bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hollow Glass Microspheres Inhibit Blast-Induced Liquefaction
Authors: Charlie WA , Johnson CF , Doehring DO 
Published: February 2009

Abstract
This paper summarizes the results of a controlled series of undrained shock tests conducted on mixtures of Monterey No. 0/30 sand, water, and hollow glass microspheres. Hollow glass microspheres, utilized to entrap gas in the sand, have a collapse strength of about 1700 kPa, are stable over time, and remain passive until a pressure sufficient to collapse them is applied. When subjected to a sub-millisecond compressive stress pulse of about 2300 kPa, peak stress transmission ratio decreased about 50% as the saturation decreased from 100 to 99.5%. Positive residual excess pore pressures (decreases in effective stress) were measured at saturations of 100, 99.9, and 99.8%. Negative residual excess pore pressures (increases in effective stress) were measured at saturations of 99.7, 99.6, and 99.5%. Analysis indicates that no change in residual pore pressure should occur at a saturation of 99.77%. The results indicated that microspheres may be used as a passive measure to inhibit blast-induced liquefaction and for reducing peak blast-induced stress in saturated soils.
Estimation of Pile Friction Degradation from Shearbox Tests
Authors: Airey DW , Al-Douri RH , Poulos HG 
Published: February 2009

Abstract
An uncemented carbonate sand has been subjected to cyclic loading in a modified shearbox apparatus under constant normal load and constant normal stiffness conditions. The behaviour in the tests using a constant normal stiffness shows many similarities with the variation of skin friction on piles under cyclic loading. It is demonstrated that the response in the shearbox tests with a constant normal stiffness may be predicted from the response observed in conventional shearbox tests, and that conventional shearbox tests can thus provide valuable information on the degradation of skin friction of piles under cyclic loading.
A Hollow Cylinder Torsional Simple Shear Apparatus Capable of a Wide Range of Shear Strain Measurement
Authors: Ampadu SK , Tatsuoka F 
Published: February 2009

Abstract
The lack of high-quality data at small strains under monotonic loads has led to the assumption of linear elasticity in small strain analysis and the use of low values of stiffness for analysis of geotechnical structures under working loads. In addition, since most simple shear apparatuses cannot measure lateral stresses, various assumptions have to be made in order to define the failure strength in terms of principal stresses. In this paper a hollow cylinder torsional simple shear system that is capable of measuring shear strains accurately from a strain level as small as 10−6 to failure in addition to measuring all stress components is described. This system is also capable of consolidating specimens along both normal and overconsolidated stress paths and during shearing is able to apply extremely small load reversals with little or no backlash effect. Using the special features of this system, the behavior of kaolin specimens under various stress histories from very small strains to failure was studied. The results show that irrespective of the consolidation stress history, the major part of the principal stress rotation occurs at the early stages of undrained simple shear, and the final direction near the peak strength is always a few degrees below 45°. The small strain behavior indicates that there exists a very small elastic zone of the order of 2 × 10−5 shear strain, and that the behavior beyond this region is highly nonlinear. The trend in the variation of the peak strength with OCR obtained in this system is similar to that obtained in the conventional simple shear apparatus as reported in the literature.
G
max-qc Relationships for Clays
Authors: Mayne PW , Rix GJ 
Published: February 2009

Abstract
Data are compiled from 31 clay sites where in-situ measurements of initial tangent shear modulus (Gmax) and cone tip resistance (qc) were available. Values of Gmax were obtained from either seismic cone penetration (SCPT), crosshole (CHT), downhole (DHT), or spectral analysis of surface wave (SASW) tests, and readings of qc were taken either by regular cone penetration (CPT) or piezocone (CPTU) tests. Multiple regression analyses indicate that in-situ values of Gmax depend on void ratio (eo), overburden stress (σ′vo), and stress history (OCR), as previously established from laboratory resonant column tests. Since qc also depends on σ′vo and OCR, a moderate association between Gmax and qc is possible, despite their incompatible strain levels. For preliminary correlative purposes, a power function relates in-situ Gmax, qc, and eo in clay deposits having a wide range in plasticity, sensitivity, stress history, and consistency.
Modified Bromhead Ring Shear Apparatus
Authors: Stark TD , Eid HT 
Published: February 2009

Abstract
The main factor affecting the drained residual strength measured in the Bromhead ring shear apparatus is the magnitude of wall friction developed along the inner and outer circumferences of the confined specimen. The magnitude of wall friction increases with the depth of the remolded specimen, and thus the plane of least wall friction occurs at or near the soil/top porous stone interface. As the top porous stone settles into the specimen container, the wall friction influencing the shear plane increases, causing an increase in the measured residual strength.
A new specimen container is proposed for the Bromhead ring shear apparatus that allows a remolded specimen to be overconsolidated and precut prior to drained shearing. This minimizes settlement of the top platen and the horizontal displacement required to reach a residual strength condition. As a result, a multistage test can be conducted without excessive settlement and thus wall friction occurring in the new specimen container. The use of a multistage test significantly reduces the time required to establish a drained residual failure envelope. The use of an overconsolidated and precut specimen also provides a better simulation of the field conditions that lead to a large post-peak decrease in drained strength in clayshales, claystones, and mudstones, and residual strengths that are in excellent agreement with field case histories.
Use of CPTu to Estimate Equivalent SPT N60
Authors: Jefferies MG , Davies MP 
Published: February 2009

Abstract
Although the CPTu offers many advantages over the SPT, it may be desirable in some instances to use SPT-based experience of soil behavior. An algorithm is presented here for estimation of equivalent N60 values directly from the CPTu without resort to soil sampling. The proposed algorithm is based on data and trends reported in the literature; the algorithm is tested against new data obtained for cross-calibration of the CPTu/SPT in a wide variety of soil types, penetration resistances, and depths. As part of the evaluation of the algorithm, replicate trials of both SPT and CPTu were carried out. The data show the CPTu is five times more precise than the SPT. Further, the equivalent N60 derived from the CPTu using the proposed algorithm is shown to be at least as reliable as values directly determined by the SPT; the much improved precision of the CPTu outweighs the uncertainty in the CPTu/SPT calibration, and the calibration in itself averages the testing error of the SPT. The proposed algorithm is tested for bias against depth, soil type, penetration resistance, and friction ratio; the algorithm is unbiased. Cumulative probability density functions are given for repeatability of the SPT, the CPTu, and an estimation of equivalent SPT values from the CPTu.
Consolidation, Pre- and Post-Peak Shearing Responses from Internally Instrumented Biaxial Compression Device
Authors: Finno RJ , Rhee Y 
Published: February 2009

Abstract
An internally instrumented, servo-controlled biaxial compression device is described for evaluating shear band formation in soils. Internally measured vertical and lateral soil displacements as well as lateral deformations of a very low friction bottom sled allow one to observe the progressive development of shear bands in a specimen. Anisotropically consolidated specimens of relatively insensitive, soft Chicago glacial clay were sheared under undrained conditions. Differences in responses based on the internal and globally derived stress and strain quantities illustrate the uniformities which are attained during both consolidation and shear. Small, outward lateral displacements were observed during K0 consolidation, which was based on globally observed axial and volumetric strains; yet, observed Ko values were similar to those measured by other means. Observed lateral deformations during undrained shear and bottom sled movements showed the progressive development of a shear band in all tests. Nonuniformity of the deformations arose after attaining a peak shear stress. The globally observed strain-softening response was both constitutive and geometric in nature.
Evaluation of Static Capacity of Deep Foundations from Statnamic Testing
Authors: Brown DA 
Published: February 2009

Abstract
A new method of load testing, called statnamic, is evaluated with respect to conventional methods of static load testing. Case histories are examined that provide a basis for comparison of static capacity as estimated from statnamic measurements with that of conventional load-deflection measurements. When evaluated using the simple procedure proposed by Middendorp, the statnamic method is shown to predict load-deflection response that is relatively close to that measured with conventional static load tests in most cases. Comparisons with conventional static load tests outlined in this paper suggest that excellent agreement can be obtained in sandy soils, but that the current evaluation procedure may tend to overpredict capacity by as much as 30% in stiff, overconsolidated clays.
Engineering Properties of Tire Chips and Soil Mixtures
Authors: Edil TB , Bosscher PJ 
Published: February 2009

Abstract
The primary objective of the research described herein is to assess the pertinent engineering properties for reusing shredded scrap tires as a construction material for light-weight fill material in highway construction, for drainage material in highway and landfill construction, and for other similar applications. Reuse of scrap tires would not only provide a means of disposing of them but would also help solve difficult economical and technical problems. This paper presents the characteristics of shredded scrap tires and their engineering properties and behavior alone or when mixed with soils. The properties considered include compaction, compressibility, strength and deformability, and hydraulic conductivity. Described are new test procedures or modification of existing methods developed to characterize this unusual material.
The Effects of Centerline Tube Sampling Strains on the Undrained Behavior of Two Stiff Overconsolidated Clays
Authors: Georgiannou VN , Hight DW 
Published: February 2009

Abstract
Some of the effects of tube sampling of stiff clays are examined. A strain path that simulates strains at the centerline of a tube sample as it is captured by a penetrating sampling tube was applied in the triaxial apparatus. Undrained triaxial strain path tests were performed on two stiff overconsolidated clays that had not previously been subjected to tube sampling. The response of the clays after simulated sampling and reconsolidation is compared with shear behavior established from tests on specimens taken from block or rotary-cored samples. The mean effective stress is reduced by about 10% as a result of the centerline tube sampling strain path. Stiffness is significantly reduced after simulated sampling and isotropic reconsolidation for both clays, whereas peak strength is only slightly affected.
Analysis and Estimation of the Coefficient of Consolidation
Authors: Narasimha Raju PSR , Pandian NS , Nagaraj TS 
Published: February 2009

Abstract
Consolidation is one of the most important behaviors of saturated fine-grained soils that needs to be understood for settlement analysis of these soils. The two most important aspects of laboratory consolidation tests are: (1) estimation of the compression index (Cc), used to predict total settlement of normally consolidated soils provided the void ratio versus log (effective stress) is linear; and (2) the coefficient of consolidation (Cv), used to predict the rate of settlement in the range of primary consolidation. Several researchers have proposed various graphical methods for obtaining estimates of Cv from laboratory oedometer tests. Olson (1985) concluded that since different graphical methods estimate different values for Cv for the same data, the only rational way to estimate the Cv value is to base it on the coefficient of volume compressibility (mv) and the coefficient of permeability (k). Guided by these considerations, an attempt has been made to establish the feasibility of estimating Cv using stress state-permeability relationships (Nagaraj et al. 1993). The input parameters are the liquid-limit void ratio (eL) and the overburden pressure (p).
Screw Plate Insertion in Sand
Authors: Brown PT 
Published: February 2009

Abstract
Laboratory measurements of the depth of penetration at the end of each revolution of a 30-mm-diameter screw plate were made when the insertion was carried out with no vertical thrust applied to the screw plate. The tests were carried out to a depth of 150 mm in a dry, uniformly graded sand with a wide range of densities and two values of surcharge pressure. The results showed that, except for sand with a relative density less than about 30%, the penetration per revolution decreases significantly with increasing depth and decreases more rapidly as the density increases. After insertion, loading tests were carried out using the screw plate; the results show a large increase in apparent modulus at the higher values of density. Measurements of elastic modulus were also made when the screw plate was inserted under the control of a threaded rod having the same pitch as the screw plate and with a flat disk buried in the sand.
A Pluvial Deposition Method to Reconstitute Well-Graded Sand Specimens
Authors: Fretti C , Lo Presti DCF , Pedroni S 
Published: February 2009

Abstract
Stationary pluviators generally use one or more sieves to spread the sand flow exiting from the hopper through one or more holes over the desired area. On the other hand, traveling pluviators do not need a sieve or mesh because in this case it is possible to move an opening or a nozzle over the area of interest. Traveling pluviators are preferable to stationary pluviators, especially in the case of well-graded cohesionless soils, because they provide more uniform specimens. However, traveling pluviators have drawbacks, specimen layering being the most relevant. This technical note illustrates an experimental procedure to reconstitute large specimens of well-graded sands using a traveling pluviator. The effects of specimen layering on mechanical soil properties became negligible with this technique as it was possible to assess performing a series of CPT tests with both a standard cone and a 20-mm cone.
Automated Determination of the Distribution of Local Void Ratio from Digital Images
Authors: Frost JD , Kuo C-Y 
Published: February 2009

Abstract
The frequency distribution of local void ratio is believed to be an important parameter, in addition to the void ratio, for describing the mechanical behavior of granular materials. Oda proposed a method to determine experimentally the distribution of local void ratio from 2-D plane sections. To date, implementations of Oda's method have depended to varying extents on operator judgment to form polygons by joining the centers of gravity of all particles that surround a void. Furthermore, the studies have involved a significant amount of manual work in making the required measurements. This paper describes a fully automated implementation of the method, which uses high-level, image-processing techniques. The proposed method eliminates operator judgment and manual work and makes the determination of the distribution of local void ratio from 2-D plane sections both repeatable and efficient. The method is illustrated with measurements performed on synthetic and real images. The importance of correcting the images to account for factors such as thickness of segmentation lines is demonstrated. Measurements that confirm the stability of the proposed polygon network generation procedure are also presented.
The Relationship Between the Soil-Water Characteristic Curve and the Unsaturated Shear Strength of a Compacted Glacial Till
Authors: Vanapalli SK , Fredlund DG , Pufahl DE 
Published: February 2009

Abstract
Soils compacted at various “initial” water contents and to various densities should be considered as “different” soils from a soil mechanics behavioral standpoint even though their mineralogy, plasticity, and texture are the same. The engineering behavioral change from one specimen to another will vary due to differences in soil structure or aggregation. The shear strength of an unsaturated soil and the soil-water characteristic curve are dependent on soil structure or the aggregation, which in turn is dependent on the “initial” water content and the method of compaction. The laboratory preparation of specimens must, therefore, closely represent the physical conditions and the stress state conditions likely to occur in the field if a proper assessment of the shear strength parameters is to be achieved. This paper is primarily concerned with the study of the relationship between the shear strength of an unsaturated soil and its soil-water characteristic curve.
Consolidated drained direct shear tests were conducted on statically compacted glacial till specimens, both under saturated and unsaturated conditions, representing three “initial” water contents and densities. The “initial” water contents and densities of the specimens were selected to represent the dry, optimum, and wet of optimum water content conditions with reference to the compaction curve. Multistage, unsaturated, direct shear tests were conducted under three different net normal stresses with varying matric suction values for each case. The soil-water characteristic curves were also developed on specimens with “initial” conditions similar to those used for the unsaturated shear strength tests.
The shear strength variation with respect to matric suction was found to be nonlinear for all the tests. The rate of increase in the shear strength contribution due to matric suction, however, was found to be related to the rate of desaturation of the soil. The desaturation characteristics are a function of the “initial” water content of the compacted specimens. For any particular net normal stress and matric suction, specimens compacted wet of optimum water content offered more resistance to desaturation and exhibited a higher shear strength when compared to specimens compacted at dry of optimum or at optimum water content conditions. Under similar “initial” conditions, the soil-water characteristic curve bears a close relationship to the unsaturated shear strength behavior of the soil.
A Device for the Measurement of Sub-Surface Ground Vibrations
Authors: Leong EC , Cheong HK , Pan TC 
Published: February 2009

Abstract
A reliable measurement of free-field stress waves from transient loading has several important applications, for example, in the design of effective wave barriers to protect sensitive equipment and in the design of underground protective structures against explosive loading, to name a few. The characteristics of a stress wave are highly dependent on the energy source and the soil medium through which it propagates. A new device in place of a buried sensor is described in the present paper that can be used to measure the free-field subsurface ground vibrations in the horizontal direction. Laboratory modal analyses showed that the device has a natural frequency of about 600 Hz. For practical applications, the upper frequency limit of the device is taken as 300 Hz, which is well above the range of frequencies normally encountered in practice. Test measurements using both the device and buried sensors in residual soils from an impact load and a blast load are presented. Evaluation of the test results shows that the characteristics of the stress waves generated by these loads can be measured accurately with the device. Compared to a buried sensor, the device has the added advantages of ease of alignment to the source and ease of retrieval.
Dynamic Characteristics of Old Bay Clay
Authors: Guha S , Drnevich VP , Bray JD 
Published: February 2009

Abstract
Unusually strong ground motions at deep stiff clay sites in the East San Francisco Bay area during the 1989 Loma Prieta earthquake called for examination of the dynamic response of this clay deposit and characterization of its dynamic properties. In this paper, correlations of Old Bay clay dynamic properties with various soil parameters (e.g., plasticity, void ratio, magnitude and duration of confinement, consolidation stress history) are presented and compared with the existing database on cohesive soils. A special effort is made to evaluate the effects of sample disturbance on the laboratory measurement of dynamic properties of stiff cohesive soils. The laboratory measurement of low-strain shear modulus and damping ratios is adjusted by considering the aging of the Pleistocene era clay deposit. These adjustments, though effective, are not sufficient to account for the effects of structural disturbance. Shear modulus is reduced significantly by structural disturbance, but, surprisingly, the damping ratio is found to remain largely unaffected.
Suggested Practice for Drilling Boreholes for Pressuremeter Testing
Authors: Briaud J-L , Gambin M 
Published: February 2009

AbstractA standard practice is suggested for the preparation of the borehole in which the pressuremeter probe is to be inserted. The practice covers the required diameter of the hole, the various drilling tools and methods used to place the probe, the test spacing and testing sequence, and the way to judge the quality of the borehole and of the test. This practice is an adjunct to the suggested practice for pressuremeter testing in soils.
Permeability Testing with Flexible-Wall Permeameters
Authors: Daniel DE , Trautwein SJ , Boynton SS , Foreman DE 
Published: February 2009

AbstractThe equipment and testing procedures used at The University of Texas at Austin for measuring the hydraulic conductivity of fine-grained soil with flexible-wall permeameters are described. The permeability cell is similar to a triaxial cell; it has interchangeable base pedestals to accomodate specimens of various diameters, is equipped with double drainage lines to the top and bottom of the test specimen, and can accomodate a differentially acting pressure transducer to measure head loss across the soil specimen. An air-over-liquid interface is maintained in devices called “accumulators.” Stainless steel accumulators designed with transparent sight tubes offer excellent resistance to corrosion, are convenient to use, and can be used with a wide range in flow rates. The permeability tests are normally performed using back pressure. Care is taken to be certain that flow is steady state and that the soil is permeated long enough for the influent liquid to pass through the soil and to appear in the effluent liquid in full concentration. When clays are permeated with dilute chemicals that are adsorbed by the soil, testing times on the order of months or years may be required to achieve full breakthrough of the permeant liquid. Use of large hydraulic gradient and excessive effective confining pressure are sometimes difficult to avoid but are two of the most important sources of potential error.