Miragrid® GX - Road Embankment Slope Failure Repair

Project Data

Project	Road Embankment Slope Failure Repair
Location	Lampoon Road, Thailand
Owner	Department of Highway, Thailand
Products used	Miragrid® GX

Overview

The road between the provincial towns of Khun Tan and Lampoon in Northen Thailand is an important economic link between the two towns. The failure of the embankment at KM 11, significantly disrupted traffic and posed a danger to road users.

Various repairs options were considered by the Thailand Department of Highways, before the decision was made to repair the slop using geogrid soil reinforcement materials.

Method of repair

The failed slope was trimmed back to solid ground. The toe if the embankment was bolstered by installing gabions, behind which a  well compacted stable foundation was constructed.

Miragrid® GX geogrids were installed at 500 mm spacings to reinforce the backfill material. The slope profile was formed by wrapping the geogrids round jute geobags filled with humus and grass seeds. This method of construction has numerous benefits. Firstly it provides employment for local labor. Secondly the method facilitates practical construction of uniformly steep slopes. During the subsequent rainy season the bags retain moisture facilitating assured germination of the grass seeds.

To control the risk of subsoil water seepage a drainage layer of stone aggregate wrapped with Polyfelt® geotextiles was constructed up the back of the structure.

The slope was constructed in a single 10 m high berm with an average slope angle of 70 degrees.

The repair works, using a local construction contractor was completed within four months. Initial vegetation growth was evident within 2 - 3 weeks of completion of the top layer.

The method of repair is especially suited for repair of failed slopes and embankments in remote rural regions. The use of geobags as the facing formwork facilitates construction of uniform slope profiles that blend into the surrounding slopes, as well as being flexible enough to accommodate protrusions such as culverts and other structures. Local labor employing medium to light construction equipment can be used to undertake the construction.

Supervision of such construction works is well within the capability of most provincial engineers. Provided the soil backfill is properly compacted and the reinforcement geosynthetics correctly installed, the finished reinforced soil structure will be stable and secure. Once the vegetation is established the slope cannot be distinguished from surrounding vegetation.

Road Embankment Slope Failure Repair

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