Applied Geology
Applied Geology tests geology used in engineering, mining, hazard assessment and planning. Expect site investigation, foundation and slope stability, dam and tunnel geology, remote sensing and GIS, and Karnataka's geohazards.
Core rules
- Site investigation uses geological mapping, boreholes, core logging, geophysics and laboratory tests.
- Rock Quality Designation (RQD) is the percentage of intact core pieces longer than 10 cm in a run.
- Slope stability is assessed by factor of safety, FS = resisting forces or moments ÷ driving forces or moments; FS > 1 is nominally stable, but design requires a margin.
- Dams require impermeable foundations; tunnels in fractured rock need support; landfills need low-permeability liners.
- Remote sensing and GIS map lineaments, land use and landslide susceptibility.
Worked example
A 100 cm core run contains 85 cm of intact pieces longer than 10 cm. Calculate RQD and interpret it. Reasoning: RQD = 85/100 × 100 = 85%. This indicates good-quality rock, but RQD is not the same as core recovery; recovery could still be 100% with many short broken pieces.
Traps
- Do not equate RQD with core recovery.
- FS = 1 is not an adequate design target; variability and water pressure matter.
- A landslide is not the same as erosion; it is mass movement.
- Karnataka's Western Ghats landslides are linked to heavy rainfall, steep slopes and laterite or weathered rock.
Karnataka link
Coastal erosion affects the Karavali coast; steep Ghat slopes need careful cut-slope design; Deccan Trap terrain in the north poses foundation and groundwater challenges.