Mountain Engineering in Srinagar: A Case Study on Slope Stability Using Ocean Hexagonal Woven Double Twisted Gabion Boxes

Ocean Non Wovens supplied and installed 1,000 units of Ocean Hexagonal Woven Double Twisted Gabion Boxes for a mountain engineering project in Srinagar, Jammu & Kashmir. The gabions stabilise a steep slope along the Srinagar highway corridor, protect the base of the mountain road and reduce erosion near settlements.

Project overview

• Location: Srinagar, Jammu & Kashmir, India
• Project type: Mountain slope stabilisation and erosion control
• Product used: Ocean Hexagonal Woven Double Twisted Gabion Box
• Quantity supplied: 1,000 boxes
• Scope: Supply and installation
• Objective: prevent slope failure, protect the base of the mountain road and reduce erosion risk near settlement zones

The project area was a steep section of the Srinagar highway corridor that regularly saw slope slips and minor landslides in the wet season. Existing masonry retaining walls nearby were showing distress from poor drainage and their rigid design.

Engineering on Himalayan slopes

The hills around Srinagar combine steep slopes, fragile geology, rain and snowmelt, which makes landslides and soil erosion common. Infrastructure here has to deal with:

• Erosion and slope instability from rainfall and snowmelt
• Retaining wall failures caused by water pressure building up behind solid walls
• Limited access for heavy machinery on steep ground
• Environmental restrictions in ecologically sensitive areas

Solutions need to be light to transport, flexible and low-impact while still durable, which is the case for gabions. Retaining and breast walls on hill roads in India are covered by the Indian Roads Congress Hill Road Manual, IRC:SP:48-1998.

Why gabions were chosen

1. Flexibility: gabion boxes can deform slightly without losing structural integrity, which suits ground that moves.
2. Permeability: water drains freely through the stone fill, so hydrostatic pressure does not build up behind the wall. This addresses the failure mode seen in the nearby masonry walls.
3. Vegetation: plants establish in the fill over time and help hold the slope.
4. Ease of installation: boxes are assembled by hand with local labour, cutting equipment and logistics costs on a site with poor access.

Ocean Hexagonal Woven Double Twisted Gabion Box

The boxes are made from galvanised or PVC-coated steel wire woven into a double-twisted hexagonal mesh. Each pair of wires is twisted together at every node, so if a wire is cut or broken locally, the mesh does not unravel. On a slope where falling rock can damage the face, that matters.

Technical specifications

• Mesh type: hexagonal, double twisted
• Mesh opening: 60 × 80 mm or 80 × 100 mm, as per design
• Wire diameter: 2.7–3.4 mm (galvanised or PVC coated)
• Wire tensile strength: ≥ 380 N/mm²
• Coating life: minimum 10–12 years in exposed conditions with PVC protection

Double-twisted gabions are commonly specified to IS 16014 in India, or EN 10223-3 and ASTM A975 internationally, with zinc-coated steel wire to standards such as ASTM A641.

Applications

• Slope protection and erosion control
• Retaining walls
• Riverbank and streambed stabilisation
• Road and embankment protection

At Srinagar, the boxes were filled with locally sourced angular stone. Angular stone interlocks better than rounded stone, and the self-weight of the filled boxes resists soil and rock movement.

Installation sequence

1. Site preparation: the unstable slope was cleared of debris, vegetation and loose soil, and drainage channels were cut to divert surface runoff.
2. Foundation layer: a geotextile separator was laid beneath the gabion foundation to stop soil migrating into the stone and to help drainage. Ocean Non Wovens geotextile was also used in some segments for added filtration.
3. Assembly and placement: the gabion boxes were assembled on site and laced together with binding wire into a continuous retaining structure.
4. Stone filling: locally quarried stone (100–200 mm) was placed in layers to keep the fill dense and minimise voids.
5. Vegetative layer: the top gabion layers were built with soil pockets so vegetation could establish and add long-term bio-stabilisation.

In general practice, stone is placed in lifts with internal bracing wires tied across each cell, so the face does not bulge as the box is filled.

Performance

Through the 2024 monsoon season after completion, the structure drained well and flexed as intended. The slopes remained stable, with no signs of bulging or soil washout.

• Less slope erosion, as observed in post-project site inspections
• Safer road, with minor rockfalls and debris kept off the carriageway
• Lower maintenance, since gabions need little upkeep compared with RCC structures

Vegetation growing over the gabions has also softened the look of the structure and returned some habitat to the slope.

Environmental and cost considerations

Filling the gabions with local stone cut the transport, and the emissions that come with it. A gabion wall uses far less cement and steel than a concrete retaining wall, so its embodied carbon is lower, and it can be built with minimal machinery, which reduces disturbance on a sensitive hillside.

Slope protection from Ocean Non Wovens

At Srinagar, 1,000 Ocean Hexagonal Woven Double Twisted Gabion Boxes replaced a failure-prone rigid wall approach with a flexible, free-draining one. Ocean Non Wovens designs and manufactures geosynthetic products for Indian infrastructure, from gabions and geotextiles to HDPE liners and geogrids. For hill sites with loose rock above the road, see also our rockfall protection systems. If your project involves slope stabilisation, erosion control or mountain infrastructure, talk to our team.