Slope Protection Of Partial Wall On Flyover

Slope Protection Of Partial Wall On Flyover

Location NH-202, Hyderabad, Andhra Pradesh
Principal Client National Highways Authority of India
Client Name GKC Projects Limited
Design Consultants Aarvee Associates
Application Slope protection of embankment above reinforced soil wall (partial wall)
System Offered StrataWeb® geocells filled with concrete
Project Completion January 2013

Background

GKC Projects Ltd., an ISO 9001 certified company, is one of the leading infrastructure organisations in the Indian Construction sector. The construction of Hyderabad – Yadgir section of NH-202 on “Build, Own, Transfer” basis in Andhra Pradesh was awarded to them.

Objective

The ramps of the grade separators are constructed either as embankments with natural slopes, or as reinforced soil walls. In case of partial walls, where sloped embankments are supported on reinforced soil walls, it is essential that the embankment slopes are given adequate protection against soil erosion, which can otherwise damage the fascia of the underlying reinforced soil wall and also induce seepage into the system.

The slopes of the embankments are of the order of 30° with the horizontal. The reinforced soil walls supporting the embankments are as high as 10m. The heights of the embankments are of the order of 5m.

Convention methods of stone pitching and PCC / RCC lining were initially considered. Stone pitching (and even PCC / RCC) would have been difficult and time consuming, considering the height of the reinforced soil walls, which would render transportation, lifting, placing and execution extremely difficult.

Solution

Considering the time factor, economy and technical issues, it was decided to adopt slope protection using StrataWeb® geocells filled with PCC. This was considered to be the most feasible and cost effective solution as compared to the other conventional methods.

A slope of 30° (1.73H : 1V) is steeper than the conventional 2H : 1V slope which is generally considered for road embankments. However, it is a moderate slope when it comes to lining with geocells which can cover slopes as steep as 1H : 1V. This factor clinched the decision to consider geocells as slope protection method. StrataWeb® Style SW 71 75 was considered. The cell depth of 75mm was found optimal as a greater depth would have increased the weight of the geocells and the concrete in-fill, thereby increasing the downward force. A shallow depth also brought about a reduction in cost of concrete.

High strength PP tendons were used for suspending the sections from the top anchors. For cell to cell and flap to flap connections between StrataWeb® panels, high strength cable ties as well as pneumatic staples were used as per designs.

Concrete (M15 grade with 100mm slump) was poured from top to bottom using a placer boom at the crest. The concrete was dressed manually with trowels and floats.

Benefits to Clients

Considering the strict construction scheduled faced by the GKC, the time-effective StrataWeb® installation on the slopes was highly appreciated. The work was completed within a short span of ten days with minimal labour. Concrete consumption was also optimized with negligible wastage and there was no obstruction or diversion on the road in spite of trucks and machinery for the work at the crest. Conventional solutions for slope protection may not have produced speedier results at lesser costs.

About STRATA

Strata India offers a comprehensive range of high-quality geosynthetic and geotechnical solution to India’s civil engineering and construction industry.

Strata India, established in 2004 as a joint venture with Strata Systems Inc. USA. began manufacturing in its ISO certified facility in Daman.

From design to execution, Strata India provides turnkey solutions like reinforced soil walls, slope protection and stabilization, erosion control, foundation improvement for structures and embankments, steep slope embankments, strengthening of paved and unpaved roads, storage yards and industrial flooring for various sectors like roads and bridges, power, port, canal, solid wastage management etc.

Strata has built a track record for ensuring timely and infallible installation and prides in delivering a matchless customer experience.