2013 Session: 291

• Full Seismic Waveform Tomography at a Highly Variable Florida Site
  Abstract: The paper presents the application of 2-D time-domain waveform tomography to a highly variable site in Florida. The measured seismic surface wave fields were inverted using a full waveform inversion technique, based on a finite-difference solution with Gauss-Newton updating. Both the compression wave (P-wave) and shear wave (S-wave) velocities are inverted independently and simultaneously for possible indications of soil types. The waveform analysis was able to delineate: (1) a shallow low-velocity layer, (2) a variable high-velocity layer, (3) a low-velocity zone embedded at 9 to 14 m depth, and (4) highly variable bedrock, laterally and vertically, at the bottom of profile. The computed shear wave velocities with depth were found to be generally consistent with cone penetration test (CPT) tip resistance. The technology is very applicable to both shallow and deep foundation design where soil stratigraphy as well as variability (horizontal and vertical) is important. Moreover, the invasive soundings (e.g. CPT, SPT) could be used for assessing properties, and the seismic waveform tomography may then be used to assess layer boundaries and horizontal spatial correlation structure.
  Authors: Tran, Khiem T.
  Authors: Tran, Khiem T.
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-1520
• Nanoindentation Test Integrated with Numerical Simulation to Characterize Mechanical Properties of Rock Materials
  Abstract: It is important to determine the mechanical properties of rock materials accurately from the viewpoint of the design, analysis, and modeling of various transportation infrastructure systems. Conventional methods have some drawbacks including relatively inaccurate measurements, cumbersome testing-analysis processes, and high variability in measurements. A nanoindentation test integrated with a numerical modeling technique has been validated in other fields as an efficient and accurate tool for the characterization of the key mechanical properties of various irregularly shaped materials such as the rock materials in this study. This paper presents an integrated experimental-numerical effort based on the nanoindentation measurement and finite element modeling of a representative rock material, limestone. The experimental efforts including specimen fabrication and laboratory tests are presented, and the corresponding analyses of test results combined with the finite element technique and linear interpolation to validate the elastic property measurements are discussed. The elastic properties estimated from the nanoindentation test are similar to the simulation results, demonstrating the validity of the test method and modeling approach. The success of the proposed approach should facilitate the better design of mixtures and structures based on the more accurate characterization of the core material properties.
  Authors: Ban, Hoki; Kim, Yong-Rak; Karki, Pravat
  Authors: Ban, Hoki; Kim, Yong-Rak; Karki, Pravat
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-2294
• Dynamic Testing of Civil Engineering Materials Using Split-Hopkinson Pressure Bar
  Abstract: The Split-Hopkinson Pressure Bar (SHPB) is a tool used to assess dynamic material properties at strain rates up to approximately 1,000 1/s. Originally developed for the testing of metals over 100 years ago, modifications now allow testing of other materials. This paper will provide results from a wide range of materials used in transportation such as wood, concrete, and sedimentary rock. The basic components of a standard SHPB consist of a cannon, striker bar, input bar, and an output bar. A cannon uses compressed gas to fire a striker bar into the input bar of the SHPB. The sample is placed between the input and output bars prior to firing the cannon, and strain gages on the two bars are used to measure the input pulse, along with the reflected and transmitted pulses. The resulting data can be used to determine the dynamic stress/strain response in compression at high rates of strain through one-dimensional wave theory.Specimens were tested using a 3-inch (76-mm) diameter SHPB. The overall function of the SHPB along with test results will be discussed. Wood, specifically hard maple specimens, consisting of sugar maple (Acer saccharum) and black maple (Acer nigrum), and eastern white pine (Pinus strobus) specimens were tested. Tests were also performed on 18-year old Portland cement concrete pavement cores along with rock cores from the Nonesuch Shale formation comprised of a very uniform siltstone. The SHPB was found to be a useful tool for assessing the dynamic stress/strain curves of these materials.
  Authors: Gilbertson, Christopher Glenn; Vitton, Stanley James
  Authors: Gilbertson, Christopher Glenn; Vitton, Stanley James
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-3380
• Impact of Modulus-Based Device Variability on Quality Control of Compacted Geomaterials Using Measurement System Analysis
  Abstract: The advances in technology have resulted in new generation of in-situ nondestructive testing devices that can estimate stiffness parameters of compacted geomaterials. These include the light weight deflectometers , portable impulse plate load test devices, electro-mechanical stiffness devices and seismic devices. Despite a number of formal research and pilot studies, only a few agencies are attempting to implement these devices in their acceptance specifications. One of the main concerns is with the large variability in the stiffness parameters obtained with these devices when compared to densities measured with traditional devices (e.g. nuclear density gauge). The sources of the variability can be material-related, operator-related or device-related. It would be beneficial to systematically delineate the contributions of these sources of variability so that the equipment developer can improve their devices, highway agencies can modify their testing protocols, and pavement geotechnical engineers can address the material-related issues. This paper contains the results of an effort to quantify the equipment- and operator-related variability in a systematic manner. Measurement system analysis principles were applied to a database of stiffness measurements made with four stiffness-measuring devices on eighteen separate specimens that were prepared from the same material at similar densities and moisture contents. It was found that most devices are reasonably repeatable and reproducible as long as the moisture content and density are rigidly controlled. Most of the site specific variability reported in the literature may be due to lack of rigid process control during construction.
  Authors: Mazari, Mehran; Garcia, Gerardo; Garibay, Jose; Abdallah, Imad N.; Nazarian, Soheil
  Authors: Mazari, Mehran; Garcia, Gerardo; Garibay, Jose; Abdallah, Imad N.; Nazarian, Soheil
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-3192
  Practice-Ready: Yes
• Linking Small and Large Strain Behavior of Soils Using Shear Wave Velocity Measurements in the Laboratory
  Abstract: Current geotechnical practice relies on empirical relationships with in situ tests to determine the effective stress strength parameters for dense cohesionless soils. Although these methods work reasonably well in practice, they cannot account for in situ effects related to time, fabric, and cementation. These factors are especially important for brittle or sensitive soils, such as loess and cemented sands. To develop methods that can predict strength in these types of soils, a better understanding of the link between small and large strain behavior is needed. The objective of this paper is to evaluate the hypothesis that there is a unique relationship between the small strain shear modulus (G0) and the effective stresses at failure (s'1f) for dilatant soils. To accomplish this objective, isotropically consolidated-drained triaxial compressional tests were performed with shear wave velocity measured throughout the tests. The soils tested in this study include a quartz sand and non-plastic silt, and the results are compared to previous studies by the authors on weakly cemented sands.It was found that the ratio G0/s'1f was approximately 197 ± 16 for the three different soils tested, and was independent of density, degree of cementation, and confining stress. If true for other soils, this finding could have important implications for evaluating staged construction on sensitive soils and estimating the strength of dilative soils in situ.
  Authors: Guadalupe, Yaurel; Baxter, Christopher; Sharma, Ravi
  Authors: Guadalupe, Yaurel; Baxter, Christopher; Sharma, Ravi
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-4893
  Practice-Ready: Yes
• Scour Assessment of Bridge Foundation Using In Situ Erosion Evaluation Probe
  Abstract: AbstractWork in this paper presents the use of the In Situ Erosion Evaluation Probe (ISEEP) for the assessment of scour depth a bridge pier. Numerical modeling and deployment of the device at a North Carolina Barrier Islands site after Hurricane Irene in 2011 demonstrated the applicability of the proposed concept. The CFD software Flow 3D was used to evaluate scour at bridge piers with the scour depth also estimated based on ISEEP data using excess stream power. The scour depth was also computed using empirical equations assuming the same conditions used in the numerical analysis. The parametric analyses indicated that among the parameters commonly used for defining the scour depth, entrainment coefficient (Ce) has the largest effect, whereas drag coefficient (Cd) has the smallest effect on the estimated scour depth. Scour depth estimated based on ISEEP data agreed relatively well with values obtained from the numerical analyses, as the data reflected the change in the properties of the sand layer with depth. On the other hand, the scour depth estimates from empirical equations were unconservative mainly due to not accounting for the two-layered profile. The use of ISEEP data provides the advantage of in situ assessment of scour parameters as the properties of the soil layers vary with depth. Further validation of the device and data reduction approach is however needed including its applicability in soils with fine contents.
  Authors: Kayser, Mohammad; Gabr, Mohammed A.
  Authors: Kayser, Mohammad; Gabr, Mohammed A.
  Year: 2013
  Document Type: Paper
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-4010
  Practice-Ready: Yes
• Full Seismic Waveform Tomography at a Highly Variable Florida Site
  Authors: Tran, Khiem
  Authors: Tran, Khiem
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-1520
• Impact of Modulus-Based Device Variability on Quality Control of Compacted Geomaterials Using Measurement System Analysis
  Authors: Mazari, Mehran
  Authors: Mazari, Mehran
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-3192
• Linking Small and Large Strain Behavior of Soils Using Shear Wave Velocity Measurements in the Laboratory
  Authors: Guadalupe, Yaurel
  Authors: Guadalupe, Yaurel
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-4893
• Scour Assessment of Bridge Foundation Using In Situ Erosion Evaluation Probe
  Authors: Kayser, Mohammad
  Keywords: poster presentation; poster design; poster template
  Authors: Kayser, Mohammad
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Geotechnology; Materials
  Session: 291
  Paper Number: 13-4010