An investigation of the effect of under-ballast reinforcing geogrids in laboratory and operating conditions

Abstract

This article presents the results of research focused on the use of reinforcing geosynth-etics inserted directly under the ballast. This technology appears to be a beneficial, cost-effective solution in cases of need for enhancing the bearing capacity of existing railway tracks with poorer track bed quality. Model constructions in a 1:1 scale with reinforcing geogrids of three types inserted under the ballast were investigated in laboratory conditions under short-term static loading and long-term cyclic loading. The contribution of geosynthetics is evaluated by comparing the values of settlement and bearing capacity of individual layers with those of a non-reinforced construction. The article also describes the up-to-date experience in the verification of the geocomposite-reinforced ballast bed in operating conditions. It is performed on a trial section of a single-rail track 200 m in length characterized by persisting long-term problems with the track geometry. The authors evaluate the used technology of mechanical geosynthetic laying by means of the ballast cleaning machine.