CVEN3203 Applied Geotechnics and Engineering Geology

Flashcards derived from the lecture notes for CVEN3203, covering key concepts in Applied Geotechnics and Engineering Geology.

What are soils formed from?

Soils are formed from the weathering/alteration and transportation of rocks.

What are the two distinct types of weathering?

Mechanical and chemical.

What is residual soil?

A soil that is formed when a rock weathers to soil and is not eroded.

What processes are included in mechanical weathering?

Destressing, gravitational creep, tree root growth, clay/ice expansion, and temperature changes.

What is chemical decomposition?

Chemical processes that cause mineral changes, weakening rock substances so they assume soil properties.

What causes chemical weathering primarily?

Circulating groundwater gaining access to low-porosity rock through defects or intact rock fabric.

What is an example of a structure formed by induced tensile failure?

Sheet joints in rocks like granite.

How do high stress concentrations affect rock failure?

They can lead to the formation of sheet joints when stress is concentrated around valley edges.

What is the typical characteristic of sheet joints?

Sheet joints are typically long, curved, and rough.

What factors contribute to the development of weathering profiles?

Climate, vegetation, rock types, defect types, erosion, time, topography, and groundwater.

What type of soils are alluvial soils?

Soils deposited in channels, flood plains, lakes, estuaries, and deltas.

What characterizes alluvial soils?

Great variability both vertically and laterally, ranging from clays to gravels.

What is slopewash?

Mixtures of clay, sand, and gravel moved downslope by soil creep and water erosion.

What is the difference between colluvial and alluvial soils?

Colluvial soils are deposited under gravity forces; alluvial soils are deposited by water.

What affects the mechanical properties of alluvial soils?

The variability of geological materials and engineering properties due to deposition conditions.

How do glaciated environments affect soil deposition?

They reshape landscapes and deposit eroded materials when glaciers melt.

What are the effects of wind on Aeolian soils?

Wind can erode landscapes, transport sand, and create dunes.

What characterizes lateritic soils?

They show high weathering with concentrated oxides of iron and aluminum.

What is the significance of cross bedding in sedimentary rocks?

It forms due to unidirectional flow of sand and reflects the flow velocity changes.

What conditions contribute to rapid weathering?

Processes that lead to rocks weathering in days to months due to factors like saturation, temperature changes, and mechanical forces.

What are the four main types of sand dune?

Transverse dunes, barchan dunes, longitudinal (seif) dunes, and stellate dunes.