Buy complete Civil Engineering Mock Test series (128 Tests) just INR 250/-

For Demo: Click Here

This Complete Civil Engineering All syllabus and Subject wise mock tests course contains more than 5800 MCQs and 128 mock tests. Which will be very useful for SSC JE, AE, AEE, ESE, GATE, ISRO, all competitive examinations.
  • Validity 2 years
  • Original worth Price INR 500/-
  • Unlimited times to reattempt the tests.
  • Individual login and course progress view -
  • Very cheap price comparing to the other mock test series platform
  • All syllabus Civil Engineering Mock tests - 59
  • Subject wise mock tests - 68
  • Tests are available in all syllabus and subject wise mode & MCQs in PDF
  • The elevation head (hz) of any point is its height above the datum line. The height of water level in the standpipe above the datum is the piezometric head (h). h = hz + hw
  • Darcy’s law states that there is a linear relationship between flow velocity (v) and hydraulic gradient (i) for any given saturated soil under steady laminar flow conditions.
  • If the rate of flow is q (volume/time) through cross-sectional area (A) of the soil mass, Darcy’s Law can be expressed as
    v = q/A = k.i
    where k = permeability of the soil
    i = Dh/L
    Dh = difference in total heads
    L = 
    length of the soil mass
  • The flow velocity (v) is also called the Darcian velocity or the superficial velocity.
  • It is different from the actual velocity inside the soil pores, which is known as the seepage velocity, vS.
  • Seepage velocity is always greater than the superficial velocity, and it is expressed as:


    where AV = Area of voids on a cross section normal to the direction of flow
    n = porosity of the soil

  • Permeability (k) is an engineering property of soils and is a function of the soil type. Its value depends on the average size of the pores and is related to the distribution of particle sizes, particle shape and soil structure.

  • The ratio of permeabilities of typical sands/gravels to those of typical clays is of the order of 106. A small proportion of fine material in a coarse-grained soil can lead to a significant reduction in permeability.

  • For different soil types as per grain size, the orders of magnitude for permeability are as follows:


    k (cm/sec)



    Coarse sand 100 to 10-1
    Medium sand 10-1 to 10-2
    Fine sand 10-2 to 10-3
    Silty sand 10-3 to 10-4
    Silt 1 x 10-5

    10-7 to 10-9

  • In soils, the permeant or pore fluid is mostly water whose variation in property is generally very less. Permeability of all soils is strongly influenced by the density of packing of the soil particles, which can be represented by void ratio (e) or porosity (n).
  • In sands, permeability can be empirically related to the square of some representative grain size from its grain-size distribution. For filter sands, Allen Hazen in 1911 found that » 100 (D10)2 cm/s where D10= effective grain size in cm.
  • Kozeny-Carman equation for laminar flow in saturated soils.
  • For silts and clays, the Kozeny-Carman equation does not work well, and log k versus e plot has been found to indicate a linear relationship.

    For clays, it is typically found that

    where Ckis the permeability change index and eis a reference void ratio.

  • Constant Head Flow
    Constant head permeameter is recommended for coarse-grained soils only since for such soils, flow rate is measurable with adequate precision. As water flows through a sample of cross-section area A, steady total head drop h is measured across length L.Permeability is obtained from:
  • Falling Head Flow
    Falling head permeameter is recommended for fine-grained soils.
  • Unconfined Flow Pumping Test
  • Confined Flow Pumping Test
  • For vertical flow
    The flow rate q through each layer per unit area is the same.
  • Horizontal flow
    When the flow is horizontal, the hydraulic gradient is the same in each layer, but the quantity of flow is different in each layer.

    The total flow is

Share to all