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    By: Engr. Imtiaz Ahmed

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    imtii06
    The document discusses key concepts in geotechnical engineering including soil properties, soil types, and physical properties of soil. It defines soil and geotechnical engineering, and describes the formation of soil over long periods of weathering and breakdown of rocks. It also lists common soil types including glacial, residual, alluvial and aeolian soils, and discusses physical properties such as color, structure, specific gravity, porosity, void ratio, moisture content and degree of saturation.

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    By: Engr. Imtiaz Ahmed

    Uploaded by

    imtii06
    35 views25 pages
    The document discusses key concepts in geotechnical engineering including soil properties, soil types, and physical properties of soil. It defines soil and geotechnical engineering, and describes the formation of soil over long periods of weathering and breakdown of rocks. It also lists common soil types including glacial, residual, alluvial and aeolian soils, and discusses physical properties such as color, structure, specific gravity, porosity, void ratio, moisture content and degree of saturation.

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    A lecture prepared for B.Tech (Civil)

    Original Title

    Lecture 01 Soil Mechanics

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    The document discusses key concepts in geotechnical engineering including soil properties, soil types, and physical properties of soil. It defines soil and geotechnical engineering, and describes the formation of soil over long periods of weathering and breakdown of rocks. It also lists common soil types including glacial, residual, alluvial and aeolian soils, and discusses physical properties such as color, structure, specific gravity, porosity, void ratio, moisture content and degree of saturation.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    35 views25 pages

    By: Engr. Imtiaz Ahmed

    Uploaded by

    imtii06
    The document discusses key concepts in geotechnical engineering including soil properties, soil types, and physical properties of soil. It defines soil and geotechnical engineering, and describes the formation of soil over long periods of weathering and breakdown of rocks. It also lists common soil types including glacial, residual, alluvial and aeolian soils, and discusses physical properties such as color, structure, specific gravity, porosity, void ratio, moisture content and degree of saturation.

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    By: Engr.

    Imtiaz Ahmed

    Introduction Soil Index Properties Identification and Classification of Soil Soil Compaction Permeability Soil Exploration Shear Strength Earth Pressure Stresses in Soil

    INTRODUCTION & SOIL CHARATERICTICS

    Soil is a natural body comprised of solids (minerals and organic matter), liquid, and gases that occurs on the land surface, occupies space, and is characterized by one or both of the following: horizons, or layers, that are distinguishable from the initial material as a result of additions, losses, transfers, and transformations of energy and matter or the ability to support rooted plants in a natural environment. Soil is formed over a long period of time. The formation of soil happens over a very long period of time. It can take 1000 years or more. Soil is formed from the weathering of rocks and minerals. The surface rocks break down into smaller pieces through a process of weathering and is then mixed with moss and organic matter.

    Branch of engineering science which enable an engineer to know theoretically or experimentally the behavior of soil under the action of loads (static or dynamic) and gravitational forces as well as under the influence of water and temperature.
    A famous scientist, Terzaghi defines it as

    It is the application of laws of hydraulics and mechanics to engineering problem dealing with sediments and other unconsolidated accumulations of solid particles produced by the mechanical and chemical disintegration of rocks

    A typical geotechnical engineering project begins with a site investigation of soil, rock, fault distribution and bedrock properties on and below an area of interest to determine their engineering properties including how they will interact with, on or in a proposed construction. Site investigations are needed to gain an understanding of the area in or on which the engineering will take place. Investigations can include the assessment of the risk to humans, property and the environment from natural hazards such as earthquakes, landslides, sinkholes, soil liquefaction, debris flows and rock falls.

    Perform soil surveys Develop soil sampling device and methods Develop soil testing device and methods Determine physical properties of soil Adoption of soil conservation techniques Adoption of most suitable methods to control sedimentation of dam reservoirs Select suitable sites for disposal of wastes

    Weathering is the process of the breaking down rocks. There are two different types of weathering. Physical weathering and chemical weathering. In physical weathering it breaks down the rocks, but what it's made of stays the same. In chemical weathering it still breaks down the rocks, but it may change what it's made of. For instance, a hard material may change to a soft material after chemical weathering.

    STAGE 1

    STAGE 2

    STAGE 3

    STAGE 4

    Following are the typical types of soil


    Glacial Residual Alluvial Aeolian (Wind Blown) 1. Dune or Dune Sand 2. Loess

    Glacial Soil:

    Developed, transported and deposited by the action of glaciers. Consists of rock fragment, boulder, gravel, sand, silt and clay

    Residual Soil:

    Found on nearly flat rock surfaces where weathering action produces a soil. Occurs when weathering is higher than removal

    Alluvial: Transported and deposited by water.

    Aeolian: Transported and subsequently deposited by wind

    Dune: Characterized by low hill and ridge formation 2. Loess: Wind blown dust (siliceous silt or silty-clay) laid down in a loose condition
    1.

    Dunes

    Loess

    Clay: very fine particles less than .002 mm in size. Flaky in shape, considerable surface area
    Silt: Between .002 and .06 mm in size. Has high capillarity, no plasticity and little dry strength Sand: Between .06 and 2 mm in size. Round to angular in shape. No plasticity, high permeability and low capillarity.

    Gravel: Between 2 to 60mm. Good foundation material. When mixed sand and silt, bearing capacity is increased.
    Cobblers or Boulders: larger than gravel. 60 to 200mm. Larger than 200mm are Boulders. Organic Matter: source is plants or animal remains. Top 12 of soil have organic matter.

    Physical Properties Of Soil

    Colour Structure Shape and Size Specific Gravity Phases Porosity Void Ratio Moisture Degree of Saturation

    Wide variety in nature Depends upon type of soil, mineral matter, organic contents and amount of coloring oxides Black due to Manganese Green or Blue= Ferrous Red, Brown or Yellow= Iron Grey= Organic Matter

    PARTICLE BONDING
    THE PARTICLE BONDING IS VERY WEAK SO RELATIVELY EASY TO GOING TO CHANGE AND HAVE NON-LINEAR BEHAVIOUR AND CHARACTERISTIC

    SHAPE, SIZE AND STRUCTURE OF SOIL PARTICLE

    S : Solid W: Liquid A: Air

    Soil particle Water (electrolytes) Air

    Void ratio e (given in decimal, 0.65) Volume of voids (Vv ) e Volume of solids (Vs )

    Porosity n (given in percent 100%, 65%) Vse e Volume of voids (Vv ) n n Vs (1 e) 1 e Total volume of soil sample (Vt )

    WATER CONTENT ; : The ratio of the amount of water (Ww) in the soil (Ws) and expressed as a percentage

    Ww 0% < < x100 % Ws


    DEGREE OF SATURATION ; S : The ratio of water volume air (Vw) to void volume (Vv) and expressed as a percentage

    Vw 0% S 100% x100 % Vv

    UNIT WEIGHT : The ratio of weight to volume

    Ww w Vw

    Ws s Vs

    W V

    SPECIFIC GRAVITY ; GS : The ratio of unit weight of soil to unit weight of water

    GS

    s w
    emax eo x100 % emax emin

    RELATIVE DENSITY ; Dr :

    Dr

    Standards

    ASTM D854-92 Standard Test Method for Specific Gravity of Soils ASTM C127-88 (Reapproved 1993) Test Methods for Specific Gravity and Absorption of Coarse Aggregate. BS 1377: Part 2:1990

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