Slope Protection
2020
ZIRAKPUR - NORTH - India
NATIONAL HIGHWAYS AUTHORITY OF INDIA (NHAI)
SLOPE PROTECTION WORKS AT ZIRAKPUR-PARWANOO SECTION NH-22
Photo 2: Before installation of slope protection measures – August 2011
Photo 3: Photograph showing Steelgrid BO on rocky slope – April 2012
Photo 4: Photograph showing Steelgrid BO on slope
Photo 5: Photograph showing MacMat R used in conjuction with Steelgrid BO
Photo 6: View after installation of slope protection measures – April 2012
Problem
The Zirakpur-Parwanoo section of the NH22 highway is situated in the Shivalik range and passes through Punjab, Haryana and Himachal Pradesh, in Northern India. It was found that the highway is affected by the rockfall from the slopes above. The local strata is composed of shale, sandstone, medium and small sized rock fragments as well as mixed strata of fine grained soil and medium sized rounded boulders exist along certain stretches. The maximum height of the slope was about 150m. Therefore any rockfall mitigation measures had to be tailored to the varied geology of the area. Three distinct zones of hazard were identified on the rocky slope above the highway: 1) Large boulders and exposed rocky outcrops. 2) Medium rock fragments. 3) Fine grained soils and smaller debris.
Solution
The highway concessionaire (Himalayan Expressway Ltd), Jaypee approached Maccaferri for providing a solution to overcome the slope hazards. The entire slope area was divided into three distinct zones. The zone where larger boulders and rocky outcrops were encountered, High Energy Absorption panels (HEA Panels)- which has characteristics of high tensile strength and stiffness, were installed. HEA panels has minimal deflection under load which is ideal to prevent large boulders detached from the slope. The areas where medium rock fragments were observed, Steelgrid BO was proposed and installed. Finally, in areas where finer particles were observed, the Steelgrid BO was used in conjunction with erosion control mat- MacMat R. It is used for providing immediate, high-performance erosion control and root reinforcement for re-establishing vegetation on vulnerable slopes. Top anchoring was done using an anchor trench wherever applicable. The meshes were secured on the rock slope using 2m long top anchors of 25 mm dia, surface anchors 0.5 m long of 25 mm dia, and bottom anchors 1m long of 16mm dia.
Used Products
Panels
Maccaferri HEA Panels (High Energy Absorption) are the stiffest products within our Mac.RO(TM) Systems mesh range, offering extreme strength at lowView
MacMat
Geomats are made of synthetic material filaments. The filaments are heat-tangled together to form a three-dimensional, highly deformable and of higView