Source: Untar Public Relations – RJ
The characteristics of tropical volcanic soil, which is sensitive to changes in moisture content, are among the factors contributing to landslides along the Dolok Sanggul–Pakkat Road in Humbang Hasundutan Regency, North Sumatra. These conditions require appropriate geotechnical solutions to prevent road damage and ensure the safety of road users.
These findings are from research conducted by Semangat Marudut Tua Debatraja, presented during an open dissertation defense at the Doctoral Program in Civil Engineering, Universitas Tarumanagara (Untar), at the Auditorium of Building M, Untar Campus I, Jakarta, on Friday (30/10/2026).
In his dissertation, entitled “Slope Failure Mechanisms in Tropical Volcanic Soil Using the Limit Equilibrium and Finite Element Methods,” Semangat examined how soil properties, climate change, and variations in moisture content affect slope stability.
The research was conducted along the Dolok Sanggul–Pakkat Provincial Road, specifically in Arbaan Village, Humbang Hasundutan Regency. The area experienced repeated landslides between 2017 and 2025, disrupting community activities and transportation.
The landslides not only damaged the road surface but also caused retaining wall failures, prolonged traffic disruptions, and increased the risk of vehicle accidents.
According to Semangat, the tropical volcanic soil in the research area has high plasticity, low permeability, and is sensitive to changes in moisture content. These characteristics affect slope stability, particularly when environmental conditions change.
To understand the mechanisms behind slope failure, Semangat conducted a series of laboratory and field soil tests. The analysis used the Fellenius and Bishop methods, along with numerical modeling using PLAXIS 3D software.
“The use of the three methods—Fellenius, Bishop, and PLAXIS 3D—helps ensure the accuracy of the results,” Semangat said.
Through this approach, the research is expected to provide a basis for determining appropriate landslide mitigation measures and road infrastructure improvements that account for local soil characteristics. Its application is also intended to improve slope stability and protect the safety of people traveling through the area.
Semangat successfully defended his dissertation in an open examination chaired by Untar Rector Prof. Dr. Amad Sudiro, S.H., M.H., M.Kn., M.M. He earned his doctoral degree with a very satisfactory distinction and became Untar’s 116th Doctor of Civil Engineering.
This research represents an academic contribution to addressing infrastructure challenges in landslide-prone areas. It also opens opportunities to apply geotechnical research findings to improve public safety and ensure sustainable transportation access. (CJ/YS)