bluuebunny/crossref_metadata_2025 huggingface dataset:
Measuring the Effect of Mixed Grading on the Maximum Dry Density of Sands
Authors: Barton ME , Cresswell A , Brown R
Published: February 2009

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

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

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

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

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

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

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

Time 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

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.
A Triaxial Testing System to Evaluate Stress-Strain Behavior of Soils for Wide Range of Strain and Strain Rate
Authors: Santucci de Magistris F , Koseki J , Amaya M , Hamaya S , Sato T , Tatsuoka F
Published: February 2009

Some important modifications were made to an existing triaxial testing apparatus to more accurately evaluate the stress-strain behavior of geomaterials for wide ranges of strain and strain rate. An electro-mechanical loading device was specifically designed to control strain states and stress paths and to study the quasi-elastic properties of geomaterials at any given stress state. The device is now driven by an a-c servo motor, allowing for changing the strain rate about three orders of magnitude without any intermission in each test. A 16-bit A/D card has been adopted also to increase the resolution in data acquisition. The long-term stability of a local axial gage, LDT, has been ensured to evaluate creep deformations as well as post-creep behavior of geomaterials, which should be properly understood for many practical engineering applications. High performance of the system is demonstrated by presenting some typical results from undrained cyclic tests at very small strain levels for a wide range of strain rate and an undrained monotonic loading test for a wide strain range, both on a compacted silty sand. It is shown that the equivalent Young's modulus and damping ratio at very small strains have a clear sensitivity to both strain rate and ageing period. For monotonic shearing tests in a wide range of strain, the isotach property and the effects of changes in the strain rate are also presented.
Model Studies of the 1988 Kettleman Hills Landfill Slope Failure
Authors: Chang M-H , Mitchell JK , Seed RB
Published: February 2009

The paper describes physical model studies of the 1988 failure of Unit B-19 waste landfill at the Kettleman Hills Landfill, Kettleman City, California. Six 1/150 scale models were tested under 1-g (g = gravity) conditions. Aims of the study were to confirm the mode of failure and to provide a better understanding of the sliding mechanism. Results showed that the failure conditions (e.g., slide direction, magnitude, and surface cracking, etc.) of the models agreed very well with those of the actual landfill. The study indicated that the sliding of model fills occurred as a coherent mass, with slip surfaces located at the interface within the underlying liner system. Internal shears and surface cracks were formed in the slide mass due to the noncircular configuration of the slip surface. Displacement paths suggested the sliding of model landfill was essentially a translational movement of a three-block system. The models accurately reproduced the 1988 Kettleman Hills Landfill failure and provided information that enabled development of an analysis method for evaluating the three-dimensional stability of waste landfills against sliding along an underlying linear system (Chang 1992).
Shear Banding in a Sedimentary Soft Mudstone Subjected to Plane Strain Compression
Authors: Hayano K , Maeshiro T , Tatsuoka F , Sato T , Wang L , Kodaka T
Published: February 2009

A plane strain compression (PSC) testing system to observe shear banding in softrock was developed. The deformation characteristics of shear band in a sedimentary soft mudstone were evaluated by locally measuring axial and lateral deformations of specimens in drained PSC tests. Shear deformation and dilatancy of shear band that occurred between the peak stress state and the start of the residual stress state were on the order of 1 and 0.5 mm. Dilatancy of the shear band continued during the residual stress state, resulting in a high-residual friction angle mobilized along the shear band. Shear band deformation characteristics of two other sedimentary softrocks were obtained from axial strains measured locally in triaxial compression tests based on the stress-state dilatancy relationship obtained from the PSC tests.
An Innovative Method of Load Testing Deep Foundations
Authors: Ooi PSK , Frederick LL
Published: February 2009

Current procedures for high strain dynamic testing of piles require estimation of the dynamic resistance. This paper presents an innovative method of load testing deep foundations that estimates the pile capacity directly. By placing and monitoring sensitive force sensors near a pile head, a force-time curve can be generated when an impact load is applied. The unique stages of the impact event are captured in a force-time plot from which the ultimate pile capacity is estimated directly. Similar sensors can be placed at the pile toe to estimate end bearing. Ancillary equipment, consisting of the same force sensors sandwiched between two thin plywood boards, can be placed on top of production piles during driving for capacity estimates. Pile capacities derived have been found to be in reasonably good agreement with values from two static load tests. It also provides information on pile integrity during driving.
Specimen Size Effects for Fiber-Reinforced Silty Clay in Unconfined Compression
Authors: Ang EC , Loehr JE
Published: February 2009

A series of laboratory unconfined compression tests were performed on specimens of a compacted silty clay to evaluate how the size of specimens used for strength testing of fiber-reinforced soil affects the measured strength and stress-strain properties. The results of these tests indicate that there is a significant effect of sample size both in terms of the magnitudes of the measured strengths as well as in terms of the variability of the measured strengths. The effects of specimen size were found to be most important for specimens compacted dry of the optimum moisture content. While no clear threshold specimen size was identified, the data indicate that specimens of 70 mm or greater in diameter are likely to produce strengths that are reasonably representative of the “mass” properties of fiber-reinforced soils.
Evaluation of Multi-Electrode Earth Resistivity Testing in Karst
Authors: Roth MJS , Nyquist JE
Published: February 2009

Multi-electrode resistivity testing is quickly becoming a common tool for geotechnical site investigation in karst areas, particularly areas with clay soils. To study the effectiveness of this method, data from over 140 resistivity tests at two sites were collected and compared with the results from 51 borings. The tests were conducted to evaluate the effect of electrode arrangement and the presence of conductive utilities, to determine the repeatability of the results, and to evaluate the effectiveness of the method in determining depth to bedrock and the location and size of voids. The results demonstrated that multi-electrode resistivity can reliably map depth to bedrock with excellent repeatability, although there was some smoothing in areas where the true bedrock surface is highly irregular. Underground utilities presented the most serious problem when oriented parallel to the resistivity electrode spread. The multi-electrode resistivity method was not as effective at locating voids. The strongest indication was provided by comparison of the resistivity data from lines collected perpendicular and parallel to the geologic strike because the results tended to be very different when collected over a cavity. Recommendations for using resistivity testing as a site investigation tool are given.
A Testing Unit for Monitoring Wall Permeability In Situ
Authors: Brauns J , Bieberstein A , Reith H
Published: February 2009

It is difficult to prove the permeability characteristics of a cut-off wall. For this reason, a special testing unit for monitoring the wall permeability in-situ was developed. The testing unit can easily be installed at any depth of a cut-off panel by hanging it into the fresh slurry. After the installation it remains in the cut-off panel and can be used for a long period. The application and evaluation of tests results are described.
Influence of Matric Suction on the Results of Plate Load Tests Performed on a Lateritic Soil Deposit
Authors: Costa YD , Cintra JC , Zornberg JG
Published: February 2009

This paper evaluates the influence of soil matric suction on the results of plate load tests conducted in an unsaturated, lateritic soil deposit at a depth of 1.5 m. Soil suction was monitored during the tests with tensiometers installed at the bottom of the testing pit. Field test results show that small increases in matric suction lead to substantial increases in bearing capacity of the soil-plate system. In situ experimental loading-collapse (LC) and suction increase (SI) yield surfaces are proposed for the soil investigated. Changes in matric sucion were observed to significantly influence settlement response, particularly for high levels of surcharge load. The rate of settlement shows a non-linear decreasing trend with increasing soil matric suction.
Centrifuge Modeling for Undergraduate Geotechnical Engineering Instruction
Authors: Dewoolkar MM , Goddery T , Znidarcic D
Published: February 2009

A small, simple, and economical instructional centrifuge has been developed at the University of Colorado at Boulder to assist in undergraduate geotechnical engineering education. Centrifuge experiments on stability of slopes and retaining walls have been developed. These experiments are conceptually simple, yet fundamental, and do not require elaborate instrumentation and data acquisition. Classical failure patterns discussed in the class can be reproduced in the models. Experimental results can be used to verify such theories as undrained slope stability analysis and Rankine's or Coulomb's lateral earth pressure theories. Each of the tests can easily be conducted up to four to five times in a 2-h laboratory session. Comprehensive laboratory reports can be generated by students discussing both qualitative and quantitative aspects of the tests in relation to the theoretical concepts taught in the classroom. In addition to the experiments on slope stability and lateral earth pressures, demonstration experiments on footings and reinforced earth slopes have also been conducted using the instructional centrifuge.
Experimental Evaluation of Consolidation Behavior of Stiff Clay Lumps in Reclamation Fill
Authors: Leung CF , Wong JC , Manivanann R , Tan SA
Published: February 2009

When stiff clay dredged from the seabed is deposited by barge as fill material, large voids exist between the stiff clay lumps in the reclamation fill. One major concern is that the voids may close up upon loading, resulting in a large and sudden increase in the fill settlement. In the present study, an experimental investigation is carried out to examine the behavior of fill made up of dredged stiff clay lumps using a large one-dimensional compression apparatus and a centrifuge modeling technique. The results revealed that much of the inter-lump voids close up during the preloading stage. In addition, the rate of consolidation of the lumpy fill is significantly faster than that of homogeneous clay with the difference in consolidation rate diminishing with increase in loading pressure. The effects of lump shape and size, and original shear strength of in situ clay on the performance of lumpy fill, are also investigated.
Changes in Clay Swelling and Shear Strength Properties with Different Sample Preparation Techniques
Authors: Attom MF , Abu-Zreig MM , Obaidat MT
Published: February 2009

This paper presents the effect of compaction methods on soil swell pressure, unconfined compressive strength, and swell potential of three types of soils in Jordan. Undisturbed and disturbed soil samples were collected from the field and used for this study. Compacted soil specimens were prepared using dynamic compaction, static compaction, and kneading compaction. Swell potential test, swelling pressure test, and unconfined compression test were conducted on identical samples compacted by different methods, and having similar initial conditions to the undisturbed samples. Other sets of experiments were also conducted to examine the influence of initial water content on swell pressure and unconfined compressive strength under different compaction techniques. Results indicated that the undisturbed samples have the highest swelling pressure and swell potential values followed by dynamic compaction, while kneading compaction gave the lowest values for the three soils. For the same soil, it has been found that the swelling pressures of the undisturbed samples were 1.5, 1.96, and 3.07 times of that for the dynamic, static, and kneading compaction, respectively. Similar trends were obtained with regard to unconfined compressive strength and swell potential. The unconfined compressive strengths of the undisturbed samples were 1.35, 1.6, and 2.53 times higher than that of the soil specimen compacted according to the dynamic, static, and kneading procedures, respectively.
Determination of Critical State Parameters in Sandy Soils—Simple Procedure
Authors: Santamarina JC , Cho GC
Published: February 2009

The critical state is arguably the most robust criterion for strength design, including post liquefaction strength. The conventional triaxial test is used for the determination of critical state parameters; however, it is time-consuming and the required set of tests is relatively expensive for common geotechnical tasks. A simplified test procedure is developed to determine the critical state line in sandy soils. The procedure is reliable, economical, and fast. In order to verify the simplified test procedure, results are compared against critical state parameters determined in conventional triaxial tests. The comparison shows very good agreement between critical state parameters obtained with the suggested procedure and those gathered with triaxial testing. Limitations are identified.
Laboratory Characterization of Stress-Strain Behavior of Soils by Stress and/or Strain Path Loading
Authors: Vaid YP , Eliadorani A , Sivathayalan S , Uthayakumar M
Published: February 2009

Strain path control during loading in addition to the often-desired stress path control is shown to constitute a versatile method of characterizing stress-strain response of soils in the laboratory. It allows probing stress or strain increments to be applied in any direction at an ambient effective stress state to study the stress history and stress-path-dependent response. The capture of even the potential strain softening and the post peak behavior is made possible with no difficulty. Some unique capabilities of a triaxial and a multiaxial hollow cylinder torsion apparatus of these types are demonstrated by results of tests on a saturated sand.
Extracting Piezometric Level and Hydraulic Conductivity from Tests in Driven Flush-Joint Casings
Authors: Chapuis RP
Published: February 2009

Permeability tests in borehole casings must satisfy many conditions to give reliable results. A test can be done only in a driven flush-joint casing. When a casing is rotated, its contact against the adjacent soil does not provide a seal good enough to assess the local k-value. Only water injection can be used (either falling-head or constant-head) because water extraction creates upward forces that destabilize the soil and induce either soil heave or clogging. Other conditions are explained in the paper. Interpretation methods differ mainly in their assumptions about solid matrix deformability during the test. The paper describes an interpretation method based on the equation of mass conservation: it leads to a graph of downward water velocity in the casing. This graph provides the error made in the quick field estimate of piezometric level (PL) for a tested zone. Several examples are provided, including tests that produce hydraulic separation between soil and casing. The PL obtained with this graph was always similar to that given by a monitoring well installed at the same level after borehole completion. From analysis of many tests at the same site, information can be obtained on natural water seepage conditions using a variation of PL versus depth.
Empirical Function Representing the Shear Strength of Unsaturated Soils
Authors: Miao L , Yin Z , Liu S
Published: February 2009

The general research situation of the shear strength of the unsaturated soils is reviewed in the paper. The hyperbola model is put forward based on the triaxial test results of the unsaturated soils. It can be used to predict the suction strength. The predicted results compare well with the measured data and show that the hyperbola model can be used to represent the shear strength of unsaturated soils.
Influence of the Loading Apparatus on the Stresses within Biaxial Specimens
Authors: Bobet A
Published: February 2009

The design and construction of a biaxial loading machine is presented in this paper. Two major concerns are addressed in designing the machine: alignment between the loading axes and the specimen, and shear stresses (friction) that may develop between the loading platens and the specimen. The alignment requirement is solved by constructing a multi-frame machine in which the horizontal frame hangs from the top of a 890 kN (200 Kip) Baldwin machine by cables and springs, thus allowing displacements and rotations of the horizontal loading axis with respect to the vertical axis. Shear stresses between the platens and the specimen are reduced by using brush platens. These platens are made of independent plates flexible enough to bend and thus reduce the transmitted friction. Numerical modeling of the interaction between the machine, platens, and the specimen shows the advantage of the multi-frame machine with brush platens over other combinations. With a multi-frame machine with brush platens, the stress field is uniform at the center of the specimen; differences between the applied and the obtained stresses are mostly within a 10% error, and are produced at the top boundary of the specimen. A single-frame machine with brush platens produces a nonsymmetric stress field and increases the confinement in the specimen as much as 5%. Rigid platens produce unloading within the specimen, which will cause an overprediction in the strength of the material.
Evaluation of Geomembranes Using an Ultrasonic Method
Authors: Yesiller N , Sungur S
Published: February 2009

An ultrasonic testing procedure was developed to evaluate geomembranes. The pulse-echo inspection technique was used on the surface of geomembranes without disturbing the material. The equipment required consists of a P-wave transducer, a pulser-receiver, and a signal acquisition system. Travel time of ultrasonic waves and waveform energy are measured to evaluate the condition of geomembranes. Laboratory tests were conducted to assess the effectiveness of the method. Defects that simulate installation damage and various in-service degradation conditions were induced on samples. The defects were identified with the ultrasonic method at a success rate higher than 98%. Changes in the thickness or the microstructure of the geomembranes were identified. Surficial and internal defects were located. Defects that were not visible from the measurement surfaces were identified. This method appears promising to monitor the condition of geomembranes in the laboratory or in the field and to assess in situ damage to geomembranes.
Properties and Behavior of Raw Sludge Mixed with Pulverized Fuel Ash and Lime
Authors: Yin JH
Published: February 2009

Raw sludge from a water treatment plant and pulverized fuel ash (PFA) from a coal-fired power plant are normally considered to be waste. The raw sludge is usually soft and weak, and takes a large area for storage if stockpiled on open ground, or requires a heavy dam/retaining structure if impounded. Strength and stiffness of the sludge are important parameters for the design and construction of facilities for sludge storage. This paper presents results from a series of tests on geotechnical properties and behavior of local raw sludge mixed with PFA and lime. The focus is on the improvement of the shear strength and stiffness of the sludge by mixing with different ratios of PFA and percentages of lime. Test results are presented and analyzed. Relationships between unconfined compression strength (UCS), PFA/Sludge (P/S) ratios, and lime contents are obtained. Relationships between the effective friction angle (and cohesion) and P/S ratios for 8% lime are also obtained from consolidated undrained (UC) triaxial tests. Correlation between secant Young's modulus E50 and the peak deviator stress qpeak is established.
A Multisleeve Friction Attachment for the Cone Penetrometer
Authors: DeJong JT , David Frost J
Published: February 2009

Accurate knowledge of the strength of soil-geomaterial interfaces is becoming of increasing importance in geotechnical engineering. Systems whose performance is heavily dependent on soil-geomaterial interfaces include deep foundations, synthetic impervious liners, trenchless technologies, and an assortment of earth retaining structures. The strength of the interface is typically estimated by applying adjustment factors to values of soil or interface strength measured in laboratory tests. These adjustment factors are intended to correct for differences between the test and anticipated operating conditions such as variations in soil type and density, strain rate, surface roughness, or confining stress and are often empirically based with little theoretical underpinnings. Of these adjustment factors, the surface roughness is considered to be of utmost importance in that it has the potential to alter the interface strength by 100% or more.

This paper describes the development of a new multisleeve Friction attachment for the cone penetrometer that allows for direct in situ measurement of the relationship between interface strength and surface ronghness. As discussed herein, the ability of the attachment to quantify this relationship, in conjunction with additional ongoing research, provides the opportunity to improve the design of friction dependent systems, as well as site characterization. A key characteristic of the penetrometer attachment is the ability to obtain four individual sleeve friction (fs) measurements at each elevation within a sounding, in addition to the conventional Cone Penetration Test (CPT) fs measurement. This allows for direct in situ analysis of the effects of sleeve roughness on the fs measurement. Considerations pertinent to the development of the device including assessments of the conventional CPT fs measurement and soil geomaterial interface mechanisms are first presented. A description of the new penetrometer attachment including key characteristics and capabilities follows. Finally, validation of the operation of the device through laboratory and field tests is described, and future applications of the attachment are discussed.
Design Considerations Related to the Performance of Erosion Control Products Combined with Soil Bioengineering Techniques
Authors: Di Pietro P , Brunet G
Published: February 2009

The combined use of erosion control products (commonly referred to as “inert materials”) and live plants for the restoration of waterways requires standardization of terminology, material function, and design criteria for each system. This will yield the combination of a correct engineering approach with the appropriate best management practices to produce the desired long-term performance. This paper will focus on combining soil bioengineering techniques with sound engineering practices when dealing with soil erosion or overall instability problems. The performance will be discussed with a proposed multidisciplinary approach, in order to achieve the desired environmental effect. The concept of “Minimum Energy Level” will also be discussed to identify the best environmentally compatible solution, typically ranging from simple to complex design scenarios. Due to the combined presence of inert materials and living plants, the field performance of the various solutions will evolve over time. This contributing factor will require testing the product strength characteristics both in the short and long term, in close relationship with the field performance criteria, in order to understand their function in waterways. The dynamics of the project site and the overall structural stability are greatly affected by these decisions.
Development of a Methodology for Evaluating Subsurface Concentrations of Pollutants Using Electrical Polarization Technique
Authors: Mohamed AMO , Said RA , AlShawawreh NK
Published: February 2009

The study involves the introduction of an electrical polarization technique to in situ analysis of subsurface pollutants by measuring and analyzing the variation of soil-pollutant dielectric properties as a function of concentration of the pollutant in the soil. The developed system was modeled using transmission line theory, and the electrical parameters were optimized using the electrical circuit simulation software (Circuit Maker™) and the experimental results. Also, a methodology was developed to evaluate soil pore fluid concentrations via the use of two important electrical properties for the medium, which are resistance and capacitance.
Stabilization of Dune Sand Using Foamed Asphalt
Authors: Asi IM , Al-Abdul Wahhab HI , Baghabra Al-Amoudi OS , Khan MI , Siddiqi Z
Published: February 2009

Foamed asphalt technology has increasingly gained acceptance as an effective and economical soil improvement and stabilization technique, mainly because of its improved aggregate penetration, coating capabilities, and handling and compaction characteristics. This laboratory research program was carried out to investigate the feasible use of foamed asphalt technology in Saudi Arabia to improve the prevalent dune sands for possible use as a base or subbase material. Several variables were investigated to evaluate the relative improvement of dune sand as well as to permit the development of design procedures for the future use of foamed asphalt technology in the harsh climatic conditions of eastern Saudi Arabia. Statistical analysis of the results was employed to verify the effects of emulsified asphalt and foamed asphalt treatment, with and without the addition of Portland cement, on the strength characteristics of the treated mixes. The results displayed significant improvement in the performance of dune sand foamed asphalt mixes, as compared to that of the emulsified asphalt mixes.
Bidimensional Swell Effect on Accuracy of Footing Heave Prediction
Authors: Abdullah WS
Published: February 2009

The direct method (the Texas Highway Department Method TEX-124-E) and the Jennings and Knight “Double Oedometer Method” are widely used by practicing engineers for heave prediction of footings located on expansive soils. These methods are simple to use and yet simulate field conditions too. These two methods, however, are characterized by overpredicting the value of footing heave. The degree to which these methods overpredict heave is dependent on the soil conditions, as well as the applied footing pressure. The present work studied the influence of footing pressure on the precision of the two mentioned methods. It was found that the factor needed to adjust the predicted footing heave by these methods (“Heave Reduction Factor Rf”) decreases markedly with increasing footing pressure. The heave reduction factor Rf decreased from 0.92 and 0.88 to 0.62 and 0.53 for the direct method and the double oedometer method, respectively, as the footing pressure increased from 25 to 50 kPa. Soil strength depends upon the level of soil suction. Soil wetting contributes to reduction in soil suction, and consequently, to a loss in bearing capacity. Therefore, a test experiment with footing pressure of 100 kPa suffered bearing capacity failure after about one day since the beginning of the test experiment.
Improved Complex Permittivity Measurement and Data Processing Technique for Soil-Water Systems
Authors: Scholte JW , Shang JQ , Rowe RK
Published: February 2009

The complex permittivity of soil-water systems is a function of a number of soil properties. By measuring the complex permittivity, one could quantitatively evaluate the soil behavior under existing conditions in the field, as well as identify changes in the environment. This paper describes the improvement of a measurement and data processing technique for the analysis of the complex permittivity of soil. A sample holder described in a previously published study is modified to reduce errors from sample handling and to increase the measurement accuracy and capacity. A modular unit is designed to measure the static conductivity and the complex permittivity of the soil simultaneously. The data processing technique is also presented, including the identification of the frequency for data analysis and extraction of the static conductivity from the measured loss factors. The results of the complex permittivity measurements on a compacted natural clayey till are presented to demonstrate the typical relationships of the soil complex permittivity as they are related to the soil volumetric water content, bulk density, and salinity.
Foundations on Rock, Second Edition
Authors: Pincus HJ
Published: February 2009

In the author's introduction to the first edition of this book, published in 1992, he states that the book's main purpose is “. . .to assist the reader in the identification of potentially unstable rock foundations, to demonstrate design methods appropriate for a wide range of geological conditions and foundation types, and to describe rock construction methods.” The intended reader, he says, is the design professional in geotechnical engineering. In his introduction to the second edition, the author states that design and construction practices have not changed since the writing of the first edition, hence the reason for writing the second edition is to include updated technical material and to “. . .add information on new projects where valuable experience on rock foundations has been documented.” The coverage in the second edition fulfills the author's stated intentions.
Statistical Analysis of Fatigue Related Microstructural Parameters for Airframe Aluminum Alloys
Authors: Liao Min , Chisholm Kyle , Mahendran Mario
Published: February 2009

This paper presents the results of statistical analysis of the fatigue related microstructural parameters, mainly on constituent particles and pores, in 7050-T7452 aluminum forging materials. The statistical distributions of the particle and pore area data, which were obtained from the metallographic measurements on polished surfaces, were fitted well with three-parameter lognormal functions. Comparative studies were carried out for the particle and pore size distributions between the core and periphery materials, and between the hand and die forging materials. An extreme value theory-based model was investigated to correlate the overall material particle distribution with the fatigue crack-nucleating particle distribution. The results indicated that the particle size is not the only parameter affecting the fatigue process; other parameters, such as grain size and grain orientation, are also important parameters for microstructure-based fatigue modeling. Therefore, orientation image microscopy (OIM) analyses were carried out on pristine 7050 samples, on different planes, to determine the grain orientation distributions. Finally, a preliminary OIM analysis was performed on a fractured sample to measure the misorientation angles between the grains near the crack nucleation and short crack regions. It is expected that the test observations and quantitative microstructural data could help to understand the effects of microstructure on the fatigue process and develop a microstructure-based fatigue modeling.
The Contribution of Materials Technology to Power Generation
Authors: Gemmill MG
Published: February 2009

The scientific principles governing metal behavior will be considered in regard to creep, fracture, and corrosion processes as they relate to the successful development of materials for high temperature engineering applications.

In the past decade the emphasis in the design and development of land power plants has shifted from the aim of higher thermal efficiency to one of greater plant component reliability. This has brought about a corresponding need to understand existing materials more thoroughly, rather than to seek new material compositions. The consequence of this will be examined in the context of fossil fueled boilers, nuclear reactors of various types, and steam and gas turbines.
Present Status of ASTM Tracking Test Methods
Authors: Mitchell GR
Published: February 2009

Three standard tracking test methods have been developed, which are in active use in evaluating materials for medium voltage applications of electrical insulation. A fourth method, intended for evaluation of materials for low voltage applications, is in the interlaboratory development stage. A fifth method is being developed specifically for outdoor medium voltage insulation applications. Each of the test methods exhibits different advantages and disadvantages. Test methods must be selected based on testing objectives.
Modified Centrifuge Technique for Hydrolytic Stability of Neopentyl Polyol Ester Lubricants
Authors: Pace JA
Published: February 2009

A modification of the ASTM Test for Hydrolytic Stability of Hydraulic Fluids (Beverage Bottle Test Method) [D 2619-67 (1972)] is proposed to permit the application to fluids with specific gravities near to that of water. Data obtained in applying this modification to MIL-L-23699 “Lubricating Oil, Aircraft Turbine Engine, Synthetic Base” are presented.
Estimation of Skid Numbers from Surface Texture Parameters in the Rational Design of Standard Reference Pavements for Test Equipment Calibration
Authors: Britton SC , Ledbetter WB , Gallaway BM
Published: February 2009

Accurate measurement of highway skid resistance has required the application of appropriate reference standards for the calibration of locked wheel skid trailers [ASTM Test for Skid Resistance of Paved Surfaces Using a Full-Scale Tire (E 274-70)] used as test equipment. This investigation was concerned with the development of criteria needed for the design of primary standard reference pavement surfaces.

A review of previous research indicated that the pavement variables influencing tire-pavement friction should be expressed in terms of six surface texture parameters. Pavement macrotexture, with characteristic dimensions between 2 and 16 mm, was expressed in terms of asperity size, spacing, and shape. The remaining three parameters, which described asperities with characteristic dimensions less than 2 mm, were expressed as microtexture size, spacing, and shape. Published studies indicated that surface texture influenced wet tire-pavement friction through water drainage, hysteresis losses in the tire, and adhesion in the tread contact area. Published equations relating pavement texture and firction have been derived on the basis of oversimplified models and, thus, required considerable experimental support to be applicable to the design of reference pavement surfaces. In particular, the theory treating the effect of surface microtexture on the adhesion component of friction was found to be incomplete, both analytically and experimentally.

A parametric study of the effect of pavement texture on skid number, comprising laboratory experiments with model pavement surfaces, offers new insight to a solution of the problem.
Sampling of Maintenance Dredgings
Authors: Hummel PL , Krizek RJ
Published: February 2009

The sampling of polluted maintenance dredgings during the different stages of a typical dredging and disposal operation presents a variety of difficult problems, and the results of tests on so-called representative samples must be evaluated with due regard for the manner in which the samples ere obtained. Described in this paper are the techniques employed and the special equipment developed to sample bottom sediments, materials from the hopper of a dredge, slurries from a discharge pipe, and soft materials from a partially consolidated hydraulic landfill; of special interest is the experience with lightweight, manually operated piston samplers in soft fills. Some appreciation for the variability of samples is given, and suggestions for improvements are advanced.
Acoustic Emission Response of Dry Soils
Authors: Lord AE , Koerner RM
Published: February 2009

An investigation into the acoustic emission response of a series of axially stressed dry soil samples is presented in this study. The correlation between acoustic emissions and strain is noted and strongly suggests that acoustic emission monitoring of soil masses may lead to a nondestructive field evaluation technique.

Preliminary insight into the fundamental mechanism of acoustic emissions in dry soils is presented. It is seen that granular soils yield higher accumulated emission counts than fine-grained soils. The summary curves which are presented show this clearly defined trend and can be regarded as laboratory calibration curves for the soils which were tested.
An Unconfined Direct Tension Test for Compacted Clays
Authors: Ajaz A , Parry RHG
Published: February 2009

Although problems associated with total stress tension arise in soil structures such as earth embankments and multilayer pavements, no standard tension test for soils exists. An unconfined direct tension test, either strain controlled or load controlled, is described, which can be used to determine the tensile (total) stress-strain characteristics of compacted clays. The overall tensile strains in the specimen are determined by observing the displacement of two surface markers spiked into the specimen with a displacement measuring optical device (DMOD) capable of measuring to one-micrometer displacement. An alternative radiographic technique of monitoring strains has shown that the distribution of average tensile strains in the specimens is substantially uniform. Moreover, the failure of the tension specimen occurs in midsection, indicating a uniaxial transmission of tensile force to the specimen. Comparison of standard triaxial unconfined compression tests with unconfined tension tests shows that elastic moduli are not equal in compression and tension for compacted clays at a given moisture content.