hammer-anvil interaction that are not well documented in the geotechnical literature. Spreadsheet output is verified by comparison to stress wave data collected under controlled laboratory conditions. The safety hammer spreadsheet is then used to assess the quality of stress wave data collected during an actual field investigation. In all cases, the modeled and measured data are in good-to-excellent agreement.
Electro-Osmotic Consolidation of Soft Bangkok Clay Using Copper and Carbon Electrodes with PVD
Authors: Bergado DT , Sasanakul I , Horpibulsuk S 
Published: February 2009

Abstract
Electro-osmotic consolidation of Bangkok clay using copper and carbon electrodes with prefabricated vertical drain was studied. A laboratory testing program was conducted on undisturbed and reconstituted samples in a small cylinder cell and a large consolidometer in order to assess the probable effectiveness of electro-osmotic treatment. The tests were performed under the voltage gradients of 60 and 120 V/m with a polarity reversal of every 24 h. The time to achieve 90% degree of consolidation induced by electro-osmosis ranges from 1.4 to 2.1 and 1.2 to 2.2 times faster than the normal consolidation using PVD only for undisturbed and reconstituted samples, respectively. The faster rate of consolidation and higher magnitude of settlement were achieved at a higher voltage gradient. Higher reduction of water content up to 9% and increase in shear strength up to 144% were obtained using electro-osmotic consolidation with PVD compared to using PVD only, especially when using the carbon electrode. The liquid limit, plastic limit, and plasticity index were increased due to increased salinity during electro-osmotic consolidation. With its total dissolved salts of 4050 ppm well below the 6000 ppm limit, the soft Bangkok clay is considered to be suitable for electro-osmotic consolidation.
Cell Size for Water Content-Dielectric Constant Calibrations for Time Domain Reflectometry
Authors: Suwansawat S , Benson CH 
Published: February 2009

AbstractTime domain reflectometry (TDR) is a nondestructive electromagnetic technique used to measure the volumetric water content of soil. A key component of the method is the calibration equation relating the apparent dielectric constant (Ka) to the volumetric water content (ϑ). In this study, tests were conducted to evaluate dimensional requirements for a TDR calibration cell. The results show that a PVC cylinder having the same dimensions as a standard compaction mold (diameter = 102 mm, height = 116 mm) is a suitable calibration cell for two-rod TDR probes having diameter = 4 mm, center-to-center spacing = 30 mm, and length = 80 mm. The cell can also be used for three-rod probes having the same dimensions as the two-rod probe, and a center-to-center rod spacing of 20 mm. Calibrations made with this small cell are essentially identical to calibrations made in a much larger cell where boundaries are unlikely to be important.
Constant Rate of Strain Consolidation Equipment and Procedure for Stabilized Soils
Authors: Kassim KA , Clarke BG 
Published: February 2009

Abstract
Stiffness, that is, the relationship between applied stress and resulting strain, is a function of applied stress and, in the case of stabilized soils, age. For that reason the standard odometer test may be unsuitable as it can take several days to complete a test and in that time the stiffness will change regardless of stress changes. The constant rate of strain consolidation (CRS) test may be the preferred test to assess the stiffness of stabilized soils. A simple CRS cell has been developed to operate with a standard triaxial loading frame. Comparisons between the results of oedometer tests and CRS tests show that the test procedure and equipment is valid. Tests on stabilized soils show the importance of minimizing the time of a test since there is an increase in stiffness with age.