Engineering Geology Concepts

Introduction to Geology and Engineering

• Geology: The scientific study of the Earth focused on rocks and soils, covering:

  • Origin

  • Occurrence

  • Evolution

  • Composition

  • Structure

  • Distribution

• Engineering: Application of scientific knowledge for practical use in an economical manner.

  • Quote by Arthur Mellen Wellington: "An engineer is a person who can do for a dollar what an ordinary person can do for two."

• Branches of Engineering Related to Earth Processes:

  • Civil Engineering: Constructs structures safely and economically on or in the Earth’s crust.

  • Mining Engineering: Designs methods to extract resources from the Earth’s crust safely and economically.

  • Petroleum and Natural Gas Engineering: Focuses on recovering hydrocarbons from the Earth’s crust.

Understanding Engineering Geology

• The need for understanding geological properties for the stability, safety, and economy of engineering work.

• Definition of Engineering Geology: The scientific study of geology in relation to engineering projects (e.g., bridges, dams, landslide prevention).

  • Practical application of geological knowledge for projects.

• Importance of Site Investigation:

  • Investigating geological conditions is critical for developing accurate ground models.

  • Models need to characterize essential elements of a site.

Skills Required for Engineering Geologists

1. Knowledge of Geology:

   • Understanding the nature, formation, and structure of soils and rocks.

   • Ability to interpret geological history.

2. Engineering Geology and Hydrogeology:

   • Techniques for sub-surface investigation and properties of soil and rock.

   • Knowledge of weathering processes and hydrogeological conditions.

   • Understanding of water pressure dynamics and drainage techniques.

3. Geomorphology:

   • Importance of land surface characteristics in engineering projects.

   • Stability analysis essential for predicting landslide hazards.

4. Civil Engineering Principles:

   • Familiarity with structure design and engineering practices.

5. Rock and Soil Mechanics:

   • Understanding behaviors of soil and rock under various stress conditions.

   • Knowledge of testing methods and geotechnical instrumentation.

Contributions of Engineering Geologists to Projects

1. Understanding Geological History: Combines regional knowledge with document examination and rock interpretation.

2. Predicting Changes During Structure Lifecycle (50-100 years):

   • Recognizing environmental hazards like rainfall, earthquakes, and flooding.

3. Weathering Analysis: Identifying weathered zones relevant to the project.

4. Cost-Effective Investigations: Focused testing addressing specific project features.

5. Ground Model Preparation: Including groundwater analysis for project performance prediction.

6. Hazard Recognition: Identifying potential risks even after thorough investigations.

7. Construction Material Identification: Assessing aggregates, ensuring safe waste disposal.

8. Project Management Insight: Addressing difficulties with contracts and poor ground conditions.

Fundamental Terms in Geology

• Earth Material: Solid material forming the Earth's crust, including soils and rocks.

• Soil: Uncemented earth material that can separate into pieces.

• Rock Mass: Volume of Earth crust with interlocked grains or cemented crystals.

• Discontinuity: Weak planes in rock masses affecting stability.

• Intact Rock: Rock material without major discontinuities.

• Rock Mechanics: Study of mechanical properties of rocks under various conditions.

Properties and Measurements in Rock Engineering

• Homogeneous vs. Heterogeneous: Uniformity in composition versus variability.

• Isotropy vs. Anisotropy: Same mechanical properties in all directions versus variability.

• Rock Mass Texture: Describes the arrangement and properties of rock elements and their discontinuities.

• System Size: Area affected by technical approaches in the earth crust.

• Surface and Underground Rock Structures: Terms describing rock masses affected by human activity.

Application Areas of Rock Engineering

• Foundations

• Rock slopes

• Tunnels

• Large underground openings

• Mining operations

• Oil and gas production

• Geothermal energy projects

• Radioactive waste storage

• Construction approaches and their geological implications.