HYDRAULIC TESTING AND DATA REPORT FOR SIX- INCH TRITON FILTER MATTRESS

Transcription

1 HYDRAULIC TESTING AND DATA REPORT FOR SIX- INCH TRITON FILTER MATTRESS Prepared for Tensar International Corporation Colorado State University Daryl B. Simons Building at the Engineering Research Center Fort Collins, Colorado

2 HYDRAULIC TESTING AND DATA REPORT FOR SIX- INCH TRITON FILTER MATTRESS Prepared for Tensar International Corporation Prepared by Christopher I. Thornton Amanda L. Cox Michael D. Turner June 2009 Colorado State University Daryl B. Simons Building at the Engineering Research Center Fort Collins, Colorado

3 TABLE OF CONTENTS TABLE OF CONTENTS...i LIST OF FIGURES... iii LIST OF TABLES...v LIST OF SYMBOLS AND ABBREVIATIONS...vi 1 INTRODUCTION TEST PROGRAM Test Facility Product Embankment Construction Filter Design and Installation Six-inch Triton Filter Mattress Construction Six-inch Triton Filter Mattress Installation Test Procedure TEST MATRIX AND DATABASE One-foot Overtopping Test Two-foot Overtopping Test Three-foot Overtopping Test Four-foot Overtopping Test Five-foot Overtopping Test Post-testing Evaluation HYDRAULIC ANALYSIS Four-foot Overtopping Test Five-foot Overtopping Test SUMMARY...37 REFERENCES...38 APPENDIX A SOIL PHYSICAL PROPERTIES...39 APPENDIX B COMPACTION VERIFICATION...41 APPENDIX C FILTER MATERIAL GRAIN-SIZE DISTRIBUTIONS...43 i

4 APPENDIX D PRODUCT INSTALLATION SPECIFICATIONS...46 APPENDIX E GRAIN-SIZE DISTRIBUTION FOR STONE INFILL...53 APPENDIX F FILTER FABRIC PRODUCT SPECIFICATIONS...55 APPENDIX G HYDRAULIC ANALYSIS DATA...57 ii

5 LIST OF FIGURES Figure 1-1. Photograph of the Six-inch Triton Filter Mattress...1 Figure 2-1. The Engineering Research Center at CSU and Horsetooth Reservoir...3 Figure 2-2. Profile View Steep Gradient Overtopping Facility set at 2:1 Slope...4 Figure 2-3. Six-inch Triton Filter Mattresses...5 Figure 2-4. Compacted Embankment before Installation of Six-inch Triton Filter Mattress...6 Figure 2-5. Profile View of Granular Filter and Embankment Toe Detail...7 Figure 2-6. Triton Mattress Baffles and Two-by-Six Frames...8 Figure 2-7. Completed Six-inch Triton Filter Mattress prior to Installation...9 Figure 2-8. Mirafi 180N over Compacted Embankment...10 Figure 2-9. Crane-installation of Six-inch Triton Filter Mattress...11 Figure Six-inch Triton Filter Mattress following Crane-installation...11 Figure Cross-sectional View of Sidewall Detail...12 Figure Photograph of Toe Wall and Toe Plate...13 Figure 3-1. Photograph of Installed Revetment System prior to Testing...16 Figure 3-2. One-foot Overtopping Test in Progress...18 Figure 3-3. Two-foot Overtopping Test in Progress...20 Figure 3-4. Three-foot Overtopping Test in Progress...22 Figure 3-5. Four-foot Overtopping Test in Progress...24 Figure 3-6. Five-foot Overtopping Test in Progress...27 Figure 3-7. Embankment following Revetment System Removal...29 Figure 4-1. Manning s n verses Unit Discharge for Three-, Four-, and Five-foot Overtopping Tests of Six-inch Triton Filter Mattress...30 Figure 4-2. Four-foot Overtopping Measured Flow Depth Data Compared to Model Flow Depth Data...32 Figure 4-3. Four-foot Overtopping Water-surface Profile Fit, Manning s n = Figure 4-4. Flow Velocity and Boundary Shear Stress for Four-foot Overtopping Test...33 Figure 4-5. Five-foot Overtopping Measured Flow Depth Data Compared to Model Flow Depth Data...34 Figure 4-6. Five-foot Overtopping Water-surface Profile Fit, Manning s n = Figure 4-7. Flow Velocity and Boundary Shear Stress for Five-foot Overtopping Test...36 Figure A-1. Sub-grade Grain Size Distribution...40 Figure B-1. Compaction Verification for Soil Embankment...42 Figure C-1. Pea Gravel Filter Material Grain-size Distribution Curve...44 Figure C-2. Angular Rock Grain-size Distribution Curve...45 iii

6 Figure D-1. Product Construction and Installation Instructions...48 Figure E-1. Grain-size Distribution for Stone Infill...54 Figure F-1. Product Data Sheet for Mirafi 180N...56 iv

7 LIST OF TABLES Table 3-1. Test Matrix for the Six-inch Triton Filter Mattress...15 Table 3-2. One-foot Overtopping Test Hydraulic Data...19 Table 3-3. Two-foot Overtopping Test Hydraulic Data...21 Table 3-4. Three-foot Overtopping Test Hydraulic Data...23 Table 3-5. Four-foot Overtopping Test Hydraulic Data...26 Table 3.6. Five-foot Overtopping Test Hydraulic Data...28 Table 4-1. Summary Hydraulics for Overtopping Test Series...31 Table G-1. Four-foot Overtopping Test Regression Data for Velocity and Shear Stress Analysis...58 Table G-2. Five-foot Overtopping Test Regression Data for Velocity and Shear Stress Analysis...63 v

8 LIST OF SYMBOLS AND ABBREVIATIONS Symbol D 0 D 50 D 100 EGL n grain size that 0% of the particles are finer than grain size that 50% of the particles are finer than grain size that 100% of the particles are finer than energy grade line Manning s coefficient of hydraulic resistance Abbreviations % percent ± plus or minus ASTM American Society for Testing and Materials avg average cfs cubic feet per second CSU Colorado State University ERC Engineering Research Center ft foot or feet ft/ft foot per foot ft/s feet per second H:V Horizontal:Vertical hr(s) hour(s) ID identification in. inch(es) lb pound(s) lb/ft 3 pounds per cubic foot mm/dd/yy month/day/year pcf pounds per cubic foot PI Plasticity Index psf pounds per square foot psi pounds per square inch SGOF Steep Gradient Overtopping Facility vi

9 1 INTRODUCTION During the fall of 2008, hydraulic performance testing was conducted by Colorado State University (CSU) on one six-inch Triton Filter Mattress manufactured by Tensar International Corporation. Testing was performed at the Hydraulics Laboratory at the Engineering Research Center. The Triton Filter Mattress was constructed and installed according to specifications provided by Tensar International Corporation. A total of five tests were conducted under the test program. Figure 1-1 presents a photograph of the six-inch Triton Filter Mattress during the installation process. Information presented within this report documents the construction and testing processes, and also provides data from hydraulic testing of a full-scale revetment system under controlled laboratory conditions for the purpose of identifying stability threshold conditions. Descriptions of the test program, test matrix, database, and test summary are presented in this report. Figure 1-1. Photograph of the Six-inch Triton Filter Mattress 1

10 2 TEST PROGRAM 2.1 TEST FACILITY Laboratory testing of the six-inch Triton Filter Mattress was performed at the Hydraulics Laboratory located at the Engineering Research Center (ERC) at CSU. Colorado State University s ERC is comprised of laboratories and offices encompassing virtually all engineering disciplines. Within the ERC, the Hydraulics Division (a subdivision of the Civil and Environmental Engineering Department) operates the Hydraulics Laboratory. Water supply to both outdoor and indoor research facilities is furnished by Horsetooth Reservoir, which is adjacent to the ERC as presented in Figure 2-1. Flow is conveyed through an existing pipe network to each facility. Outdoor facilities are gravity fed from Horsetooth Reservoir with a capacity of approximately 170,000 acre-feet of water and a maximum, static pressure of approximately 110 pounds per square inch (psi) at the ERC pipe network. Each outdoor facility has its own independent water delivery system. 2

11 College Lake Outdoor Facilities Horsetooth Reservoir ERC Figure 2-1. The Engineering Research Center at CSU and Horsetooth Reservoir For this testing program, an overtopping test facility was utilized, which was 4 ft wide by 40 ft long and with a 2H:1V (Horizontal:Vertical) slope. The head-box configuration in this flume allowed for a maximum of 6 ft of overtopping depth. Figure 2-2 presents a profile drawing of the Steep Gradient Overtopping Facility (SGOF) utilized for the testing program. 3

12 Flow Straightener Six-inch Triton Filter Mattress 12-in. Soil 10-ft 1 Toe Plate and Cap 2 40-ft 12-in. Not To Scale Five-foot Granular Filter Figure 2-2. Profile View Steep Gradient Overtopping Facility set at 2:1 Slope 2.2 PRODUCT The six-inch Triton Filter Mattress was tested under controlled conditions to provide data consistent with the current state-of-the-practice in calculating hydraulic performance thresholds. Three sections of geogrid baffles four-feet in width were provided by Tensar International Corporation, which consisted of lengths of two twenty-foot sections and an eleven-foot section. The baffle sections were filled with angular stone, and the finished six-inch Triton Filter Mattress was tested under the duress of an overtopping test protocol. A photograph of the sixinch Triton Filter Mattresses is presented as Figure

13 Figure 2-3. Six-inch Triton Filter Mattresses 2.3 EMBANKMENT CONSTRUCTION The testing program included construction of an earthen embankment section compacted between vertical walls of an outdoor flume. To prevent subgrade edge effects from compromising the integrity of the embankment, channel iron was installed along the walls of the flume. Soil was placed within the head and toe walls of the test section, and compacted in two equal lifts of six inches. Soil consisted of a clayey sand with a Plasticity Index (PI) of 10. The test section was constructed to a height where the finished soil embankment surface was 1 ft above the floor of the testing facility. Embankment geometry incorporated a horizontal 10 ft long crest section, and a specified slope length of 40 ft at a angle of 2H:1V. Figure 2-4 presents a photograph of the compacted soil embankment prior to installation of the six-inch Triton Filter Mattress. 5

14 Figure 2-4. Compacted Embankment before Installation of Six-inch Triton Filter Mattress Soil information determined and documented during embankment construction included the following: Soil Texture (ASTM D2487 classification); Grain size distribution curve (ASTM D422); and Atterberg Limits (ASTM D4318). All of the documented physical properties of the soil are located in Appendix A. Soil moisture content and in-situ dry unit weight were determined by nuclear density gage along the centerline of the embankment as determined by Terracon, Inc. (ASTM D2922 and D3017) Three locations on the compacted soil embankment were evaluated for their in-situ moisture content and dry unit weight. From the crest of the test section, these locations were approximately 10 ft apart. The in-situ moisture contents for these locations were 8.7, 7.8, and 6

15 7.6 percent by volume and the corresponding compaction percentages were 93, 92, and 90 percent. The Field Density Test Report verifying compaction is located in Appendix B. 2.4 FILTER DESIGN AND INSTALLATION To reduce the pore pressure created at the downstream end of the embankment, a filter was designed according to current industry standards and installed just upstream of the porous toe wall, extending 5 ft upstream. The filter was constructed using angular rock with a D 50 of 26 mm, pea gravel with a D 50 of 5.7 mm, and sand with a D 50 of 0.70 mm. Grain size distribution curves for the filter material are provided in Appendix C. The filter was installed using the angular rock extending 2.5 ft upstream of the toe plate with a 2:1 pea gravel to sand mixture extending the remaining 2.5 ft, creating a total filter thickness of 5 ft. The division between the soil embankment and granular filter was further established with the placement of a Mirafi 180N barrier. In addition, a ¼-inch perforated steel plate was placed between the filter mattress and granular filter. Figure 2-5 presents a schematic of the granular filter layer described above. 12 in. Mirafi 180N Six-inch Triton Filter Mattress Soil Perforated Steel Plate 2:1 Pea Gravel:Sand Toe Plate and End Cap 2.5 ft Angular Rock NOT TO SCALE 2.5 ft Figure 2-5. Profile View of Granular Filter and Embankment Toe Detail 7

16 2.5 SIX-INCH TRITON FILTER MATTRESS CONSTRUCTION Construction of the six-inch Triton Filter Mattresses was reflective of standard procedures provided by Tensar International. The installation instructions are presented in Appendix D. The geogrid sections were laid flat on the ground, and all vertical seams of the mat were tied with standard half-hitch knots. Subsequently, two-by-six inch frames were constructed and placed in alternating baffle sections to add vertical rigidity for the placement of stone infill. The seamed mat and frames can be seen in Figure 2-6. Figure 2-6. Triton Mattress Baffles and Two-by-Six Frames Following the frame installation, angular stone with a D 0 of 1.50 inches, D 50 of 2.25 inches, and D 100 of 3.00 inches was placed in the baffles. A grain size distribution for the stone installed into the baffles is presented in Appendix E. Stone was placed in the baffles such that the stone fill level was slightly above the upper vertical edge of the mattress. The top of the mattress was then sealed with the stitch configuration provided in the manufacturer s instructions. The six-inch Triton Filter Mattress following construction can be seen in Figure

17 Figure 2-7. Completed Six-inch Triton Filter Mattress prior to Installation 2.6 SIX-INCH TRITON FILTER MATTRESS INSTALLATION Installation was reflective of standard procedures for revetment systems for hydraulic stability and accommodated a four foot width of the filter mattress. Mirafi 180N non-woven geotextile fabric was placed on the compacted embankment. The product data sheet for Mirafi 180N is presented in Appendix F. The geotextile fabric was placed over the embankment and forced to follow the contour over the transition between the horizontal approach and 2H:1V test sections. At the crest of the slope, a V-notch was cut into the fabric and sealed using silicone adhesive. Also, all joints between the geotextile and facility were sealed with silicone adhesive. The embankment with the geotextile installed is presented as Figure

18 Figure 2-8. Mirafi 180N over Compacted Embankment Subsequently, the six-inch Triton Filter Mattress was craned onto the embankment per the instructions provided by Tensar International. The mattress sections were then sewn to one another with the stitch configuration provided in the assembly instructions. Figure 2-9 presents a photograph of the six-inch Triton Filter Mattress while being craned into the facility and, Figure 2-10 presents a photograph of the six-inch Triton Filter Mattress after crane-installation. 10

19 Figure 2-9. Crane-installation of Six-inch Triton Filter Mattress Figure Six-inch Triton Filter Mattress following Crane-installation 11

20 Following standard installation procedures for revetment system testing, potential for artificially induced scour along the sidewalls was prevented by placing foam wadding along the one-half inch voids of the revetment system. The edges were then covered with angle iron as presented in Figure 2-11, which provides a cross-sectional diagram of the test section. Flume Wall Silicone Seal Securing Bolt Flashing Foam Wadding Channel Iron Six-inch Triton Filter Mattress Mirafi 180N Soil Not to Scale Figure Cross-sectional View of Sidewall Detail The edge treatment prevented water from flowing unobstructed down the edges of the flume. Flashing was secured to the flume walls and sealed to terminate the filter fabric, ensure the filter mattress could not be completely removed from the flume, and to restrain the foam edge treatment. Horizontal projection of the side protection extended five inches into the flume. The filter was secured at the embankment toe by means of a steel plate which prevented vertical displacement of the filter mattress, but allowed for expansion of the mattress in the downstream direction. A photograph of this toe plate is presented in Figure

21 Figure Photograph of Toe Wall and Toe Plate 2.7 TEST PROCEDURE A test consisted of a continuous 4-hr flow over the six-inch Triton Filter Mattress at a uniform discharge. The performance threshold for the six-inch Triton Filter Mattress tested within this test program was defined as the point at which deformation, soil loss, or loss of intimate contact with the embankment sub-grade occurred. Provided that the revetment system successfully endured the 4-hr flow without exceeding the defined performance threshold, the procedure was repeated at the next higher target discharge or until the flow capacity of the testing facility was reached. Typically, target discharges corresponded to predetermined overtopping depths above the embankment crest elevation (e.g., 1 ft, 2 ft, etc.), although any discharge could be conveyed through the system provided proper measurement and reporting procedures were followed. Hourly data collection was maintained for the entire 4 hr test duration, unless the performance threshold was exceeded. 13

22 Hourly measurements of water-surface elevations were made at 4 ft intervals (stations) along the centerline of the embankment during each test. Bed elevations (top of revetment surface) were established prior to and after the termination of each test at the same measurement stations as the water-surface readings. Locations on the revetment system were identified with a mark on the wall to ensure consistency in measurement. Flow and elevation measurements were made to the nearest 0.01 ft using a point gage and survey level. Discharge was determined independently of the measurements made within the test section. Determination of the discharge was made using an in-line sonic flow meter located in the inflow pipe. The in-line sonic flow meter was accurate to ±3%. 14

23 3 TEST MATRIX AND DATABASE A test matrix was developed to summarize and present the details of the testing program. Table 3-1 presents the test matrix which includes five tests with overtopping depths of 1-ft through 5-ft. The 5-ft overtopping test was conducted until intimate contact was lost between the Triton Filter Mattress and soil embankment. Each test was conducted on the 2H:1V embankment slope. After completion of the tests outlined in Table 3.1, the collected data were entered into a database for analysis. The following sections briefly describe conditions during testing with photographic documentation, and provide the supporting database. Test ID Table 3-1. Test Matrix for the Six-inch Triton Filter Mattress Test Date (mm/dd/yy) Embankment Slope (H:V) Overtopping Depth Measured Discharge (cfs) Test Duration (hrs) one-foot 11/20/2008 2: two-foot 11/20/2008 2: three-foot 11/21/2008 2: four-foot 11/21/2008 2: five-foot 11/24/2008 2: ONE-FOOT OVERTOPPING TEST Testing of the six-inch Triton Filter Mattress initiated on November 20 th, The system was installed as per standard protocol described in Sections 2.3 through 2.6 utilizing a slope length of 40 ft and a total embankment length including the horizontal approach section of 50 ft. Figure 3.1 is a photograph of the completed installation prior to testing. The system was surveyed, and photographed to prepare for testing. 15

24 Figure 3-1. Photograph of Installed Revetment System prior to Testing 16

25 Testing commenced with a discharge intended to season the embankment by allowing the system to become saturated. After the system was seasoned, the discharge was increased until the water level in the headbox was one foot above the embankment. The discharge recorded for the one-foot overtopping test was 11 cfs. Initially, data were collected at the preestablished stations, and subsequently at the start of every hour for the remainder of the test. The test was allowed to proceed for the full 4 hrs as described in Section 2.7, with data collection at the start of each hour. In addition, aerated water was observed beginning approximately 4 ft downstream of the crest and extended throughout the remainder of the test section. Therefore, depth measurements beyond Station 4 should be considered approximate. At the conclusion of the fourth hour, the discharge was terminated and post-test bed elevation readings were recorded, indicating that there had not been any deformation of the system or loss of intimate contact with either the subgrade embankment or granular drainage layer. Figure 3-2 is a photograph of the one-foot overtopping test in progress. Table 3-2 presents the one-foot overtopping test data. 17

26 Figure 3-2. One-foot Overtopping Test in Progress 18

27 Table 3-2. One-foot Overtopping Test Hydraulic Data 19 Tape Station Horizontal Station Position ID Pre-test Bed Reading Pointgage Survey Bed Watersurface Reading hr 1 Watersurface Reading hr 2 Watersurface Reading hr 3 Watersurface Reading hr 4 Watersurface Average Reading Watersurface Depth Vertical Depth Continuity Velocity (ft/s) EGL (Continuity) Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center

28 3.2 TWO-FOOT OVERTOPPING TEST Upon conclusion of the one-foot overtopping test of the six-inch Triton Filter Mattress, there was no observable contact loss or deformation. The two-foot overtopping test initiated on November 20 th, Flow over the system was increased gradually to the two-foot overtopping depth, achieved at 28 cfs. Figure 3-3 is a photograph of the two-foot test in progress. Figure 3-3. Two-foot Overtopping Test in Progress Initially, data were collected at the pre-established stations, and subsequently at the start of every hour for the remainder of the test. Aerated water was observed beginning approximately 10 ft downstream of the crest and extended throughout the remainder of the test section. Therefore, depth measurements beyond Station 10 should be considered approximate. The test was conducted for the full 4 hrs as there was no observable system deformation during the overtopping test. At the conclusion of the fourth hour, the discharge was terminated and post-test bed elevations were recorded, confirming that the system had not exceeded the performance threshold. Table 3-3 presents the two-foot overtopping test data. 20

29 Table 3-3. Two-foot Overtopping Test Hydraulic Data 21 Tape Station Horizontal Station Position ID Pre-test Bed Reading Pointgage Survey Bed Watersurface Reading hr 1 Watersurface Reading hr 2 Watersurface Reading hr 3 Watersurface Reading hr 4 Watersurface Average Reading Watersurface Depth Vertical Depth Continuity Velocity (ft/s) EGL (Continuity) Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center

30 3.3 THREE-FOOT OVERTOPPING TEST Upon conclusion of the two-foot overtopping test, there was no observable contact loss or deformation. The three-foot overtopping test initiated on November 21 st, The system was initially seasoned at a low flow rate. Subsequently, the flow over the system was increased gradually to the three-foot overtopping depth, achieved at 50 cfs. Figure 3-4 is a photograph of the three-foot overtopping test in progress. Figure 3-4. Three-foot Overtopping Test in Progress Initially, data were collected at the pre-established stations, and subsequently at the start of every hour for the remainder of the test. Aerated water was observed beginning approximately 20 ft downstream of the crest and extended throughout the remainder of the test section. Therefore, depth measurements beyond Station 20 should be considered approximate. The test was conducted for the full 4 hrs as there was no observable system deformation during the overtopping test. At the conclusion of the fourth hour, the discharge was terminated and post-test bed elevations were recorded, confirming that the system had not exceeded the performance threshold. Table 3-4 presents the three-foot overtopping test data. 22

31 Table 3-4. Three-foot Overtopping Test Hydraulic Data 23 Tape Station Horizontal Station Position ID Pre-test Bed Reading Pointgage Survey Bed Watersurface Reading hr 1 Watersurface Reading hr 2 Watersurface Reading hr 3 Watersurface Reading hr 4 Watersurface Average Reading Watersurface Depth Vertical Depth Continuity Velocity (ft/s) EGL (Continuity) Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center

32 3.4 FOUR-FOOT OVERTOPPING TEST Upon conclusion of the three-foot overtopping test, there was no observable contact loss or deformation. The four-foot overtopping test initiated on November 21 st, The system was initially seasoned at a low flow rate. Subsequently, the flow over the system was increased gradually to the four-foot overtopping depth, achieved at 78 cfs. Figure 3-5 is a photograph of the four-foot overtopping test in progress. Figure 3-5. Four-foot Overtopping Test in Progress 24

33 Initially, data were collected at the pre-established stations, and subsequently at the start of every hour for the remainder of the test. Aerated water was observed beginning approximately 26 ft downstream of the crest and extended throughout the remainder of the test section. Therefore, depth measurements beyond Station 26 should be considered approximate. The test was conducted for the full 4 hrs as there was no observable system deformation during the overtopping test. At the conclusion of the fourth hour, the discharge was terminated and post-test bed elevations were recorded, confirming that the system had not exceeded the performance threshold. Table 3-5 presents the four-foot overtopping test data. 25

34 Table 3-5. Four-foot Overtopping Test Hydraulic Data 26 Tape Station Horizontal Station Position ID Pre-test Bed Reading Pointgage Survey Bed Watersurface Reading hr 1 Watersurface Reading hr 2 Watersurface Reading hr 3 Watersurface Reading hr 4 Watersurface Average Reading Watersurface Depth Vertical Depth Continuity Velocity (ft/s) EGL (Continuity) Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center

35 3.5 FIVE-FOOT OVERTOPPING TEST Upon conclusion of the four-foot overtopping test, there was no observable contact loss or deformation. A maximum test was initiated on November 24 th, The system was initially seasoned at a low flow rate for five minutes. Subsequently, the flow over the system was increased until the maximum discharge available at the facility was reached. The recorded discharge was cfs, which corresponded to 5.0 feet of overtopping depth. Figure 3-6 is a photograph of the cfs test in progress. Figure 3-6. Five-foot Overtopping Test in Progress The test was conducted for a duration of 2 hours and two sets of water surface elevation data were collected. Aerated water was observed beginning approximately 36 feet downstream of the crest, and therefore, depth measurements beyond this location should be considered approximate. After two hours the system became compromised, evident as loss of intimate contact between the mattress and granular filter, and shutdown procedures were initiated. Following shutdown, bed elevation data were recorded over the intact portions of the test section, and the six-inch Triton Filter Mattress was carefully removed from the facility. Table 3.6 presents the cfs test data. 27

36 Table 3.6. Five-foot Overtopping Test Hydraulic Data 28 Tape Station Horizontal Station Position Pre-test Bed Reading Point Gage Survey Bed Water Surface Reading hr 1 Water Surface Reading hr 2 Water Surface Average Reading Water Surface Depth Vertical Depth Continuity Velocity ID (ft/s) EGL (Continuity) Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center Center

37 3.6 POST-TESTING EVALUATION Upon conclusion of the cfs test, the six-inch Triton Filter Mattress was removed from the flume in order to inspect the underlying subgrade embankment and rock drainage layer. After inspection, it was determined that intimate contact had been lost over the lower 30 feet of the test section, resulting in exceedance of the performance standard. Figure 3-7 presents photographs of the embankment following the test series. Figure 3-7. Embankment following Revetment System Removal 29

38 4 HYDRAULIC ANALYSIS Hydraulic analyses were conducted for Tests 1 through 5. For all tests, water-surface profiles were evaluated using a standard step fore-water hydraulic model which computed the best-fit Manning s roughness for the collected data. The hydraulic model developed theoretical water-surface profiles with varying Manning s roughness values to determine the best-fit Manning s roughness for each profile. The best-fit Manning s roughness was determined from maximizing the coefficient of determination, R 2. A plot of Manning s n verses unit discharge is presented as Figure Manning's n Unit Discharge (ft 2 /sec) Figure 4-1. Manning s n verses Unit Discharge for Three-, Four-, and Five-foot Overtopping Tests of Six-inch Triton Filter Mattress 30

39 Based on the developed best-fit profile, velocity and shear stress values were computed. Appendix G provides the supporting data for the hydraulic analysis presented in this section. Table 4-1 presents the unit discharge, maximum shear stress, maximum velocity, Manning s n, and system condition for the six-inch Triton Filter Mattress for each overtopping test. Table 4-1. Summary Hydraulics for Overtopping Test Series Test Number Unit Discharge Maximum Shear Stress Maximum Velocity Manning's n Condition (ft 2 /sec) (psf) (fps) * * * Stable * Stable Stable Stable Unstable * Values not calculable due to the presence of aerated water over the majority of the revetment system For this testing series, Tests 4 and 5 were considered to be critical in establishing stability thresholds for the six-inch Triton Filter Mattress. Therefore, because Test 4 was the final stable test and Test 5 resulted in destabilization of the revetment system, detailed hydraulic analyses of Tests 4 and 5 are presented below. 4.1 FOUR-FOOT OVERTOPPING TEST Water-surface profile data for the four-foot overtopping test were used with the standard step fore-water hydraulic model to conduct the hydraulic analysis. The Manning s roughness coefficient was determined to be using the hydraulic model. Figure 4-2 provides a graphical comparison of the measured flow depth data to the model output flow depth data. Furthermore, Figure 4-3 presents the theoretical water-surface profile and energy grade line for the model profile. 31

40 Vertical Depth Measured Data Model Data Station Figure 4-2. Four-foot Overtopping Measured Flow Depth Data Compared to Model Flow Depth Data Bed Water Surface Energy Grade Line Station Figure 4-3. Four-foot Overtopping Water-surface Profile Fit, Manning s n =

41 Flow velocities and boundary shear stresses were computed at each station for the model profile. The continuity equation was used to compute flow velocities and boundary shear stresses were computed using the momentum equation. Figure 4-4 provides a graph of velocity and shear stress versus horizontal station for the four-foot overtopping test. The highest flow velocity and boundary shear stress at the downstream end of the test section were determined to be 22.6 ft/s and 21.5 psf, respectively Velocity (ft/s) Velocity Shear Stress (psf) Momentum Shear Stress Station Figure 4-4. Flow Velocity and Boundary Shear Stress for Four-foot Overtopping Test 4.2 FIVE-FOOT OVERTOPPING TEST Water-surface profile data for the five-foot overtopping test were used with the standard step fore-water hydraulic model to conduct the hydraulic analysis. The Manning s roughness coefficient was determined to be using the hydraulic model. 33

42 Figure 4-5 provides a graphical comparison of the measured flow depth data to the model output flow depth data. Furthermore, Figure 4-6 presents the theoretical water-surface profile and energy grade line for the model profile Vertical Depth Measured Data Model Data Station Figure 4-5. Five-foot Overtopping Measured Flow Depth Data Compared to Model Flow Depth Data 34

43 Bed Water Surface Energy Grade Line Station Figure 4-6. Five-foot Overtopping Water-surface Profile Fit, Manning s n = Flow velocities and boundary shear stresses were computed at each station for the model profile. The continuity equation was used to compute flow velocities and boundary shear stresses were computed using the momentum equation. Figure 4-7 provides a graph of velocity and shear stress versus horizontal station for the five-foot overtopping test. The highest flow velocity and boundary shear stress at the downstream end of the test section were determined to be 26.2 ft/s and 24.9 psf, respectively. However, these values for velocity and shear stress reflect the threshold exceedance for the six-inch Triton Filter Mattress, and represent a point at which system instability was observed. 35

44 Velocity (ft/s) Velocity Shear Stress (psf) Momentum Shear Stress Station Figure 4-7. Flow Velocity and Boundary Shear Stress for Five-foot Overtopping Test 36

45 5 SUMMARY During the fall of 2008, hydraulic performance testing of the six-inch Triton Filter Mattress was conducted by Colorado State University. Testing was performed at the Hydraulics Laboratory located at the Engineering Research Center. Descriptions of the revetment installation, test facility, test program, test matrix, and resulting database are presented in this report. In addition, a preliminary hydraulic analysis was conducted, which identified the largest shear stress and velocity maintained within the test section. From this analysis, the revetment system was determined to be stable for velocities and shear stresses up to 22.6 ft/s and 21.5 psf, respectively. For velocities and shear stress values of 26.2 ft/s and 24.9 psf, respectively, the revetment system was determined to be unstable. This report provides data from the hydraulic testing of a full-scale revetment system under controlled laboratory conditions for purposes of identifying stability threshold conditions. 37

46 REFERENCES ASTM. Standard Test Method for Particle-Size Analysis of Soils. D422, developed by Subcommittee D18.03 of the American Society for Testing and Materials. ASTM. Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft 3 (2,700 kn-m/m 3 )). D1557, developed by Subcommittee D18.03 of the American Society for Testing and Materials. ASTM. Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System). D2487, developed by Subcommittee D18.07 of the American Society for Testing and Materials. ASTM. Standard Test Methods for Density of Soil and Soil-aggregate in Place by Nuclear Methods (Shallow Depth). D2922, developed by Subcommittee D18.08 of the American Society for Testing and Materials. ASTM. Standard Test Method for Water Content of Soil and Rock in Place by Nuclear Methods (Shallow Depth). D3017, developed by Subcommittee D18.08 of the American Society for Testing and Materials. ASTM. Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. D4318, developed by Subcommittee D18.03 of the American Society for Testing and Materials. 38

47 APPENDIX A SOIL PHYSICAL PROPERTIES 39

48 100 3-in 2-in 1-in 0.5-in Percent Finer by Weight - % Grain Size in millimeters Figure A-1. Sub-grade Grain Size Distribution

49 APPENDIX B COMPACTION VERIFICATION 41

50 Figure B-1. Compaction Verification for Soil Embankment 42

51 APPENDIX C FILTER MATERIAL GRAIN-SIZE DISTRIBUTIONS 43

52 100% 90% 80% Percent Finer (%) 70% 60% 50% 40% 30% 20% 10% 0% Particle Diameter (mm) Figure C-1. Pea Gravel Filter Material Grain-size Distribution Curve 44

53 Percent Finer (%) Particle Diameter (mm) D 84 =30.7 mm D 50 = 26.9 mm D 16 = 19.1 mm Figure C-2. Angular Rock Grain-size Distribution Curve

54 APPENDIX D PRODUCT INSTALLATION SPECIFICATIONS 46

55 47

56 Figure D-1. Product Construction and Installation Instructions 48

57 49

58 50

59 51

60 52

61 APPENDIX E GRAIN-SIZE DISTRIBUTION FOR STONE INFILL 53

62 10 1 Particle Size (inches) Figure E-1. Grain-size Distribution for Stone Infill % 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Percent Finer Than 54

63 APPENDIX F FILTER FABRIC PRODUCT SPECIFICATIONS 55

64 Figure F-1. Product Data Sheet for Mirafi 180N 56

65 APPENDIX G HYDRAULIC ANALYSIS DATA 57

66 Table G-1. Four-foot Overtopping Test Regression Data for Velocity and Shear Stress Analysis Station Bed Water-surface Vertical Depth Flow Depth Flow Velocity (ft/s) Energy Grade Line Local EGL Slope (ft/ft) Momentum Shear Stress (psf) n/a n/a n/a n/a

67 Bed Water-surface Vertical Depth Flow Depth Flow Velocity (ft/s) Energy Grade Line Local EGL Slope (ft/ft) Momentum Shear Stress (psf) Station