geotechnics

Geotechnics is a branch of civil engineering focused on the behavior of earth materials—soil and rock—under engineering actions. It underpins the planning, analysis, and design of foundations, earthworks, slopes, tunnels, dams, and other underground or soil-structure interactions. The aim is to ensure safety, serviceability, and cost-effective performance while addressing environmental and risk considerations.

Core concepts include effective stress, shear strength, compressibility, stiffness, permeability, and consolidation. Soils are characterized by particle size and behavior, with classifications such as the Unified Soil Classification System (USCS). Field and laboratory testing provide properties used in design: laboratories perform tests like triaxial, oedometer, and direct shear tests, while field tests such as standard penetration tests (SPT) and cone penetration tests (CPT) help characterize in-situ conditions. Site investigations gather soil and rock profiles, groundwater data, and geologic context.

Design in geotechnics covers bearing capacity, settlement, slope stability, liquefaction, seepage, and earth-retaining systems. Analyses employ limit equilibrium, finite element methods, and empirical approaches to design shallow and deep foundations, tunnels, and earthworks, as well as to plan ground improvement and monitoring strategies. Construction practices include compaction, grouting, stabilization, and the use of geosynthetics, with instrumentation like piezometers and inclinometers to monitor performance.

Geotechnical practice also addresses hazards such as landslides, ground subsidence, seismic liquefaction, and stability failures. Projects span foundations for buildings and infrastructure, embankments and dams, tunnels, and mining works. Codes and standards vary by country, including Eurocode 7, ASTM standards, and national guidelines. The field integrates geology, hydrology, and engineering to manage the variability of earth materials in design and construction.