GRL Engineers Inc.
GRL Engineers Inc.
Park Y.J.,Tunnel Geotechnical Engineer |
Gabr M.A.,North Carolina State University |
Robinson B.R.,GRL Engineers Inc. |
Borden R.H.,North Carolina State University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2012
The stability of subgrade soils is a major concern during roadway construction with inappropriately soft layers often undercut and replaced by competent or stabilized materials. Systematic undercut criteria are established using numerical modeling with varying the strength and stiffness parameters of the subgrade and representing the mechanistic behavior as an elastic-perfectly plastic medium. Two modes of domain configurations were considered: the plane strain and axisymmetric conditions. The plane strain mode is assumed to simulate proof roller loading with four parallel tires and mainly provides information about excessive pumping response as materials at deeper layers are affected. The axisymmetric mode provides information related to excessive rutting and is used to simulate the effect of single or dual tires representing construction traffic, rather than a series of closely spaced axle loads. Undercut criteria are proposed for meeting a deformation limit state of 25 mm for both pumping and rutting, with the additional requirement of a performance capacity ratio (PCR) of 1.5. The proposed criteria are applied to data from four field cases in which decisions were made regarding the need for undercutting, and the applicability of the criteria is discussed. © 2012 American Society of Civil Engineers.
Dai Q.,Michigan Technological University |
Ng K.,IET Inc |
Liu Y.,GRL Engineers Inc. |
Yu X.,Case Western Reserve University
Journal of Materials in Civil Engineering | Year: 2013
This study investigates the internal-frost damage due to ice-crystallization pressure in the concrete pore system. The methodology integrates thermodynamic analysis and a microdamage model as well as a unique time-domain reflectometry (TDR) sensor. The crystallization pressure in the microscale pore system of concrete at subcooling temperatures was calculated based upon thermodynamic analysis. An extended finite-element method (XFEM) was applied to simulate the fracture development induced by internal frost, with the estimated internal crystallization pressure as the input. The XFEM fracture simulation was conducted on a digitized concrete sample obtained with imaging processing and ellipse-fitting techniques. The simulated crack development under the crystallization pressure was found to match the observed fracture patterns of the tested single-edge notched specimen. The XFEM simulation results were verified by the open-mode fracture behavior in both middle-notched single-edge notched beam bending test and freezing-damage tests. Furthermore, the crystallization-pressure analysis and freezing-damage simulation were conducted to demonstrate the freezing-damage process using cement samples with idealized pore structures. To provide direct estimation of the crystallization pressure, an innovative TDR tube sensor was developed to nondestructively monitor the extent of freezing in concrete specimens. The results show that this new sensor provides noninvasive measurement of freezing degree, which can be used to directly estimate the internal crystallization pressure for XFEM analyses. Avolume-based damage criterion was also proposed based on the new TDR sensor. This work established a framework to integrate sensor and simulations to holistically predict the internal-frost damage process in concrete specimens. © 2013 American Society of Civil Engineers.
Webster S.,GRL Engineers Inc. |
Robinson B.,GRL Engineers Inc.
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2013
Pile driveability analyses for offshore platforms require a unique set of criteria, which may not normally be associated with other pile foundation installations. The selected hammers, pile makeup details and soil profile must be carefully reviewed, as these factors will determine if pile installations will be successful. The most important of the variables to establish is the expected Soil Resistance to Driving (SRD). Common practice is to relate the SRD to the Static Soil Resistance (SSR) which is normally provided based upon the American Petroleum Institute (API) methods of calculation or some variance based upon local site conditions and experience. In addition, due to the substantial use of hydraulic hammers hammer operating energies must be selected such that pile driving can be accomplished while avoiding pile damage. Current procedures used for driveability analysis will be provided and the methods of parameter selection discussed in detail. These procedures, which have been used on several offshore projects in various offshore fields around the world, will be presented with the original driveability analysis and therecorded pile installation records. A method to determine the expected SRD will be discussed based upon the experience collected from these sites which are in numerous offshore fields worldwide. Four Case Studies are shown to validate the described methodology. Copyright © 2013 by ASME.
Beim G.,Pile Dynamics Inc. |
Kluge R.,American Transmission Co. |
Lohry M.,American Transmission Co. |
Belardo D.,GRL Engineers Inc.
Electrical Transmission and Substation Structures 2015: Technical Challenges and Innovative Solutions in Grid Modernization - Proceedings of the 2015 Electrical Transmission and Substation Structures Conference | Year: 2015
Transmission line foundations often consist of concrete piers. Examples of construction situations that may result in problematic piers are presented to motivate the use of deep foundation non-destructive testing methods. Advantages and shortcomings of established testing methods are briefly reviewed. A newer technology, Thermal Integrity Profiling (TIP), is then discussed and compared with established ones. TIP is based on the premise that heat energy released during cement hydration depends on cement content and on total concrete volume. Temperature measurements obtained inside a curing foundation correlate with the effective radius of the foundation and with concrete quality. The theoretical background of thermal integrity profiling is summarized; descriptions of alternate ways of obtaining internal temperature measurements follow. Measurement interpretation is discussed, including relating data measured at the reinforcement cage during curing to concrete quality, shaft diameters, local concrete cover, and reinforcement cage alignment. Case studies of electrical transmission line construction where this technology was employed are presented. © ASCE.
Honeycutt J.N.,GRL Engineers Inc. |
Kiser S.E.,AMEC Environment and Infrastructure Inc. |
Anderson J.B.,Auburn University
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2014
This study examined the energy transfer ratio (ETR) of Central Mine Equipment (CME) automatic standard penetration test (SPT) hammers utilizing a large database of SPT energy measurements. The database consisted of energy measurements from 17,825 SPT hammer blows obtained from 33 CME automatic hammers over a 5-year period, many of which were tested multiple times. The average ETR for all 17,825 CME automatic hammer blows in the database was 82.9% with a COV of ±7:4%. The database also provided an opportunity to determine the impacts of hammer calibration, test depth, and calibration interval on the measured ETR. The impact on average ETR of eliminating hammer blows due to D4633-10 restrictions was also demonstrated. © 2014 American Society of Civil Engineers.
Rausche F.,GRL Engineers Inc. |
Robinson B.,North Carolina State University
Proceedings of the Symposium on the Application of Geophyics to Engineering and Environmental Problems, SAGEEP | Year: 2010
For the past half century, great efforts have been made and progress has been achieved in developing a variety of electronic testing methods for the quality control and quality assurance of deep foundations. These developments took advantage of major advances in ever more accurate and sensitive sensor manufacturing and faster and more powerful computers. The dynamic pile testing methods were the primary beneficiaries of these R & amp;D efforts and its application has been expanded from bearing capacity assessment of driven piles to drilled shafts, micro piles and even penetrometers. In addition to soil resistance, results from construction monitoring now provide information about stresses along the pile, pile integrity and occasionally soil vibrations. Dynamic pile testing methods also include nondestructive techniques involving sonic and ultra sonic signals. Much of the recent developments involved not only ruggedizing hardware and preparation of more user friendly software, but also deriving reliable calculation procedures and presenting results in a way which is easy for the report recipient to understand. Additionally, experiences from construction sites showed that an immediate assessment of the foundation characteristics is imperative. This requirement lead to the need for easily used simulation software and workshops. Today such training events are frequently performed over the internet. This presentation summarizes several recent hardware and software developments and shows a few typical results.
Lamiman E.C.,Froehling and Robertson Inc. |
Robinson B.,GRL Engineers Inc.
Geotechnical Special Publication | Year: 2014
This paper presents a case history where 91.4-centimeter (36-inch) diameter open-end pipe piles were installed using both impact and vibratory installation techniques. Thirteen dynamically tested piles were installed along a new sheet pile containment wall located in the Southern Branch of the Elizabeth River, bounded by Chesapeake and Portsmouth, Virginia. The soil conditions encountered generally consisted of interbedded layers of silt, sand, and clay forming the Alluvium and the Norfolk Formations. The piles were advanced into the underlying Yorktown Formation bearing stratum consisting of clayey to silty sand with varying amounts of marine shell fragments. At two test pile locations, impact-driven test piles were extracted and relocated by vibratory hammer and subjected to restrike driving with dynamic analysis to assess bearing capacity. Seven to 14 day restrikes were performed on the 13 hammer-driven test piles. Restrikes at one or more months were performed on one impact-driven pile, and both vibratory installed test piles. Signal matching analyses of restrike-driving events indicate an approximate 50% reduction in overall bearing capacity of the vibrated piles compared with the driven piles. Additionally, long-term restrike driving of vibrated piles did not continue to gain capacity akin to driven piles. © 2014 American Society of Civil Engineers.
Yu W.,China offshore Oil Engineering Co. |
Liang L.,Pile Dynamics Inc. |
Givet R.,GRL Engineers Inc. |
Qin L.,China offshore Oil Engineering Co. |
And 2 more authors.
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013
This paper presents the application of HSDT to dynamically monitor the underwater foundation pile installation of the Liwan 3-1 CEP Jacket in South China Sea. The eight-legged CEP Jacket, standing in a water depth of approximately 189.5m, is secured to the seafloor with 16×ø108" (2743mm)×158m foundation piles. It is very challenging to apply this technique to underwater piling, especially as deep as this project. The testing procedure is discussed in detail and summarized in this paper. The test results combined with CAPWAP® analysis are presented. A refined wave equation analysis was performed to help determine the capacities of other piles not tested. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).
Allin R.,Pile Dynamics Inc. |
Likins G.,GRL Engineers Inc. |
Honeycutt J.,GRL Engineers Inc.
Geotechnical Special Publication | Year: 2015
Energy formulas have historically been used to estimate capacity for driven piles. Some engineers still rely on them today and researchers attempt to refine the safety factors or resistance factors to allow a more economic result. However, energy formulas make broad assumptions about "average hammer performance" that cannot always be properly accounted for during installation and thus leave themselves open to gross inaccuracies on any "individual project", and therefore significant risk. Additionally, since common energy formulas do not model the driving system or pile or soil, observing hammer stroke and blow count is not sufficient to guarantee a specific capacity has been achieved on an individual project. It has been well documented by measurements that supposedly similarly rated hammers can transfer significantly different energies to the pile. Using the wave equation analysis to model these vastly different hammer system efficiencies, the resulting variance on calculated capacity from commonly used energy formulas is investigated and presented. Set-up assumptions contribute to further inaccuracies. © ASCE 2015.
Rausche F.,GRL Engineers Inc. |
Likins G.,Pile Dynamics Inc. |
Liang L.,Pile Dynamics Inc. |
Hussein M.,GRL Engineers Inc.
Geotechnical Special Publication | Year: 2010
Signal matching is the preferred analysis method for Dynamic Load Test (DLT) evaluations. It is applicable to DLT records of driven piles, auger-cast piles, drilled shafts, and even on dynamic penetrometers. Although signal matching is considered standard best-practice, required by many code specifications and therefore routinely used on thousands of deep foundation projects worldwide, and of significant importance to the deep foundation industry, many features of the CAPWAP® signal matching model and procedure are not well known. CAPWAP's signal matching is possible because of the availability of redundant measurements of load and movement, and it is necessary to determine the unknown boundary conditions. The goal of CAPWAP is the determination of dynamic and static soil resistance parameters of the generally accepted Smith-type pile-soil interface model. However, the classic Smith model cannot explain some of the phenomena that occur during the impact event. For reliable signal matching results, therefore, several modifications of the original Smith model were made. While some modifications fundamentally do not affect the signal match, other more substantial changes are of considerable importance to the reliable determination of the all-important static load bearing capacity result. Before discussing the CAPWAP procedure and its automatic analysis tools, this paper describes the more unusual CAPWAP pile and soil model parameters and their effects on the final results. Measurement and analysis results from actual projects demonstrate the various features of the program and aspects of the models. The paper includes a summary of recommended limits for model parameters, match qualities, and calculation procedures and a few suggestions for additional research. © ASCE 2010.