bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Soil Structure and Matric Suction in Collapse of a Compacted Clay Soil
Authors: Rao SM , Revanasiddappa K 
Published: February 2009

Abstract
This paper examines the role of microstructure and matric suction in the collapse behavior of a compacted clay soil from Bangalore District in Karnataka State, India. The microstructure of the compacted specimens was examined by mercury intrusion porosimetry (MIP), and the ASTM Filter Paper Method was used to determine their matric suction. The microstructure and matric suction of the compacted specimens were changed by varying their compaction water content, dry density, and clay content (&lt;2 µm fraction). Experimental results showed that relative abundance of coarse (60 to 6 µm) pores was mainly affected by increasing the dry density of the specimens from 1.49 to 1.77 g/cm3. The relative abundance of coarse and fine (0.01 to 0.002 µm) pores was affected by increasing the compaction water content from 10.6 to 26.4%. Variations in dry density, compaction water content, and clay contents notably affected the matric suction of the compacted specimens. The collapse behavior of the compacted specimens is explained from analysis of the MIP and matric suction results.
Influence of Specimen-Reconstituting Method on the Undrained Response of Sand
Authors: Vaid YP , Sivathayalan S , Stedman D 
Published: February 2009

Abstract
An experimental study aimed at a direct comparison of the undrained behavior of sand using specimens reconstituted by different techniques is presented. It is shown that at identical initial void ratio and effective stress state, the moist-tamped sand is potentially liquefiable, but in the water-deposited state may even be dilative. Water-deposited specimens are shown to be very uniform in contrast to the large nonuniformities that usually occur on moist tamping, rendering their results questionable from the standpoint of laboratory element tests. A direct comparison of the behavior of truly undisturbed sand specimens retrieved by in-situ ground freezing and their corresponding reconstituted counterparts after consolidating to identical initial states is also presented in support of the contention that the fabric that ensues on water pluviation closely simulates that of the natural alluvial and hydraulic fill sands, enabling the use of reconstituted specimens as substitutes for the expensive undisturbed frozen specimens for material characterization.
Influence of Reconsolidation Techniques and Strain Rate on the Stiffness of Undisturbed Clays from Triaxial Tests
Authors: Lo Presti DCF , Pallara O , Cavallaro A , Jamiolkowski M 
Published: February 2009

AbstractThis paper concerns the stiffness assessment of undisturbed clays from triaxial tests. The paper summarizes the research activity undertaken at the authors' universities over the last five years by means of triaxial cells equipped with local gages for axial and radial strain measurements and with piezoceramic bender elements for the measurement of the propagation velocity of differently polarized shear waves. The main purpose of this research was to define reliable test procedures in order to determine the stiffness of geomaterials to be used for settlement analysis under working load conditions. In particular the paper deals with four different topics: (1) evaluation of sample disturbance by means of different methods, (2) assessment of the reconsolidation techniques that minimize the sample disturbance effects, (3) influence of strain rate on the stiffness of undisturbed clays, (4) stiffness anisotropy of undisturbed clays at small strains.
Simplified Seepage Consolidation Test for Soft Sediments
Authors: Sridharan A , Prakash K 
Published: February 2009

Abstract
The consistency of very soft sediments prevents the conventional oedometer test from being applied to study their compressibility and permeability characteristics. The hydraulic consolidation test in existence requires sophisticated instrumentation and testing procedures. The present paper proposes a seepage-force-induced consolidation testing procedure for studying the compressibility and permeability behavior of soft sediments at low effective stress levels. The good agreement that has been observed between the results obtained from the proposed method and the conventional oedometer test at overlapping effective stress levels indicates that the proposed method can be used to study the compressibility and permeability characteristics of soft sediments at low effective stress levels satisfactorily.
Index Properties of Illite-Bentonite Mixtures in Electrolyte Solutions
Authors: Sivapullaiah PV , Savitha S 
Published: February 2009

Abstract
Bentonite, commonly used for liner constructions in waste containment systems, possesses many limitations. Illite or illite containing bentonite has been proposed as an alternative material for liner construction. Their properties in different types of pore fluids are important to assess the long-term performance of the liner. Further, the illite-bentonite interaction occurs and changes their properties. The effect of these interactions is known when the pore fluid is only water. How their properties are modified in electrolyte solutions has been brought out in this paper. The index properties have been studied since they give an indication of their engineering properties. Due to reduction in the thickness of the diffused double layer and consequent particle aggregation in bentonite, the effect of clay-clay interaction reduces in electrolyte solutions. In electrolyte solutions, the liquid limit, the plasticity index, and free swell index of bentonite are lower than illite. The plasticity index of bentonite is further reduced in KCl solution. Clays with a higher plasticity index perform better to retain pollutants and reduce permeability. Hence, the presence of both illite and bentonite ensures better performance of the liner in different fluids.
Applied Research Using a Transparent Material with Hydraulic Properties Similar to Soil
Authors: Welker AL , Bowders JJ , Gilbert RB 
Published: February 2009

Abstract
An innovative material, transparent soil, was used to study flow from a prefabricated vertical drain (PVD). Transparent soil is a mixture of mineral oil, solvent, and amorphous silica. Before using the material to study PVD flow patterns, testing was completed to verify previously published values for hydraulic conductivity and porosity. The results of the independent testing matched the published results well. Experiments using scaled-down and full-size PVDs were completed in cells with diameters ranging from 10.2 to 30.0 cm, respectively. The results of these tests compared favorably to those obtained using an electrical analog and a mathematical model. The transparent soil was an acceptable representation of soil; however, degradations in transparency can be a problem in larger samples. Some other difficulties in using transparent soil, such as finding acceptable sealants and preventing dying of the silica particles, are discussed. In addition, recommended areas of continued research are presented.
Time Domain Reflectometry Development for Use in Geotechnical Engineering
Authors: Siddiqui SI , Drnevich VP , Deschamps RJ 
Published: February 2009

AbstractThis study extends the use of time domain reflectometry (TDR) in geotechnical engineering, a technique originally developed to locate faults in transmission lines. Different elements of the TDR technique are developed, including design of TDR probes, probe installation/test methodology, and relationships between TDR measured dielectric constant and water content of soil. A coaxial probe is developed that is used for measuring the dielectric constant of soil prepared in a cylindrical cell or compaction mold. A multiple-rod field probe is developed that modifies previously developed multiple-rod probes and extends their capability for measuring the in-place dielectric constant of soil. An analytical solution is developed to determine the sampling volume and spatial bias of the TDR measurement. The solution is extended to study the effect of soil disturbance and presence of air gaps due to probe insertion. Experimental results validate the solutions. New relationships are proposed between dielectric constant and water content to eliminate some of the limitations of the existing calibration relationships. Several possible applications of the developed probes, test methodology, and calibration equations for measuring water content and density of soil are illustrated.
Load and Resistance Factor Design (LRFD) for Driven Piles Using Dynamic Methods—A Florida Perspective
Authors: McVay MC , Birgisson B , Zhang L , Perez A , Putcha S 
Published: February 2009

Abstract
The parameters for load and resistance factor design (LRFD) of driven piles using dynamic methods are presented based on a database of 218 pile cases in Florida. Eight dynamic methods were studied: ENR, modified ENR, FDOT, and Gates driving formulas, Case Analysis with Wave Analysis Program (CAPWAP), Case Method for Pile Driving Analyzer (PDA), Paikowsky's energy method, and Sakai's energy method. It was demonstrated that the modern methods based on wave mechanics, such as CAPWAP, PDA, and Paikowsky's energy methods, are roughly twice as cost effective to reach the target reliability indices of 2.0 to 2.5 (failure probability = 0.62 to 2.5%) as the ENR and modified ENR driving formulas. The Gates formula, when used separately on piles with Davisson capacities smaller or larger than 1779 kN, has an accuracy comparable to the modern methods. The utilizable measured Davisson capacity, defined as φ/λ (ratio of resistance/mean capacity) obtained from testing at beginning of redrive (BOR), is only slightly larger than the end of drive (EOD) values. Furthermore, past practice with driving formulas reveals the existence of a large redundancy in pile groups against failure. The latter suggests the use of a lower relatively reliability target index, βT = 2.0 (pf = 2.5%) for single pile design. Also, the utilizable measured Davisson capacity, φ/λ, for all the dynamic methods studied, is quite similar to published values (Lai et al. 1995; Sidi 1985) for static estimates from in situ tests.
A Dynamic Method for Determining the Soil Water Characteristic Curve for Coarse-Grained Soils
Authors: Rassam DW , Williams DJ 
Published: February 2009

Abstract
The air-entry suction is an extremely important parameter in the water characteristic curve, but is difficult to identify when using conventional static methods such as the pressure plate apparatus. In the dynamic method described herein, instantaneous measurement of matric suction and water content are acquired from a soil specimen undergoing a slow drying cycle with the aid of a tensiometer and a soil moisture probe, respectively. The method offers a quick and reliable way of quantifying the drying soil-water characteristic curve (SWCC) for matric suctions of up to 80 kPa. The large number of data points acquired make it easy to obtain an accurate estimate of the air-entry suction. It is particularly effective for soils ranging from medium sands to sandy silts where a nearly continuous SWCC is provided.
A New Technique of Kneading Compaction in the Laboratory
Authors: Kouassi P , Breysse D , Girard H , Poulain D 
Published: February 2009

Abstract
The mechanical behavior of unsaturated compacted soil affects the security of embankments. The aim of compaction methods in the laboratory is to reproduce the compaction effect induced by on-site equipment. This paper summarizes all the results obtained on kneading compaction in order to define a compaction procedure that simulates the action of compacting machines in the field.
Comparison of Internal and Surface Erosion Using Flow Pump Tests on a Sand-Kaolinite Mixture
Authors: Reddi LN , Lee I-M , Bonala MVS 
Published: February 2009

Abstract
The purpose of this paper is to assess the difference between surface and internal erosion processes using results from flow pump tests. Samples of 70% Ottawa sand + 30% kaolinite mixture were used with distilled water and NaCl solutions as permeants. Two kinds of tests were conducted, a surface erosion test where the permeant was pumped through a cylindrical hole of 7-mm diameter and an internal erosion test where the permeant was pumped through intact compacted samples in compaction permeameters. A simple capillary tube model was used to estimate the critical shear stresses needed to cause erosion in surface erosion experiments. It was found that although surface erosion critical shear stresses were exceeded in the intact soil samples, particle clogging in the pores and redeposition of eroded particles prevented mobilization of particles into the effluent stream. Erosion rates estimated using surface erosion parameters were significantly greater than those observed in internal erosion experiments. The results suggest that the fate of eroded particles, including particle redeposition and pore clogging, may govern the internal erosion process far more than the surface erodibility of the soil.
Determination of Thickness of Smooth Geomembranes
Authors: Yesiller N , Cekic A 
Published: February 2009

Abstract
Tests were conducted to determine thickness of smooth, nonreinforced geomembranes using three methods: mechanical (according to ASTM and European standards), ultrasonic, and magnetic methods. The mechanical method is the standard procedure used for determining thickness of geomembranes. The ultrasonic and magnetic methods are not commonly used for geomembranes; however, they are used for testing other materials such as metals. Tests were conducted on 15 geomembranes representing five types of polymers (HDPE, LLDPE, PVC, PP, and EPDM). The results of the testing program indicated that the level of pressures applied affected the thickness measurements in mechanical tests. While the low pressures were not sufficient to flatten particularly the rigid geomembranes, the high pressures tended to compress the geomembranes excessively. Both high and low pressures prevented obtaining representative measurements. The measurements obtained using the ASTM method were more reliable than the measurements obtained with the European method, although it is believed that the most reliable measurements can be obtained by the nondestructive methods (ultrasonic and magnetic). These techniques are sensitive only to the thickness of the materials due to the inherent properties of the test procedures, and they work equally well for rigid and flexible geomembranes. Of the two nondestructive methods, ultrasonic testing is better due to several advantages: it allows for testing from the top surface of geoembranes in the laboratory or in the field, and it can be used on coupons of geomembranes as well as on whole sheets without the need for removing test samples. Both nondestructive methods can be improved for application to geomembranes.
Shear Displacement Dependent Strength of Municipal Solid Waste and Its Major Constituent
Authors: Pelkey SA , Valsangkar AJ , Landva A 
Published: February 2009

Abstract
A limited amount of data exist on the shear strength properties of municipal solid waste. Similar to the soil strength parameters, the data on wastes are reported in terms of a cohesion intercept and an angle of internal friction. Most often the strength parameters reported are for the maximum values mobilized in laboratory testing. Recent state-of-the-art review papers on the topic have summarized the available strength data and noted that large shear displacements are required to mobilize peak shear strength parameters. In comparison, other components of a landfill system such as mineral and geosynthetic liners mobilize peak strengths at much smaller shear displacements. There are, therefore, shear displacement incompatibility issues that need to be resolved. In this paper the shear strength data from the direct shear tests performed on municipal solid waste samples and its major constituent (paper) are presented as a function of shear displacement. Results of a limited number of simple shear tests performed on municipal waste samples are also presented and compared with the data from direct shear testing.
Determination of Specific Gravity and Void Ratio of Pumice Materials
Authors: Wesley LD 
Published: February 2009

Abstract
The vesicular nature and the soft grains of pumice deposits create difficulties in testing them and in interpreting the test results. This note examines the difficulty of measuring specific gravity and estimating void ratio. The difficulty arises from the presence in the particles of a network of internal voids or vesicles, some of which are interconnected and open to the external surface, while others are isolated inside the particle. The void ratio measured by conventional methods invariably includes some of the internal void space, and is therefore, not a true measure of void ratio in terms of the normal definition or understanding of the term. This paper examines different ways of measuring the specific gravity, and the influence of particle size on the results.
Non-Linear Behavior of Lateral-Loaded Pile Taking into Account the Shear Stress at the Sand
Authors: Belkhir S , Mezazigh S , Levacher D 
Published: February 2009

Abstract
Due to recent research advances in understanding mechanisms that govern deep behavior foundations, vertical piles can now be used to correctly support lateral loads.
This paper concerns the development of a computer program for studying non-linear behavior of lateral-loaded piles taking into account the shear stress at the sand.
Some examples issued from the numerical code are compared with experimental results from centrifuge modeling loaded piles tests and with other numerical results from a well-known code used in France.
The influence of shear stress at the soil on the behavior laterally loaded piles was also studied.
Development of Pile Driver and Load Set for Pile Group in Centrifuge
Authors: Pan S , Pu J , Yin K , Liu F 
Published: February 2009

Abstract
When testing piles in a geotechnical centrifuge, it is more efficient to drive piles into the soil in centrifuge flight instead of placing piles prior to running the centrifuge in order to simulate the real conditions. A new pile driver with loading set used to drive and load piles in a centrifuge has been designed and manufactured successfully by the authors. The apparatus on the model container is light and can be maneuvered in the X-Y plane easily. With this apparatus, the piles can be driven or pushed into the soil in centrifuge flight at any position in the X-Y plane. Furthermore, the pile group can be driven into the soil one by one, and the loading test of the pile group can be performed without stopping the operation of the centrifuge.
Ring Shear Tests on a Carbonate Sandy Silt
Authors: Tika TE 
Published: February 2009

Abstract
The paper describes a series of ring shear tests on a carbonate sandy silt designed to simulate soil shearing caused by pile installation and soil shearing resistance developed during pile loading. The tests were performed on the soil and on soil-steel interfaces at large displacements. The soil tests were carried out at constant normal stress conditions, whereas the soil-steel tests were carried out at constant normal stress and constant normal stiffness conditions. The results of the tests are presented and their implications for the behavior of displacement piles are then discussed.
Strength and Deformation Behavior of Soft Bangkok Clay
Authors: Seah TH , Lai KC 
Published: February 2009

AbstractThe influence of stress history and stress state during consolidation and shearing were studied experimentally under undrained triaxial compression and extension modes, by using the Recompression and SHANSEP techniques. In the SHANSEP tests, the samples were consolidated to a vertical consolidation stress of about 1.5 to 2 times of the preconsolidation pressure under Ko consolidation condition, followed by swelling to required overconsolidation ratio before subjecting to undrained shear. Whereas in the Recompression technique, the samples were directly consolidation to in situ effective stress before undrained shearing, the volumetric strains of the reconsolidation were less than 2%, indicating relatively reasonable sampling quality. From the undrained shear results, the Recompression tests give higher undrained shear strength than estimated from SHANSEP tests by about 28%, indicating that some destructuring of soil structure may have occurred in the SHANSEP tests due to large vertical deformation during consolidation. Consequently, the undrained shear strength and the undrained modulus obtained from the SHANSEP tests were much lower.
Shake Table Calibration and Specimen Preparation for Liquefaction Studies in the Centrifuge
Authors: Dief HM , Figueroa JL 
Published: February 2009

AbstractRecently, a new geotechnical centrifuge was installed at Case Western Reserve University (CWRU). To use this facility in studying soil liquefaction required the development of a feedback correction procedure for the shake table input signals and an appropriate procedure for model preparation, as well as the design of a saturation system setup. These procedures are discussed in detail. Dynamic centrifuge tests at a scale of 60 g's were conducted on scaled pore fluid-saturated models. This fluid is a solution of a water-soluble polymer derived from cellulose at 60 times the viscosity of water. A comparison between the behavior of pore pressure responses during two identical dynamic centrifuge tests using either water or a scaled viscous fluid is documented in this paper.
A New Torsional Shear Device
Authors: d'Onofrio A , Silvestri F , Vinale F 
Published: February 2009

Abstract
Reliable small-strain measurements of deformational characteristics of soils have been one of the challenging aims in geotechnical engineering laboratories over the past decade, in particular when the mechanical behavior of stiff clays and soft rocks has to be analyzed under working conditions.
A new torsional shear apparatus has been developed at the University of Naples, “Federico II,” Italy, suited for accurate and continuous measurement of deformational characteristics at both small strain levels and high stress levels.
In order to accomplish these requirements, the new device incorporates a special electromagnetic loading system designed to apply a maximum torque of more than 5 Nm, and a high-resolution monitoring system, which allows accurate measurements at strain levels below 10−3%. In this paper the design criteria are described in detail, and the efficiency of the new device is shown by several experimental results using a prototype device.
Time-Dependent Stress-Strain Behavior of Soft Hong Kong Marine Deposits
Authors: Zhu J-G , Yin J-H , Luk S-T 
Published: February 2009

Abstract
To investigate the time-dependent stress-strain behavior of Hong Kong marine deposits (HKMD), three types of triaxial tests have been conducted under both compression and extension states. The first is conventional undrained shear tests at different strain rates ranging from 0.0025 to 0.25%/min. The second type is stress relaxation tests. The last type is undrained creep tests. The results are reported in this paper. One order increment of logarithmic strain rate causes about 5 to 9% increase of undrained shear strength. In stress relaxation tests, the pore-water pressure increase is about 10% of the consolidation pressure under extension states. A power law equation is presented to calculate the decay of the deviator stress in relaxation. In multi-stage triaxial creep tests, the log(strain rate)-log(t) relationship of the lower stress level is linear. The slopes of these lines are dependent on current deviator stress as well as stress history.