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Expansive Soils

GEOL 4093

Risk Asssessment

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Expansive Soils

Also called shrink-swell soils

Expand greatly when saturated with water

Expansion largely due to chemical

attraction of water molecules between

layers of clay minerals called smectites.

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Hydrocompaction

Expansive clays can also dry out and

decrease in volume

Hydrocompaction is the process of

shrinkage and/or collapse from water loss

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Expansion of a single smectite grain as a result of the addition

of water between clay layers. From Murck et al., 1997,Dangerous Earth.

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The type of structural damage that

can result from soil expansion

beneath a building. From Murck

et al., 1997,Dangerous Earth.

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Other Types of Soils

In addition to expansive clays, other soils

can decrease in volume (compact)

Water-saturated organic peat

Sensitive soils

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Engineering Geology

Check out Richard Meehans web site

www.dnai.com/~meehan/rlmce/expan/mast

er.html

He is an engineering geologist with a great

deal of information on the problem of

expansive soils and how to deal with it

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Typical problems and one

solution when dealing with

compaction. Seewww.dnai.com/~meehan/rlmce

/expan/master.html.

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Dealing with slope problems. See

www.dnai.com/~meehan/rlmce/expan/master.html.

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Typical setting for future problems, and dealing with it by having

deep pilings. Seewww.dnai.com/~meehan/rlmce/expan/master.html.

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Simple load removal can

cause expansion problems.

This might occur during

mining, for example. Seewww.dnai.com/~meehan/rlmc

e/expan/master.html.

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National Resource Conservation Service (part of USDA) Map,

Phoenix area.

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National Resource ConservationService (part of USDA) Map,

Tuscon area.

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Perhaps the worlds

most famous example

of problems with

compacting soils.