Considering the weak sub-grade and the heavy loading, a solution using StrataWeb StyleSW35, 150-mm cell depth was worked out

Background
Jawaharlal Nehru Port (JNP) at Nhava Sheva, Navi Mumbai is spread over 10 sq. kms. and is the largest container port in India. The PWD Maharashtra bears the responsibility of maintaining all the State Highways in and around the JNP area. State Highway SH-84 connects the JNP-Panvel Road junction to the ONGC terminal at Uran and experiences very heavy traffic movement. Due to heavy loads, the road stretch has always had issues of cracking and subsidence, requiring recurring and persistent annual rehabilitation.

Technical information
• Main client: PWD Maharashtra
• Solution offered: StrataWeb Geocells
• Project area: 2,200 sq. metres
• Application: Road sub-grade strengthening with StrataWeb• Project duration: Seven days in November 2012.

Objective
Due to the heavy traffic movement on account of the ONGC Terminal, the road stretch was under distress time and again and its regular maintenance was proving to be an expensive exercise for PWD.  Such maintenance would require frequent shutting down of sections of the road and traffic diversions, which further compounded the woes on this vital link to the terminal.

Considering all factors for long-term sub-grade improvement, longevity and economy, a StrataWeb engineered solution was finalised. To prove the efficacy of StrataWeb, the stretch closest to the terminal was taken up initially, about 450 metres (km 9.2 to km 9.65) with road width of 5.5 metres.

Design solutions
Considering the weak sub-grade and the heavy loading, a solution using StrataWeb StyleSW35, 150-mm cell depth was worked out. High strength polymer cable ties were used for cell to cell and flap to flap connections between StrataWeb panels. The StrataWeb cells were filled with GSB (Granular Sub-base) Gr-III material.

Construction overview
StrataWeb panels of size 2.6-metre X 5.6-metre were used. The 2.6-metre side was placed along the width of the carriageway, while the 5.6-metre side was along the length of the stretch. GSB Gr-III was filled within the cells using highway dumpers. The geocells were filled to full depth of 150 mm, plus an additional cushion of 50 mm. The GSB was spread with a front loader.

In this way, one lane of 2.6-metre width was opened to traffic speedily as a diversion, and the balance road-width was taken up and completed in a similar manner.  The entire width of the stretch was completed in a record time.

Results
According to Strata Geosystems, the rapid installation of StrataWeb and re-opening of the road to heavy traffic within record time was much appreciated by the PWD, and more so by the ONGC Terminal. The entire stretch was satisfactorily completed in seven days with minimum labour and without disrupting the free flow of traffic. Other than diverting the traffic along the adjoining lane, no obstruction or diversion of the road was required, and no heavy machinery was needed. The conventional system of road rehabilitation could not have been done at a faster pace.

The project was trendsetting and a major success, considering that this was done for the first time in Maharashtra on a State Highway.

About Strata Geosystems
Strata Geosystems (India) Pvt. Ltd., established in 2004, is a joint venture with Strata Systems Inc., USA – a part of the 130 year old Glen Raven Group of Companies. Strata Geosystems provides end-to-end technical solutions, from design to execution of geotechnical applications such as reinforced soil walls (flyovers, road over bridges etc.), soil embankment stabilisation, reinforced steep slopes, reinforced foundations, slope protection, load support for paved and unpaved roads and bearing capacity improvement, landfills and reservoirs. Strata is reputed for its quality and cost effectiveness and manufactures conforming to strict international quality standards. Its team of experienced design and project engineers ensures timely and accurate installation.