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Geology · 400 Level
This is the complete lecture note for GEY 410 Engineering Geology, prepared for Geology students at 400 Level. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS GEY 410: Engineering Geology (2 Units C: LH 30) Course Code: GEY 410 Course Title: Engineering Geology Course Unit: 2 Units C Series 1: Principles And Applications Of Soil Mechanics Series 2: Geotechnical Techniques And Terrain Classification Series 3: Site Investigations And Sampling Methods Series 4: Engineering Geological Applications In Structures And Infrastructure Series 5: Erosion, Material Quality Control, And Geological Reporting Series 1 Principles And Applications Of Soil Mechanics • Part 1.1 Fundamentals of soil mechanics • 1.1.1 Definition and scope of soil mechanics • 1.1.2 Soil composition and classification • 1.1.3 Basic soil properties • Part 1.2 Principles of soil behaviour • 1.2.1 Stress and strain in soils • 1.2.2 Permeability and seepage • 1.2.3 Consolidation and settlement • Part 1.3 Applications of soil mechanics in engineering geology • 1.3.1 Foundations and slope stability • 1.3.2 Highways and embankments • 1.3.3 Dams and water retaining structures Introduction Soil mechanics is a cornerstone of engineering geology, as it explains how soils behave under different conditions and how this behaviour influences the design and safety of structures.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Engineers and geologists rely on soil mechanics to predict settlement, stability, and water movement, all of which are critical in construction projects. The aim of this Series is to equip you with the knowledge of soil mechanics principles and to show you how these principles are applied in engineering geology. By the end of the Series, you will be able to define soil mechanics, analyse soil behaviour, and apply these concepts to practical engineering problems. We shall commence this Series by exploring the fundamentals of soil mechanics, including its definition, scope, and basic properties. Next, we will examine the principles of soil behaviour, focusing on stress, permeability, and consolidation. Finally, we will conclude with applications of soil mechanics, considering how these principles are used in foundations, slopes, highways, and dams. Series Learning Outcomes Upon completing this Series, you should be able to: • SLO 1.1 define soil mechanics and explain its scope in engineering geology, • SLO 1.2 classify soils based on composition and properties, • SLO 1.3 describe basic soil properties relevant to engineering geology, • SLO 1.4 analyse stress and strain behaviour in soils, • SLO 1.5 explain permeability and seepage processes in soils, • SLO 1.6 evaluate consolidation and settlement in soil structures, • SLO 1.7 apply soil mechanics principles to foundations and slope stability, • SLO 1.8 demonstrate the application of soil mechanics in highways and embankments, and • SLO 1.9 assess the role of soil mechanics in dams and water retaining structures. 1.1 Fundamentals Of Soil Mechanics 1.1.1 Definition and scope of soil mechanics Soil mechanics is the branch of engineering geology that studies the properties and behaviour of soils under different conditions. It provides the scientific basis for understanding how soils respond to loads, water movement, and environmental changes. The scope of soil mechanics includes classification of soils, analysis of their strength, compressibility, and permeability, and application of these properties in engineering design. Soil mechanics is essential because it helps engineers predict settlement, design stable foundations, and prevent structural failures. Short description: Diagram showing soil layers with applied loads and water movement.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Caption: Figure 1.1 Scope of soil mechanics in engineering geology Fill in the blank: The branch of engineering geology that studies soil properties and behaviour is called soil ______. 1.1.2 Soil composition and classification Soil composition refers to the mixture of minerals, organic matter, water, and air that make up soil. The proportions of these components determine soil behaviour. Soil classification is the process of grouping soils based on their physical and chemical properties, such as grain size, texture, and plasticity. Common classification systems include the Unified Soil Classification System (USCS) and the AASHTO system, which categorise soils into groups like sands, silts, clays, and gravels. Classification is important because it guides engineers in selecting appropriate construction methods and predicting soil performance. Table 1.2 Soil classification systems and categories
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Soil Category USCS (Unified Soil Classification System) AASHTO (Highway System) Key Functional Difference Gravels Particles $> 4.75$ mm (No. 4 sieve). Symbols: GW, GP. Particles $> 2.0$ mm (No. 10 sieve). Groups: A-1, A-3. AASHTO has a narrower definition of gravel, often grouping fine gravel with sand. Sands Particles between $0.075$ mm and $4.75$ mm. Symbols: SW, SP, SM, SC. Particles between $0.075$ mm and $2.0$ mm. Groups: A-1, A-2, A-3. USCS distinguishes more strictly between "well-graded" and "poorly-graded" sands. Silts Fines passing No. 200 sieve ($< 0.075$ mm) with low plasticity. Symbol: ML. Fines passing No. 200 sieve. Groups: A-4, A-5. AASHTO uses the Group Index (GI) to further evaluate the quality of silty subgrades. Clays Fines passing No. 200 sieve ($< 0.075$ mm) with high plasticity. Symbol: CL, CH. Fines passing No. 200 sieve. Groups: A-6, A-7. USCS uses the Plasticity Chart (A-line) to separate silts from clays; AASHTO uses Liquid Limit/Plasticity Index. Fill in the blank: The process of grouping soils based on their properties is called soil ______. 1.1.3 Basic soil properties Soil properties are the measurable characteristics that determine how soil behaves under different conditions. Key properties include permeability (the ability of soil to transmit water), plasticity (the capacity of soil to be moulded without cracking), and shear strength (the resistance of soil to sliding along internal surfaces). These properties are critical in engineering geology because they influence settlement, slope stability, and the design of foundations. Engineers must evaluate soil properties before construction to ensure safety and durability. Box 1.3 Key soil properties in engineering geology
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Property Definition Engineering Significance Permeability ($k$) The capacity of a soil or rock to allow fluids (water, oil, or gas) to pass through its interconnected pores. Determines the rate of drainage under a foundation or the flow rate of hydrocarbons in a reservoir. Plasticity The ability of a soil (typically clay) to undergo unrecoverable deformation at constant volume without cracking or crumbling. Indicated by Atterberg Limits; helps predict if a soil will swell, shrink, or settle excessively. Shear Strength ($\tau$) The internal resistance of a soil per unit area to failure or sliding along any plane within it. The most critical property for calculating the bearing capacity of soils and the stability of slopes/embankments. Compressibility The measure of the relative volume change of a soil in response to a pressure (stress) change. Used to calculate the "settlement" of a building over time as water is squeezed out of the soil pores. Fill in the blank: The resistance of soil to sliding along internal surfaces is called shear ______. Pilot questions 1.1 1. What is soil mechanics? 2. Name one aspect of the scope of soil mechanics. 3. What are the main components of soil composition? 4. Mention one soil classification system. 5. Define shear strength. 1.2 Principles Of Soil Behaviour 1.2.1 Stress and strain in soils Stress is the internal force per unit area within soil caused by external loads, while strain is the resulting deformation or change in shape. Together, stress and strain describe how soils respond
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS to applied forces. In engineering geology, understanding stress and strain is crucial for predicting settlement and ensuring stability of structures. Stress can be vertical, horizontal, or shear, and soils may deform elastically or plastically depending on their properties. Short description: Diagram showing soil under vertical load with stress and strain response. Caption: Figure 1.4 Stress and strain in soils Fill in the blank: The internal force per unit area within soil is called ______. 1.2.2 Permeability and seepage Permeability is the ability of soil to transmit water through its pores. Seepage refers to the actual movement of water through soil. These processes are important in engineering geology because they affect the stability of slopes, foundations, and earth dams. Permeability depends on soil type: sands and gravels are highly permeable, while clays are less permeable. Engineers must evaluate permeability to design drainage systems and prevent water-related failures. Short description: Diagram showing water seepage through sandy soil compared to clay soil.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Caption: Figure 1.5 Permeability and seepage in soils Fill in the blank: The ability of soil to transmit water through its pores is called ______. 1.2.3 Consolidation and settlement Consolidation is the gradual reduction in soil volume due to expulsion of water from its pores under sustained load. Settlement is the downward movement of a structure as the soil beneath compresses. Both processes are critical in foundation design, as excessive settlement can damage buildings and infrastructure. Engineers use consolidation tests to predict
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