Settlement of ballasted track under traffic loading: Application to transition zones

Abstract

Transition zones corresponding to the passage from railway tracks on embankment to natural ground or settlement free structures are frequently problematic for maintenance. Changing stiffness of the track and differential settlements are the main causes for the degradation of tracks and foundations at transitions. This paper presents a methodology to predict the settlement of the track due to train loading, applicable to transition zones. The methodology is based on dynamic calculations using a (non-linear) train-track interaction model and an incremental settlement model. Important non-linear aspects in dynamic models for railway transitions are the loss of contact between the sleepers and the ballast and the non-linear constitutive behaviour of the ballast. The settlements are calculated paying attention to the factors that most influence the long-term behaviour of ballast, such as the amplitude of the applied dynamic force and the number of loading cycles. The importance of the dynamic loading from the trains and of the constitutive models used for the trackbed layers is analysed.

Analysis of the Dynamic Wheel Loads in Railway Transition Zones Considering the Moisture Condition of the Ballast and Subballast

“…In the case of hanging sleepers, the sleepers should generate a nonlinear interaction force to the ballast under compression and separable without loading [53]. Therefore, contact elements are applied between sleepers and ballast.…”

“…The nonlinear connection between sleepers and ballast is important for modelling of the ballast degradation mechanism [48,53]. In the case of hanging sleepers, the sleepers should generate a nonlinear interaction force to the ballast under compression and separable without loading [53].…”

“…Despite the fact that the responses of unbound granular materials such as ballast, subballast, and subgrade can be more accurately modelled using nonlinear constitutive models, simplifications have to be adopted in the large-scale study (e.g., transition zones) to reduce the computational expense. Many studies (e.g., [10,[48][49][50][51][52][53]) have proved that some behaviour of ballast and hanging sleepers can be modelled accurately using simplified methods (e.g., solid elements with elastic material properties). Following [10,[48][49][50][51][52][53], the ballast and subgrade in this model are also modelled by solid elements with elastic material properties.…”

Evaluating railway track support stiffness from trackside measurements in the absence of wheel load data

“…This is most obvious on transitions between soft and hard supports, such as the approaches/exits from bridges (e.g. Coelho et al, 2011;Paixao et al, 2013;Varandas et al, 2014;Milne et al, 2014).…”

Application of Polyurethane Polymer and Assistant Rails to Settling the Abnormal Vehicle-Track Dynamic Effects in Transition Zone between Ballastless and Ballasted Track

“…Other studies investigated remedies to effectively address the resultant problems. In general, most approaches that have been tested and proven effective at vibration control in the railway transition section, such as using larger sleepers, resilient sleepers, and track-lifting techniques [11][12][13], have reduced the abrupt change in track stiffness. However, such measures may be expensive and difficult to apply to an established railway.…”