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Technical blog

Infrastructures|Stabilisation of railway tracks
10.03.2020

URETEK geopolymers injection technology allows repairing railway embankments in the shortest time, while not affecting train traffic. Geopolymer resins help to strengthen and stabilise sunken crushed stone layer, also level concrete slabs of railway tunnels, stations, crossings and depots and lift them to designed height where necessary.

Railway infrastructure consists of many objects, including sections with railway tracks, tunnels, bridges, stations, depots, repair workshops, etc. All these objects suffer from loads caused by train traffic, as well as weather conditions and surface water.

Construction regulations prescribe establishment of groundworks consisting of crushed stone before installing rails. Railway embankment is made of bulk material (e.g. crushed stone). Regular load on rails and crushed stone causes uneven subsidence of different track sections. When subsidence exceeds maximum limits, the position of rails changes and using the tracks becomes unsafe. By using modern URETEK geopolymers injection method, it takes only a couple of hours to restore safe condition of tracks and strengthen crushed stone layer.

Stabilisation of crushed stone layer of railway embankment

Using geopolymers allows strengthening of soil under railway tracks and stop subsidence of crushed stone layer without dismantling rails and sleepers. Meanwhile, stabilisation of railway embankment does not require adding crushed stone. It is sufficient to insert geopolymer resin directly in railway embankment or the soil under it. Geopolymer material expands and exerts pressure vertically, thus lifting the tracks to their designed height.

Lifting of reinforced concrete slabs

In several sections (crossings, tunnels, stations, depots, etc.) tracks are mounted on reinforced concrete slabs. Such slabs can also sink due to changes in surface water level or soil erosion resulting from disruption of drainage systems.

Sections with concrete slabs can also be levelled and stabilised, using URETEK technology to strengthen subsoil. For that purpose, geopolymers are injected through holes drilled in concrete slabs. Meanwhile, there is no need for dismantling slabs and railway embankment. Soil deep under reinforced concrete slab is strengthened by using Deep Injection method, slabs are lifted and levelled by using Slab Lifting method.

Specifics of geopolymers injection

For injection of geopolymers, holes with diameter of 12–16 mm are drilled in crushed stone layer of railway embankment or in reinforced concrete slabs. Geopolymer material is inserted through hoses into pipes with diameter of 8–14 mm. Immediately after injection, geopolymer material expands, filling cavities and voids in soil and thus ensures lifting and stabilisation of structures. The process of lifting is monitored in real time by means of laser level.

Geopolymer achieves required durability in only 15 minutes. This allows quick completion of all works without altering train schedule.

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