RAILWAY SUBSTRUCTURE EVALUATION USING FWD

Transcription

1 RAILWAY SUBSTRUCTURE EVALUATION USING FWD LNEC - Laboratório Nacional de Engenharia Civil, Lisbon, Portugal

2 Railway substructure evaluation using FWD main issues MEASUREMENT SYSTEM - STUDIES PERFORMED ON AN EXISTING RAILWAY LINE CLIMATIC INFLUENCE - TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE LOAD INFLUENCE - TESTS PERFORMED ON PHYSICAL MODEL GRANULAR VS BITUMINOUS INTERPRETATION - BACK-CALCULATION OF GRANULAR MATERIAL LAYERS CONCLUSIONS LNEC 2

3 MEASUREMENT SYSTEM STUDIES PERFORMED ON AN EXISTING RAILWAY LINE FWD UPGRADE TO RAILWAYS LOAD PLATE ADDAPTED TO MEASURE ON BALLAST LNEC 3

4 STUDIES PERFORMED ON A OLD RAILWAY LINE The experimental studies presented in this work aimed to construct and evaluate four solutions for structural reinforcement of old railway tracks, maintaining the ballast layer as structural layer. Ballasted track section 36 m long, (4 experimental sections) Iberian gauge (1.668 m) bi-block sleepers limestone ballast. LNEC 4

5 Before reinforcement FWD upgrading for railways tests LNEC 5

6 Load tests PLT and FWD before reinforcement FWD.4 m diameter plate/ 5 kpa PLT & FWD results Deformation moduli (E) E =.75. d p δ 12 Plate load tests (PLT).45m diameter plate / 2 kpa E (MPa) Position related to initial point of test zone (m) FWD ECP MPa existing 12 MPa design LNEC 6

7 GPR results on experimental sections GPR results LNEC 7

8 Load tests on experimental sections LFWD on the subgrade FWD on the top of the reinforcement.3 m diameter plate 2 kpa E ~ 7-8 MPa..3 m diameter plate 4 kpa 2 FWD test series August September LNEC 8

9 FWD results on experimental sections GPR results 25 section 1 section 2 section 3 section 4 E (MPa) August 5 September 2 MPa 15% - 2% lower 13 MPa 15% lower 8 MPa 3% lower Position related to initial point of test zone (m) LNEC 9

10 FWD results on experimental sections Deflection (µm) Deflection (µm) 6 section Distance to the centre of the plate (m) 6 section Distance to the centre of the plate (m) August September Deflection (µm) 15 section Distance to the centre of the plate (m) LNEC 1

11 Backcalculation of FWD results Deformation moduli obtained E (Mpa) FWD-August E (MPa) FWD-September E (MPa) Cement bound granular material (CBGM) 6 5 Unbound granular material (UGM) UGM mixed with ballast (UGM+B) Fouled Ballast (FB) Subgrade (SG) 8 6 UGM and fouled ballast modulus are adequate and similar to resilient modulus obtained in triaxial tests Subgrade soil modulus is similar to the LFWD results. Cement bound granular material modulus is low probably due to the difficulty of adequately mix the materials on site Decrease in the modulus values after rainfall: subgrade soils, UGM. LNEC 11

12 Backcalculation of FWD results Deflection (µm) Deflection (µm) Deflection (µm) 5 section measured 3 back-calculated Distance to the centre of the plate (m) 5 4 section measured 3 back-calculated Distance to the centre of the plate (m) 8 section measured 4 2 back-calculated Distance to the centre of the plate (m) DIFFICULIES IN BACKCALCULATION Deflection (µm) 8 6 a) b) 4 2 Deflection (µm) Deflection (µm) Deflection (µm) section measured back-calculated Distance to the centre of the plate (m) 5 section measured back-calculated Distance to the centre of the plate (m) section measured section back-calculated Distance to the centre of the plate (m) measured back-calculated Distance to the centre of the plate (m) LNEC 12

13 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE E MODULI INCREASE DURING DRY WEATHER SIGNIFICANTLY MEASUREMENT PROBLEMS - DEFLECTION MEASUREMENT MEASUREMENT PROBLEMS - INCREASE NUMBER OF DROPS UNTIL DEFLECTIONS STABILISE DIFFICULIES IN BACKCALCULATION LNEC 13

14 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE Falling Weight Deflectometer (FWD) tests were undertaken during the construction of a 29 km new railway line, at the top of the substructure and in different months November, December, January and March (June) Quality control during construction. Analyse and compare test results for different climatic conditions LNEC 14

15 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE NDT tests were performed at the top of the sub-ballast layer

16 Several load levels in service traffic construction traffic Testing campaigns in different seasons CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE Several other tests were performed PLT HFWD Portancemetre

17 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE LNEC 17

18 Change in layer thickness GPR MEASUREMENT

19 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE LNEC 19

20 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE LNEC 2

21 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE Deformation modulus values November and December Bridge January and March LNEC 21

22 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE It can be observed that the values obtained in November and December are quite similar, while in January they are 3 to 5% lower than those obtained in November. Then, in March, the deformation modulus values tend to increase again to values closer to the ones obtained in the first two campaigns. LNEC 22

23 CLIMATIC INFLUENCE TESTS PERFORMED DURING CONSTRUCTION OF SUBSTRUCTURE Backcalculated sub-ballast elastic moduli variation with load peak November vs June June November

24 LOAD INFLUENCE TESTS PERFORMED ON PHYSICAL MODEL E MODULI INCREASE WITH LOAD MEASUREMENT PROBLEMS - DEFLECTION MEASUREMENT MEASUREMENT PROBLEMS - INCREASE NUMBER OF DROPS UNTIL DEFLECTIONS STABILISE DIFFICULIES IN BACKCALCULATION LNEC 24

25 LOAD INFLUENCE TESTS PERFORMED ON PHYSICAL MODEL Two different substructures were reproduced in physical models, with different subballast materials: Traditional solution.3m granite unbound granular material (UGM) Italian HSL solution.12m bituminous material Cells dimension: 4.x2.m 2 by 2.8m depth 4.m 4.m

26 Non destructive tests Non destructive tests Falling Weight Deflectometer (FWD) Ground Penetrating Radar (GPR) > FWD tests location six locations (A, B, C, D, E and F) spaced approximately by.5 m > FWD tests characteristics nine transducers (D1 to D8) 3 mm load plate (segmented) Stress levels applied (16 to 52 kpa)

27 LOAD INFLUENCE TESTS PERFORMED ON PHYSICAL MODEL Cell 1 25 kn Cell 2-25 kn Deflexão (µm) Distância do pistao (m) D1 D2 D3 D4 D5 D6 D7 D8 Deflexão (µm) ,9 1,75 2,65 3,55 4,3 Distância do pistao (m) D1 D2 D3 D4 D5 D6 D7 D8 C1-25 kn - dist,9m C2-25 kn - dist,9m,e+ D1 D2 D3 D4 D5 D6 D7 D8 D9,E ,E+1 1,E+1 Deflexão (mm) 8,E+1 1,2E+2 deflexões estimadas deflexões medidas Deflexão (µm] 2,E+1 3,E+1 4,E+1 deflexões estimadas deflexões medidas 1,6E+2 5,E+1 2,E+2 6,E+1 BITUMINOUS

28 LOAD INFLUENCE TESTS PERFORMED ON PHYSICAL MODEL E 1 moduli for top layer E (MPa) C1 - Força 25 kn,9 1,75 2,65 3,55 4,3 25 E1 25 E2 25 E3 25 E4 Módulo de Deformabilidade [MPa] C2 - Força 25 kn,9 1,75 2,65 3,55 4,3 25 E1 25 E2 25 E3 25 E4 Distânica [m] Distânica [m] BITUMINOUS

29 LOAD INFLUENCE Five levels of loading were applied: 25, 5, 75, 9 e 12 kn (MPa) E1 (MPa) - Célula 1,9 1,75 2,65 3,55 4,3 Distância (m) E1 (MPa)- Célula 2 DIP (15) BITUMINOUS (MPa) ,9 1,75 2,65 3,55 4,3 Distância (m) DIP (15)

30 Railway evaluation using FWD DEBATE MEASUREMENT SYSTEMS ON RAILWAY LINES?? TEST LOCATION GEOPHONES POSITION ON SURFACE CLIMATIC INFLUENCE THE E MODULI CAN BE SO DIFFERENT?? (5 X) LIMESTONE GRANULAR E > 1 MPa HOW YOU CORRECT THE VALUES ACCORDING TO SEASON?? LOAD INFLUENCE GRANULAR VS BITUMINOUS HOW YOU CORRECT THE VALUES ACCORDING TO SEASON?? TESTING AND INTERPRETATION TESTING PROCEDURE, NUMBER OF DROPS, NUMBER OF TESTS, GEOPHONES POSITION ON SURFACE BACK-CALCULATION OF GRANULAR MATERIAL LAYERS. LNEC 3

31 Thank you for your attention! LNEC 31