Roadside Slope Rehabilitation with ACEMat™ R, Aboriginal Tribe, Miaoli County, Taiwan

P'anoh is located at an aboriginal tribe in Miaoli County that gathers P'anoh, Ciupus, Sinpitu, and other tribes with beautiful scenery. The Ciupus access road is the critical path for local indigenous tribes to make a living. In recent years, the government has vigorously promoted the development of aboriginal tribe tourism to improve the tribal economy and upgrade living standards, which largely preserves the traditional aboriginal culture. Consequently, the demand for using Ciupus access road has been increased, and the government has to keep the annual budget to maintain the quality of roads.

The mountains within the tribe are high and steep, with a large range of unstable historical colluvium. Vegetation also is not easy to grow steadily because of long-term erosion of slope surface. Large-scale landslides therefore often occur after attacks by typhoons and heavy rains. For this project, there are five large-scale collapsed slopes required for rehabilitation. It is very challenging for design and construction because of the geological fractures and ongoing sliding.

1. The slope at the site is steep, which is extremely unfavorable for vegetation to grow. To quickly green a large area of the slope, vegetation by means of hydroseeding was adopted. The native grass seeds were mixed with the plant substrate and sprayed evenly from top to bottom. It has made the slope rapidly restored to the appearance of natural landscape, and integrated with the local vegetation scenery.

2. To reduce the loss of the seeded vegetation and the fine-grained soil on the slope surface caused by the rainfall after construction, ACEMat™ R was used as the anti-erosion material for this project. It is flexible and adaptable to the changeable terrain, and thus able to ensure the greatest retention for the seeded vegetation. In addition, the high-strength ACEMat™ R can be classified as High-Performance Turf Reinforcement Mat (HPTRM) which will be the most suitable for the protection of long and steep slopes such as the case in this project.

3. For collapsed slope with greater undulated terrain, it is necessary to install anchoring nails with denser spacing to ensure the lightweight ACEMat™ R can be intimately attached to the slope surface for better surface protection and planting productivity. However, because of the larger slope area at the site, anchoring nails with closer spacing certainly go beyond the budget. Therefore, a diamond-shape galvanized wire welded mesh with a wire diameter of 4 mm and a mesh opening of 60 mm x 60 mm was used to cover the ACEMat™ R. With a higher rigidity, ACEMat™ R therefore can be more intimately fastened on the slope by the wire welded mesh, which reduces the gap between ACEMat™ R and the slope. The erosion of soil or washed out of the seeded vegetation caused by the surface runoff can be eliminated during rainfall.

4. The ACEMat™ R and the galvanized wired welded mesh were fixed on the slope using ACENail™ EB50, a 2 m long corrosion-resistant grouted nail. They were staggered, installed at a spacing of 1.5*1.5 m in both directions. In addition to providing anchorage security of mesh material, it also has the effect of stabilizing shallow slope.

Sustainable Safety
The diamond-shape wire welded mesh and ACEMat™ R were fixed with grouted ACENail™ EB50 for slope protection. Since the restoration, no slope failure has occurred in the treated site, even after many attacks of typhoons and heavy rains. It can be seen that the rehabilitation method has played an effective safety mechanism and provided a secure road for local residents and tourists.

Green Construction
ACEMat™ R provided full protection against erosion. It protected the seeded vegetation well and facilitated the site to achieve a greening landscape within a short time. It can be used to replace the imperfect tradition shotcrete slope protection method. In addition to implementing the concept of energy-saving and carbon reduction, negative carbon emissions after planting make a particular contribution to the global goal of net-zero emissions.

Eco-friendly Environment
Using ACEMat™ R, a flexible green mesh material, instead of the traditional rigid, poor gray shotcrete for slope protection certainly has created a more attractive environment, which is more favorable to ecological restoration. In addition, the application of native plants can better initiate a harmonious ecology and reduce the damage to the local ecosystem.