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1、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:/ Rock: a natural aggregate of mineral grains connected by strong and permanent cohesive fo
2、rces. 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. Nevertheless, there is no sharp distinction between rock and soil. 1 Sunday, June 2, 2019,Identification of Soils and Rocks,II. * Clas
3、sification of rocks According to their mode of origin, rock materials are commonly classified into three groups: igneous, sedimentary, and metamorphic rocks. Types of rocks Igneous rock: primary rocks formed by the cooling of molten magmas, or by the recrystallization of older rocks under heat and p
4、ressure great enough to render them fluid 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) Features * Classified on the basis of texture and color * Hard, coarsely crystalline to glassy textures * Principle mineral constituents: quartz(石英）, felds
5、par（长石）, hornblende（角闪石）, biotite（黑云母）, augite（斜辉石）, and olivine（橄榄石） 2 Sunday, June 2, 2019,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
6、disintegration of igneous, sedimentary, or metamorphic rocks Types of sedimentary rocks * sandstone （砂岩） * limestone （石灰岩） * shale （页岩） * conglomerate （砾岩/碎屑岩） * gypsum（石膏） Features * Main elements: quartz, calcite（方解石）, clay minerals * Eminent structural features: their bedding or stratification 3
7、Sunday, June 2, 2019,Identification of Soils and Rocks,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） align
8、ment 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 hydrotherma
9、l 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） 4 Sunday, June 2, 2019,Identification of Soils and Rocks,II. Classification of rocks * The st
10、ructure 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 The most important properties utilized in identification of rocks are texture, structure, and mineralogical com
11、position. III. Definitions of Soils To a Pedologist: Soil is the substance existing on the earths surface, which grows and develops plant life. 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 ROC
12、K irrespective of its hardness. *To a Civil Engineer: Soil is the unaggregated or un-cemented deposits of mineral and/or organic particles or fragments covering large portion of the earths crust. 5 Sunday, June 2, 2019,Identification of Soils and Rocks,III. Definitions of Soils *Soil Mechanics: the
13、study of soil, its behavior and application as an engineering material. IV. Principle Types of Soil (according to particle size) Coarse grained soils (MIT) Gravel 2mm Sand 2mm0.06 mm Coarse sand 2mm0.6mm Medium sand 0.60.2 mm Fine sand 0.20.06mm Fine grained soils Silt: inorganic, rock flour, plasti
14、c silt Clay 6 Sunday, June 2, 2019,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) Soils are esp
15、. notable for their variability. Gravels and coarse sands respond to loads in essentially the same way. According to the way soils respond to load, soils fall into: Cohesionless soils: gravels, sands, cohesionless silts; Cohesive soils: clays, cohesive silts. USCS, based on both grainsize and plasti
16、city (Details to be developed) 7 Sunday, June 2, 2019,Identification of Soils and Rocks,V. Factors determining the engineering properties of a soil The mechanism of geologic transport, deposition, burial, and exposure Ground water Residue of vegetation Exercises: What are the similarities and differ
17、ences between soil and rock in the engineering sense? List the basic sub-types of the three types of rocks according to their mode of origin. Quiz on rocks 8 Sunday, June 2, 2019,Identification of Soils and Rocks,Meta-: Change; transformation: metachromatism 异染性; metagenesis 世代交替; metamorphosis 变形;
18、metabolic 新陈代谢的; metaprotein 变性蛋白质; metabasis 病状转变 Beyond; transcending; more comprehensive: metalinguistics 超语言学; metabiology超生物学； At a higher state of development: metazoan 多细胞动物的 Morph-: form, shape; structure: morphogenesis 形态发生morphology形态学、形态论, Morpheme: 词素 morphophonemics 词素音位学morphology 语法词法、词态学 Back 9 Sunday, June 2, 2019,schist,