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    Direct Shear Test

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    Denver James Rabara
    The document discusses shear strength of soils and the direct shear test method. It provides details on how a direct shear test is conducted using a shear box apparatus. It then presents sample direct shear test data and questions to calculate soil properties like cohesion and internal friction angle. Specifically: 1. A direct shear test was performed on a clayey soil and test results including normal force, shear force at failure are given. Determine cohesion and internal friction angle from this data. 2. Properties of a dense sand layer are given. Determine shear strength along a horizontal plane at mid-depth under original and flooded conditions. 3. For a direct shear test of dry sand, determine internal friction angle given normal force and

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    Direct Shear Test

    Uploaded by

    Denver James Rabara
    10 views6 pages
    The document discusses shear strength of soils and the direct shear test method. It provides details on how a direct shear test is conducted using a shear box apparatus. It then presents sample direct shear test data and questions to calculate soil properties like cohesion and internal friction angle. Specifically: 1. A direct shear test was performed on a clayey soil and test results including normal force, shear force at failure are given. Determine cohesion and internal friction angle from this data. 2. Properties of a dense sand layer are given. Determine shear strength along a horizontal plane at mid-depth under original and flooded conditions. 3. For a direct shear test of dry sand, determine internal friction angle given normal force and

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    Foundation lecture and examples

    Original Title

    Direct-shear-test

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    The document discusses shear strength of soils and the direct shear test method. It provides details on how a direct shear test is conducted using a shear box apparatus. It then presents sample direct shear test data and questions to calculate soil properties like cohesion and internal friction angle. Specifically: 1. A direct shear test was performed on a clayey soil and test results including normal force, shear force at failure are given. Determine cohesion and internal friction angle from this data. 2. Properties of a dense sand layer are given. Determine shear strength along a horizontal plane at mid-depth under original and flooded conditions. 3. For a direct shear test of dry sand, determine internal friction angle given normal force and

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    10 views6 pages

    Direct Shear Test

    Uploaded by

    Denver James Rabara
    The document discusses shear strength of soils and the direct shear test method. It provides details on how a direct shear test is conducted using a shear box apparatus. It then presents sample direct shear test data and questions to calculate soil properties like cohesion and internal friction angle. Specifically: 1. A direct shear test was performed on a clayey soil and test results including normal force, shear force at failure are given. Determine cohesion and internal friction angle from this data. 2. Properties of a dense sand layer are given. Determine shear strength along a horizontal plane at mid-depth under original and flooded conditions. 3. For a direct shear test of dry sand, determine internal friction angle given normal force and

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 6

    Shear strength of Soil

    - Internal pressure per unit area that the soil mass can
    offer to resist failure and sliding along any plane inside it.
    (Braja M Das.)

    Mohr-Coulomb Failure Criterion


    DIRECT SHEAR TEST
    The direct shear test is the oldest and simplest form of shear test
    arrangement. A diagram of the direct shear test apparatus as shown. The
    test equipment consists of a metal shear box in which the soil specimen is
    placed. The box is split horizontally into halves. Normal force on the
    specimen is applied from the top of the shear box. Shear force us applied
    by moving one half of the box relative to the other to cause failure in the soil
    specimen.
    Considering upper half of free body diagram.

    Mohr’s failure envelope and Mohr=Colulomb failure criteria (with cohesion)


    1. Direct shear tests were performed on a clayey soil. The size of
    the specimen was 50mm x 50mm x 20mm. Test results are as
    follows. Determine the cohesion and angle of internal friction for
    the soil sample.
    Trial Normal Force (N) Shear Force at Failure (N)

    1 120 114

    2 220 179

    3 320 239

    4 420 286
    2. The subsoil at the site consists of a 10m thick homogeneous
    layer of dense sand having the following properties: Yd = 16
    kN/m^3, Gs = 2.68, ∅ = 35°. The natural ground water table lies at
    2m below the ground surface.
    a. Determine the shear strength of the soil along a horizontal
    plane through the middle of sand layer.
    b. If during monsoon, the water table rises to the ground level,
    determine the shear strength of the soil along a horizontal plane
    through the middle of sand layer.
    c. Determine the change in shear strength at 10m depth.
    3. A direct shear test is performed on a specimen of dry sand. The
    shear box is circular in cross-section with a diameter of 50mm.
    The normal force imposed on the specimen is 250N. The soil
    shears when the shear force is 150N. Determine the angle of
    internal friction of this sand.

    4. A 7-m thick soil has water table 3m below the ground surface.
    The soil above the water table has degree of saturation of 45%,
    void ratio of the soil is 0.4 and solids have specific gravity of 2.7.
    Tests show that she soil have angle of internal friction of 32 deg.
    and cohesion of 14.6 kPa. What is the potential shear strength on
    a horizontal plane at a depth of 2m below the ground surface?

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