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Michael A Mooney - One of the best experts on this subject based on the ideXlab platform.
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anisotropy in the spatial distribution of roller measured Soil Stiffness
International Journal of Geomechanics, 2010Co-Authors: Norma W Facas, Michael A Mooney, Reinhard FurreAbstract:The geostatistical analysis of roller-measured Soil properties (from continuous compaction control and intelligent compaction) is required for advanced quality control/quality assurance of earthwork and asphalt compaction. This paper explores the existence of anisotropy in the spatial distribution of roller-measured Soil Stiffness and the effect of anisotropy on kriging. Field testing was conducted to collect roller measurement value (MV) data over typical roadway embankment evaluation areas and on a large square area to enable a robust investigation of anisotropy. The semivariogram analysis of the field data clearly indicates that range anisotropy exists. The spatial distributions of roller MV data are different in the longitudinal x -direction than in the transverse y -direction. Magnitudes of range anisotropy ( x-range/y-range ) varied from 2.4 to over 5. The observed range anisotropy is not due to the roller measurement system; rather, it is likely due to the directional nature of earthwork constructi...
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influence of rocking motion on vibratory roller based measurement of Soil Stiffness
Journal of Engineering Mechanics-asce, 2010Co-Authors: Norma W Facas, Paul Van Susante, Michael A MooneyAbstract:Experimental data have shown that vibratory roller compactors often exhibit rotational kinematics in addition to translation during operation. This rotation is not considered in roller-integrated measurement systems that estimate Soil Stiffness based on drum vibration. To model and explore the effect of rotation, a lumped parameter roller/Soil model was developed. The machine parameters for this model were tuned from suspended drum testing that isolated the drum from the ground. The model was then verified using field data collected over a range of excitation frequencies on spatially homogenous Soil, and over transversely heterogeneous Soil using one excitation frequency. Rotational motion was found to significantly influence roller-integrated measurement of Soil Stiffness based on single position drum vibration data. Rotational motion causes single position measurement system results to be nonunique and to vary depending on the direction of roller travel. Using the model, various alternative measurement ...
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in situ Soil response to vibratory loading and its relationship to roller measured Soil Stiffness
Journal of Geotechnical and Geoenvironmental Engineering, 2009Co-Authors: Michael A Mooney, Robe V RinehaAbstract:An investigation was conducted to characterize and relate in situ Soil stress-strain behavior to roller-measured Soil Stiffness. Continuous assessment of Soil Stiffness via roller vibration monitoring has the potential to significantly advance performance based quality assurance of earthwork. One vertically homogeneous and two layered test beds were carefully constructed with embedded sensors for the field testing program. Total normal stress and strain measurements at multiple depths reveal complex triaxial Soil behavior during vibratory roller loading. Measured cyclic strain amplitudes were 15–25% of those measured during static roller passes due to viscoelasticity and curved drum/Soil interaction. Low amplitude vibratory roller loading induces nonlinear in situ modulus behavior. Roller-measured Stiffness and its dependence on excitation force is influenced by the stress-dependent modulus function of each Soil, the varying drum/Soil contact area, and by layer characteristics (modulus ratio, thickness) when layering is present. On vertically homogeneous clayey sand, roller-measured Stiffness decreased with increasing excitation force, a behavior attributed to stress-dependent modulus reduction observed in situ. On the crushed rock over silt test bed, roller-measured Stiffness increased with increasing excitation force despite the mild stress-dependent modulus reduction observed in the crushed rock. In this case, the stiffer crushed rock takes on a greater portion of the load, resulting in the increase in roller-measured Stiffness.
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comparison of stress states and paths vibratory roller measured Soil Stiffness and resilient modulus testing
Transportation Research Record, 2009Co-Authors: Robert V Rinehart, J R Berger, Michael A MooneyAbstract:Vibratory roller-based measurement of Soil Stiffness during intelligent compaction and continuous compaction control can be used for performance-based quality assurance of unbound materials. To realize this potential, the relationship between the roller-measured Soil Stiffness and the Soil modulus, particularly resilient modulus, must be understood. The in situ stress states and paths experienced by Soil beneath a vibratory roller were compared with stress states and paths during laboratory resilient modulus testing. Observed stress fields within the 1-m depth of influence varied considerably for both vertically homogeneous embankment Soil and layered base over subgrade conditions. During low excitation force vibration, roller-induced levels of deviator stress were notably greater than those used during laboratory resilient modulus testing, whereas levels of mean stress were less. Predicted modulus variation with depth was strongly influenced by modulus function parameters. With typical granular Soil parameters, modulus was found to be constant with depth for the embankment conditions. With modulus parameters of more fine-grained behavior, modulus increased considerably with depth.
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surface wave testing to investigate the nature of roller determined Soil Stiffness
20th EEGS Symposium on the Application of Geophysics to Engineering and Environmental Problems, 2007Co-Authors: Nils Ryde, Michael A MooneyAbstract:Continuous compaction control (CCC) with instrumented vibratory roller compactors is an effective tool to estimate the relative Soil Stiffness over the complete area of a construction site. However, research is still needed to extract roller measured Stiffness values directly comparable with pavement design parameters and laboratory measurements. In this study we have used surface wave testing over a compacted subgrade along with CCC to study the influence depth of the roller measured Stiffness value. Results show that shear wave velocity with depth profiles can be useful to study the influence depth of roller measured Stiffness values.
Auckpath Sawangsuriya - One of the best experts on this subject based on the ideXlab platform.
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application of Soil Stiffness gauge in assessing small strain Stiffness of sand with different fabrics and densities
Geotechnical Testing Journal, 2006Co-Authors: Auckpath Sawangsuriya, Pete J Ossche, Tunce EdilAbstract:The Soil Stiffness gauge (SSG) exhibits particular promise for determining the in situ Soil Stiffness at small strains. Because the SSG is new, its application in laboratory Stiffness measurements is limited. The use of the SSG in assessing small-strain Stiffness of sand with different fabrics, densities, and specimen sizes is presented herein. Two types of test containers were utilized and the results indicate that the SSG Stiffness obtained from both containers show a similar trend but are offset by a constant value, which might be due to the effect of specimen dimensions and boundary configurations. A comparison with other small-strain Stiffness tests indicates that the Young's moduli obtained from the seismic tests are consistently higher than those from the SSG tests. The plots of shear modulus versus shear strain amplitude suggest that the SSG modulus appears to be corresponding to a strain amplitude level higher than the strain amplitude of the seismic test, even though the SSG induces a strain amplitude comparable to that of seismic tests. Nonetheless, the SSG is found to be a potential and useful device for assessing the Stiffness of sand with different fabrics and densities.
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relationship between Soil Stiffness gauge modulus and other test moduli for granular Soils
Transportation Research Record, 2003Co-Authors: Auckpath Sawangsuriya, Tunce Edil, Peter J BosscherAbstract:Recently, there has been a concerted effort to develop methods for direct measurement of Soil Stiffness, modulus, or both. A new field test device called the Soil Stiffness gauge (SSG), which is currently marketed as GeoGauge, shows potential to assess near-surface Stiffness. A comparison is presented of moduli obtained from the SSG with moduli obtained from other tests on granular Soils. The maximum single-amplitude dynamic force produced during the SSG measurement is determined to be 17.3 N. On this basis, an estimate of the shear strain amplitude produced from the SSG is made by finite element analysis. A plot of shear modulus versus shear strain amplitude on a medium sand obtained from different laboratory tests, including the SSG, is presented. The comparison of the SSG modulus with the moduli from other laboratory tests indicates that the SSG outputs a dynamic modulus corresponding to a strain amplitude approximately 20 times higher than the expected range and with a magnitude lower than it should be on the basis of the induced strain. Nevertheless, the SSG modulus is still higher than that from the resilient modulus test typically used for pavement design.
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laboratory evaluation of the Soil Stiffness gauge
Transportation Research Record, 2002Co-Authors: Auckpath Sawangsuriya, Pete J Ossche, Tunce EdilAbstract:A new alternative geotechnical field testing device called the Soil Stiffness gauge (SSG), also known as GeoGauge™, exhibits particular promise for monitoring in situ Soil Stiffness during construction quality control. However, there has been only limited research on this device regarding its characteristics and limitations. The results of laboratory testing and a finite-element analysis (FEA) of the SSG are presented. Based on the FEA and the SSG measurement in the test box, the radius of measurement influence extends to 300 mm. For two-layer materials with different Stiffness, the SSG starts to register the Stiffness of an upper-layer material of 125 mm or thicker. The effect of the lower layer, however, may continue to be present even at an upper-layer material thickness of 275 mm, depending on the relative Stiffness of the layer materials. Caution needs to be exercised in interpreting the results from the SSG when it is used on multilayer systems, especially those with geosynthetic separators. The pre...
Tunce Edil - One of the best experts on this subject based on the ideXlab platform.
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relationship between Soil Stiffness gauge modulus and other test moduli for granular Soils
Transportation Research Record, 2003Co-Authors: Auckpath Sawangsuriya, Tunce Edil, Peter J BosscherAbstract:Recently, there has been a concerted effort to develop methods for direct measurement of Soil Stiffness, modulus, or both. A new field test device called the Soil Stiffness gauge (SSG), which is currently marketed as GeoGauge, shows potential to assess near-surface Stiffness. A comparison is presented of moduli obtained from the SSG with moduli obtained from other tests on granular Soils. The maximum single-amplitude dynamic force produced during the SSG measurement is determined to be 17.3 N. On this basis, an estimate of the shear strain amplitude produced from the SSG is made by finite element analysis. A plot of shear modulus versus shear strain amplitude on a medium sand obtained from different laboratory tests, including the SSG, is presented. The comparison of the SSG modulus with the moduli from other laboratory tests indicates that the SSG outputs a dynamic modulus corresponding to a strain amplitude approximately 20 times higher than the expected range and with a magnitude lower than it should be on the basis of the induced strain. Nevertheless, the SSG modulus is still higher than that from the resilient modulus test typically used for pavement design.
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laboratory evaluation of the Soil Stiffness gauge
Transportation Research Record, 2002Co-Authors: Auckpath Sawangsuriya, Pete J Ossche, Tunce EdilAbstract:A new alternative geotechnical field testing device called the Soil Stiffness gauge (SSG), also known as GeoGauge™, exhibits particular promise for monitoring in situ Soil Stiffness during construction quality control. However, there has been only limited research on this device regarding its characteristics and limitations. The results of laboratory testing and a finite-element analysis (FEA) of the SSG are presented. Based on the FEA and the SSG measurement in the test box, the radius of measurement influence extends to 300 mm. For two-layer materials with different Stiffness, the SSG starts to register the Stiffness of an upper-layer material of 125 mm or thicker. The effect of the lower layer, however, may continue to be present even at an upper-layer material thickness of 275 mm, depending on the relative Stiffness of the layer materials. Caution needs to be exercised in interpreting the results from the SSG when it is used on multilayer systems, especially those with geosynthetic separators. The pre...
Robert V Rinehart - One of the best experts on this subject based on the ideXlab platform.
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comparison of stress states and paths vibratory roller measured Soil Stiffness and resilient modulus testing
Transportation Research Record, 2009Co-Authors: Robert V Rinehart, J R Berger, Michael A MooneyAbstract:Vibratory roller-based measurement of Soil Stiffness during intelligent compaction and continuous compaction control can be used for performance-based quality assurance of unbound materials. To realize this potential, the relationship between the roller-measured Soil Stiffness and the Soil modulus, particularly resilient modulus, must be understood. The in situ stress states and paths experienced by Soil beneath a vibratory roller were compared with stress states and paths during laboratory resilient modulus testing. Observed stress fields within the 1-m depth of influence varied considerably for both vertically homogeneous embankment Soil and layered base over subgrade conditions. During low excitation force vibration, roller-induced levels of deviator stress were notably greater than those used during laboratory resilient modulus testing, whereas levels of mean stress were less. Predicted modulus variation with depth was strongly influenced by modulus function parameters. With typical granular Soil parameters, modulus was found to be constant with depth for the embankment conditions. With modulus parameters of more fine-grained behavior, modulus increased considerably with depth.
Justin P Milburn - One of the best experts on this subject based on the ideXlab platform.
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engineering behavior of stabilized Soils
Transportation Research Record, 2003Co-Authors: Robert L. Parsons, Justin P MilburnAbstract:Stabilization of Soils is an effective method for improving Soil properties and pavement system performance. For many Soils, more than one stabilization agent may be effective, and financial considerations or availability may be the determining factor on which to use. A series of tests was conducted to evaluate the relative performance of lime, cement, Class C fly ash, and an enzymatic stabilizer. These products were combined with a total of seven different Soils with Unified Soil Classification System classifications of CH, CL, ML, and SM. Durability testing procedures included freeze-thaw, wet-dry, and leach testing. Atterberg limits and strength tests also were conducted before and after selected durability tests. Changes in pH were monitored during leaching. Relative values of Soil Stiffness were tracked over a 28-day curing period using the Soil Stiffness gauge. Lime- and cement-stabilized Soils showed the most improvement in Soil performance for multiple Soils, with fly ash-treated Soils showing substantial improvement. The results showed that for many Soils, more than one stabilization option may be effective for the construction of durable subgrades. The enzymatic stabilizer did not perform as well as the other stabilization alternatives.