Professional Courses
Industry-relevant training in Business, Technology, and Design to help professionals and graduates upskill for real-world careers.
Categories
Interactive Games
Fun, engaging games to boost memory, math fluency, typing speed, and English skills—perfect for learners of all ages.
Typing
Memory
Math
English Adventures
Knowledge
Enroll to start learning
You’ve not yet enrolled in this course. Please enroll for free to listen to audio lessons, classroom podcasts and take practice test.
Interactive Audio Lesson
Listen to a student-teacher conversation explaining the topic in a relatable way.
Residual Soils
Unlock Audio Lesson
Today, we'll start with residual soils, which are formed in the same location where they originate. Who can tell me how these soils develop?
Are residual soils made only from local rocks?
Good question! Yes, residual soils primarily come from the local rocks through chemical weathering. What conditions do you think affect this process?
Maybe the weather conditions like temperature and moisture?
Exactly! Warm and humid regions increase the rate of chemical weathering. Can anyone remember what happens to the soil depth in these conditions?
It can vary from 5 to 20 meters, right?
Spot on! As we go deeper, the degree of weathering decreases. Let's summarize: residual soils are locally formed, influenced by climate, and can vary in depth.
Transported Soils
Unlock Audio Lesson
Now, let's shift to transported soils. Who remembers what transports these soils?
I think they are moved by agencies like rivers or wind?
Correct! They are moved by various forces. Can we classify these based on how they are transported?
Yes! For example, soils deposited by rivers are called alluvial deposits.
Great! And what about soils deposited by lakes or glaciers?
Lacustrine and glacial deposits!
Perfect! So remember: transported soils include alluvial, lacustrine, marine, glacial, and aeolian deposits based on transportation methods.
Three-phase System
Unlock Audio Lesson
Let's discuss the three-phase system of soil. What are the main components you think make up this model?
Solid particles, water, and air!
Exactly! These components can change in proportion. How would this affect the state of the soil?
It can be fully saturated, partially saturated, or dry!
Right! In a saturated soil, we don't consider the air phase. This model is important for understanding soil behavior in engineering. Why do you think that is?
Because it helps predict how soil will react under load or moisture!
Well said! Let's recap: the three-phase system comprises solids, water, and air, and it adjusts based on soil saturation.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
The section explains two main types of soils—residual and transported—and their formation, characteristics, and classification. It also details the three-phase system of soil, which comprises solid particles, water, and air, and describes the conditions of partial saturation, full saturation, and dryness.
Detailed
Three-phase System
Soils are classified into residual and transported categories based on their formation and location. Residual soils form at their original site, commonly in warm, humid areas where chemical weathering is high, leading to significant soil formation. In contrast, transported soils originate from weathered materials moved by natural forces such as water, wind, and glaciers, categorized by their transportation mode.
In understanding the composition of soils, a three-phase system is introduced, where soil is viewed as consisting of solid particles, water, and air, with possible variations in their proportions. The model aids in conceptualizing soil types under different saturation states: fully saturated, partially saturated, or completely dry. The importance of this three-phase model lies in its utility in geotechnical engineering and soil management.
Youtube Videos
Audio Book
Dive deep into the subject with an immersive audiobook experience.
Introduction to Soil Phases
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
Soils can be partially saturated (with both air and water present), or be fully saturated (no air content) or be perfectly dry (no water content).
Detailed Explanation
Soils exist in different moisture conditions which define their phases. When a soil is fully saturated, it means that all the pores in the soil are filled with water; hence, there is no air. In a partially saturated soil, there is a mixture of both air and water in the soil pores. A perfectly dry soil has no water at all, meaning it's completely filled with air. Understanding these phases is essential for various applications in agriculture, civil engineering, and environmental studies.
Examples & Analogies
Think of a sponge. When you immerse a sponge in water and then lift it out, it becomes fully saturated, just like a fully saturated soil. If you squeeze the sponge lightly, it retains some water but also lets air into the pores; this is similar to partially saturated soil. Finally, if you leave the sponge out to dry completely, it becomes perfectly dry, resembling dry soil.
Reduction of Phases in Soil
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
In a saturated soil or a dry soil, the three-phase system thus reduces to two phases only, as shown.
Detailed Explanation
The three-phase system of soil - consisting of solid particles, water, and air - simplifies under certain conditions. When soil is saturated, the air phase disappears, leaving only solids and water. Similarly, in dry soil, all water is removed and only solids and air remain. This reduction to two phases is useful for simplifying calculations and understanding characteristics such as soil strength and permeability.
Examples & Analogies
Consider preparing a recipe that calls for only two main ingredients: flour and water. If you add the water to the flour, it becomes a dough (saturated condition, with only solids and liquid). If you let the dough air dry, it will turn into a solid cake (dry condition, with only solids and air). In both cases, you've reduced the mixture to just two phases, making it easier to manage.
Importance of the Three-Phase System
Unlock Audio Book
Signup and Enroll to the course for listening the Audio Book
As the relative proportions of the three phases vary in any soil deposit, it is useful to consider a soil model which will represent these phases distinctly and properly quantify the amount of each phase.
Detailed Explanation
Soil engineers and scientists need to understand the proportions of solids, water, and air in soil because these ratios influence the soil's stability, fertility, drainage, and overall behavior. By using a soil model that quantifies these phases, it becomes easier to predict how a soil will perform under different conditions, which is crucial for construction projects, agriculture, and environmental management.
Examples & Analogies
Imagine a bowl where you mix three different colored beads representing solid particles, water, and air. Depending on how many beads of each color you add, you can predict how the mix will look or behave. If there's a lot of water (blue beads), the mixture is wet and tends to stick together, which is beneficial for certain plants. If you only have solid and air beads (red and yellow), the mix becomes dry and loose, which can be good for other types of plants. By learning to count and visualize these proportions, you can apply that knowledge to grow healthy plants or build stable structures.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
-
Residual Soils: Formed in place from local rocks.
-
Transported Soils: Moved by environmental forces and categorized by transport method.
-
Three-phase System: Conceptual model of soil consisting of solids, water, and air.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
Residual soils in tropical climates, like clay-rich soils, contrast with sandy residual soils in arid regions.
-
Alluvial soils from riverbanks are often rich in nutrients, making them ideal for agriculture.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
🎵 Rhymes Time
-
Soil activity, both thick and thin, Residual sits where it’s always been.
📖 Fascinating Stories
-
Imagine a tree by a river; its roots help develop residual soil around it, while the river carries soils elsewhere, creating transported layers.
🧠 Other Memory Gems
-
RAP: Rocks -> Air -> Particles (Solid, Air, Watery! - Three phases).
🎯 Super Acronyms
STARS
- Solid
- Water
- Air (three components of soil).
Flash Cards
Review key concepts with flashcards.
Glossary of Terms
Review the Definitions for terms.
-
Term: Residual Soils
Definition:
Soils that are formed from the weathering of rocks at their original site.
-
Term: Transported Soils
Definition:
Soils that have been moved from their original location by natural forces.
-
Term: Alluvial Deposits
Definition:
Soils deposited by rivers.
-
Term: Lacustrine Deposits
Definition:
Soils deposited in or near a lake.
-
Term: Glacial Deposits
Definition:
Soils that result from materials deposited by melting glaciers.
-
Term: Threephase System
Definition:
A model representing soil as consisting of solids, water, and air.