bluuebunny/crossref_metadata_2025 huggingface dataset:
Suction-Moisture Content Calibration of Filter Papers from Different Boxes
Authors: Sibley JW , Smyth GK , Williams DJ
Published: February 2009

The filter paper method is probably the simplest of the methods available for estimating the suction of a clay soil. The method measures soil suction indirectly by simply measuring the moisture content of a filter paper having been brought to the same suction as the soil. Calibration of representative specimens of the filter paper over a range of known suctions defines the suction-moisture content characteristic of the material. The calibration must be carried out in a closely temperature-controlled environment using various apparatus depending on the particular level of suction. There have been a number of impediments to the wider application of the filter paper method. One of these is the need to have access to a closely temperature-controlled laboratory with a range of specialist calibration apparatus. This difficulty has been exacerbated by the belief that to account for the possible variability of filter papers between boxes, even from the same production batch, representative specimens from each box require separate calibration. Based on the results of careful calibration and subsequent analysis, it appears that, provided the boxes are all from the same production batch and are purchased from the same outlet at the same time, the calibration of only one box is necessary.
Influence of Storage and Reconsolidation Procedures on Clay Properties
Authors: Graham J , Jamieson MR , Ho DY-F , Azizi F
Published: February 2009

The delay between sampling and testing of clay specimens and the control kept over their volumes during storage are known to affect the strengths and compressibilities subsequently measured in the laboratory. The measured properties are also affected by reconsolidation procedures. This paper deals with reconstituted specimens of illite stored for fixed periods of up to one week, reconsolidated using three different procedures, and then sheared undrained. Results are compared for overconsolidated specimens (OCR = 2) prepared with Koc = 0.53 or 1.0. The paper provides qualitative evidence for the well-known result that the best recovery of stress-strain behavior is obtained from specimens stored at constant volume (undrained) for as short a time as possible and then reconsolidated to their in-ground stress state before shearing. Providing this is done, results suggest that undrained strengths su and Af-values should be recoverable with an accuracy of about ±5 to 6%. Much larger differences can be expected in the relative stiffness E50/su.
An Experimental Laboratory Facility for Studying Shock-Induced Liquefaction
Authors: Veyera GE , Charlie WA
Published: February 2009

Our paper describes a new experimental laboratory apparatus developed to investigate the transient and long-term porewater pressure response of saturated soils subject to compressional stress wave loading. An overview of the laboratory system, the various components, and the experimental procedure followed are presented. Measurements include porewater pressure-time histories for the specimen and total stress time histories for the applied load. Test results indicate that Monterey No. 0/30 sand can be liquefied even at high initial densities and effective stresses under undrained, one-dimensional, confined compressive shock loadings.
Simplified Heave Prediction Model for Expansive Shale
Authors: Dhowian AW
Published: February 2009

A model is suggested to predict heave of expansive shale formation based on soil suction change. The model satisfactorily described the field volume change where the anticipated heave is compared with direct measurement obtained from an instrumented field station. The prediction is further simplified by introducing a model that only uses the moisture content variation to determine the amount of heave. Close agreement is observed between measured and model-predicted shale behavior. Application of this simplified model eliminates the difficulty of recovering an undisturbed specimen of shale which is highly weathered and friable as well as laminated.
Determination of Design Parameters of a Mesh-Type Soil Reinforcement
Authors: Lo S-CR
Published: February 2009

Problems in determining design parameters of a new mesh-type soil reinforcement are investigated. A special apparatus referred to as the split-box was developed to enable measurement of design parameters with large-scale laboratory tests. In addition to the scale of the tests, the design innovations of the split-box ensure reliability of test results, as verified by a number of calibration tests. Test data are highly consistent and support the relevance of conducting tests with the split-box.
Effects of Imperfect Fixity in Spring-Top Resonant Column Tests
Authors: Min T , Drnevich VP , Wang J
Published: February 2009

A two-degree-of-freedom model is proposed to study the effects of imperfect fixity at the active end of the spring-top resonant column apparatus. A computer program using the SYMPHONY spreadsheet is developed to calculate the dimensionless frequency, F, from which the modulus can be determined. It is found that the effect of reaction mass through the parameter, Tr; on dimensionless frequency, F, cannot be ignored if Tr < 20. As the ratio of mass attached to the active end of the specimen to specimen mass, T0, increases, the variation of F increases. When Tr ≥ 20, the effect of T0 becomes small. It is recommended that Tr be greater than 20 if the single-degree-of-freedom model is used to determine modulus of soil. It also is found that damping ratios of specimen and apparatus do not strongly affect the dimensionless frequency, F.
Procedures for Prediction of Dynamic Lateral Pile Group Response in Clay from Single Pile Tests
Authors: Blaney GW , O'Neill MW
Published: February 2009

The design of pile foundations for dynamic lateral loads is significant in the design of both offshore and onshore structures subject to vibratory loads and earthquake motion. Sophisticated numerical models are available for predicting the response of these foundations; however, simple and cost-effective methods are needed to confirm the analysis results and improve the understanding of the overall system behavior. A field testing procedure consisting of slow cyclic load tests and plucking tests is suggested and integrated with simplified single-degree-of-freedom and modal analyses of the test results to produce response functions for dynamic design. The technique is particularly attractive because the field tests may be performed quickly and economically on a test pile or piles installed at the site to determine bearing capacity and/or drivability. The proposed test and analyses procedures were applied to a single pile and nine-pile group installed in stiff clay and tested at the University of Houston pile test facility, and the results are compared favorably with more detailed response information published previously. A good approximation of the pile group dynamic behavior was obtained from the simplified single pile response analysis.
A Cohesive Soil for Large-Size Laboratory Deposits
Authors: McManus KJ , Kulhawy FH
Published: February 2009

The preparation of high-quality, large-size cohesive soil deposits is possible using the slurry method and is practicable if a suitable soil material is used. The requirements for such a soil are discussed and the results of a survey of available ingredient materials presented. A testing program of six trial soil mixtures is described, including consolidation of slurry in a special apparatus. Each trial soil is evaluated, and detailed properties of the selected material, called Cornell clay, are presented. The results from a series of CIUC triaxial tests show that Cornell clay has normalized strength parameters similar to many naturally occurring cohesive soils. Supply sources for the ingredient materials are given.
A Method for Determining the Surface Area of Quarried Rocks
Authors: Garga VK , Townsend R , Hansen D
Published: February 2009

A coating method which used nickel powder to determine the surface area of angular rock particles was found to be reproducible and required no special equipment. The technique utilized the difference in weight between uncoated and coated rock particles. Four calibration methods were considered. Relationships between surface area and an estimate of the volume of individual rocks were obtained for graded rock having a mean diameter of 25.6 mm and for unisized rock having a mean diameter of 130 mm. The volume of each rock was estimated by measuring the three orthogonal axes of each rock. An analysis of covariance showed that whether or not a rock was spheroid in shape was statistically significant for the evaluation of surface area. Curves relating the hydraulic mean radius to porosity for a range of unisized rock sizes are presented. A procedure for estimating the hydraulic mean radius for a graded media is also discussed.
Sample Size for Laboratory Calibration of Subsurface Neutron Moisture Gauges
Authors: Morris PH , Williams DJ
Published: February 2009

The estimation of adequate sample size is critical to all laboratory methods of calibration of neutron moisture gauges. Neutron gauge response is a function of the true sample geometry rather than an arbitrarily defined spherical geometry. A two-group solution is obtained for neutron flux in a homogeneous, finite, cylindrical sample. The theoretical flux distributions for this solution and for infinite and spherical samples are compared for three representative media. The results show that significant reductions of sample size are possible for media with low moisture contents if the true cylindrical geometry is considered.
Small Diameter Piston Sampling with Cone Penetrometer Equipment
Authors: Kay JN
Published: February 2009

A small diameter piston sampler that can be operated by a cone penetrometer rig has been developed specifically for recovery of sand and clay samples under conditions where sample recovery using ordinary means is difficult. The 22-mm-diameter sample that is recovered in a polythene sheath is valuable for visual examination of the soil rather than for most laboratory testing purposes. Provided the soils are penetrable, the sampler may be pushed to any desired depth before the sampling operation; then the central 12-mm-diameter rod in the drill stem is held stationary while the sampling operation takes place. In initial tests when applied to soft, wet, interlayered sands and clays that could not be recovered in open tubes, essentially 100% recovery was obtained.
Measurements of Strength Parameters of Concrete-Rock Contact at the Dam-Foundation Interface
Authors: Lo KY , Ogawa T , Lukajic B , Dupak DD
Published: February 2009

A long-term dam safety program has been initiated by Ontario Hydro to evaluate the safety of existing dams. Most of the dams in operation were constructed between 1910 and 1975. The larger dams are often of the concrete gravity type founded on rock.

As an integral part of this program, laboratory methods for the measurement of the complete strength envelope of bonded concrete-rock contact and strength parameters of unbonded contact have been developed. The principal method and interpretation of each type of test are described in this paper. Typical results of tests on samples of dam-foundation interface recovered from existing dams are presented. The methods developed enable the determination of the strength envelope appropriate for the working stress level during operation of dams and the direct measurement of tensile strength and cohesion, thus removing the uncertainty of extrapolation for the cohesion component of strength in conventional triaxial and direct shear tests.
Effects of Back Pressure on Geotextile Transmissivity Tests
Authors: Huang A-B , Holtz RD , Wilcox AM
Published: February 2009

To evaluate the effects of back pressure on the measurements of geotextile in-plane transmissivity, a new test device has been developed. A series of transmissivity tests were performed under back pressures ranging from 6.9 to 414 kPa. Results show that the influence of back pressure is significantly less than that caused by the variability among different specimens. However, to obtain repeatable results and to conduct the tests efficiently, it is strongly recommended using deaired water and to flush the specimen before testing.
Simulation of Climatic Conditions in Centrifuge Model Tests
Authors: Craig WH , Bujang BKH , Merrifield CM
Published: February 2009

A review is presented of the need for simulation of effects associated with tide, rainfall, temperature variations, etc., in geotechnical centrifuge models. Interest in the overall theme was generated by a perceived need to model rainfall in long-term testing of models of an embankment which was otherwise found to dry out. The system used to overcome this particular problem is outlined, and results are presented. Experience of the authors and others in the wider field is summarized.
A Clay Calibration Chamber for Testing Field Devices
Authors: Anderson WF , Pyrah IC , Fryer SJ
Published: February 2009

This paper describes the design of a calibration chamber suitable for the preparation of uniform clay beds in which the performance of full-size field test devices may be studied. Details are given of the clay bed preparation procedure by which clay slurry is initially consolidated under K0 conditions and then further conso using equal or unequal horizontal and vertical stresses. Field equipment may be tested in the clay bed, which is maintained under known horizontal and vertical boundary stresses during the test. Self-boring pressuremeter tests have been successfully carried out in the clay bed.
Clay-on-Steel Ring Shear Tests and Their Implications for Displacement Piles
Authors: Tika-Vassilikos T
Published: February 2009

This paper presents results from ring shear tests involving shearing of clay against steel interfaces. The effect of rate of shearing on the shear resistance between the soil and steel at large displacements was examined. It is shown that the rate of shearing has a significant effect on the shear resistance between soil and steel. The implications of the results for the behavior of displacement piles are discussed.
Total Stress Probe Determination of Clay Slurry Density
Authors: Tan S-A , Liang K-M , Tan T-S , Karunaratne G-P
Published: February 2009

The progress of sedimentation, self-weight consolidation, and gain in surface strength of a hydraulic clay fill were observed by monitoring the density improvement of the clay slurry with time. A practical method of measuring the in situ slurry density profile with depth is to employ a submersible gamma-source, backscattertype nuclear density gauge. A slurry consolidation test in the laboratory has demonstrated that above 1.5 times the liquid limit, the horizontal and vertical total stresses are equal. Hence, from the horizontal total stress measurements with a vertical probe, the in situ vertical total stress profile of the slurry can be obtained. In principle, the integration of the density profile with depth gives the vertical total stress profile. Therefore, an estimate of the density can be made from the gradient of the vertical total stress with depth. Comparisons of field measurements of the total stress profile of a clay slurry in a reclamation project using the total stress probe and the density profile by the nuclear density gauge demonstrates this principle, thus confirming that the total stress probe with appropriate data interpretation can be used to measure the density of an in situ clay slurry around its surface.
Total Suction of Artificial Mixtures of Soil Compacted at Optimum Water Content
Authors: Acar YB , Nyeretse P
Published: February 2009

The effect of soil composition on total suction is investigated. Thermocouple psychrometers are used to measure total suction of compacted specimens of artificial soil mixtures prepared using kaolinite, sodium montmorillonite, and a fine sand. Specimens are compacted in a Harvard miniature compaction mold at the optimum water content. The measured total suction is related to fine fraction and activity of the soil mixtures. The total suction is also compared with the swelling potential. A classification system is presented.
Effect of Clod Size on Hydraulic Conductivity of Compacted Clay
Authors: Houston SL , Randeni JS
Published: February 2009

A study has been conducted to identify the causes for field-measured values of hydraulic conductivity of clay liners being typically two orders of magnitude greater than laboratory-measured values. It has been found through laboratory testing on large specimens that the size and gradation of clods and clumps of clay, prior to compaction, can significantly affect the measured hydraulic conductivity.

The results of this study are compared to existing studies on the effect of clods on hydraulic conductivity, and general agreement is found. It is concluded that, for clod sizes and gradations likely to occur in field compaction of clay liners, that differences in clod gradation and size between lab and field conditions can essentially account for the observed roughly two orders of magnitude discrepancy between lab and field-measured conductivities.

Revised laboratory testing procedures for both the before-liner construction and after-liner construction cases are recommended. The revised laboratory testing procedures are designed to correct the deficiencies in conventional lab testing and to produce unbiased estimates of field hydraulic conductivity values.
Properties of Some Kaolin-Based Model Clay Soils
Authors: Rossato G , Ninis NL , Jardine RJ
Published: February 2009

Kaolin has been widely used both in fundamental studies of soil behavior and in physical model tests. However, the properties of pure kaolin are somewhat atypical of natural clay soils. In the first part of this paper we compare the mechanical properties of sedimented kaolin to median trends established from tests on natural clays and argue that artificial soils incorporating a substantial granular fraction reflect more closely the behavior of “destructured” real clays. In the second part we report a laboratory investigation of one particular mixture and describe the stress-strain behavior and strength properties observed in a series of K0 consolidated triaxial tests in which local strain instrumentation was used to better define the stiffness characteristics at small strains.
Maximum Dry Density of Cohesionless Soils by Pluviation and by ASTM D 4253-83: A Comparative Study
Authors: Lo Presti DCF , Pedroni S , Crippa V
Published: February 2009

Maximum dry densities of a variety of granular soils, ranging from silty sand to sandy gravel (Dmax = 9.5 mm), were determined by ASTM Test Methods for Maximum Index Density of Soils Using a Vibrating Table (D 4253-83) and by pluviation. The effects of various test conditions during pluviation were also investigated. The pluviation method offers several advantages compared to that of the ASTM method: higher dry density, no particle crushing, less effect of segregation, and better repeatability. In addition, the pluviation method can be performed with greater facility in less time.
Measurements of Coupled Normal Deformation, Permeability, and Heat Transfer in Rock Joints Using a Triaxial Test Facility
Authors: Zhao J
Published: February 2009

A description is presented of a rock-mechanics triaxial test facility capable of coupled testing of medium-sized cylindrical rock specimens at axial loads to 2.67 MN, confining pressures to 140 MPa, pore pressures to 105 MPa, and specimen temperature to 400°C. The test cell of the system is modified to carry out tests on fluid mass and heat transfer through rock joints/fractures and thermomechanical deformation of joints/fractures. Details of test procedures and techniques for conducting the coupled hydro-thermo-mechanical tests are described. Data on both natural joints and artificially induced extension fractures in the Carnmenellis granite are presented and discussed in order to illustrate the multifunctional capability of the testing system to cover the requirement for further understanding of rock joint/fracture and rock masses.

The study showed that joint/fracture permeability and mechanical aperture decrease with increasing effective normal stress. The relationship between the changes of mechanical aperture and permeability is influenced mainly by discontinuity surface characteristics. The permeability decreases with increasing temperature while measured mechanical aperture increases. Heat transfer coefficient measured during hydro-thermo-mechanical tests varies from 300 to 1200 W/m2-°C and is affected by flow velocity, temperature, and joint/fracture surface properties.
Temperature Dependence of Soil Water Potential
Authors: Mohamed A-MO , Yong RN , Cheung SCH
Published: February 2009

To understand the process of coupled heat and water transport, the relationship between temperature and soil water potential must be known. Two clays, Avonlea bentonite and Lake Agassiz clay, are being considered as the clay-based sealing materials for the Canadian nuclear fuel waste disposal vault. Avonlea bentonite is distinguished from Lake Agassiz clay by its high sealing potential in water. A series of experiments was performed in which the two clays were mixed with equal amounts of sand and were compacted to a dry density of 1.67 Mg/m3 under various moisture contents and temperatures. A psychrometer was placed within the compacted clay-sand to measure the soil water potential based on the electromotive force measured by the psychrometer. The results indicate that the soil water potential at a particular temperature is higher for both clay-sand mixtures than predicted by the change in the surface tension of water; this effect is much more prominent in the Avonlea bentonite and at low moisture contents. The paper presents empirical equations relating the soil water potential with the moisture content and temperature of the two clay-sand mixtures.
A New Method to Measure the Effective Porosity of Clays
Authors: Meegoda NJ , Gunasekera SD
Published: February 2009

The effective porosity is a required parameter for the mass flow rate calculations in groundwater hydrogeology. It is also a useful parameter in geotechnical engineering. In this paper, a methodology based on the tracer analysis technique is proposed to measure the effective porosity of clays. A test apparatus was developed and operational conditions were optimized to measure the effective porosity in the laboratory. Then the effective porosity of three clays under different chemical environments was measured. The measured effective porosity values showed that there is no unique effective porosity value for a given clay when tested under different chemical environments. The ratio of effective to total porosity values for silty and low plastic clays decreased while those for high plastic clay increased with the increase in degree of contamination.
Dispersive Behavior of Nonswelling Clays
Authors: Sridharan A , Rao SM , Dwarkanath HN
Published: February 2009

This paper examines the possible factors that contribute to the dispersive behavior of compacted nonswelling clays and proposes the use of a synthetic organic stabilizing agent to reduce the dispersive tendency of such soils. Results of chemical tests on saturation extracts of the clays tested failed to identify them as piping susceptible. However, pinhole tests on statically compacted specimens showed the materials to be intermediate (ND3, slightly to moderately dispersive clays that slowly erode under 180 or 380 mm head) to completely dispersive (D1 dispersive clays that fail rapidly under 50-mm head). Use of a concentrated salt solution (2N CaCl2) and a solvent with lower dielectric constant (methanol, dielectric constant = 32.6) did not reduce the dispersive tendency of the compacted kaolinite in the pinhole test (diameter of hole = 1 mm), suggesting that deflocculation triggered by diffuse double layer repulsion does not contribute significantly to the dispersive tendency of nonswelling clays.

Pinhole tests conducted with variously saturated (33 to 84%), compacted kaolinite specimens (γd = 1.28 Mg/m3 in all instances) suggested that compression of entrapped air in the voids by capillary absorption of water is not the primary factor causing dispersion of nonswelling clays.

Experimental results showed that pinhole test classification of statically compacted kaolinite changes from D1 (dispersive) to ND3 (intermediate) on reducing the remolding water content from wet of optimum (w = 34%) to a dry of optimum (w = 27%) value. The differences in structure of the compacted clay due to differences in molding water content are considered responsible for the higher erosion resistance of the compacted kaolinite on lowering the molding water content. Subsequent lowering of water content below 27% has no further influence on the pinhole test classification of the compacted clay.

The use of a synthetic long chain organic polymer, poly vinyl alcohol (PVA), in improving the resistance of compacted nonswelling soils was tested. The addition of 1% PVA solution to kaolinite transforms the nonswelling clay from dispersive D1 to the dispersive D1/D2 category suggesting that the long chain organic polymer can improve the dispersion tendency of nonswelling clays to a slight extent.
On the Measurement of Critical State Parameters of Dense Granular Soils
Authors: Chu J , Lo S-CR
Published: February 2009

Existing test methods for measuring the critical state parameters of granular soils are reviewed and critically evaluated. It is concluded that, in triaxial testing of dense sand, significant nonhomogeneous deformation will develop prior to approaching a critical state. Hence, the critical state parameters so measured are questionable. A new test method, referred to as post-failure undrained testing, is presented. The proposed method is simple, but can bring a dense granular sand to a critical state without development of noticeable nonhomogeneous deformation. The critical state parameters so measured with dense specimens agree well with those measured with loose specimens. This is consistent with the postulate that the critical state surface is unique.
A Low-Compliance Bi-Directional Cyclic Simple Shear Apparatus
Authors: Boulanger RW , Chan CK , Seed HB , Seed RB , Sousa JB
Published: February 2009

A new simple shear apparatus is described which can apply bi-directional simple shear cyclic and monotonic loading. Cylindrical specimens are placed in a pressure chamber so that confining pressure and back pressure can be applied. Bi-directional shear loads are applied to the specimen's base, which is mounted on a series of two horizontal rolling tables which can be independently loaded in two orthogonal directions while preventing cap and base platen “rocking.” A computer-automated feedback-loop-controlled pneumatic servovalve system provides excellent control of loads and displacements. Displacement control during cyclic tests on softening specimens is improved by the inclusion of a parallel stiffness. Procedures and test results are presented for three different undrained cyclic simple shear loading conditions and for a strain-controlled monotonic loading condition.
Filtration Opening Size of Geotextiles by Hydrodynamic Sieving
Authors: Mlynarek J , Lafleur J , Rollin A , Lombard G
Published: February 2009

The latest development on the hydrodynamic sieving technique (HST) using glass beads to determine the filtration opening size (FOS) of geotextiles is presented. The FOS value is defined as the 95% (by mass) diameter of the glass beads which have passed through the geotextile under the hydrodynamic sieving action. The data of an experimental program to verify the repeatability and reproducibility are reported and discussed. The technique was found to be simple and repeatable for all types of geotextiles. The FOS of geotextiles measured by the HST is related to the geotextiles' general parameters such as their mass per unit area and thickness. The FOS value can be roughly estimated from simple knowledge of these parameters using the relationship established for the type of product.
A New Model of Shear Strength of Simulated Rock Joints
Authors: Juang CH , Lee D-H , Chang C-I
Published: February 2009

This paper documents a new model of shear strength of simulated rock joints based on roughness characteristics of the joints. The new model incorporates the concept of shear strength of rock joints proposed by Peek (1981) and Saeb (1990). The model is verified by results of an experimental program involving direct shear tests and the measurement of roughness profiles of simulated joints. The paper concludes that the new model is valid, based on experimental results, for simulated joints made of plaster. More study on other joints made of different materials and on real rock joints is needed to verify the general validity of the model.
Rockfill Placement and Compaction Guidelines
Authors: Breitenbach AJ
Published: February 2009

The purpose of this article is to establish general guidelines for rockfill placement and compaction procedures. The guidelines are based on experience gained from the design and construction of several large rockfill tailing dams in the western United States. Valuable rockfill information was obtained from construction test fills using test procedures similar to those developed by the Corps of Engineers in the 1960s and modified for modern-day compaction equipment. The rockfill guidelines establish basic procedures that can be readily adapted to site-specific conditions.
Compatibility of Compacted Soils with Municipal Waste Combustion Ash Leachates
Authors: Sai JO , Anderson DC , Sullivan BP
Published: February 2009

Hydraulic conductivity values for three compacted soils were used as indices of compatibility of the soils with two municipal waste combustion (MWC) ash leachates. Specimens of the three soils were compacted to 90% of proctor compaction (ASTM D 693) in double-ring permeameters and permeated first with water (0.005 N CaSO4) and then with MWC ash leachate. The hydraulic conductivity values of the soils did not change significantly after passage of more than two pore volumes of either MWC ash leachate. All three compacted soils were compatible with both MWC ash leachates.
δ-t/δ Method for the Determination of Coefficient of Consolidation
Authors: Sridharan A , Prakash K
Published: February 2009

Terzaghi's theoretical time factor, degree of consolidation relationship when plotted as U versus T/U, enables one to get a convenient form of curve-fitting method to determine the coefficient of consolidation. The time corresponding to 90% consolidation can be obtained more precisely from the proposed δ-t/δ method than the δ−√t method. The present article deals with the theoretical and practical aspects of results obtained from δ-√tand δ-t/δ representations.
Round One—Longitudinal and Transverse Pulse Velocities, Unconfined Compressive Strength, Uniaxial Elastic Modulus, and Splitting Tensile Strength
Authors: Pincus HJ
Published: February 2009

An interlaboratory study has been conducted using four ASTM rock-property test methods (longitudinal and transverse pulse velocity, indirect tensile strength, unconfined compressive strength, and uniaxial elastic modulus) on four types of intact rock (Barre Granite, Berea Sandstone, Salem Limestone, and Tennessee Marble). There were five replications per test per rock type. The rock testing was preceded by pilot testing on aluminum alloy 6061 T6 test specimens of four sizes, using the two nondestructive ASTM test methods (pulse velocity and elastic modulus) with three replications. The number of laboratories producing data for this report ranged from six to eight.

The test results for aluminum are generally more precise than those for rock. The rock-property tests with the largest and smallest precision are longitudinal pulse velocity and indirect tensile strength, respectively. The rock types yielding the greatest and least precise test results are Barre Granite and Berea Sandstone, respectively.

Proposed precision statements are presented for the four ASTM rock-property test methods used in this study.
An Initial Study of Surface Wave Inversion Using Artificial Neural Networks
Authors: Meier RW , Rix GJ
Published: February 2009

An artificial neural network is proposed as an expeditious alternative to the trial-and-error and least-squares surface wave inversion techniques that are currently available. To use an artificial neural network for surface wave inversion, synthetic dispersion curves are calculated for representative shear wave velocity profiles using a theoretical wave propagation algorithm. An artificial neural network is then “taught” to map these dispersion curves back into their respective shear wave velocity profiles. Once the network has been successfully trained on these synthetic dispersion curves, experimental dispersion curves can be inverted by passing them through the neural network. Because the neural network requires only a single forward pass of the data, it performs inversions much more quickly than iterative procedures.

To determine the feasibility of using an artificial neural network for surface wave inversion, a two-dimensional wave-propagation algorithm was used to create synthetic dispersion curves for 99 000 randomly generated, two-layer velocity profiles. A backpropagation neural network was then trained to associate the synthetic dispersion curves with their respective velocity profiles. The trained network was evaluated using synthetic dispersion curves for another 1000 randomly generated velocity profiles as surrogate experimental curves.
Compactor Force and Energy Measurements
Authors: Filz GM , Brandon TL
Published: February 2009

Two hand-operated compactors (a vibrating plate compactor and a rammer compactor) were instrumented to measure the dynamic contact force and energy transfer between compactor and soil. The instrumentation schemes, data acquisition techniques, and data reduction methods are described. The instrumented compactors were operated on two soils: a moist, silty sand and a dry, clean fine sand. The measured forces and energies are presented and compared to the manufacturer's ratings.
Determination of Swell Potential of Al-Qatif Clay
Authors: Abduljauwad SN , Al-Sulaimani GJ
Published: February 2009

Knowledge of the swell potential of expansive soil at the outset of an investigation can be helpful in avoiding possible damage to the structure. A review is presented of several methods that have been proposed to identify swell potential and test techniques, which are used to quantify the amount of swell. A site investigation was conducted to obtain hand-carved block specimens from a fresh excavation site near Al-Qatif, Eastern Province of Saudi Arabia. Laboratory tests were used to determine geotechnical and physicochemical properties and mineralogical composition. The results of a range of laboratory tests, including oedometer types, filter paper, triaxial, and new stainless steel tank apparatus, showed the problems associated with investigating swell behavior of soils. A field swelling test was conducted, and results are compared with laboratory tests to establish guidelines for estimation of swell potential.
A New Approach to Measuring Dilatancy in Saturated Sands
Authors: Campanella RG , Kokan MJ
Published: February 2009

The determination of in situ properties of sand has proven to be a difficult objective, especially when it includes assessing volume change characteristics like dilatancy. Difficulty in obtaining representative undisturbed specimens as well as problems with extrapolating laboratory test results to the field has caused many to place increased reliance on in situ testing. One such test that is continuing to gain acceptance is the piezocone penetration test (CPTU). While the CPTU is particularly good for stratigraphic detailing and evaluating many geotechnical parameters, the assessment of volume change characteristics is, as yet, not well defined.

A new approach has been developed which uses the measurement of bulk soil resistivity, a geophysical technique, to evaluate in situ dilatancy characteristics of sand. The method makes use of a module mounted behind a standard piezocone to measure resistivity. The interpretation is based on the resistivity contrast between remolded sand at constant volume conditions and relatively undisturbed sand. These measurements are recorded continually along with the usual CPTU data and are therefore logging the dilatancy characteristics at high-depth resolution. A discussion of the method of analysis, assumptions, and limitations is given, and typical results are presented and compared. To date the results suggest that the method developed does not require groundwater sampling or laboratory testing, an obvious advantage. Thus, a dilatancy parameter is measured in combination with the CPTU identified soil stratigraphy and geotechnical properties, and all data are obtained at the same speed and reliability.
Influence of Test Chamber Boundary Conditions on Sand Bed Response
Authors: Al-Douri RH , Hull TS , Poulos HG
Published: February 2009

Two series of tests were performed on calcareous and silica sands in different test chamber sizes and with different base conditions to investigate the influence of test chamber boundary conditions on model pile foundation behavior.

The first series of tests investigated the effects of shear resistance between the soil and the internal wall of the test chamber upon the distribution of vertical stress down the chamber, which in turn influences the behavior of model foundations tested in the sand bed. The measured values of the vertical stress developed at the base of the sand bed show good agreement with theoretical predictions. The second series of tests studied the surface deflection of calcareous sand in the largest of the chambers during consolidation and also during the process of foundation loading. The results of this series of tests have been compared with results from other published data and are found to be in reasonable agreement.
Time-Dependent Triaxial Relaxation Behavior of a Resedimented Clay
Authors: Sheahan TC , Ladd CC , Germaine JT
Published: February 2009

The paper describes the results of K0 consolidated-undrained triaxial compression relaxation tests on resedimented Boston Blue Clay (BBC) using a computer-automated triaxial apparatus. Specimens were either normally consolidated (overconsolidation ratio, OCR = 1) or had an OCR = 4, and they were sheared at different axial strain rates to axial strains (εa) from 0.1 to 15%. Each strain level was maintained until the monitored shear stress and pore pressure reached equilibrium levels. The results show that a single specimen can be used reliably for multiple relaxation tests. During relaxation, the rate of normalized shear stress decay with log time, (−Δq/σ′vm)/Δlogt, is approximately constant, regardless of εa or OCR. Changes in shear-induced pore pressure during relaxation were negligible except when specimens were rapidly sheared. Independent of OCR, end-of-relaxation equilibrium stress states for relaxation strains εa ≤ 1.5% lie on a line of obliquity defined by K = σ′h/σ′v = 0.50, compared to K0 = 0.49 for OCR = 1 BBC; whereas, for εa ≥ 2.5%, the equilibrium states lie on a steeper obliquity line defined by K = 0.40.
Instrumentation for a Weigh In Motion System Using Pavement Strain
Authors: Marsh JG , Jewell RJ
Published: February 2009

A line of vertical strain transducers installed at a depth of 500 mm in a dense sand subgrade across one wheel path of the left hand lane of a busy highway was used to measure vehicle weights. The strain transducers, the custom-made LVDTs they incorporate, the method of installation, and the data acquisition system are described.
Expansion Potential of Compacted Fine-Grained Soils Using Suction Measurements
Authors: Garbulewski K , Zakowicz S , Karim Al-Helo I
Published: February 2009

Fine-grained soils in arid climates are most often unsaturated. If such soils have a swelling potential, their expansive pressure must be determined for structural design. Hitherto employed swelling test methods are time consuming and not reliable. Testing methods based on suction potential measurements are being introduced in order to evaluate the expansive potential.

Swelling test results on three fine-grained soils are described in the paper. Two testing systems were used: (1) a traditional method of constant soil volume and (2) a proposed method utilizing suction pressure measurements. The tested soil samples were characterized by different consolidation initial-moisture-content conditions. The test results presented herein were used to develop a mathematical relationship between expansive pressure and suction pressure for a given soil. A design procedure for estimating swelling pressure is proposed in the paper.
Test Procedures to Evaluate Absorption and Swelling of Grout
Authors: Krizek RJ , Borden RH
Published: February 2009

Described in this paper are test procedures and resulting data used in the laboratory to evaluate the absorption of water and the swelling pressures of several different mixtures of a particular acrylate grout when placed in situ. The water absorption characteristics were determined for both neat grout and grouted sand under conditions of either free swell or moderate confinement. Swelling pressures were assessed primarily by measuring the vertical stress required to prevent vertical swell under conditions of lateral constraint, but consistent data from a few different tests were found to provide supporting evidence. An interesting aspect of this study is that two separate test programs were undertaken simultaneously, but independently, in two different laboratories, and the results became known and were shared only after the testing was essentially complete. The data show that (a) a grouted sand manifests a much lower tendency to swell and absorb water than a neat grout, (b) moderate confinement under the equivalent of a meter or so of overburden significantly reduces the tendency of either neat grout or a grouted sand to absorb water and swell, and (c) the swelling behavior of a grouted sand cannot be predicted from a knowledge of the swelling behavior of the neat grout. Although the test procedures explained herein were applied to only one particular grout type for illustrative purposes, they are generally applicable to any grout or grouted soil that manifests swelling tendencies.
Moisture Increase in Expansive Soils at Developed Sites
Authors: Sikh TS
Published: February 2009

The purpose of this paper is to provide information pertinent to post-development depth-of-moisture increase in expansive soils underlying developed sites. In southern California, the developments are generally accompanied by irrigation around buildings and other improvements. Local experience indicates that the major source of water that contributes to moisture variation in expansive soils is heavy surface irrigation to support lush landscaping. Recent findings indicate that irrigation produces an equivalent annual rainfall of about 178 cm. In contrast, for example, the natural annual rainfall in the San Diego area is about 28 cm. Accordingly, at developed sites, the change in moisture content in soils underlying developed sites does not necesssarily follow a typical seasonal or cyclic pattern. Consequently, the main problem in this region is generally soil swell rather than shrinkage. Due to the introduction of moisture into the subsurface soils on a relatively regular and constant basis, the upper soil profile undergoes an increase in moisture content to a certain depth. Ultimately, at certain times after the completion of the construction, the moisture content stabilizes and becomes nearly constant with depth. The data from six developed sites were evaluated. These sites were developed about 10 years ago. The data indicate that the depth of moisture change was approximately 2 to 3.5 m. The climatic rating (Cw) of the southern California region is about 15, and the Thornthwaite Moisture Index (TMI) generally ranges between +20 to −40, which is similar to many other parts of the country and the world.
Rigid Plate Settlements on Soils with Varying Deformation Properties
Authors: Reznik YM
Published: February 2009

The need to reliably predict foundation settlements has led to the use of plate-loading tests as a method of in situ determination of soil-deformation properties. The results of bearing-plate tests, especially when presented in graphical form, serve as a way to estimate allowable pressures and deformation moduli calculations. The magnitudes of plate settlements and the configurations of plate load-settlement curves determine decisions as to the acceptance of certain types and dimensions of foundations. This paper describes settlements of plates/experimental footings on soils in which deformation properties improve with increasing depth. A simple interpretation formula is offered to calculate allowable pressures. The application of this formula is demonstrated in plate-load test results published in the literature. Erratum to this paper appears in 18(3).
Effects of Sustained and Repeated Tensile Loads on Geogrid Embedded in Sand
Authors: Min Y , Leshchinsky D , Ling HI , Kaliakin VN
Published: February 2009

Design methods for reinforced soil structures under static loading conditions are relatively well established. Little research has been conducted on the behavior of embedded geosynthetics subjected to repeated loadings. Such research is needed to improve the design of reinforced soil structures subjected to traffic and seismic loadings. The study reported here is related to the long-term performance of a geogrid embedded in Ottawa sand under several confining pressures and subjected to various tensile loads. Different magnitudes of sustained and repeated tensile loads were applied to the geogrid incrementally using a pullout device. The confining pressure increased the soil-geogrid interface friction force and thus affected strain distribution along the geogrid length. Creep developed in the geogrid as the applied tensile load increased. The geogrid creep strain rate at a given tension force was found to be independent of confining pressure at the point of this force application, that is, creep can be viewed as an intrinsic property of the geogrid. A rapid pullout failure of geogrid occurred as the applied sustained load approached the ultimate pullout capacity. Conversely, under repeated loading the pullout occurred progressively. The ultimate pullout load and interaction coefficient, Ci, obtained from repeated loading tests were about 20% less than the values obtained from sustained loading tests. This suggests that a Ci smaller than that obtained in static (conventional) tests should be used in structures subjected to dynamic load. Creep under repeated load was smaller than that under sustained load.