How do residual soil and colluvium differ?

Residual soil remains where its parent rock weathered; colluvium is transported mainly by gravity.

What do $D_{10}$ and $D_{50}$ represent?

$D_{10}$ is the size for which 10% of particle mass is finer; $D_{50}$ is the size for which 50% is finer.

How are porosity and void ratio defined?

Porosity is void volume divided by total volume, $n=V_v/V_t$. Void ratio is void volume divided by solid volume, $e=V_v/V_s$.

What is degree of saturation?

The fraction of a soil's void volume occupied by water: $S=V_w/V_v$.

Civil engineeringLesson 2 of 5 in the course Geotechnical engineering

Soil Mechanics: Formation, Classification, Stress, and Strength

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Soil mechanics explains how soil behaves under forces and how water moves through it. Unlike a uniform solid or fluid, soil is a mixture of mineral and organic particles, water, and air. This lesson introduces how soils form, how they are transported, and how their basic components and proportions are described.

Most soil forms as rock breaks down through weathering. Physical weathering includes freeze-thaw action, temperature changes, wind, rain, impacts, and grinding by soil organisms. Chemical weathering dissolves or transforms minerals; for example, feldspar can weather into clay minerals. Biological weathering includes organic acids released by roots and fungi and compounds produced by bacteria. Human activities such as excavation and blasting can also create or redistribute soil.

All flashcards

What does soil mechanics study?: How soil behaves under forces and how water moves through it.
How do residual soil and colluvium differ?: Residual soil remains where its parent rock weathered; colluvium is transported mainly by gravity.
What do $D_{10}$ and $D_{50}$ represent?: $D_{10}$ is the size for which 10% of particle mass is finer; $D_{50}$ is the size for which 50% is finer.
How are porosity and void ratio defined?: Porosity is void volume divided by total volume, $n=V_v/V_t$ . Void ratio is void volume divided by solid volume, $e=V_v/V_s$ .
What is degree of saturation?: The fraction of a soil's void volume occupied by water: $S=V_w/V_v$ .

Quiz questions

Which three broad types of weathering contribute to soil formation?Answer: Physical, chemical, and biological weathering.
Why is quartz common in sand and silt?Answer: It resists weathering more effectively than many other minerals.
A soil has a broad, smoothly distributed range of particle sizes. How is it described?Answer: Well graded.
A soil sample has void volume $V_v=0.6$ and solid volume $V_s=1.0$ , in consistent units. What is its void ratio?Answer: $e=V_v/V_s=0.6$ .
What does an overconsolidation ratio greater than 1 indicate?Answer: The soil's maximum past effective stress exceeds its current effective stress.

Based on the Wikipedia article Soil mechanics, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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