Chair and Institute of Road, Railway and Airfield Construction Munich, Germany Professor Dr.-Ing. Stephan Freudenstein Fon: 089/ Fax: 089/ Internet: Lateral Stability of Ballasted Track with Conventional Ties and with Under Tie Pads

Agenda Study of elastic under tie pads Measuring of lateral resistance of conventional ties and with under tie pads in both laboratory as well as in real operational tracks Application of the recorded parameters to FEM

Determination of bedding modulus of elastic tie pads Geometric Ballast Plate (GBP) Standard Ballast Plate (SBP) Even Plate TUM-Plate with glued real ballast stones

Determination of bedding modulus of elastic tie pads on bottom side of tie on smaller specimen (300x300 mm) on ties in ballast bed SBP 20 cm Concrete SBP

Determination of bedding modulus of elastic tie pads bedding modulus decreases Static bedding modulus of tie pad [N/mm 3 ] Analysis area: σ = 0.01 – 0.10 [N/mm 2 ] method of testing 300 x 300 mm tie pad with concrete block PMG04 with fleeceG04 with LVD Even Plate SBP GBP TUM-Plate SBP bottom side of tie PMG04 with fleeceG04 with LVD on ballast bed tie B 70 with under tie pad PMG04 with fleeceG04 with LVD

Minimal bedding modulus of underground and ballast min C total = 0.05 N/mm 3 best load-distribution effect of rail 60 E2 could be activated allowable tensile stress on rail foot will not be exceeded 1/C total = 1/C tie pad + 1/C underground+ballast + (1/C rail pad ~ 0) minimal total bedding modulus C total [N/mm 3 ] tie pad type bedding modulus C tie pad [N/mm 3 ] (B70 consolidated ballast) minimal bedding modulus underground and ballast C underground+ballast [N/mm 3 ] 0.05 PM0.14 ≥ 0.08 G04 with fleece0.07 ≥ 0.20 G04 with LVD0.06 ≥ 0.36

Simulating the service loading - Measurement of lateral resistance in consolidated condition -Contact stress between ballast and bottom side of tie

Contact stress between ballast and bottom side of tie B 70 with soft tie pad (G04 with fleece ) B 70 with stiff tie pad (PM) conventional B 70 conventional tie with tie under tie pad

Lateral resistance of conventional ties and with under tie pads The lateral resistance of ties with UTP depends firstly on: -Elastic material properties of UTP -Tie geometry -Properties of the ballast Required laboratory tests: -Determination of elastic properties of the UTP -Determination of ballast properties -Determination of lateral resistance of ties with and without UTP

Investigations on ballast type A (quarry A) und type B (quarry B), both class “S” Lateral resistance is positively influenced by: Lateral resistance of conventional ties and with under tie pads (EN 933-1) Far tiered grading curve High mass percentage of gravel stones > 40 mm Less fine grain < 0.5 mm Less fines < mm (EN 933-4) Compact grain shape length : width < 3:1 (EN ) Los Angeles-Test: high impact strength (EN ) Micro-Deval-Test: high abrasion resistance - ballast type B shows better properties regarding lateral resistance as type A lateral resistance with ballast type B is about 20 % higher as with type A

Determination of lateral resistance of ties B 70 in laboratory Lateral resistance of conventional ties and with under tie pads Measurements in both unconsolidated and consolidated conditions Determination of static and dynamic lateral resistance Determination of lateral resistance under wet ballast conditions (rain fall) Determination of individual parts of lateral resistance tie ballast rig tie pad neutral axis ballast

- bi-linear load-displacement curve, continuously slope change point due to under tie pads - ties with under tie pads show a higher lateral resistance than conventional ties - lateral resistance is increasing with decreasing of the tie pad stiffness Lateral resistance of conventional ties and with under tie pads Load-displacement curve of single ties B 70 horizontal force F H (at 2 mm displacement) B 70 with G04, LVD (very soft) 8.5 kN B 70 with G04, fleece (soft) 8.1 kN B 70 with PM (stiff) 7.4 kN B 70 without tie pad 6.7 kN B 70 with pad G04, LVD (very soft) B70 with pad G04, fleece (soft) B 70 with pad PM (stiff) B 70 without tie pad horizontal force [kN] lateral displacement of the tie [mm] consolidated ballast type B

Determination of lateral resistance in laboratory Lateral resistance of conventional ties and with under tie pads ballast type/ underground B 70 with or without under tie pad unconsoli- dated track consoli- dated track increasing of lateral resist. due to consolidation consolidated track wet ballast bed (rain fall) dynamic loading F = 2 kN, 50Hz lateral resist. [N/mm] [%] lateral resist. [N/mm] type A, concrete ground without tie pad 6.4 G04 with fleece 8.3 type B, concrete ground without tie pad 8.3 Paul Müller9.6 G04 with fleece 9.2 G04 with LVD 9.5 ballast type/ underground B 70 with or without under tie pad unconsoli- dated track consoli- dated track increasing of lateral resist. due to consolidation consolidated track wet ballast bed (rain fall) dynamic loading F = 2 kN, 50Hz lateral resist. [N/mm] [%] lateral resist. [N/mm] % % % % % % ballast type/ underground B 70 with or without under tie pad unconsoli- dated track consoli- dated track increasing of lateral resist. due to consolidation consolidated track wet ballast bed (rain fall) dynamic loading F = 2 kN, 50Hz lateral resist. [N/mm] [%] lateral resist. [N/mm] type A, concrete ground without tie pad %7.8 G04 with fleece %9.1 type B, concrete ground without tie pad %8.4 Paul Müller % - G04 with fleece %10.9 G04 with LVD %12.1 ballast type/ underground B 70 with or without under tie pad unconsoli- dated track consoli- dated track increasing of lateral resist. due to consolidation consolidated track wet ballast bed (rain fall) dynamic loading F = 2 kN, 50Hz lateral resist. [N/mm] [%] lateral resist. [N/mm] type A, concrete ground without tie pad % G04 with fleece % type B, concrete ground without tie pad % % -- G04 with fleece % G04 with LVD % PM

Determination of lateral resistance in service track Lateral resistance of conventional ties and with under tie pads location tie B 70 with or without under tie pad consolidated track lateral resist. [N/mm] service track without tie pad12.7 G04, fleece14.4 laboratory ballast type B without tie pad11.3 G04, fleece13.4 Difference of absolute values of lateral resistance due to: - ballast properties and underground performance - width of front ballast - initiated tamping work Qualitative agreement of results in laboratory and service track

Application of recorded parameters to FEM rail tie structure points of tie structure points of rail

Verifying FE-Model for straight track from full-scale test section in Rohrbach Application of recorded parameters to method of Meier and to FEM failure of track irregularity = 23 mm length of track irregularity = 16,2 m lateral resistance = 9,2 N/mm Verschiebeweg des Gleisrostes [mm] Verschiebeweg des Gleisrostes [mm]

Verifying FE-Model for curved track with R = 360m from full-scale test section in Daglfing Application of recorded parameters to FEM failure of track irregularity = 13 mm length of track irregularity = 16,8 m lateral resistance = 4,4 N/mm

Results of FEM: Influence of service load on lateral track stability Application of recorded parameters to method of Meier and to FEM - increasing of lateral resistance - under wheel loads - application of dynamic lateral - resistance - considering the uplift wave (reduction of bottom resistance) - simulation of track conditions: perfect conditions, rain falls, vertical track irregularity, insufficient ballasting of ties lateral resis- tance Ties B 70 with tie pad G04 and fleece, straight track rail deflection [mm]

Results of FEM regarding lateral track stability Application of recorded parameters to FEM  Lateral resistance and imperfections have significant influence  Lateral resistance - ties with under tie pads are better than conventional ties  Critical imperfections - bigger track failures - length of track irregularity appr. 10 m - 12,5 m (straight track) - length of track irregularity appr. 5 m (curved track with R = 360 m)  Rail profile - smaller Cross sections are saifer against track buckling Q

- increasing of track elasticity reduction of rail seat load protecting the other track components - increasing of contact area between ballast and bottom side of tie reduction of contact stress extension of maintenance interval - allowable tensile stress on rail foot should not be exceeded - ballast deterioration on the tie sides The application of elastic under tie pads has many advantages Elastic under tie pads should not be too soft Conclusion

Chair and Institute of Road, Railway and Airfield Construction Technical University Munich, Germany Univ. Prof. Dr.-Ing. Stephan Freudenstein