محمدنبي ادرم

Abstract: In this study, the effect of reducing the ballast height outside the rail gauge on the longitudinal resistance of railway track substructures was investigated, focusing on three types of concrete sleepers (B70, intermediate-wing, an‎d winged). Longitudinal resistance tests were conducted at four levels of ballast height reduction outside the rail gauge (0, 10, 20, an‎d 30 cm) up to a displacement of 15 mm using a specialized laboratory setup. To accurately eva‎luate the longitudinal resistance, full-scale tests were performed on panels consisting of seven concrete sleepers. Longitudinal forces were applied simultaneously to both UIC60 rails using hydraulic jacks, an‎d the responses were recorded with precise load cells. LVDT sensors were installed on the first, fourth, an‎d seventh sleepers as well as at the load application points to monitor longitudinal displacement along the panels, enabling the determination of longitudinal resistance (TLRF), longitudinal stiffness (TLS), an‎d relative rail–sleeper displacement. The results showed that, under the reference condition, the maximum longitudinal resistance for the intermediate-wing sleeper was 96.5 kN, for the winged sleeper 85.95 kN, an‎d for the B70 sleeper 77.45 kN. With a 10 cm reduction in ballast height, the resistance decreased by 13.51%, 13.52%, an‎d 18.48% for intermediate-wing, winged, an‎d B70 sleepers, respectively; with a 20 cm reduction, by 29.10%, 17.10%, an‎d 28.35%; an‎d with a 30 cm reduction, by 35.09%, 29.00%, an‎d 39.00%. The intermediate-wing sleeper demonstrated the highest resistance under full geometry an‎d severe ballast reduction, whereas the winged sleeper maintained the greatest relative stability at moderate reduction (20 cm). The B70 sleeper exhibited the lowest resistance across all cases. Longitudinal stiffness (TLS) analysis indicated that the intermediate-wing sleeper had the highest stiffness under full geometry (26.28 kN/mm) an‎d decreased to 66.28% of its initial value with a 30 cm reduction. The winged sleeper, with an initial stiffness of 28.29 kN/mm, preserved the highest relative stability, maintaining 76.60% of its initial stiffness at 30 cm reduction. The B70 sleeper, with an initial stiffness of 24.71 kN/mm, experienced the largest dro‎p at the initial 10 cm reduction, retaining only 74.30% of its original stiffness. Furthermore, the relative rail–sleeper displacement measured on the fourth sleeper showed maximum values of 1.83 mm for B70, 0.94 mm for intermediate-wing, an‎d 0.56 mm for winged under full geometry. With a 30 cm ballast height reduction, these displacements decreased to 0.38, 0.21, an‎d 0.18 mm, respectively, highlighting the critical role of sleeper type an‎d sleeper–ballast interaction in providing longitudinal resistance of railway tracks. Keywords: longitudinal resistance, TPPT , ballast outside rail gauge, B70 sleeper, mid-winged sleeper, winged sleeper, crib ballast, shoulder ballast, continuous welded rail (cwr), railway track.

مقاومت طولي , آزمايش مقاومت طولي , بالاست ناحيه خارج قاب ريل , تراورس B70 , تراورس ميان بال , تراورس بالدار , بالاست آخوري , بالاست شانه , ريل با جوشكاري پيوسته ( CWR ) , خطوط ريلي

longitudinal resistance , TPPT , , ballast outside rail gauge , B70 sleeper , mid-winged sleeper , winged sleeper , crib ballast , shoulder ballast , continuous welded rail (cwr) , railway track

Mohammad Nabi Adrom

Jabbarali Zakeri