ANALYTICAL AND EXPERIMENTAL STUDY OF SLEEPER SAT S 312 IN SLAB TRACK SATEBA SYSTEM

Transcription

1 ANALYTICAL AND EXPERIMENTAL STUDY OF SLEEPER SAT S 312 IN SLAB TRACK SATEBA SYSTEM C. Guigou-Carter M. Villot C.S.T.B. Center for Building Science and Technology St Martin d Hères, France B. Guillerme C. Petit SATEBA Chalon/Saône, France Paris La Défense, France

2 Introduction Work carried out for SATEBA within framework of the new Eurostar train track construction below London city. Simple prediction tool based on 2D model to predict the performance of track-work Determination of sleeper pads dynamic stiffness corresponding to specific mitigation levels Development of experimental rig on a full width section of track to measure the dynamic stiffness of sleeper pads

3 Track-Work Prediction Model 2D Model Unsprung Mass x z Applied Force Rail Rail Pad Sleeper Sleeper Pad Concrete Slab Ground Insertion Gain per 1/3 octave band calculated from velocity level at ground/slab interface Reference track : without sleepers and sleeper pads

4 Track-Work Characteristics Three types of trains : Eurostar with maximum 2150 kg/axle Domestic passenger stock with maximum 1309 kg/axle freight stock with maximum 3750 kg/axle Rail pads with stiffness of 720 MN/m 2 and loss factor of 20% Sleepers spaced every 0.6 m correspond to 350 kg/m Sleeper pads of different stiffness and loss factor 16%

5 Insertion Gain (db) 5.0 Track-Work Prediction Results Effect of Train Type - Sleeper Pads Dynamic Stiffness 60 MN/m Eurostar Domestic Passenger Stock Freight Stock -40 Frequency (Hz)

6 Insertion Gain (db) 5.0 Track-Work Prediction Results Effect of Sleeper Pads Dynamic Stiffness - Eurostar Train Type Sleeper Pad 35 MN/m2 Sleeper Pad 60 MN/m2 Sleeper Pad 106 MN/m2-40 Frequency (Hz)

7 Experimental Test Rig - Measurement Principle Measurement of Sleeper Pads Dynamic Stiffness Static pre-load rams Vibration Exciter Vibration insulators NF EN ISO Excitation mass m 1 Blocking mass m 2 Tested system Force transducers F blocking Displacement transducer u 1 Displacement transducer u 2 Transfer dynamic stiffness K 2,1 (F blocking /u 1 )

8 Experimental Test Rig - General View Vertical static load Dynamic vibration exciter U-shaped support Front Vibration insulator Excitation mass m 1 (8-shaped support) Blocking mass m 2 Sleeper block Rail track Horizontal static jack Sleeper block boot Force transducer Rear

9 Experimental Test Rig - Accelerometers Mounting Accelerometer on rail Accelerometer on blocking mass m 2

10 Experimental Test Rig - Shaker Mounting Vertical static load U-shaped support Spring suspension Dynamic vibration exciter Stinger Vibration insulator Excitation mass m 1 (8-shaped support)

11 Experimental Test Rig - Blocking Force Measurement Blocking force measured with 3 force transducers F blocking = F 1 + F 2 + F 3 Total blocking force corrected by the inertial force F total blocking = F blocking + F inertial = F blocking + m 2 (2 f) 2 u 2

12 Experimental Test Rig - Lateral Load Application

13 Experimental Test Rig - Stiffness Characterization Requirements : Decoupling 20 log 10 (u 1 /u 2 ) 15 db Inertial force correction < 10% Displacement difference between rails head < 15% Dynamic stiffness calculation of sleeper pads K rear = F total blocking / u 1 rear rail K front = F total blocking / u 1 front rail K pads = (K rear + K front ) / 2 and K pad = K pads / 2

14 Limitations of Experimental Test Rig Vibration levels on laboratory floor were negligible Horizontal velocity of both rails and both sleeper blocks found negligible Static and dynamic force distribution between rear and front was good Blocking mass m 2 presented modal behavior around 100, 125 and 156 Hz. Inertial force correction 20 % at 63 Hz : above requirements Measurements valid at 8, 16 and 31.5 Hz

15 Measurement Results at 8 Hz Static Load Vertical 40 kn Vertical 40 kn Vertical 64 kn Vertical 64 kn Horizontal 10 kn Horizontal 5 kn Rear/Front Displacement Difference (%) Front decoupling (db) Rear decoupling (db) Blocking force F blocking (N) Total Blocking force F blocking total (N) Blocking force error (%) Pad dynamic stiffness (MN/m) With inertial force correction Dynamic stiffness increases with applied vertical static load with applied horizontal static load and with excitation frequency

16 Concluding Comments Simple prediction tool was presented and used to define sleeper pads dynamic stiffness corresponding to specific mitigation levels Experimental rig to characterize sleeper pads dynamic stiffness was described and its limitations discussed Measurements were performed for different sleeper pads under different vertical and horizontal static loads