Slope Stability Geology and Soil Conditions during Road Construction along the Lupeta–Wimba–Izumbwe Road Intersections in Mbeya District, Tanzania

Abstract

In the realm of geotechnical engineering, maintaining slope stability is critical, especially in newly cut slopes during road construction. Consequently, the objective of this paper was to evaluate the Slope Stability Geology and Soil Conditions during Road Construction along the Lupeta–Wimba–Izumbwe Road Intersections in Mbeya District of Tanzania using appropriate standard procedures. Laboratory analysis determined shear strength parameters, with cohesion (c) ranging from 5 to 30 kN/ m²,  an angle of internal friction (Ø) between 20° and 35°, unit weight of soil (γ) varying from 16 to 20 kN/m³, and slope angles (α) between 25° and 45°. The study established a strong linear correlation between the angle of internal friction and the Dynamic Penetration Index (DPI), yielding a regression coefficient of 0.8, with the correlation equation Ø = 1.2515DPI + 0.3297. However, no reliable correlation was found between cohesion and DPI. The Finite Element Method (FEM) was employed to assess slope stability, revealing an overall factor of safety (FS) of 0.68, indicating slope instability.  Acknowledging limitations related to pore water pressure and moisture content, the study introduces a quick methodology for slope stability monitoring using FEM, achieving early detection of slope failure.