bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Deformation Properties of Collapsible Soils
Authors: Reznik YM
Published: February 2009

Mechanical properties of loessial soils are the functions of their in-situ physical conditions, geological history, as well as actual load distribution at the site of interest. It is well known that the bearing capacity of loesses and loessial soils decreases with an increase in their porosity and water content. Physical and mechanical properties of soils can be determined by different laboratory and field methods. Technical and economic advantages and/or disadvantages of utilizing these methods are discussed. Field and laboratory test results are presented in tabulated form and analyzed. The paper describes the technique of plate load tests performed at three construction sites located near the city of Odessa (Soviet Union). Information obtained during the field tests was compared with results of soil tests carried out in the laboratory on hand-carved (undisturbed!) specimens.
The Thermal Probe—Measurement of the Thermal Conductivity and Drying Rate of Soil in the Field
Authors: Ewen J , Thomas HR
Published: February 2009

The thermal probe is a metal rod with an internal heating element and temperature sensor. In the field it is pushed into a predrilled hole in otherwise undisturbed soil, and the thermal properties of the soil are estimated from the temperatures recorded at intervals after a constant power is supplied to the heating element. The following are discussed in this paper: the theory behind the methods for identifying the thermal properties, the design of the probe and auxiliary equipment, the results of laboratory trials, the field testing procedures, and the results of field trials. The probe, the theory, and the testing procedures extend the application of thermal probes from their traditional use for thermal conductivity measurement beyond their more recent use for the study of the thermal stability of soil near underground power cables to the measurement of native thermal conductivity, dry thermal conductivity, and the rate at which drying fronts move within the soil.
Strain-Controlled, Variable Frequency Cyclic Loading System for Soft Soils
Authors: Kramer SL , von Laun F-Y , Sivaneswaran N
Published: February 2009

A mechanical, strain-controlled, variable frequency loading system has been developed for cyclic testing for soft soils. The system consists of a variable speed driving system (variable speed electric motor) and a rotation/translation converter (crank and crank-shaft system). It is capable of producing a simple harmonic time history of axial strain at an infinite number of desired strain levels. The loading system is simple and can be easily fabricated at low cost. Performance of the system is verified by performing frequency sweep tests on a San Francisco Bay mud specimen.
Strength Changes in Sand Following Cyclic Shear
Authors: Turner JP , Kulhawy FH
Published: February 2009

Static torsional simple shear tests were performed on poorly graded sand, with and without prior cyclic loading, to evaluate changes in static shear strength. Specimens were prepared at three densities (loose, medium, and dense) and were subjected to one of three levels of cyclic loading corresponding to 0.25, 0.50, or 0.75 times the static stress level, causing failure with no prior cyclic loading. The test results indicate that post-cyclic shear strength increases in specimens that are contractive and decreases in specimens that are dilative during cyclic loading. Results showing the change in friction angle as a function of initial density and level of prior cyclic loading are presented. The observed behavior is consistent with a model that predicts strength changes following cyclic loading as a function of soil volume change characteristics and drainage conditions.
A Statistical Methodology to Analyze the Effect of Changes in Testing Technology on Measurement Results
Authors: Livneh M , Ben-Akiva M
Published: February 2009

In the field of soil mechanics and highway engineering, there is great interest in the comparison of two different instruments or two different measuring technologies that measure the same characteristics of given items (or samples). This interest holds also for comparison of semi-identical instruments having minor changes in a given testing technology. All such comparisons involve statistical methods which permit the researcher to estimate separately the natural variability of the characteristic and the variability caused by measurement errors. However, previous studies consider only two components of measurement error: (a) the random error of measurement and (b) the instrumental systematic additive bias, thus skipping over the important third component, i.e., the instrumental systematic multiplicative bias. This paper deals with the above-mentioned modifications for the two-instrument case of the randomized-pair comparison sets. It is shown that this case necessitates a preliminary assumption in order to identify the different errors in the statistical analysis. The appropriate assumption depends on the nature of the testing mechanisms as demonstrated in this paper by three examples involving testing with the dynamic cone penetrometer. Finally, it should be mentioned that the nonnormally distributed case is very frequent, especially when the pool of results includes tests performed on different types of soils, even when the results of each type are regarded as normally distributed with different means and variances. Thus, the paper suggests sensitivity tests for the calculated parameters which include the above-mentioned case. Also, in the paper's appendix, the known t and F tests are modified for the same purpose.
Simulation of Ground Loss in Centrifuge Model Tests
Authors: Stone KJL , Brown TA
Published: February 2009

This note presents a computer-controlled mechanical system developed to simulate ground loss in centrifuge model tests. The main application of the system to date had been in the field of mining subsidence prediction. This involves the replication of total extraction of thin mineral seams at depth. A brief overview of total extraction methods is presented, and the performance of the system to replicate these methods in centrifuge model tests is briefly illustrated. The versatility of the system to other applications involving ground loss or boundary displacement problems is also illustrated.
Soft Oedometer—A New Testing Device and Its Application for the Calibration of Hypoplastic Constitutive Laws
Authors: Kolymbas D , Bauer E
Published: February 2009

The problem addressed is how to obtain the material parameters of soils and other granular materials by means of a simple and fast laboratory test which fulfills the requirement of homogeneous specimen deformation. A new laboratory testing device called “soft oedometer,” characterized by an extensible lateral supporting ring, makes it possible to measure not only the vertical but also the lateral stress and strain of the specimen. The construction principles are presented as well as test results. The suggested evaluation of the latter makes it possible to determine the friction angle and all parameters entering hypoplastic constitutive equations without the need to achieve the limit state.

In the present paper, the new apparatus is shown to make possible a particular test (oedometric test) which serves to fit a mathematical model called “hypoplastic constitutive law.” Using this model, other test types can be simulated realistically.
Swelling Pressure Behavior Under Controlled Suction
Authors: Habib SA , Karube D
Published: February 2009

An experimental study has been conducted to study the swelling pressure behavior of expansive soil in both vertical and lateral directions simultaneously under controlled suction. A series of one-dimensional consolidation tests was carried out on compacted soil specimen using a newly developed oedometer with devices for controlling suction and measuring lateral pressure. The test results show that while both vertical swelling pressure and lateral pressure are path dependent, there are lower and upper values of mean effective pressure depending on initial soil conditions. Based on this approach, the safe swelling pressure can be determined. The results of this method were compared with other results and found to be in agreement with the proposed one.
Evaluation of Fill Compaction
Authors: Sikh TS
Published: February 2009

Compaction was evaluated of existing fills at seven sites. The field densities were evaluated with three different techniques. These techniques included: (1) the sand-cone method, ASTM D 1556; (2) the drive-cylinder method, ASTM D 2937; and (3) a smaller version of drive cylinder that was driven manually into the ground. Two comparisons were made: between sand cone and drive cylinder (ASTM D 2937), and between sand cone and smaller (manual) drive cylinder. The results indicate excellent agreement. A linear regression analysis of all the data points indicates a correlation coefficient of 0.972.
Effects of Strain Rate on Instability of Granular Soils
Authors: Yamamuro JA , Lade PV
Published: February 2009

An experimental study of the effect of strain rate on the stability of granular soils at high pressures has shown that there is no apparent effect on the location of the instability line. However, during undrained triaxial compression tests the deviator stress, effective stress path, effective stress friction angle, and pore pressures are significantly affected by changes in strain rate. Strain rate effects during drained triaxial compression tests are also presented, but do not appear to be as significant as in undrained tests.
Preparation of Large-Size Cohesive Specimens for Calibration Chamber Testing
Authors: Voyiadjis GZ , Kurup PU , Tumay MT
Published: February 2009

This paper describes the design of an automated slurry consolidometer and calibration chamber system used to prepare largesize cohesive soil specimens for testing in-situ devices, model foundations, and ground anchors. A two-stage technique for the preparattion of homogeneous cohesive specimens subjected to a known stress history is described. Briefly summarized are the data acquisition/control system and the instrumentation details for monitoring the spatial pore pressure distributions in the specimen, the vertical and lateral stresses on the specimen, and specimen settlement during slurry consolidation and subsequent reconsolidation in the chamber. The specimens prepared were reproducible and of uniform quality as indicated by the settlement and pore pressure dissipation histories and by the water content results obtained from samples taken from chamber specimens. The homogeneity of the specimens is confirmed by the cone penetration test results.
Evaluation of the Drop Bar Test for Concrete and Rock Quality
Authors: Charlie WA , Ross CA , Skinner MM , Burleigh JB
Published: February 2009

The bearing capacity of rock foundations is being determined by the sound produced by impacting the foundations with a steel bar. This paper evaluates the sound and stress produced. Instrumenting the steel drop bar extends the capabilities of the test and makes the test less subjective. The steel bar produced a characteristic ringing sound when the specimen's unconfined compressive strength was greater than 5000 kPa or the compressional wave velocity was greater than 2400 m/s. The research suggests that the peak stress and sound frequency produced by dropping a steel bar can be used to evaluate in situ dynamic properties and, indirectly, in situ static properties of concrete and rock. A potential limitation of the noninstrumented bar is that the frequency of ringing (1770 to 10 070 Hz) is in the same frequency range that sensorineural hearing losses are known to occur with advancing age or noise exposure.
Preparation of Large-Size Laboratory Deposits of Cohesive Soil
Authors: McManus KJ , Kulhawy FH
Published: February 2009

High-quality, large-size cohesive soil deposits can be prepared in the laboratory using the slurry method, which has many advantages for research and calibration purposes. The requirements for such deposits are discussed, and details are presented of the apparatus used successfully to prepare deposits of Cornell clay. Fifteen medium-size deposits (0.6 m diameter by 1.2 m deep) and one large-size deposit (1.4 m diameter by 2.1 m deep) were prepared. The results from a large number of water content tests made during dissection of each deposit and from in situ shear strength tests show that the deposits were very uniform and that the soil properties were both predictable and repeatable from one deposit to another. Details of the construction and operation of the apparatus are given.
Axisymmetric Tension Testing of Geomembranes
Authors: Merry SM , Bray JD , Bourdeau PL
Published: February 2009

The newly developed axisymmetric tension test is useful in evaluating the performance of geomembranes subjected to out-of-plane stress conditions such as those that can develop due to localized subsidence under waste-containment cover and liner systems. In this paper, the equations necessary to describe the geomembrane stresses and strains during testing are derived, and equations used to calculate geomembrane stresses during axisymmetric field loadings are also presented and compared. Finally, the testing equipment and procedures are investigated.
In-Plane Flow of Four Geosynthetics for Landfill Drainage
Authors: Campbell RP , Wu JTH
Published: February 2009

The in-plane flow behavior of four geosynthetics, including three geonets and one geocomposite, for landfill drainage applications was investigated. Laboratory testing was performed to evaluate the effect of boundary material (cover material), hydraulic gradient, applied normal compressive stress, and time on the flow rate. The boundary materials investigated were a geomembrane, geotextile, sand, clay, two geosynthetic clay liners, and foam rubber. Testing was performed at hydraulic gradients from 0.03 to 1.0, with normal compressive stresses from 25 to 930 kPa. The highest flow rate was obtained with the geonet or geocomposite between two geomembranes. The flow rate was lower for the other configurations materials due to intrusion of the boundary material into the flow path. The type of soil used as a boundary material did not have a large effect on the flow rate. Foam rubber appears to be a suitable replacement for soil as a boundary material for flow testing. The flow rate was found to decrease with time due to creep of the geonet or geocomposite core and additional intrusion of the boundary material. Design implications based on the test results are addressed.
Torsional Motion Monitoring System for Small-Strain (10−5 to 10−3%) Soil Testing
Authors: Kim D-S , Stokoe KH
Published: February 2009

For accurate measurements of stress-strain hysteresis loops at strains below 10−3%, a torsional motion monitoring system was modified to incorporate micro-proximitors. A micro-proximitor system with enlarged target arms resulted in about 50 times higher resolution in motion monitoring than previously possible. The four proximitor signals (instead of two) were measured, compared, and averaged to insure that pure torsion of the system was generated and that any bending did not enter the measurement. Ambient noise was controlled by using a low-pass filter and/or a vibration isolation table. With this new system, shear modulus was measured at strains as low as 2 · 10−5%, and hysteretic damping was measured at strains as low as 6 · 10−5%. Below the elastic threshold strain, shear modulus of dry sand measured in the cyclic torsional shear test is independent of strain amplitude. Hysteretic damping exists below the elastic threshold and is independent of strain amplitude, even though the value is quite small.
A Critical Evaluation of the Gradient Ratio Test
Authors: Fannin RJ , Vaid YP , Shi Y
Published: February 2009

Tests performed in a permeameter have been used to evaluate the gradient ratio test method. The evaluation is based on observed variations of water head and permeability in the composite soil and geotextile specimen with respect to time and with imposed hydraulic gradient. A water pluviation technique was used to reconstitute homogeneous, saturated sand specimens in the permeameter at any targeted density. An energy dissipator was used to prevent disturbance of the top of the specimen by inlet water at large flow rates. Some physical clogging of the soil may result from a blinding action due to fines in the recirculating water. Biological clogging may also occur, but is eliminated by treatment of the water with an algicide.
The Effects of Particle Shape and Surface Roughness on the Hydraulic Mean Radius of a Porous Medium Consisting of Quarried Rock
Authors: Sabin GCW , Hansen D
Published: February 2009

The influence of particle shape and surface roughness on the hydraulic mean radius are investigated, and quantitative measures for each are proposed. A particle shape factor is estimated with the aid of a new mathematical approximation for the surface area of an ellipsoid. The particle surface roughness is calculated based on inferences made from surface area data previously obtained for a sample of rocks described in Garga et al. (1991). The effect of surface roughness on the hydraulic mean radius was found to be greater than that of shape for this sample of crusher-run quarried limestone. A diagram is presented to show the relative importance particle shape and surface roughness.
Water Content Relationships of a Sensitive Clay Subjected to Cycles of Capillary Pressures
Authors: Silvestri V
Published: February 2009

This paper presents the results of an experimental investigation carried out to determine the volume change response of a sensitive clay subjected to cycles of air pressure in a pressure plate apparatus. Several clay samples of varying initial water content were used in the test program. It was found that at high air pressures initially soft clay specimens become less compressible than initially stiff clay specimens of comparable water content. In addition, the clay became unsaturated at a water content varying between 25 and 30%.
A Method for Interpretation of Plate Load Test Results
Authors: Reznik YM
Published: February 2009

The selection of allowable pressure is one of the major problems in the foundation design process. Plate load tests are considered the most reliable sources for the determination of that parameter. This paper addresses the interpretation technique of plate load test results accepted in Eastern Europe/CIS (former USSR). The “four-point” method of the proportionality limit evaluation for a plate load-settlement curve is presented and analyzed. A simple formula describing bearing plate displacements under applied loads has been developed. A new approach for the selection of allowable pressure values is proposed, and a formula for allowable pressure calculations is derived. The values of soil allowable pressure calculated using the proposed formula are compared with proportionality limits found with the traditional “four-point” method.
Compressibility of Contaminated Fine-Grained Soils
Authors: Meegoda NJ , Ratnaweera P
Published: February 2009

An experimental study was performed to investigate factors that control the compression index of contaminated soils and to evaluate the applicability of the correlations proposed by Skempton (1944) and Arulanandan et al. (1983) for contaminated soils. The literature search indicated that the compressibility of a soil depends on mechanical as well as physicochemical factors. The addition of chemicals to a soil changes its pore-fluid properties, and causes a change in mechanical and physicochemical factors and hence its settlement characteristics.

Experimental results indicated that the compressibility of the two soils used in this study changed with the type and amount of chemicals in pore fluids. It was also found that the pore fluid viscosity influenced the compressibility of contaminated soils. Both correlations were unable to provide reasonable estimates of the compression indices for contaminated soils.

The electrical properties reflect the changes in physicochemical interactions but not the changes in mechanical factors due to soil contamination. Both mechanical and physicochemical factors control the compressibility and liquid limit of a soil but to a different degree. Therefore, the changes in mechanical factors brought about by changes in the pore fluid viscosities were included in the above correlations as correction factors. With the correction factors, both correlations appear to predict the settlement characteristics of the contaminated soils used in this study.
Improved Velocity Method for the Determination of Coefficient of Consolidation
Authors: Pandian NS , Sridharan A , Kumar KS
Published: February 2009

Parkin (1978) suggested the velocity method based on the observation that the theoretical rate of consolidation and time factor plot on a log-log scale yields an initial slope of 1:2 up to 50% consolidation. A new method is proposed that is an improvement over Parkin's velocity method because it minimizes the problems encountered in using that method. The results obtained agree with the other methods in use.
Cyclic Undrained Behavior and Liquefaction Potential of Sand Treated with Chemical Grouts and Microfine Cement (MC-500)
Authors: Maher MH , Ro KS , Welsh JP
Published: February 2009

The effect of chemical grouting on the response of sand to monotonic and cyclic load is evaluated. Triaxial compression (CD and CU) tests and cyclic triaxial tests are performed to evaluate the effect of chemical grouting on the potential for liquefaction flow failure, initial liquefaction, and 5% cyclic mobility. The influence of selected material parameters and test variables (i.e., grout mixture proportions, grout type and curing time, sand void ratio, cyclic stress ratio, number of cycles) on the behavior of chemically grouted sand is examined. The effect of chemical grouting on the increase in resistance to liquefaction is quantified.
Deformability of Rock-Like Materials Using a Sharp Cone Test
Authors: Leite MH , Ladanyi B , Gill DE
Published: February 2009

This paper presents a new idea for a field testing technique, the sharp cone test (SCT), for the determination of certain deformability parameters of rock-like materials. The test is described, and the theoretical background required for its interpretation is given. The influence of the interpretation model hypotheses is assessed by a finite element analysis. The results of sharp cone tests in materials of known linear elastic and viscoelastic behaviors are presented to validate the interpretation model.
Design and Evaluation of a Flow Pump System for Column Testing
Authors: Redmond PL , Shackelford CD
Published: February 2009

The design of the equipment components of a flow pump system for the measurement of solute (effluent) breakthrough curves from soil columns is described. In addition, the performance of the system in terms of the effects of equipment components and temperature on measured differential pressure fluctuations across soil specimens is illustrated. The flow pump for the system provides continuous flow of permeant liquid to the specimen, which is essential to produce the several pore volumes of flow required for measurement of solute (effluent) breakthrough curves for laboratory column testing.

Differential pressure fluctuations due to effects of high back pressures, imperfections in the flow pump equipment, the sampling of effluent, and temperature fluctuations within the laboratory are illustrated. While the magnitude of these differential pressure fluctuations can be large (e.g., as much as 6.9 kPa in some cases), the influence of these fluctuations did not affect significantly the measured hydraulic conductivity of a processed kaolin specimen at a flow rate of 2.65 × 10−4 cm/s. However, an evaluation of these effects is recommended before such testing commences since the ability to accurately test soil specimens at low flow rates is one of the reported advantages of flow pump systems.

An electrical conductivity cell used to measure the electrical conductance (EC) of the effluent while providing for continuous permeant flow during sampling is described. The cell provides a quick method for determining the electrical conductance and pH of the effluent, and sampling of effluent from the cell produced only minor differential pressure fluctuations across the soil specimen. Test results indicate good agreement between the EC values measured within the constructed probe and EC values measured at a later time using potentiometric methods on effluent samples recovered from bladder accumulators. However, the pH values measured in Cell EC2 were about 1.5 pH units lower than the values measured on recovered effluent samples presumably due to release of CO2 gas from the back-pressure saturated specimen after sampling.
Tensile Stress-Strain Characteristics of Lightly Cemented Sand
Authors: Dass RN , Yen S-C , Das BM , Puri VK , Wright MA
Published: February 2009

Laboratory tensile and unconfined compression test results on lightly cemented sand specimens are reported. Type I portland cement was mixed with sand in proportions of 4, 6, and 8% by weight to prepare the specimens. Tensile strength was determined by indirect tensile strength testing and direct tension testing. The variation of tensile strain with stress in indirect tensile strength tests was measured by a computer-aided image analysis method. Based on the test results, tensile and compressive strengths and strain levels at failure have been determined and compared. Nondimensional tensile stress-strain relationships in the form of a rectangular hyperbola as obtained from the indirect tensile strength tests and direct tension tests have been developed.
Use of Fuzzy Control in Automated Soil Testing
Authors: Huang A-B , Hsu S-P , Kuhn H-R
Published: February 2009

A servo-control algorithm that uses fuzzy logic has been developed for automated soil testing. The algorithm emulates the reasoning process of an experienced operator in controlling the pressure. The amount of pressure adjustment and time delay between adjustments is determined by fuzzy inference matrices. The fuzzy control logic provides a framework for the development of intelligent control algorithms which can be adapted in other aspects of automated soil testing. This paper introduces the concept of fuzzy control and its application in soil testing. Results of controlled gradient consolidation tests are presented to demonstrate the efficacy of fuzzy control.
A Compaction Test Method for Soil-Rock Mixtures in which Equipment Size Effects are Minimized
Authors: Donaghe RT , Torrey VH
Published: February 2009

The development of a standard effort compaction test method for determining compaction characteristics of soil-rock mixtures having maximum particle sizes up to 51 or 76 mm (2 or 3 in.) is described. The method is based on results of a testing program to develop testing procedures for 305 and 457-mm (12 and 18-in.)-diameter molds in which equipment size effects are minimized, i.e., procedures where results for materials tested using a conventional 152-mm (6-in.)-diameter mold may be reproduced with the larger equipment required to test materials having maximum particles sizes of 51 and 76 mm (2 and 3 in.). The testing program consisted of a series of standard effort compaction tests performed using 152, 305, and 457-mm (6, 12, and 18-in.)-diameter molds on four test materials having a maximum particle size of 19.1 mm (3/4 in.) and either plastic or nonplastic fines. Hammer weight was isolated as the main testing variable for use in developing the procedure while maintaining as many features of the conventional procedure as possible. It was found that in the case of 305-mm (12-in.)-diameter mold tests, varying hammer weight did not produce significant effects on results and that 152-mm (6-in.)-diameter mold results could be reproduced with any of the hammers used. In the case of the 457-mm (18-in.)-diameter mold, it was found that 152-mm (6-in.)-diameter mold results could be reproduced with the heaviest hammer [59.6 kg (131.4-lbf) used in the 305-mm (12-in.)-diameter mold tests]. The test method resulting from the investigation utilizes a mechanical compactor equipped with 305 and 457-mm (12 and 18-in.)-diameter molds and a 59.6-kg (131.4-lbf) hammer with a 305-mm (12-in.) drop. Additional tests performed using the test method on minus No. 4 (4.76-mm) sieve fractions of the 19.1-mm (3/4-in.) maximum particle size materials produced significant differences in results due to varying equipment sizes, thus indicating it may be impossible to minimize equipment size effects to the same extent for finer gradations.
Proposed New Standard Test Method for Laboratory Compaction Testing of Soil-Rock Mixtures Using Standard Effort
Authors: Donaghe RT , Torrey VH
Published: February 2009

The purpose of this proposed standard is to standardize a test method for determining standard effort compaction characteristics of soil-rock mixtures containing particles larger than the 3/4-in. (19.0-mm) sieve and finer than the 3-in. (76.2-mm) sieve. The proposed method utilizes a mechanical compactor equipped with a 12-in. (304.8-mm) or 18-in. (457.2-mm)-diameter mold and a 131.4-obf (584.5-N) rammer dropped from a height of 12 in. (304.8 mm).
Development and Potential of Core-Logging Manuals
Authors: Ettensohn FR
Published: February 2009

Characterizing the in-place conditions of rock masses commonly depends upon continuous diamond-core drilling for site investigation or resource characterization. However, because of incomplete or inconsistent core descriptions, potentially valuable information may be lost or unavailable for other users. This situation suggested the potential value of photographic core-logging manuals and descriptive codes to facilitate consistency in core description and ease in the transfer and computerization of these descriptions. To that end, this article describes the development of such manuals and codes using the U.S. eastern gas and oil shales as examples. Although the described manual was developed specifically for these rocks because of their energy-related significance, the concept and coding scheme are readily applicable to core description for all types of engineering and geological purposes.
A Simulation of Tube Sampling Effects on the Stiffness of Clays
Authors: Hird CC , Hajj AR
Published: February 2009

The effect of tube sampling disturbance on the prefailure behavior of reconstituted kaolin was investigated in the triaxial cell. Previously published forms of stress paths followed by normally consolidated and overconsolidated clays during simulated sampling have been substantiated. After the initial stresses were restored, the behavior of the undisturbed clay at small strains (up to 0.1%) was recovered in undrained compression and extension tests, although not accurately for normally consolidated specimens tested in extension. At larger strains, the effects of simulated sampling were significant for normally consolidated specimens, but not for overconslidated ones. The findings in relation to small-strain behavior do not necessarily apply for natural clays, but do help to provide a framework for interpreting the behavior of such soils.
Empirical Theory of Vacuum-Assisted Steam Stripping of Organic Pollutants from Contaminated Soils
Authors: Lord AE
Published: February 2009

A theoretical model was developed for the removal of organic chemicals from soil via vacuum-assisted steam stripping. The model considers a homogeneous, isotropic soil described by a single steam permeability coefficient. (The author realizes that this is an idealization of most field situations.) It is assumed that the entire soil mass has been steam heated to 100°C (or slightly above), so the temperature can be considered a constant for the entire decontamination process. The steady-state steam pressure and velocities are determined by solving Laplace's equation for two geometries: a circular symmetry model and a point source model (results for the latter are available upon request). One-dimensional laboratory experiments were conducted to determine the needed steam permeability and decontamination rate of a particular pollutant during steady-state steam flow. The rate of decontamination was determined over a range of steam velocities. The soils used in this particular study were 100% sand, 75% sand/25% Delaware River silt, and 50% sand/50% Delaware River silt. The “pollutant” was commercially available kerosene at a level of 5% by weight in the soil. The soil was initially moisture-free.

Results are presented as the time needed to produce either 80 or 100% decontamination. These times depend on the position in the soil—the higher the steam-flow velocity, the shorter the times to decontaminate. Drawing on previous work, the times to reach steady state are also presented. For contaminated regions as large as 10 m in diameter for these three soil types, the times to decontaminate to at least 98% appear reasonable.
Application of the Bubble Point Method to the Characterization of the Pore-Size Distribution of Geotextiles
Authors: Bhatia SK , Smith JL
Published: February 2009

For the design of a geotextile as a filter, reliable information about the pore-size distribution of the geotextile is needed. The bubble point method is one technique that is able to provide this information for a geotextile. The bubble point method is a simple and rapid technique for evaluating pore-size distributions of virgin, clogged, and stretched geotextiles. In addition, the bubble point equipment is also capable of providing information as to the degree of clogging within a geotextile and the permeability of a geotextile. The geotextile pore-size distribution results obtained by the bubble point method showed good repeatability. However, the bubble point method was only able to distinguish between geotextiles that had significantly different cross sections. Pore-size distribution results for geotextiles with similar cross sections, but of increasing thickness, were very similar. The dry sieving (ASTM D 4751), hydrodynamic sieving (CAN/CGSB-148.1-10), AND WET SIEVING (sw-640550-83) METHODS ARE GENERALLY only useful for evaluating the larger pore openings (O95, O90) of the geotextiles. In addition, the methods are time consuming. The mercury intrusion porosimetry method (ASTM D 4404) was also performed; however, there was little difference in pore-size distribution results for any of the 28 different geotextiles tested (Smith 1993). There are also environmental concerns with using mercury. The bubble point method showed potential for characterizing the pore-size distribution of geotextiles.
A Resistance Wire Transducer for Circumferential Strain Measurement in Triaxial Tests
Authors: Skopek P , Cyre GP
Published: February 2009

A resistance wire transducer was designed to measure circumferential deformation of a partially saturated triaxial specimen. It utilizes for the measurement changing output voltage in a resistance wire transducer wound around the specimen as it bulges, i.e., increases in circumference. This circumferential change can be converted into lateral deformation. The proposed transducer is very small, so it is possible to mount several of them along the height of a specimen and monitor accurately its changing cross sections. The volume of the specimen at any recording time can be calculated from the deformed cross section and axial deformation. The resistance wire transducer is a simple device whose principle provides the potential for a broad spectrum of analogous applications.
A Constant Normal Stiffness Direct Shear Device for Static and Cyclic Loading
Authors: Ooi LH , Carter JP
Published: February 2009

A device has been designed and built to carry out both static and cyclic direct shear tests on specimens of soil and rock and on interfaces of soil or rock and construction materials. The device has the special capability of allowing the shear deformation to proceed under conditions of constant normal stiffness. This is in contrast to the more conventional direct shear devices, which permit shearing under conditions of constant normal stress. It is expected that the constant normal stiffness conditions will be more representative of many in-situ conditions of shear deformation; an important example occurs at the interface of a pile and the formation in which it is placed (particularly those piles that are grouted into the formation). When used with a servo-controlled testing machine the device is capable of applying either static or cyclic shear loading to the test specimens utilizing either load or displacement control. The device is described in this paper, and typical results are presented for static and cyclic loading of a variety of interfaces including some that dilate on shearing and others that collapse as they are sheared.
Reproducibility of Borehole Shear Test Results in Marine Clay
Authors: Lutenegger AJ , Timian DA
Published: February 2009

An investigation was conducted to determine the variability of borehole shear test results obtained in testing soft and medium consistency marine clays. A statistical comparison of the results of stage tests obtained by different operators at two test depths at a research site is made. An additional comparison of the results obtained from stage tests and fresh shearing and a brief discussion of the linearity of both types of tests is also made. A short summary discussing the applicability of the results is also presented.
Suggested Method for Performing the Borehole Shear Test
Authors:   ASTM Subcommittee D18.02
Published: February 2009

ASTM Committee D18.02 on Sampling and Related Field Testing for Soil Investigation (Mr. Ralph Brown, Chairman) suggested that this proposed suggested method be published herein to provide exposure and solicit comments for users. The purpose is to improve its clarity, accuracy, and acceptibility, so that in the future, Committee D18.02 may submit it for publication in the Annual Book of ASTM Standards. Suggestions for revision and other comments should be sent to Alan J. Lutenegger, Subcommittee D18.02.12. The subcommittee will fully consider all comments and suggestions that provide specific improvements to the proposed method.
Pressuremeter Creep Testing in Ice: Calibration and Test Procedures
Authors: Kjartanson BH , Shields DH , Domaschuk L
Published: February 2009

In situ pressuremeter creep tests of ice require that particular attention be paid to the precision with which the borehole diameter is measured because failure of ice often occurs at strains as small as 1%. Therefore, precision is important to obtain an accurate picture of the stress-strain-time response of the ice before failure. Also, the pressure applied to the ice must be known precisely since the creep rate varies as the cube of the stress. Thus, careful calibration of the pressuremeter is necessary.

This paper outlines how a monocellular pressuremeter equipped with an internal caliper should be calibrated to take into account freezing temperatures and the long duration of creep tests. The probe in question contains a two-arm caliper system which determines the diameter of the probe electromechanically; this system must be calibrated before each test. Secondly, both the thickness and resistance of the rubber membrane must be known at any stage of a test; both are dependent on temperature, internal probe pressure, displacement, and elapsed time. The paper also discusses preferred test procedures.
Axial Deformation Measurement in Repeated Load Triaxial Testing
Authors: Nataatmadja A , Parkin AK
Published: February 2009

This paper describes a method of axial deformation measurement for use in repeated load triaxial testing of pavement materials. An internal deformation measurement system is necessary because of the low strain regime involved, but normal transducers can only be used in an inert cell fluid. As this is both expensive and messy, the use of sealed transducers in water is preferable, but the cost of such units induces the use of a system based on a single transducer. Therefore, aluminium rings are used in an arrangement that allows the mean axial deformation over the central portion of the specimen to be determined by the use of a single hermetically sealed displacement transducer.
Statistical Description of Triaxial Shear Test Results
Authors: Schoenemann MR , Pyles MR
Published: February 2009

Any probabilistic approach to slope stability assessment requires an adequate statistical description of soil strength. Current statistical methods of strength description are unsuitable for this purpose. A statistical technique of soil strength description appropriate for the probabilistic assessment of slope stability in c′, φ′ soils under drained conditions is developed here. The technique is applied to a set of results from triaxial strength tests on residual soil materials. Techniques for assessing the adequacy of a statistical description are discussed.
Effects of Arching on Response Time of Miniature Pore Pressure Transducer in Clay
Authors: Kutter BL , Sathialingam N , Herrmann LR
Published: February 2009

A study of the response time of miniature pore pressure transducers embedded in clay soils is presented. The highly nonuniform pore pressure distributions around the transducers due to arching and stress concentration can have a significant effect on transducer response especially when the surrounding soil is loaded anisotropically. This is caused by the difference in compressibility of the soil and the transducer housing. Finite-element analysis and experimental results confirm the importance of these effects. A spherical porous stone or a cylindrical stone with top and side drainage results in significant reduction in response time and in overshoot due to arching effects.
Influence of Soil Structure on the Stress-Strain Behavior of Sand-Bentonite Mixtures
Authors: Wan AWL , Graham J , Gray MN
Published: February 2009

The influence of soil structure on the behavior of clay-rich mixtures has been examined. Mixtures of sand and bentonite, known as buffer, have been studied to determine their suitability for nuclear fuel waste containment. Triaxial tests have been performed on compacted specimens to determine the strength and constitutive behavior of the buffer. Two techniques were followed in preparing specimens. In the first method, specimens were compacted to dry densities of 1.5 Mg/m3 and 28% moisture content and were allowed to equilibrate to their confining pressures prior to test. The second method, which aimed at shortening the test durations, involved forming specimens at dry densities corresponding to equilibrium states at the test pressure levels. This required compacting sand-bentonite mixtures at different densities and moisture contents.

The study indicates that the compressibility and stress-strain behavior of the buffer are strongly influenced by specimen preparation techniques. Because of the different degrees of soil manipulation and moulding moisture contents, the specimens had different macrostructures. This affected the swelling and shear behavior of the buffer. However, preyield porewater pressure response and ultimate shear resistance appeared to be unaffected by preparation techniques. Shear test results suggest that the buffer is anisotropic and slightly strain softening in shear. An ultimate strength envelope of c' = 0 kPa and φ' = 14° is determined in the pressure range of 0 to 1.5 MPa.
Frequency Response of Diaphragm Pore Pressure Transducers in Dynamic Centrifuge Model Tests
Authors: Lee F-H
Published: February 2009

A theoretical relation for estimating the frequency response of diaphragm pore pressure transducers is derived by considering the interaction between the diaphragm, porous cap, air, and pore fluid inside the transducer. Using this relation, the frequency response of a pore pressure transducer under several centrifuge modeling environments is studied. The results indicate that the viscous drag imposed by the porous cap on the pore fluid can significantly reduce the sensitivity of the transducer to high frequency pore pressure fluctuation. This may impair the accuracy of dynamic pore pressure measurements in high-g centrifuge modeling of dynamic events if viscosity scaling is used.
Measuring Strains in Buried Flexible Pipes
Authors: Moore CA , Donaldson CF
Published: February 2009

A field measurement system is described for determining strains in buried flexible pipes. The microprocessor-based system obtains data that is subsequently analyzed on minicomputers or mainframe machines. The field system is also capable of analyzing the data using its own microprocessor provided that a graphics terminal is available. Numerical algorithms for analyzing the data are developed, and typical results are presented.
Preparation of Grouted Sand Specimens for Dynamic Testing
Authors: Chang T-S , Woods RD , Li NH
Published: February 2009

Improvement of soil properties by means of chemical grouting, cement grouting, and cement/fly ash stabilization has been widely used in practical geotechnical applications. Knowledge of dynamic behavior of cemented soil is essential for seismic research and design. A laboratory testing program is conducted for determining the low-strain dynamic properties of artificially cemented soils. The major significances of this research are: 1. Focusing on the effect of confining pressure because confining pressure is one of the most important factors affecting the dynamic properties of cemented soils and directly implies the in-situ depth of soil, which is also significant in a practical grouting project. 2. Defining the “degree of cementation” as a percentage of void space between soil particles occupied by cementing material instead of the percent weight of cementing material to total weight of the soil to be cemented as normally used in previous research. Degree of cementation by volume as defined in this study gives clearer description regarding the soil-cement-void interaction of a cemented sand. 3. Using various types of cementing materials and soils to cover sufficient range of parameters involved in the study. 4. Two methods for preparing cemented sand specimens are developed in compliance with the methods practically used in the field for the testing materials selected in the study (injection method and “mix-compact” method).
Statistical Evaluation of Bangkok Clay Shear Strength Parameters
Authors: Ali MM
Published: February 2009

All natural soils show some variation in properties due to the inherent variation in composition and consistency during formation or to the differences in testing techniques and the methods used to analyze a given set of test results. A statistical approach to the evaluation of the measured parameters offers a means to define these variabilities by providing a basis to quantify the reliability involved in the analysis. This paper presents a statistical study for the evaluation of shear strength parameters (c, Φ, ¯c, ¯Φ, Af) for Bangkok clay and makes a comparison with previous findings for this material.

The results obtained show that the variations of strength parameters can be approximated by a Beta I distribution function. The accuracy in estimating the distribution parameters depends on the number of observations. In an actual sampling there are relatively few specimens and the true mean can be estimated with some confidence limits by means of statistical analysis.