Numerical Investigation of Slope Stability in Valles Marineris, Mars

Abstract

The rock walls of Valles Marineris (VM) valleys on Mars reveal significant gravitational failures, resulting in a sequence of massive landslides spanning several hundred cubic kilometers in volume. For further Mars exploration missions, it is critical to understand which characteristics impact the stability of these rock walls. In this work, ArcGIS is used to identify 30 steep slopes. Utilizing the finite element method, we calculate the proposed seven possibly landslide-prone slopes based on geometry in VM. Using Strength Reduction Method (SRM) in Midas GTS NX, the impacts of variations in cohesion, internal friction angle, unit weight, and elastic modulus of soil and rock on the slope safety factor against landslides are evaluated. The Strength Reduction Method (SRM) is a widely used approach in geotechnical engineering to assess slope stability. It involves systematically reducing the strength parameters of the soil and rock materials within the slope until failure occurs. By iteratively reducing the strength parameters, the SRM calculates the factor of safety against landslides. Internal friction angle is the most critical factor in determining the stability of a slope under low gravity circumstances since it has the widest range of possible alterations. Furthermore, the material’s cohesion and unit weight significantly impact the safety factor, although elastic modulus barely affects slope stability. A modulus of elasticity of more than 35 GPa will not enhance the factor of safety. There is no significant difference in soil suction between Earth and Martian gravities near the surface water table. However, as the groundwater depth increases, soil suction under Martian gravity becomes notably lower than that on Earth. Additionally, consistent with prior investigations, the Vadose zone on Mars is positioned at higher elevations relative to Earth, indicating the presence of a higher capillary fringe. Furthermore, the factor of safety for slope stability consistently outperforms Earth for equivalent slope configurations under unsaturated conditions, with approximately 2.5 times higher factor of safety for higher suctions and approximately 1.5 times higher factor of safety for lower suctions compared to Earth.