Soil Mechanics Study in the Huacariz area and Slope Stability Assessment on Santa Apolonia

Abstract

This study evaluates the geotechnical properties of soils in the Huacariz sector (Cajamarca, Peru) and the stability of a natural slope in the Santa Apolonia hill, aiming to determine its suitability for infrastructure development. Standard soil classification tests were conducted, including natural moisture content, grain size distribution, specific gravity, plasticity limits, and field density. The results allowed classifying the predominant soil as silty sand (SM), non-plastic, with frictional and draining behavior, favorable for shallow foundations and controlled fills. The average natural moisture content (17%) indicates adequate volumetric stability under natural conditions. Slope stability was analyzed using limit equilibrium methods (Bishop, Spencer, and Janbu) in Slide software. The obtained safety factors (1.13–1.07) are below the recommended minimum for permanent slopes (FS ≥ 1.50), indicating a limiting stability condition and high susceptibility to failure due to moisture variation or additional loads. Stabilization measures are therefore required to ensure geotechnical safety. Additionally, an experimental section of the study evaluated the incorporation of igneous rock as partial replacement of fine aggregate in 300 kg/cm2 concrete. Mechanical performance improved, with a 10.87% increase in compressive strength (15% replacement) and a 22.03% improvement in flexural strength (10% replacement). Statistical analysis confirmed the significance of these improvements. In conclusion, the area presents soils with adequate performance for foundations; however, the slope requires geotechnical reinforcement. Moreover, igneous rock is confirmed as a viable alternative to enhance concrete resistance for local infrastructure.