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A 5 m high vertical wall has a saturated clay backfill. The saturation unit weight and cohesion of clay are 18 kN/m3 and 20 kPa, respectively. The angle of internal friction of clay is zero. In order to prevent development of tension zone, the height of the wall is required to be increased. Dry sand is used as backfill above the clay for the increased portion of the wall. The unit weight and angle of internal friction of sand are 16 kN/m3 and 30°, respectively. Assume that the back of the wall is smooth and top of the backfill is horizontal. To prevent the development of tension zone, the minimum height (in m, round off to one decimal place) by which the wall has to be raised, is __________.
    Correct answer is '2.5'. Can you explain this answer?
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    A 5 m high vertical wall has a saturated clay backfill. The saturation...

    To prevent tension crack,

    q =  γdx = 40
    x = 40/16 = 2.5 m
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    A 5 m high vertical wall has a saturated clay backfill. The saturation...
    °, respectively. Determine the minimum height of the wall required to prevent the development of tension in the clay.

    Solution:

    Given:

    Height of the wall (H) = 5 m

    Saturation unit weight of clay (γsat) = 18 kN/m3

    Cohesion of clay (c) = 20 kPa

    Angle of internal friction of clay (ϕ) = 0°

    Unit weight of sand (γ) = 16 kN/m3

    Angle of internal friction of sand (ϕ) = 30°

    Let the height of the increased portion of the wall be h.

    The total height of the wall after the increase = H + h

    Assuming that there is no tension in the clay and the sand above the clay is dry, the active earth pressure acting on the wall can be calculated using Coulomb's earth pressure theory.

    The active earth pressure coefficient (Ka) can be calculated as:

    Ka = tan2(45 - ϕ/2) = tan2(45 - 30/2) = 0.577

    The active earth pressure (Pa) can be calculated as:

    Pa = Kaγ(H + h)2/2 = 0.577 × 16 × (5 + h)2/2 = 4.616(25 + 10h + h2) kN/m2

    The passive earth pressure coefficient (Kp) for the sand can be calculated as:

    Kp = tanϕ = tan30° = 0.577

    The passive earth pressure (Pp) for the sand can be calculated as:

    Pp = Kpγh2/2 = 0.577 × 16 × h2/2 = 4.616h2 kN/m2

    To prevent the development of tension in the clay, the active earth pressure should be equal to or greater than the passive earth pressure.

    Therefore, we can write the following inequality:

    Pa ≥ Pp

    4.616(25 + 10h + h2) ≥ 4.616h2

    115.4 + 46.16h + 4.616h2 ≥ 4.616h2

    46.16h + 115.4 ≥ 0

    h ≥ -2.5 (This value is not acceptable as height cannot be negative)

    Therefore, the minimum height of the increased portion of the wall required to prevent the development of tension in the clay is:

    h = 0.0 m

    This means that the height of the wall needs to be increased by at least 0.0 m to prevent the development of tension in the clay. In other words, the total height of the wall needs to be maintained at 5 m.
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    A 5 m high vertical wall has a saturated clay backfill. The saturation unit weight and cohesion of clay are 18 kN/m3 and 20 kPa, respectively. The angle of internal friction of clay is zero. In order to prevent development of tension zone, the height of the wall is required to be increased. Dry sand is used as backfill above the clay for the increased portion of the wall. The unit weight and angle of internal friction of sand are 16 kN/m3 and 30°, respectively. Assume that the back of the wall is smooth and top of the backfill is horizontal. To prevent the development of tension zone, the minimum height (in m, round off to one decimal place) by which the wall has to be raised, is __________.Correct answer is '2.5'. Can you explain this answer?
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    A 5 m high vertical wall has a saturated clay backfill. The saturation unit weight and cohesion of clay are 18 kN/m3 and 20 kPa, respectively. The angle of internal friction of clay is zero. In order to prevent development of tension zone, the height of the wall is required to be increased. Dry sand is used as backfill above the clay for the increased portion of the wall. The unit weight and angle of internal friction of sand are 16 kN/m3 and 30°, respectively. Assume that the back of the wall is smooth and top of the backfill is horizontal. To prevent the development of tension zone, the minimum height (in m, round off to one decimal place) by which the wall has to be raised, is __________.Correct answer is '2.5'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about A 5 m high vertical wall has a saturated clay backfill. The saturation unit weight and cohesion of clay are 18 kN/m3 and 20 kPa, respectively. The angle of internal friction of clay is zero. In order to prevent development of tension zone, the height of the wall is required to be increased. Dry sand is used as backfill above the clay for the increased portion of the wall. The unit weight and angle of internal friction of sand are 16 kN/m3 and 30°, respectively. Assume that the back of the wall is smooth and top of the backfill is horizontal. To prevent the development of tension zone, the minimum height (in m, round off to one decimal place) by which the wall has to be raised, is __________.Correct answer is '2.5'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A 5 m high vertical wall has a saturated clay backfill. The saturation unit weight and cohesion of clay are 18 kN/m3 and 20 kPa, respectively. The angle of internal friction of clay is zero. In order to prevent development of tension zone, the height of the wall is required to be increased. Dry sand is used as backfill above the clay for the increased portion of the wall. The unit weight and angle of internal friction of sand are 16 kN/m3 and 30°, respectively. Assume that the back of the wall is smooth and top of the backfill is horizontal. To prevent the development of tension zone, the minimum height (in m, round off to one decimal place) by which the wall has to be raised, is __________.Correct answer is '2.5'. Can you explain this answer?.
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