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Gantry-crane pavements and foundations are significant assets within intermodal facilities. The performance of these pavements, which are subjected to highly-variable loads, is critical to safe operations. Traffic interruptions and costs associated with maintaining and rehabilitating distressed or failed pavements in associated areas are of particular importance. The purpose of this study was to evaluate structural behavior and improve design procedures for gantry crane way pavement used at intermodal facilities by assessing interactions among pavements, subgrades, and operational loading conditions. The performance of the gantry crane pavements and foundations was assessed using a finite-element (FE) model, while pavement structural response to a crane load was measured using strain gages installed in the field. Measuring material properties using in-situ/laboratory tests was not possible in this work due to the limited resources, restricted access to intermodal facilities, and tight schedule of rail freight transport(i.e. tight schedule of cranes). To verify the materials properties and ensure a consistent behavior of the developed FE model with respect to the field measurements, an inverse design approach was implemented. Because of the significant cost of FE simulation, the gradient-based solver used in this study is based on a trust region algorithm. The verified model was used to predict the critical responses of Portland cement concrete (PCC) layer, base course, and subgrade soil. These parameters were then used to conduct a pavement fatigue damage analysis, parametric analyses of material strength and slab geometry were carried out based on Model Code, and resulting fatigue-life recommendations for improved designs were made. The developed FE model along with the inverse approach create a framework that can be used in further health monitoring problems when a specific parameter cannot be directly observed.
Parnian Ghasemi; Mohamad Aslani; Jeramy C. Ashlock; R. Christopher Williams; Vernon R. Schaefer. Evaluating gantry crane-way pavement performance: An inverse approach. Transportation Geotechnics 2021, 27, 100500 .
AMA StyleParnian Ghasemi, Mohamad Aslani, Jeramy C. Ashlock, R. Christopher Williams, Vernon R. Schaefer. Evaluating gantry crane-way pavement performance: An inverse approach. Transportation Geotechnics. 2021; 27 ():100500.
Chicago/Turabian StyleParnian Ghasemi; Mohamad Aslani; Jeramy C. Ashlock; R. Christopher Williams; Vernon R. Schaefer. 2021. "Evaluating gantry crane-way pavement performance: An inverse approach." Transportation Geotechnics 27, no. : 100500.
Computational continuum models of piles embedded in disturbed zones are developed using the Boundary Element Method (BEM) for application to three-dimensional dynamic soil-pile group interaction in layered soils. The enhanced 3D BEM code BEASSI is validated for handling pile group problems by comparison with reference solutions. A general sub-structuring formulation is developed to calculate theoretical accelerance functions. A 3D disturbed-zone computational model is then extended to handle the dynamic response of a typical 2 × 2 pile group. The performance of the model is illustrated through convergence studies and a case study corresponding to full-scale field tests. The results indicate strong frequency-dependent pile-soil-pile interaction by impedance functions, group efficiency ratios, and pile deformations. The findings from this study provide new insights into dynamic soil-pile group interaction, and the general approach can be used to examine other pile and soil conditions.
Zhiyan Jiang; Jeramy C. Ashlock. Computational simulation of three-dimensional dynamic soil-pile group interaction in layered soils using disturbed-zone model. Soil Dynamics and Earthquake Engineering 2019, 130, 105928 .
AMA StyleZhiyan Jiang, Jeramy C. Ashlock. Computational simulation of three-dimensional dynamic soil-pile group interaction in layered soils using disturbed-zone model. Soil Dynamics and Earthquake Engineering. 2019; 130 ():105928.
Chicago/Turabian StyleZhiyan Jiang; Jeramy C. Ashlock. 2019. "Computational simulation of three-dimensional dynamic soil-pile group interaction in layered soils using disturbed-zone model." Soil Dynamics and Earthquake Engineering 130, no. : 105928.
Nondestructive testing methods have been increasingly used to evaluate in situ layered stiffness of pavement systems. However, different testing methods could yield considerable different results, which can bring confusions and difficulties to road agencies when conducting mechanistic-based designs or setting specifications for constructions. This study compares a newly improved multichannel analysis of surface waves (MASW) method and the falling weight deflectometer (FWD) test for estimating in situ moduli of various mechanically and chemically stabilized unpaved road sections, which will serve as foundations for future surface upgrade. The comparisons showed that the trends of MASW moduli generally agree with those of the FWD test for the sections without a geosynthetic layer, but the MASW moduli are much higher than the FWD moduli for the aggregate layers. The discrepancies between the two tests were found to be greatly influenced by the different testing strain levels, which were estimated using the KENLAYER analysis. By combining the MASW and FWD moduli and calculated testing strain levels, in situ modulus reduction characteristics of the various stabilized aggregate layers can also be determined, which provides a better understanding of the in situ mechanistic performances of the different stabilization methods under different traffic loading conditions.
Cheng Li; Jeramy C. Ashlock; Shibin Lin; Pavana K.R. Vennapusa. In situ modulus reduction characteristics of stabilized pavement foundations by multichannel analysis of surface waves and falling weight deflectometer tests. Construction and Building Materials 2018, 188, 809 -819.
AMA StyleCheng Li, Jeramy C. Ashlock, Shibin Lin, Pavana K.R. Vennapusa. In situ modulus reduction characteristics of stabilized pavement foundations by multichannel analysis of surface waves and falling weight deflectometer tests. Construction and Building Materials. 2018; 188 ():809-819.
Chicago/Turabian StyleCheng Li; Jeramy C. Ashlock; Shibin Lin; Pavana K.R. Vennapusa. 2018. "In situ modulus reduction characteristics of stabilized pavement foundations by multichannel analysis of surface waves and falling weight deflectometer tests." Construction and Building Materials 188, no. : 809-819.
A series of full-scale dynamic vibration tests and cyclic lateral tests are to be performed on a single pipe pile and a 2×2 pile group as part of an ongoing research project. The parallelized boundary element method (BEM) code BEASSI was modified and used to predict the three-dimensional vibration response of the pile group with account of the layered soil profile including material damping and radiation damping in the viscoelastic system. The concept of the disturbed-zone model for pile groups is employed to account for pile installation effects, soil inhomogeneity, and stress- and strain-dependent modulus and damping in the near-field, while simultaneously capturing three-dimensional wave propagation and rigorously accounting for radiation damping in the far-field. To acquire accurate soil profiles as input to the analyses, a comprehensive site investigation was recently conducted, including seismic cone penetration testing with pore pressure measurement (SCPTu), standard penetration testing (SPT), and Shelby tube sampling. In the present paper, the acceleration sensor responses from SCPT tests at various depths are analyzed by the cross-correlation method to obtain shear wave velocity profiles, and the results are compared to those by the arrival time and cross-over methods, as well as empirical correlations to CPT tip resistance and sleeve friction. Material damping in the soil is also estimated from the SCPT data by the spectral ratio slope (SRS) method, which aims to minimize effects of radiation damping. The BEM program is then used with the resulting shear wave velocity profiles to calculate impedance functions in the frequency domain, which explicitly quantify the three-dimensional interaction between all the piles in the group. A general formulation based on the sub-structuring method is employed to analyze the dynamic response of pile groups using the impedance functions to obtain accelerance functions of the pile cap in vertical and coupled lateral-rocking vibration modes for validation. The findings demonstrate the accuracy and stability of the cross-correlation method for estimating shear-wave velocity from SCPT data, and an average minimum material damping ratio of 2.6% by the SRS method for the clay soils encountered. The impedance functions of the pile group indicate strong frequency-dependent dynamic soil-pile-soil interaction for the case examined. Results of this study will aid development of the proposed disturbed-zone continuum models, and provide insights into future physical pile group tests.
Zhiyan Jiang; Jeramy C. Ashlock. Prediction of Three-Dimensional Dynamic Soil-Pile Group Interaction in Layered Soil by Boundary Element Analysis and Seismic Cone Penetration Tests. Geotechnical Earthquake Engineering and Soil Dynamics V 2018, 1 .
AMA StyleZhiyan Jiang, Jeramy C. Ashlock. Prediction of Three-Dimensional Dynamic Soil-Pile Group Interaction in Layered Soil by Boundary Element Analysis and Seismic Cone Penetration Tests. Geotechnical Earthquake Engineering and Soil Dynamics V. 2018; ():1.
Chicago/Turabian StyleZhiyan Jiang; Jeramy C. Ashlock. 2018. "Prediction of Three-Dimensional Dynamic Soil-Pile Group Interaction in Layered Soil by Boundary Element Analysis and Seismic Cone Penetration Tests." Geotechnical Earthquake Engineering and Soil Dynamics V , no. : 1.
Cheng Li; Jeramy C. Ashlock; David J. White; Charles T. Jahren; Bora Cetin. Gyratory abrasion with 2D image analysis test method for evaluation of mechanical degradation and changes in morphology and shear strength of compacted granular materials. Construction and Building Materials 2017, 152, 547 -557.
AMA StyleCheng Li, Jeramy C. Ashlock, David J. White, Charles T. Jahren, Bora Cetin. Gyratory abrasion with 2D image analysis test method for evaluation of mechanical degradation and changes in morphology and shear strength of compacted granular materials. Construction and Building Materials. 2017; 152 ():547-557.
Chicago/Turabian StyleCheng Li; Jeramy C. Ashlock; David J. White; Charles T. Jahren; Bora Cetin. 2017. "Gyratory abrasion with 2D image analysis test method for evaluation of mechanical degradation and changes in morphology and shear strength of compacted granular materials." Construction and Building Materials 152, no. : 547-557.
Cheng Li; Pavana K.R. Vennapusa; Jeramy Ashlock; David J. White. Mechanistic-based comparisons for freeze-thaw performance of stabilized unpaved roads. Cold Regions Science and Technology 2017, 141, 97 -108.
AMA StyleCheng Li, Pavana K.R. Vennapusa, Jeramy Ashlock, David J. White. Mechanistic-based comparisons for freeze-thaw performance of stabilized unpaved roads. Cold Regions Science and Technology. 2017; 141 ():97-108.
Chicago/Turabian StyleCheng Li; Pavana K.R. Vennapusa; Jeramy Ashlock; David J. White. 2017. "Mechanistic-based comparisons for freeze-thaw performance of stabilized unpaved roads." Cold Regions Science and Technology 141, no. : 97-108.
Poor subsurface drainage is frequently identified as a factor leading to the accelerated damage of roadway systems. Geocomposite drainage layers offer an alternative to traditional methods but have not been widely evaluated, especially in terms of the impact of changes on both drainage capacity and stiffness. In this study, both paved and unpaved test sections with and without an embedded geocomposite drainage layer were constructed and tested. The geocomposite layers were installed directly beneath the roadway surface layers to help the rapid drainage of any infiltrated water and thus prevent water entering the underlying foundation materials. The laboratory, field, and numerical analysis results showed that the geocomposite layers increased the permeability of roadway systems by two to three orders of magnitude and that it can effectively prevent the surface and foundation materials from becoming saturated during heavy rainfall events. For the stiffness of the sections, the paved sections with and without a geocomposite layer showed that the composite modulus values measured at the surface were more reflective of the foundation layer support conditions beneath the geocomposite layer than the geocomposite layer itself. The unpaved road section with the geocomposite layer yielded lower composite modulus values than the control section but showed overall better road surface conditions after a rain event due to the improved subsurface drainage condition.
Cheng Li; Jeramy Ashlock; David White; Pavana Vennapusa. Permeability and Stiffness Assessment of Paved and Unpaved Roads with Geocomposite Drainage Layers. Applied Sciences 2017, 7, 718 .
AMA StyleCheng Li, Jeramy Ashlock, David White, Pavana Vennapusa. Permeability and Stiffness Assessment of Paved and Unpaved Roads with Geocomposite Drainage Layers. Applied Sciences. 2017; 7 (7):718.
Chicago/Turabian StyleCheng Li; Jeramy Ashlock; David White; Pavana Vennapusa. 2017. "Permeability and Stiffness Assessment of Paved and Unpaved Roads with Geocomposite Drainage Layers." Applied Sciences 7, no. 7: 718.
The goal of this study is to examine the feasibility of using a bridge structural testing system and finite element modeling (FEM) to assess the impact of heavy hauls in terms of stresses and the corresponding reduction in service life for portland cement concrete (PCC) pavements on grade. FEM simulation results are compared for various numerical treatments of the subgrade using the programs EverFE and COMSOL. With the simplified dense liquid foundation subgrade treatment used in EverFE, the experimentally measured bending strain profile in the slab could not be accurately captured using a single coefficient of subgrade reaction. A more general optimized 3D solid subgrade model was developed in COMSOL using the pseudo-coupled method, by modeling a large solid soil domain surrounding the slab, with the subgrade modulus increasing from the center to the edge of the slab in three separate regions. The optimized 3D solid subgrade model resulted in better agreement with experimental strains.
Joseph Podolsky; Jeramy C. Ashlock; R. Christopher Williams; Thomas L. Brandon; Richard J. Valentine. Measurement and Finite Element Modeling of the Pavement Response to Superloads. Geotechnical Frontiers 2017 2017, 1 .
AMA StyleJoseph Podolsky, Jeramy C. Ashlock, R. Christopher Williams, Thomas L. Brandon, Richard J. Valentine. Measurement and Finite Element Modeling of the Pavement Response to Superloads. Geotechnical Frontiers 2017. 2017; ():1.
Chicago/Turabian StyleJoseph Podolsky; Jeramy C. Ashlock; R. Christopher Williams; Thomas L. Brandon; Richard J. Valentine. 2017. "Measurement and Finite Element Modeling of the Pavement Response to Superloads." Geotechnical Frontiers 2017 , no. : 1.
Jeramy C. Ashlock; Zhiyan Jiang; Thomas L. Brandon; Richard J. Valentine. Three-Dimensional Soil-Pile Group Interaction in Layered Soil with Disturbed Zone by Boundary Element Analysis. Geotechnical Frontiers 2017 2017, 334 -344.
AMA StyleJeramy C. Ashlock, Zhiyan Jiang, Thomas L. Brandon, Richard J. Valentine. Three-Dimensional Soil-Pile Group Interaction in Layered Soil with Disturbed Zone by Boundary Element Analysis. Geotechnical Frontiers 2017. 2017; ():334-344.
Chicago/Turabian StyleJeramy C. Ashlock; Zhiyan Jiang; Thomas L. Brandon; Richard J. Valentine. 2017. "Three-Dimensional Soil-Pile Group Interaction in Layered Soil with Disturbed Zone by Boundary Element Analysis." Geotechnical Frontiers 2017 , no. : 334-344.
Vincent P. Drnevich; Jeramy C. Ashlock; Thomas L. Brandon; Richard J. Valentine. Measurement of Damping in Soils by the Resonant Column Test. Geotechnical Frontiers 2017 2017, 80 -91.
AMA StyleVincent P. Drnevich, Jeramy C. Ashlock, Thomas L. Brandon, Richard J. Valentine. Measurement of Damping in Soils by the Resonant Column Test. Geotechnical Frontiers 2017. 2017; ():80-91.
Chicago/Turabian StyleVincent P. Drnevich; Jeramy C. Ashlock; Thomas L. Brandon; Richard J. Valentine. 2017. "Measurement of Damping in Soils by the Resonant Column Test." Geotechnical Frontiers 2017 , no. : 80-91.
Surface waves propagating in layered media inherently possess multimodal dispersion characteristics. However, traditional surface wave testing methods employing measurements at the free surface usually capture only a single apparent dispersion curve, especially when using short geophone arrays common to near surface and geotechnical-scale investigations. Such single-mode or fragmented multimode apparent dispersion curves contain only a fraction of the possible dispersion information, thus limiting the accuracy of inverted profiles. To enable more robust measurement of higher Rayleigh-wave modes, a recently developed hybrid minimally invasive multimodal surface wave method is combined herein with the widely used geotechnical standard penetration test (SPT), which is employed as a practical and ubiquitous downhole source. Upon superimposing surface wave dispersion data for a range of SPT impact depths within the soil, higher modes can be measured more consistently and reliably relative to traditional non-invasive testing methods. As a result, misidentification of multiple dispersion modes can be practically eliminated, significantly improving the accuracy and certainty of inversion results.
Shibin Lin; Jeramy C. Ashlock. Improved seismic profiling by minimally invasive multimodal surface wave method with standard penetration test source (MMSW-SPT). Geophysical Journal International 2016, 208, 1308 -1312.
AMA StyleShibin Lin, Jeramy C. Ashlock. Improved seismic profiling by minimally invasive multimodal surface wave method with standard penetration test source (MMSW-SPT). Geophysical Journal International. 2016; 208 (3):1308-1312.
Chicago/Turabian StyleShibin Lin; Jeramy C. Ashlock. 2016. "Improved seismic profiling by minimally invasive multimodal surface wave method with standard penetration test source (MMSW-SPT)." Geophysical Journal International 208, no. 3: 1308-1312.
Granular surface and base layers of low-volume roads (LVRs) are frequently subjected to severe damage that adversely affects safety and requires regular repair and maintenance. Various stabilisation methods have been evaluated for mitigating damage and improving serviceability of LVR systems. However, few well-documented comparisons exist of the field mechanical performance, durability and construction costs of different stabilisation methods under the same set of geological, climate, and traffic conditions. Therefore, the present study was conducted to identify the most effective and economical among several stabilisation methods for repairing or reconstructing granular surface and base layers of LVRs. In this study, a range of promising technologies from a comprehensive literature review was selected and examined using field demonstration sections. A total of nine geomaterials, three chemical stabilisers, and three types of geosynthetics were used to construct various test sections over a 3.22 km stretch of granular-surfaced road. Extensive falling weight deflectometer (FWD) and dynamic cone penetrometer tests were performed to evaluate the multilayered elastic moduli and strengths of the various sections. This paper details the design and construction of each test section, compares the as-constructed mechanistic performance of all test sections, and assesses stiffness changes of several sections one year after construction. To provide a statistical basis for the comparisons, a pairwise multiple-comparison procedure applied for unequal sample sizes and variances and the paired t-test were used to analyse the FWD test results, demonstrating that the performance measures of the various sections were significantly different.
Cheng Li; Jeramy C. Ashlock; David J. White; Pavana K. R. Vennapusa. Mechanistic-based comparisons of stabilised base and granular surface layers of low-volume roads. International Journal of Pavement Engineering 2016, 20, 112 -124.
AMA StyleCheng Li, Jeramy C. Ashlock, David J. White, Pavana K. R. Vennapusa. Mechanistic-based comparisons of stabilised base and granular surface layers of low-volume roads. International Journal of Pavement Engineering. 2016; 20 (1):112-124.
Chicago/Turabian StyleCheng Li; Jeramy C. Ashlock; David J. White; Pavana K. R. Vennapusa. 2016. "Mechanistic-based comparisons of stabilised base and granular surface layers of low-volume roads." International Journal of Pavement Engineering 20, no. 1: 112-124.
Highlights•MSOR testing is equivalent to MASW for characterizing dispersion data of soil profiles.•MSOR testing with embedded geophones in the form of MMSW testing can measure more extensive multimodal dispersion data.•MSOR can reduce instrumentation cost and improve portability. AbstractThis paper presents a study on the application of the multichannel simulation with one-receiver (MSOR) surface-wave testing method for geophysical profiling of soil sites. The MSOR method reverses the roles of source and receiver in the widely-used multi-channel analysis of surface waves (MASW) method. To examine the feasibility and accuracy of utilizing MSOR for soil sites, finite element simulations of MSOR testing are performed for three types of soil profiles containing horizontal interfaces, a vertical fault, and a dipping interface, respectively. The effects of variations in the moving impact locations on the uncertainty and repeatability of the dispersion trends are analyzed for the different soil profiles. Real-world case studies are carried out to examine the equivalency of the MSOR and MASW methods for quantifying surface-wave dispersion trends of soil profiles, as well as the advantages of MSOR testing with embedded geophones to obtain more extensive multimodal dispersion data. From the computational simulations and field case studies, MSOR is demonstrated to be equivalent to MASW testing for practical purposes. In addition, MSOR has the advantages of reduced instrumentation cost, improved portability, enhanced ability to measure multi-mode dispersion curves by utilizing borehole geophones, and the potential for improving efficiency of 3-D stiffness profiling.
Shibin Lin; Jeramy C. Ashlock. Surface-wave testing of soil sites using multichannel simulation with one-receiver. Soil Dynamics and Earthquake Engineering 2016, 87, 82 -92.
AMA StyleShibin Lin, Jeramy C. Ashlock. Surface-wave testing of soil sites using multichannel simulation with one-receiver. Soil Dynamics and Earthquake Engineering. 2016; 87 ():82-92.
Chicago/Turabian StyleShibin Lin; Jeramy C. Ashlock. 2016. "Surface-wave testing of soil sites using multichannel simulation with one-receiver." Soil Dynamics and Earthquake Engineering 87, no. : 82-92.
Shibin Lin; Jeramy C. Ashlock; R. Christopher Williams. Nondestructive quality assessment of asphalt pavements based on dynamic modulus. Construction and Building Materials 2016, 112, 836 -847.
AMA StyleShibin Lin, Jeramy C. Ashlock, R. Christopher Williams. Nondestructive quality assessment of asphalt pavements based on dynamic modulus. Construction and Building Materials. 2016; 112 ():836-847.
Chicago/Turabian StyleShibin Lin; Jeramy C. Ashlock; R. Christopher Williams. 2016. "Nondestructive quality assessment of asphalt pavements based on dynamic modulus." Construction and Building Materials 112, no. : 836-847.
Can Chen; R. Christopher Williams; Mervyn G. Marasinghe; Jeramy C. Ashlock; Omar Smadi; Scott Schram; Ashley Buss. Assessment of Composite Pavement Performance by Survival Analysis. Journal of Transportation Engineering 2015, 141, 04015018 .
AMA StyleCan Chen, R. Christopher Williams, Mervyn G. Marasinghe, Jeramy C. Ashlock, Omar Smadi, Scott Schram, Ashley Buss. Assessment of Composite Pavement Performance by Survival Analysis. Journal of Transportation Engineering. 2015; 141 (9):04015018.
Chicago/Turabian StyleCan Chen; R. Christopher Williams; Mervyn G. Marasinghe; Jeramy C. Ashlock; Omar Smadi; Scott Schram; Ashley Buss. 2015. "Assessment of Composite Pavement Performance by Survival Analysis." Journal of Transportation Engineering 141, no. 9: 04015018.
A Minimally-invasive Multimodal Surface Wave (MMSW) geophysical testing method, which is a hybrid of surface and borehole seismic methods, was developed recently by the authors to measure more extensive multi-mode dispersion data and thus improve the accuracy of inversion profiles. The new MMSW method employs a borehole geophone at selected depths to record seismic waves from different source offsets on the soil surface. Presented in this paper is a procedure for estimating a range of optimum geophone depths to capture a given higher mode by the MMSW method. Stiffness matrix and finite-element-based numerical simulations of the MMSW method are performed to identify the relationships between critical geophone depths and apparent cutoff frequencies of higher modes. Specifically, it is shown for increasing velocity profiles that 1) at a given borehole sensor measurement depth, the apparent cutoff frequencies of higher modes increase with mode number, 2) at a given frequency, the critical geophone depth at which a higher mode will first become dominant increases with mode number, and 3) for a given higher mode, the apparent cutoff frequency decreases as measurement depth increases. A preliminary field test is conducted using a vertical geophone placed at five different depths while impacts are applied to the soil surface from 3.66 to 43.89 m from the borehole, with an impact spacing of 3.66 m. Dispersion images from the five geophone depths are superimposed to produce a dispersion image having three modes with improved clarity relative to the surface-only Multichannel Analysis of Surface Waves (MASW) method. A comparison of the experimental and theoretical apparent cutoff frequencies for higher modes is used to validate the theoretical prediction of critical depths by the stiffness matrix method. Matching of experimental and theoretical apparent cutoff frequencies could provide additional optimization constraints to reduce the uncertainty of final inversion profiles.
Jeramy C. Ashlock; Shibin Lin. Critical Depths for Higher Modes by Minimally-invasive Multimodal Surface Wave (MMSW) Method: Simulations and Field Test. Journal of Environmental and Engineering Geophysics 2015, 20, 195 -202.
AMA StyleJeramy C. Ashlock, Shibin Lin. Critical Depths for Higher Modes by Minimally-invasive Multimodal Surface Wave (MMSW) Method: Simulations and Field Test. Journal of Environmental and Engineering Geophysics. 2015; 20 (2):195-202.
Chicago/Turabian StyleJeramy C. Ashlock; Shibin Lin. 2015. "Critical Depths for Higher Modes by Minimally-invasive Multimodal Surface Wave (MMSW) Method: Simulations and Field Test." Journal of Environmental and Engineering Geophysics 20, no. 2: 195-202.
For more than 50 years, the resonant column test has been used to measure the shear modulus and damping of soils for shear strains ranging from 10−5 % to 0.5 %. For most soils, the test is non-destructive, and tests may be performed on the same specimen at multiple confining stresses simulating in situ conditions from near surface to great depths. This paper makes use of the transfer function approach for resonant column theory to obtain simple solutions for the test and applies it for two types of resonant column apparatus: the conventional fixed-base free top (including spring top) now referred to as device type 1, and for a new type of resonant column device, device type 2, where a torque transducer is mounted in the bottom platen of the device. Device type 2 uses the torque measured at the base of the specimen and the rotation measured at the top of the specimen to determine the shear modulus and damping. The advantage for taking torque measurements at the base of the specimen is because the torque that is measured is that transmitted by the specimen alone. Calibrations of top platen inertia, stiffness, damping, and torque input are not needed for device type 2. Solution of these equations with complex variables can be done with any number of programming languages. For example, simple, single page, Excel spreadsheets for each device type are provided. The paper concludes with a discussion of issues that need to be addressed before procedures involving non-resonant frequencies can be introduced into ASTM D4015 [ASTM D4015: Standard Test Method for Modulus and Damping of Soils by Fixed-Base Resonant-Column Method, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007].
Vincent P. Drnevich; Salim Werden; Jeramy C. Ashlock; John R. Hall. Applications of the New Approach to Resonant Column Testing. Geotechnical Testing Journal 2014, 38, 1 .
AMA StyleVincent P. Drnevich, Salim Werden, Jeramy C. Ashlock, John R. Hall. Applications of the New Approach to Resonant Column Testing. Geotechnical Testing Journal. 2014; 38 (1):1.
Chicago/Turabian StyleVincent P. Drnevich; Salim Werden; Jeramy C. Ashlock; John R. Hall. 2014. "Applications of the New Approach to Resonant Column Testing." Geotechnical Testing Journal 38, no. 1: 1.
Shibin Lin; Jeramy C. Ashlock. Multimode Rayleigh wave profiling by hybrid surface and borehole methods. Geophysical Journal International 2014, 197, 1184 -1195.
AMA StyleShibin Lin, Jeramy C. Ashlock. Multimode Rayleigh wave profiling by hybrid surface and borehole methods. Geophysical Journal International. 2014; 197 (2):1184-1195.
Chicago/Turabian StyleShibin Lin; Jeramy C. Ashlock. 2014. "Multimode Rayleigh wave profiling by hybrid surface and borehole methods." Geophysical Journal International 197, no. 2: 1184-1195.
Two 1.5 m (5 ft) diameter drilled shafts with lengths of 25.9 m (84.9 ft) and 23.5 m (77.0 ft) were constructed with artificial defects and tested by thermal integrity profiling (TIP) and crosshole sonic logging (CSL) methods. Prefabricated artificial defects consisting of low-strength precast concrete cylinders in the first shaft and plastic molds containing aggregates, sand, and water in the second shaft were secured to the inside of the rebar cages at two depths on each shaft. The defects constituted approximately 4% of the shaft cross-sectional area for the first shaft and 8% for the second. Both test methods clearly indicated the presence of the O-cell, while neither method strongly signaled the presence of the smaller defects. The larger defects were detected by CSL testing and resulted in minor local temperature reductions in TIP tests. The study indicates a possible lower bound resolution of at least 8% of the shaft cross-sectional area for a defect to be reliably detected by TIP.
Jeramy C. Ashlock; Mohammad K. Fotouhi. Thermal Integrity Profiling and Crosshole Sonic Logging of Drilled Shafts with Artificial Defects. Geo-Congress 2014 Technical Papers 2014, 1795 -1805.
AMA StyleJeramy C. Ashlock, Mohammad K. Fotouhi. Thermal Integrity Profiling and Crosshole Sonic Logging of Drilled Shafts with Artificial Defects. Geo-Congress 2014 Technical Papers. 2014; ():1795-1805.
Chicago/Turabian StyleJeramy C. Ashlock; Mohammad K. Fotouhi. 2014. "Thermal Integrity Profiling and Crosshole Sonic Logging of Drilled Shafts with Artificial Defects." Geo-Congress 2014 Technical Papers , no. : 1795-1805.
Jeramy C. Ashlock; Vincent P. Drnevich; Ronald Y. S. Pak. Strain Measures for Transfer Function Approaches to Resonant Column Testing. Geotechnical Testing Journal 2013, 36, 20120130 .
AMA StyleJeramy C. Ashlock, Vincent P. Drnevich, Ronald Y. S. Pak. Strain Measures for Transfer Function Approaches to Resonant Column Testing. Geotechnical Testing Journal. 2013; 36 (4):20120130.
Chicago/Turabian StyleJeramy C. Ashlock; Vincent P. Drnevich; Ronald Y. S. Pak. 2013. "Strain Measures for Transfer Function Approaches to Resonant Column Testing." Geotechnical Testing Journal 36, no. 4: 20120130.