Download Identification of Soils and Rocks

Identification of Soils and Rocks
I. Contents to be covered
* Definitions of rocks and soils
* Classification of rocks
* Features of each rock
* Types of soils (MIT)
* Properties of soils
II. Definitions http://galleries.com/rocks/default.htm
1.
Rock: a natural aggregate of mineral grains connected by
strong and permanent cohesive forces.
2.
Soil: a natural aggregate of mineral grains, with or without
organic constituents, that can be separated by gentle
mechanical means such as agitation in water.
3.
Nevertheless, there is no sharp distinction between rock and
soil.
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Identification of Soils and Rocks
II. * Classification of rocks
1.
According to their mode of origin, rock materials are commonly
classified into three groups: igneous, sedimentary, and
metamorphic rocks.
2.
Types of rocks
1)
Igneous rock: primary rocks formed by the cooling of molten
magmas, or by the recrystallization of older rocks under heat and
pressure great enough to render them fluid
(1)
Types of igneous rock
* Granite (花岗岩）basalt (玄武岩）
* Scoria (熔渣岩）
* Pumice （浮/泡沫岩）
* Obsidian （黑曜石/十胜石)
(2)
Features
* Classified on the basis of texture and color
* Hard, coarsely crystalline to glassy textures
* Principle mineral constituents: quartz(石英）, feldspar（长石）,
hornblende（角闪石）, biotite（黑云母）, augite（斜辉石）, and
olivine（橄榄石）
Identification of Soils and Rocks
II. Classification of rocks
2) Sedimentary rocks: the products of deposition of plant
and animal remains, and of materials formed by the
chemical decomposition and physical disintegration of
igneous, sedimentary, or metamorphic rocks
(1) Types of sedimentary rocks
* sandstone （砂岩）
* limestone （石灰岩）
* shale （页岩）
* conglomerate （砾岩/碎屑岩）
* gypsum（石膏）
(2) Features
* Main elements: quartz, calcite（方解石）, clay
minerals
* Eminent structural features: their bedding or
stratification
Identification of Soils and Rocks
3)
(1)
(2)
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Metamorphic rocks: those produced by internal processes
acting on pre-existing rocks of any kind, with the limitation that
the rocks concerned remained essentially solid during their
transformations
Types of metamorphic rocks
* schist （页岩） alignment of the flat or elongated grains of
mica, hornblende, and other minerals into thin layers, or
foliation (at least 50 percent of the mineral grains in schist are
aligned this way, less than 50 percent makes it gneiss)
* gneiss （片麻岩）
Features
*Agent of metamorphism: heat, pressure, and hydrothermal
solutions
* Eminent features: foliated structure with the nearly parallel
arrangement of platy or needle-like minerals
* Typical minerals: chlorite（绿泥石）, sericite（绢云母）,
talc（云母）, hornblende, biotite （黑云母）
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Identification of Soils and Rocks
II. Classification of rocks
* The structure as gneissic（片麻岩的） (coarse), schistose
（片岩的） (medium), or slaty （板石的）(microscopic/fine)
* Distinguished from the parent sediment by their greater
density, hardness, and crystallinity
2.
The most important properties utilized in identification of
rocks are texture, structure, and mineralogical composition.
III. Definitions of Soils
1.
To a Pedologist: Soil is the substance existing on the earth's
surface, which grows and develops plant life.
2.
To a Geologist: Soil is the material in the relative thin
surface zone within which roots occur, and all the rest of the
crust is grouped under the term ROCK irrespective of its
hardness.
3.
*To a Civil Engineer: Soil is the unaggregated or uncemented deposits of mineral and/or organic particles or
fragments covering large portion of the earth's crust.
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Identification of Soils and Rocks
III. Definitions of Soils
4.
*Soil Mechanics: the study of soil, its behavior and
application as an engineering material.
IV. Principle Types of Soil (according to particle size)
1.
Coarse grained soils (MIT)
1)
Gravel > 2mm
2)
Sand 2mm—0.06 mm
(1) Coarse sand 2mm—0.6mm
(2) Medium sand 0.6—0.2 mm
(3) Fine sand 0.2—0.06mm
2.
Fine grained soils
1)
Silt: inorganic, rock flour, plastic silt
2)
Clay
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Identification of Soils and Rocks
III. Principle Types of Soil
3) Methods to distinguish silt from clay:
not grainsize but dry strength, shaking test,
plasticity, Atterberg limits, and dispersion test.
IV. Properties of Soils (Details to be developed)
1.
Soils are esp. notable for their variability.
2.
Gravels and coarse sands respond to loads in
essentially the same way.
3.
According to the way soils respond to load, soils fall
into:
1) Cohesionless soils: gravels, sands, cohesionless silts;
2) Cohesive soils: clays, cohesive silts.
4.
USCS, based on both grainsize and plasticity
(Details to be developed)
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Identification of Soils and Rocks
V. Factors determining the engineering properties of a
soil
1. The mechanism of geologic transport, deposition,
burial, and exposure
2. Ground water
3. Residue of vegetation
Exercises:
1. What are the similarities and differences between
soil and rock in the engineering sense?
2. List the basic sub-types of the three types of rocks
according to their mode of origin.
3. Quiz on rocks
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Identification of Soils and Rocks
Meta-:
1) Change; transformation: metachromatism 异染性;
metagenesis 世代交替; metamorphosis 变形;
metabolic 新陈代谢的; metaprotein 变性蛋白质;
metabasis 病状转变
2) Beyond; transcending; more comprehensive:
metalinguistics 超语言学; metabiology超生物学；
3) At a higher state of development: metazoan 多细
胞动物的
Morph-:
1) form, shape; structure: morphogenesis 形态发生
morphology形态学、形态论,
2) Morpheme: 词素 morphophonemics 词素音位学
morphology [语法]词法、词态学
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schist