INFLUENCE OF INCORPORATING A BITUMINOUS SUB-BALLAST LAYER ON THE DEFORMATIONS OF RAILWAY TRACKBED Tiago Ferreira ABSTRACT This paper analyses theoretically the performance of a bituminous sub-ballast against environmental actions as an alternative to the conventional sub-ballast layers. The comparison
with typical railroad ballast and sub-ballast materials to ensure optimum mechanical interlock. Geogrids with larger apertures (for example, Tensar® TX190L) are used to stabilize the coarser aggregates typically used for ballast layers. BALLAST AND SUB-BALLAST STABILIZATION Tensar TriAx Geogrids are used to stabilize the trackbed
Slope Protection. Soil erosion is a major concern considering the integrity of the sub-ballast and ballast layers may be affected by severe cuts arising due to weathering.Conventionally, stone pitching has been the preferred solution to reduce erosion.
Geotechnical properties of ballast and the role of ... physical and mechanical characteristics of the rail substruc-ture, and of the ballast layer in particular. Accordingly, the University of Wollongong under the ... The experimental programme on railway ballast based on large-scale triaxial testing 92 B. Indraratna et al. (Jeffs and Marich ...
Railway ballast is packed beneath the train rails to interlock with the capping layer subgrade and provide a uniform support layer. More ballast is also packed between the sleepers and rail itself to lock them in place to resist the high loads from passing trains (Figure 1). Rail ballast …
breaching of the ballast layer will commence. In this section, we evaluate the material properties of both new and used ballasts. A channel experiment that simulates seepage ﬂow through a railway ballast layer was con-ducted in order to understand the critical ﬂow condition that causes ballast layer …
Railway track formations generally consist essentially of a layer of coarse aggregate, or ballast, in which the sleepers are embedded (see Fig. 12.1). The ballast may rest directly on the subgrade or, depending on the bearing capacity, on a layer of blanketing sand.
Railway subballast which serves between ballast layer and subgrade layer is composed of much finer particles than the upper ballast. It was widely considered to work as a filter which on the one hand prevented the mutual penetration be-tween ballast and soft soil subgrade (known as the slurry
Spectra ® Rail Railway Improvement System. The Spectra ® Rail System allows the optimization of trackbed structure design with the use of Tensar ® Geogrids. Stabilizing aggregate in rail ballast and sub-ballast layers, Tensar Geogrids stiffen the roadbed section, typically reducing the dynamic deflection that occurs at the surface for each load cycle by 40-50%*.
Getzner Ballast Mats have a multi-layer structure that consists of a load distribution layer and a resilient layer. Load Distribution Layer. The top layer of the mats consists of a geotextile or fleece with high stretch and tear resistance. This layer deforms under the load of the ballast.
supported on the initial ballast layer. E. Replace damaged and defective ties. F. Before laying rail, clean the wearing surface of the tie and tie plate of any debris. 3.08 CUTTING AND DRILLING OF RAIL A. Use only approved rail saw and abrasive cutting wheel for cutting rail. Cuts shall be square and clean.
aggregates were placed into the ballast box in three layers. 175 For each layer, the aggregates were tamped and leveled. A 2H: 1V slope176 as typical in a railroad ballast layer was formed at the 177 top. Two ties were placed on the top of the ballast layer with 1/3 of the depth buried into the 178 ballast…
• All or some of the "old" ballast layer becomes "new" subballast layer when new ballast is added, but old material likely to be of marginal quality and layer function may be compromised • Bottom ballast and subballast differentiation becomes blurred • "Ballast" layer often described as having a "top" ballast
A bituminous ballast construction may consist of one or more separate layers of possibly different composition. Depending on the design the various layers each perform a specific role in the construction. The properties of bitumen offer good opportunities to apply this type of material in railway track construction. Bituminous Ballast as Sub Ballast Layer.
The proposed two layered ballast system described in this thesis replaces the crib ballast around the sleepers by stones of size smaller than standard railway ballast. The aim is to fill the voids below the sleepers before they become unacceptably large, without use of expensive plant or manual intervention.
Geofabrics offers a range of solutions for new track construction as well as renewal or maintenance of existing railway tracks which can deliver both construction savings and life-cycle optimisation. Our solutions incorporate control of track geometry and rail alignment, stabilisation of the ballast and capping layers and complete drainage systems.
changes (Eq. 2) on control points located over the rail axis line between the sub-ballast and the formation layers. To allow a theoretical approach, a simplified method was adopted, where for each layer (Figure 1) it is assumed a given reduction of the relative humidity (RH) of the air from the atmosphere.