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GRAC Proposals

GRAC Proposals. Ron Gibbons & Skip Watts VTTI / Radford University. Proposals. We are considering two projects which can provide input for VDOT in the selection and application of barriers Establishment of a Rockfall Barrier Lifetime Testing Program

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GRAC Proposals

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  1. GRAC Proposals Ron Gibbons & Skip Watts VTTI / Radford University

  2. Proposals • We are considering two projects which can provide input for VDOT in the selection and application of barriers • Establishment of a Rockfall Barrier Lifetime Testing Program • Evaluation of Rockfall Behavior for the Selection of Rockfall Barriers

  3. Barrier Selection • rigid and Flexible Rockfall Barrier Systems • The economic balance of a fence and flexible system needs to be identified in order to determine which systems are the most suitable for each application. • Typically: • rigid systems • Areas which have few rock strikes • Flexible systems • Areas which have significant (continuous) rock events

  4. Establishment of a Rockfall Barrier Testing Program • One of the inputs to an economic analysis would be the lifetime of the barrier system • This project considers the development of a Barrier testing program which will provide this data

  5. Barrier Lifetime • Flexible systems have a lifetime which is determined by the tension/available slack in the brake ring • Lifetime can be violated by a pole strike • rigid systems are not designed to deform • Their lifetime is determined by number of hits until a deformation occurs • Pole or fence deformation

  6. Barrier Testing • Very few sites have on-going rockfall barrier testing programs • Switzerland • Italy • Japan • Colorado • Site now closed • Some other state programs exist to test in-situ • California • Ohio – Just started • Oregon • Washington

  7. Test Methods Vertical Drop Slide

  8. Test Rocks • Calibrated standard weight cuboctahedrons • Painted for video analysis

  9. Test Methods • There are few existing test methods for the evaluation of barriers • TRB project assessing Recommended Practices for testing Flexible barriers • No known rigid testing procedures

  10. Project Proposal • On a controlled rock slope with an installed barrier, rocks are rolled into the barrier. • Deformation and energy absorption is measured. • The total lifetime can be calculated. • Rolling results can also be verified in lab testing • Swing armature testing with weighted ball • We propose this is for a rigid barrier system only

  11. Project Tasks • Setup of the test site • The Smart Road can provide a consistent slope in a controlled environment that can allow for the testing • Equipment Setup • Need: • High speed video cameras (2 or 3) to measure the rolling rock and capture the deformation • Tension and Stress meters on the fence and the posts • Fence Installation • Meeting the spec of VDOT • Testing • Rolling stones • Lifetime Estimation • Calculation of total allowable energy and stress impacts before fence failure

  12. Smart Road Test Area

  13. Smart Rocks • Consider developing Smart Rocks • Since we are creating the rocks, we can add intelligence to the system • Acceleration and speed remotely transmitted through radio frequency to determine energy characteristics at the point of impact • Possibility of adding a data logger to the rock as well • Access can be an issue • Need to add close distance radio detection to the required equipment

  14. Mobile Testing Fields • Once the test method has been developed in a controlled environment, we should be able to test at any location with the developed equipment setup • Testing a variety of rockfall and slope conditions • Appalachian Plateau versus Ridge and Valley • Testing a variety of fence systems

  15. Benefits to VDOT • This project would provide a system for continual rockfall barrier testing for VDOT. • It would also provide the method for lifetime estimation of the rockfall barrier systems and the subsequent cost benefit analysis.

  16. Evaluation of Rockfall Behavior for the Selection of Rockfall Barriers • Develop a method to select the appropriate type of rockfall barrier based on the potential for rockfall events • Consider both Hazard and Risk • Hazard: • A condition likely to produce a rockfall • Risk • Probablity of a hazardous event causing damage or loss • Develop a cost assessment method to assist in the selection and specification of the mitigation techniques

  17. Development of Hazard Model • Develop a model which can predict the probability of a rockfall event • Based on typical rockfall triggers • Climate • Erosion • Slope type • Rock type • Underlying Geology

  18. Existing Models • Several Models exist that can predict rockfall behavior: • These systems consider geology only, or geology and weather factors • Early models are limited: • Do not consider all rockfall modalities • Do not consider all risk types • Many do not consider Mitigation factors • Some new models provide probability along with the assessment of slopes through video and LIDAR data collection • Missouri • Utah • Athens, Greece • NCHRP IDEA Project 119

  19. Hazard Monitoring • On going monitoring of the rockwalls can provide on-going hazard assessment • Colorado • California • Missouri • These systems typically: • Analyze the rockslope over time with repeated LIDAR measurements • Compare changes • Identify and track potential problems • Typically Software models • ROCKPACK • Split-FX • CRSP

  20. LIDAR Change Identification

  21. Risk Assessment • Some areas have developed Risk Assessment models • These models consider both the hazard probability and the potential outcome • The models must consider Roadway Design Factors and Human Exposure • Roadway • Ditch capacity • Barriers • Medians • Human Exposure • Stopping distance • AADT • Speed • Traffic Volume

  22. Rating System

  23. Alternative Systems – Fault Trees

  24. Project Tasks • Phase I – Model Development • Hazard Model Verification • Using existing data from VDOT and Brian Bruckno, evaluate the models that are available for the probability of rockfall events • Risk / Mediation Development • Link exposure models from other activities • Develop rating system • Develop economic analysis for rockfall mediation • Phase II – Scanning and Data Collection Development • Link Measurement activities • LIDAR scanning • Software prediction

  25. Benefits to VDOT • This project would provide a method for VDOT to select the appropriate equipment and ensure that the VDOT expenditures are appropriately assigned. • Future Efforts can provide an evaluation and control method to maximize effectiveness of VDOT investments

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