Slope Protection Engineering with Geosynthetics

Slope protection engineering is increasingly important because soil erosion frequently occurs due to growing human activity and climate change. The continuous loss of soil particles causes landslides, especially on steep slopes. Landslides in countries with high rainfall often claim many lives. Therefore, measures to prevent slope erosion must be taken as early as possible.

The most common erosion prevention method uses vegetation. Vegetation can absorb rainwater and prevent wind from blowing away topsoil. However, vegetation needs time to grow and provide full slope protection. The period from planting until the vegetation becomes established is critical, when the erosion rate is very high, especially during the rainy season.

Several geotechnical engineering methods use erosion control blankets to prevent erosion. The most common materials include woven coconut coir, geomat and geocell.

Slope Protection Engineering

Woven Coconut Coir

An erosion control blanket made from woven coconut coir is a natural material with a rough surface that has proven quite effective at preventing erosion. However, because it is natural, it has a shorter service life than polymer materials.

Geomat

Geomat resembles a synthetic mesh that helps protect the topsoil and supports the growth of vegetation with strong roots, thereby helping to prevent slope erosion.

Geocell for Slope Protection Engineering

Geocell is a three-dimensional structure that creates a confinement effect within the soil structure. This confinement greatly limits the movement of soil particles, making geocell highly effective for slope protection.

Referring to scientific research presented at “The 2018 World Congress on Advances in Civil, Environmental, & Materials Research (ACEM18),” several slope protection materials were studied.

Slope Protection Engineering

Refer to: Franz Erickson Paz, Performance evaluation of soil erosion control geotextile materials on road cut slope

The research results showed that geomat had the lowest particle loss in January, while geocell produced low particle loss over the long term. Over a one-month period, coconut coir was the most effective slope protection material for reducing slope erosion, followed by geocell.

The research identified the slope soil as clay and showed that plants or vegetation grew very well on slopes covered with geocell. Geocell has pocket-like openings that allow plant roots to become established properly and more quickly. Guo (2015) stated that the smaller openings in other geotextiles make root penetration more difficult, resulting in slower growth.

Geocell’s effectiveness in addressing slope erosion has led to its use in various construction projects in Indonesia. One example is slope protection for the PT Krakatau Posco reservoir project.

Problem

A slope with a 1:1 gradient or an angle of 45 degrees is vulnerable to erosion during rainfall. In risk management, continuous erosion can potentially create a landslide risk.

Solution

Given the considerable slope height and its erosion-prone gradient, we recommended 15 cm-high geocell to prevent erosion. Our design and specifications were processed and implemented by the highly skilled personnel of Krakatau Engineering. After the geocell was laid using the required technique, it was immediately filled with soil. Once the soil inside the geocell had been compacted across the entire area, grass was planted, leaving the slope standing securely with lush green cover.