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    5.0 Triaxial Test#

    Uploaded by

    Gayan Indunil Jayasundara
    This document describes the results of an undrained unconsolidated (UU) triaxial test on a soil sample. Key results include: 1) The undrained cohesion (Cu) of the soil was determined to be 74.5 kPa based on calculations of deviator stress and normal stress at failure. 2) The undrained angle of friction (Φu) was calculated to be 0 degrees since there is no resistance to shear under undrained unconsolidated conditions. 3) Other parameters such as bulk density, moisture content before and after testing are also presented in a table of results.

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    5.0 Triaxial Test#

    Uploaded by

    Gayan Indunil Jayasundara
    38 views7 pages
    This document describes the results of an undrained unconsolidated (UU) triaxial test on a soil sample. Key results include: 1) The undrained cohesion (Cu) of the soil was determined to be 74.5 kPa based on calculations of deviator stress and normal stress at failure. 2) The undrained angle of friction (Φu) was calculated to be 0 degrees since there is no resistance to shear under undrained unconsolidated conditions. 3) Other parameters such as bulk density, moisture content before and after testing are also presented in a table of results.

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    This document describes the results of an undrained unconsolidated (UU) triaxial test on a soil sample. Key results include: 1) The undrained cohesion (Cu) of the soil was determined to be 74.5 kPa based on calculations of deviator stress and normal stress at failure. 2) The undrained angle of friction (Φu) was calculated to be 0 degrees since there is no resistance to shear under undrained unconsolidated conditions. 3) Other parameters such as bulk density, moisture content before and after testing are also presented in a table of results.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    38 views7 pages

    5.0 Triaxial Test#

    Uploaded by

    Gayan Indunil Jayasundara
    This document describes the results of an undrained unconsolidated (UU) triaxial test on a soil sample. Key results include: 1) The undrained cohesion (Cu) of the soil was determined to be 74.5 kPa based on calculations of deviator stress and normal stress at failure. 2) The undrained angle of friction (Φu) was calculated to be 0 degrees since there is no resistance to shear under undrained unconsolidated conditions. 3) Other parameters such as bulk density, moisture content before and after testing are also presented in a table of results.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 7

    TRIAXIAL TEST

    INDUNIL J.M.G.
    PG/E/GT/2016/01
    CE642
    12.03.2016
    DATA
    P.R. Dial Constant = 0.6804 lb/div
    Axial deformation dial gauge factor = 0.01 mm
    SPECIMEN CALCULATION
    Considering 10th set of readings from Triaxial Test Observations table,
    Axial deformation dial gauge reading = 225div
    Axial deformation = 225 x 0.01 mm
    = 2.25mm

    P.R. Reading = 58 div


    Load applied, P = 58 x 0.6804 x 0.4536 x 9.81/ 1000
    = 0.176 kN

    Initial height of the sample, l = 10.17 cm


    = 101.7 mm
    Axial deformation, Δl = 2.25 mm

    Height of the sample at this stage = l – Δl


    = 101.7 – 2.25
    = 99.45 mm

    Volume of the sample, v = π (D2/4) h


    = 3.14 x (50.6)2/4 x 101.7
    = 204,405.1 mm3
    Cross sectional area at the stage, A = (v- Δ v)/ (l – Δl)
    Since undrained test was carried out, Δ v =0
    So, A = 204,405.1/ 99.45
    = 2,055.36 mm2

    Deviator stress on the sample = P/ A


    = (0.176x1000) / (2,055.36x10-6)
    = 85.4 kPa.

    Axial Strain, εa = Δl/ l


    = (2.25/ 101.7) x 100%
    = 2.21%
    TABULATION
    Table 01: Deviator stress vs Axial strain
    Axial
    Deviator
    Strain/
    stress/ kPa
    (%)
    0.0 0.00
    12.0 0.25
    22.5 0.49
    32.9 0.74
    43.3 0.98
    53.6 1.23
    62.3 1.47
    71.1 1.72
    78.3 1.97
    85.4 2.21
    91.1 2.46
    98.2 2.70
    102.3 2.95
    107.9 3.20
    113.5 3.44
    116.1 3.69
    120.1 3.93
    122.7 4.18
    126.7 4.42
    129.2 4.67
    130.3 4.92
    132.9 5.16
    135.4 5.41
    137.9 5.65
    138.9 5.90
    140.0 6.15
    142.4 6.39
    143.5 6.64
    144.5 6.88
    146.9 7.13
    146.5 7.37
    147.5 7.62
    147.1 7.87
    148.1 8.11
    149.1 8.36
    148.7 8.60
    148.3 8.85
    149.3 9.10
    148.9 9.34
    148.5 9.59
    148.1 9.83
    CALCULATION
    From Graph 01,
    Maximum deviator stress at the failure,σ1-σ3 = 149 kPa
    Cell pressure, σ3 = 100 kPa
    σ1-σ3 = 149
    σ1 = 149 + 100
    σ1 = 249 kPa

    Under unconsolidated undrained conditions, value of undrained friction angle, (∅cu ) becomes zero.
    Therefore, resistance to shear failure is totally taken by undrained cohesion,(Ccu ). So, the line of failure
    envelope is parallel to the axis of normal stress.

    Failure envelope

    Cu

    σ3 σ1

    Figure 01: Shear Stress vs Normal Stress

    Undrained cohesion from Figure 01, Cu = (σ1- σ3) / 2


    = (249-100) / 2
    = 74.5 kPa

    Undrained angle of friction, Φu = 00

    Volume of the sample = π (D2/4) h


    = π (50.62/4) x 101.7
    = 204,508.74mm3
    Total mass of the soil sample = 376.79g
    Bulk density of the sample = 376.79 x 10-3/ (204,508.74x10-9)
    ρ = 1842.42 kg/m3
    Moisture content calculation.
    a) Before test,
    Wt. of Container No14 = 16.87g
    Wt. of soil+Container = 46.21g
    Wt. of dry soil+container = 41.87g
    Moisture weight = 46.21-41.87
    = 4.34g
    Wt. of soil = 41.87-16.87
    = 25.00g
    Moisture content = 4.34/29.34 x100%
    = 17.4 %

    Wt. of Container No19 = 16.32g


    Wt. of soil+Container = 46.87g
    Wt. of dry soil+container = 41.94g
    Moisture weight = 46.87-41.94
    = 4.93g
    Wt. of soil = 41.94-16.32
    = 25.62g
    Moisture content = 4.93/25.62 x100%
    = 19.2 %

    Average moisture content = (17.4+19.2)/2


    = 18.3 %

    b) After test,
    Wt. of wet sample + container = 453.19g
    Wt. of dry sample + container = 394.87g
    Weight of container = 72.05g
    Wt. of water = 453.19- 394.87
    = 58.32g
    Weight of soil = 394.87-72.05
    = 322.82g
    Moisture content = 58.32/322.82x100%
    = 18.1 %
    RESULTS
    Table 02: Results from UU triaxial test
    Parameter Unit Value
    Cu (Undrained cohesion) kPa 74.5
    Φu (Undrained angle of friction Deg 0
    Bulk density kg/m3 1842.42
    Moisture content
    Before test % 18.3
    After test % 18.1

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