REHABILITATION OF NATIONAL HIGHWAY DAMAGED BY RAIN USING GEOSYNTHETICS IN HILLY TERRAIN – A CASE STUDY (Paper 850)

Geosynthetics are increasingly used in the design of flexible paved pavement sections. One style of geosynthetics best suited for pavement applications is the geocell. Geocells are unique three-dimensional rhomboidal cellular confinement systems whose characteristics provide additional rigidity to the pavement structure. The walls of the geocells are perforated to effectively facilitate drainage. Incorporating the infilled geocell within any granular component of a flexible pavement on a weak subgrade improves the resilient modulus of the layer. This reduces the strains at critical point between the base course and the bituminous layers and at the subgrade level. Hence pavement thickness can be reduced and / or the life of the pavement can be extended according to the designer’s requirements. The authors present a case study where geocells have been effectively used in reconstruction of the National Highway NH-44 traversing over hilly and forested terrain across the Assam – Tripura border, which was destroyed during torrential rain since March 2016 and to-and-fro traffic was badly affected. The affected section was between Malidoor (Assam-Meghalaya border) and Churaibari (Assam-Tripura border).  NH-44 is the only road connecting Tripura to the rest of country.  The CBR of the subgrade along the damaged section was reported as low as 0.50% with traffic as high as 20msa.  Rehabilitation was designed and executed with the judicious use of geocells, woven and Non-woven geotextiles.  The work was executed jointly by PW (Buildings and NH) Division of Assam and Strata Geosystems (India) Pvt. Ltd. This Paper records the design, construction and performance of the highway reconstructed with geocells and geotextiles.