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    Workshop 2 - Shoring Questions (Solutions)

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    Workshop 2 - Shoring Questions (Solutions)

    Uploaded by

    guanglichen0
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    8 views6 pages

    Workshop 2 - Shoring Questions (Solutions)

    Uploaded by

    guanglichen0

    Copyright:

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

    CVEN4102 OPERATIONS AND PROJECTS

    Term 1, 2024

    WEEK 2: Workshop on Shoring Design

    Question 1

    What is the type of shoring system used in the project below? Discuss about
    potential risks on the site that may cause the failure of the shoring system.

    Ref. Answers:
    Shoring system: Sheet Piling

    Potential risks:
    • Water infiltration
    • Damage from machinery
    • Overloading
    • External factors
    • Vibrations from heavy equipment
    • Corrosion
    • Design and installation errors

    1
    Question 2

    Describe the type of retaining structure used in the project below. Explain the
    construction sequence for building such a structure.

    Ref. Answers:
    Retaining system: Reinforced earth.
    Construction procedures
    1. Excavate to the bottom level of ground
    2. Install bottom facing element and reinforcing elements
    3. Back fill soil and compact the soil of bottom layer
    4. Repeat steps 2-4 until reaching the desired height.

    2
    Question 3

    Calculate the embankment depth D given the Factor of Safety being 1.5 for the
    trenching project. (2.5 m)

    Kp=3.3

    Solutions

    Based on the soil mechanics theories, we know that for each kind of soil:
    Ka * Kp = 1

    For this kind of soil:


    Ka = 0.33 and Kp = 3.3 So: 0.33 * 3.3 = 1

    As the Factor of Safety (FS) is 1.5, the horizontal active and passive forces
    implemented on retaining wall should be meet the requirement:

    FS = Fp / Fa

    Also,
    σ h = Ka * σ v , σ v = γ * h

    Fa = ½*Ka*γ*ha2 = ½ * .33 * 20 * (4+D)2

    Fp = ½*Kp*γ*hp2 = ½ * 3.3 * 20 * D2

    So:
    1.5 Fa = Fp

    1.5 * ½ * 0.33 * 20 * (4+D)2 = ½ * 3.3 * 20 * D2

    1.5 * 0.33 (4+D)2 = 3.3 D2

    3
    (4/D + 1)2 = 6.67

    4/D + 1 = 2.583

    D = 2.527 m

    (note: rounding could affect the final answer, e.g. 2.532m is also possible)

    4
    Question 4

    For a shoring system subjected to the lateral load given below, calculate total driving
    horizontal force. (387.187 KN/m)

    Coarse Sand and Gravel


    1.2 m
    Ka1 = 0.249

    Fine Sand
    1.8 m
    Ka2 = 0.333

    6.2 m

    Solutions

    As can be seen, there are water and different soils implementing active force on the
    retaining wall. We have the following information for all layers.

    Layer 1:
    γ1= 20.4 KN/m3, Ka1= 0.249, h1= 1.2 m

    Layer 2:
    γ2= 16.1 KN/m3, Ka2= 0.333, h2= 1.8 m

    Layer 3:
    γsat= 19.4 KN/m3, γ’= 9.6 KN/m3, γwater= 9.8 KN/m3, Ka3= 0.333, h3= 6.2 m

    5
    In the first step, it is needed that we calculate the horizontal stresses in the border of
    layers.
    α1= σ1- = Ka1 * γ1 * h1 = 0.249 * 20.4 * 1.2 = 6.096 KN/m2
    α2= σ1+ = Ka2 * γ1 * h1 = 0.333 * 20.4 * 1.2 = 8.152 KN/m2
    α3=α2 + Ka2 * γ2 * h2 = 8.152 + 0.333 * 16.1 * 1.8 = 17.802 KN/m2
    α4 = α3 + Ka3 * γ’ * h3 = 17.802 + 0.333 * 9.6 * 6.2 = 37.622 KN/m2
    α5= γwater * h3 = 9.8 * 6.2 = 60.76 KN/m2

    In the next step, we calculate forces implemented on the 1 meter of width of the
    retaining wall.
    F1= ½ * α1 * h1= ½ * 6.096 * 1.2 = 3.658 KN/m
    F2 = α2 * h2 = 8.152 * 1.8 = 14.674 KN/m
    F3 = ½ * (α3-α2) * h2 = ½ * (17.802 - 8.152) * 1.8 = 8.685 KN/m
    F4 = α3 * h3 = 17.802 * 6.8 = 110.372 KN/m
    F5 = ½ * (α4-α3) * h3 = ½ * (37.622-17.805) * 6.2 = 61.442 KN/m
    F6 = ½ * α5 * h3 = ½ * 60.76 * 6.2 = 188.356 KN/m

    In the last step, the total driving force is calculated by summing all of the active
    forces calculated above.

    Total driving force = 3.658 + 14.674 + 8.685 + 110.372 + 61.442 + 188.356

    Total driving force = 387.187 KN/m

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