FORMATION TREATMENT WORK IN AGARTALA SABROOM BG RAILWAY LINE (NFR)

Tripura had inadequate transport infrastructure in the past, which was an impediment in its development. In order to meet extension requirements of the railway line up to Sabroom, the NFR initiated a project for the stretch length of 112.00 Km. The alignment of the Railway line passed through more or less flat country and covered two districts namely West Tripura and South Tripura. It passed through towns of Bishalgarh, Udaipur & Belonia in Tripura. Throughout the 112 km section of track length, there was unstable formation in lines causing disturbance to the track parameters. By avoiding the conventional method, NFR was keen to investigate new methods of track bed stabilization, with guidelines from RDSO as a technical advisor & consultant. They were exploring the use of geosynthetic solutions which can increase the effective bearing capacity of an underlying soft subgrade & also prevent intermixing of the soil particles in between blanketing material & subgrade. They also thought about the solution that would offer extension of maintenance cycle- the period between ballast cleaning and replacement operations.

The consultant proposed woven multifilament geotextile as a separation & filtration purpose in between blanketing & subgrade material along with biaxial Geogrid. Maccaferri supplied Mactex W1 along with MacGrid EG 30S and was available in the sizes of 50m length and 3.95m width of rolls. MacTex W1 is made of polypropylene multifilament yarns, woven together into a stable fabric structure with a superior combination of mechanical & hydraulic properties with having excellent resistance to biological & chemical agents normally found in soils & stable against short term exposure to ultraviolet radiation. MacGrid EG 30S geogrids are produced with high tensile stiffness in both longitudinal and transverse directions and rigid square square apertures. When the ballast is compacted over these geogrids, it partially penetrates and projects through the apertures to create the positive interlock. It also restrains the ballast from lateral spread.