Geotechnical Engineering

Home/Geotechnical Engineering

Do you need to remove the ads? Get the paid membership

Discy Latest Questions

Asked: In:
Vinnarasan
Vinnarasan

Vinnarasan

View Profile
User

Why we conduct soil penetration test in soil investigation?

  1. AdityaBhandakkar

    AdityaBhandakkar

    View Profile
    AdityaBhandakkar User
    Why we Conduct the SPT Test in Soil investigation?

    As a civil engineer to check the geotechnical properties of soil, three guests must be performed the shear test, bearing test, and penetration test. A penetration test is performed by three methods, standard penetration test A dynamic cone penetration test Cone penetration test or Dutch cone penetraRead more

    As a civil engineer to check the geotechnical properties of soil, three guests must be performed the shear test, bearing test, and penetration test.

    A penetration test is performed by three methods,

    1. standard penetration test
    2. A dynamic cone penetration test
    3. Cone penetration test or Dutch cone penetration test.

    In Geotechnical engineering, the value of standard penetration test is widely used for determining technical properties of soil.

    1. To check the soil parameters
    2. Value of cohesion and angle of internal friction with imperial relations.
    3. To know the deformation modulus.
    4. To check the consistency of soil
    5. For determining the bearing capacity of soil

    This test is globally used to determine various engineering and geotechnical properties for soil investigations.

    See less
    • 47
Asked: In:
Vivek Patel
Vivek Patel

Vivek Patel

View Profile
User

What is a triaxial test? Why it is significant to know soil property? and which type of property?

  1. nikeetasharma

    nikeetasharma

    View Profile
    nikeetasharma Guru

    Triaxial test ; The triaxial test is one of the most versatile and widely performed tests in the geotechnical laboratory. It allows shear strength and stiffness of soil and rock to be determined for use in geotechnical design. - Procedure of triaxial test :- The triaxial test typically involves subjRead more

    Triaxial test ;

    The triaxial test is one of the most versatile and widely performed tests in the geotechnical laboratory. It allows shear strength and stiffness of soil and rock to be determined for use in geotechnical design.

    – Procedure of triaxial test :-

    The triaxial test typically involves subjecting a cylindrical specimen of soil, whose diameter ranges from 38mm to 100mm, into a cell that can be pressurized. Most of the specimens have an approximate 2:1 height to dia ratio and are sealed with a rubber membrane. The specimen preparation generally depends upon the type of soil. Cohesive soil samples are prepared directly from saturated compacted samples, either undisturbed or remolded. The specimen for cohesion-less soil is prepared with the help of the mold that maintains the required shape of the specimen.

    And then the specimen is vertically covered with a thin rubber membrane and placed between two rigid ends inside a pressure chamber. The upper plate can move vertically and apply vertical stresses to the specimen. The axial stress/strain of the sample is controlled by the movement of this vertical axis. The water pressure surrounding the sample in the pressure chamber controls the confining pressure. Also, the volume change of the sample is controlled by measuring the exact volume of moving water.

     

    There are three primary triaxial test carried out in a laboratory, depending upon the combination of loading and drainage condition ;

    • Consolidated – Drained (CD)
    • Consolidated – Undrained (CU)
    • Unconsolidated – Undrained (UU)

    Triaxial test is significant to know soil property because it determines the ability of soil to resist shear stress and strain. Different combination of confining and axial stresses can be applied. Drained and undrained test can be carried out. The types of properties of soil which can be known by triaxial test are followed ;

    1. Shear strength and stiffness of soil
    2. Stress/Strain behavior
    3. Pore water pressure of soil
    See less
    • 32
Asked: In:
RaghavArora
RaghavArora

RaghavArora

View Profile
Learner

What is a tachometry? What is it’s used in civil engineering projects?

  1. Soumyadeep Halder

    Soumyadeep Halder

    View Profile
    Best Answer
    Soumyadeep Halder User

    ans- defination Tacheometric is a branch of surveying in which horizontal and vertical distances are determined by taking angular observation with an instrument known as a tachometer. Tacheometric surveying is adopted in rough in rough and difficult terrain where direct levelling and chaining are eiRead more

    ans- defination

    Tacheometric is a branch of surveying in which horizontal and vertical distances are
    determined by taking angular observation with an instrument known as a tachometer.
    Tacheometric surveying is adopted in rough in rough and difficult terrain where direct levelling
    and chaining are either not possible or very tedious.
    Tacheometric survey also can be used for Railways, Roadways, and reservoirs etc.
    Tacheometric surveying is very rapid, and a reasonable contour map can be prepared for
    investigation works within a short time on the basis of such survey.
    An ordinary transits theodolite fitted with a stadia diaphragm is generally used for tacheometric
    surveying.

    Uses of Tachometry in civil engineering
    Tachometry is used for preparation of topographic map where both horizontal and vertical
    distances are required to be measured; survey work in difficult terrain where direct methods of
    measurements are inconvenient; reconnaissance survey for highways and railways etc.;
    Establishment of secondary control points.

    See less
    • 4
Asked: In:
Gopal Mishra
Gopal Mishra

Gopal Mishra

View Profile

In the absence of test data for calculating SBC of soil. What are the assumed safe bearing capacity values for different soils?

  1. Fasi Ur Rahman

    Fasi Ur Rahman

    View Profile
    Fasi Ur Rahman

    The capacity of the soil to allow the loads coming from the foundation is called the bearing capacity of the soil. It is essential to know the bearing capacity of the soil before designing the foundation. Different field tests can determine it. However, standard safe bearing capacity values are avaiRead more

    The capacity of the soil to allow the loads coming from the foundation is called the bearing capacity of the soil.
    It is essential to know the bearing capacity of the soil before designing the foundation. Different field tests can determine it. However, standard safe bearing capacity values are available for different soil types, and these values can be assumed where test data is limited or speedy construction is required.

    S.No Type of Soil Safe Bearing Capacity ( kN/m2)
    Cohesive Soils
    1. Soft shale, hard or stiff clay in a deep bed, dry state 440
    2. Medium clay readily indented with a thumbnail 245
    3. Moist clay and Sand clay mixture, which can be indented by thumb pressure 150
    4. Black cotton soil/expansive clay ( 50% saturated) in the dry state 130 to 160
    5. Soft clay indented with moderate thumb pressure 100
    6. Very soft clay which can be penetrated with the thump up to few centimeters 50
    Cohesionless Soil
    7. Compact gravel/sand and gravel mixture with good resistance against penetration of tools 440
    8. Compact and dry coarse sand 440
    9. Compact and dry medium sand 245
    10. Loose gravel or sandy gravel mixture, dry state 245
    11. Fine sand and silt ( consists of dry lumps) 150
    12. Loose and dry fine sand 100
    Rocks
    13. Hard rocks such as granite trap, diorite, etc. 3240
    14. Laminated rocks such as sandstone, limestone, etc. 1620
    15. Residual deposits of shattered and broken bedrock and hard shale cemented material 880
    16. Soft rocks 440
    See less
    • 48
Asked: In:
Anitha
Anitha

Anitha

View Profile
User

Explain the various factors that help decide the number and depth of boreholes required for subsoil investigation

  1. Rohan

    Rohan

    View Profile
    Rohan User

    When the depth and position of exploration are selected one has to comply with the following guidelines: • Points of exploration have to be distributed in such a way that foundation soil layering can be determined across the location • Points of exploration for a building or structure have to be posRead more

    When the depth and position of exploration are selected one has to comply with the following guidelines:

    • Points of exploration have to be distributed in such a way that foundation soil layering can be determined across the location
    • Points of exploration for a building or structure have to be positioned on the critical point of the structure in relation to shape, behavior and expected load transfer of the structure
    • For route structures, points of exploration have to be distributed on appropriate distances from the central line, depending on a total width of structure such as the width of embankment or width of a cut
    • For structures on slopes and cuts (including excavations) or in their vicinity, points of exploration have to also be distributed outside the design area and positioned so that the slope or excavation stability can be determined; if anchors are foreseen one has to take into account probable stresses in the vicinity of their load transfer area
    • Points of exploration have to be distributed so that they pose no danger for structures, construction works or the environment
    • The considered area has to stretch into the neighboring location. The length has to cover the expected negative influence in that location.
    • For points of underground water measurement, one has to take into account the possibility of usage, after the initial positioning, for the continuance of measurement during and after construction.

    If the conditions in the foundation soil are relatively equal or it is known that the foundation soil has satisfying stiffness and strength, less exploration point can be foreseen or they can be on bigger distances. In any case, that kind of selection has to be justified by experience.

    If structures are built on layers that satisfy stiffness and strength, depth of exploration can be reduced to za = 2,0 m unless equal geological conditions when at least one borehole should reach the depth of za = 5,0 m. If the bedrock is located on a depth that matches the foreseen base of the structure, that depth has to be taken as a referent point za. Otherwise, za is referred to as the solid bedrock.

    See less
    • 2
Asked: In:
andanr123
andanr123

andanr123

View Profile
User

What is swell pressure test of soil and it’s laboratory procedure?

  1. Neenu S K

    Neenu S K

    View Profile
    Neenu S K

    The objective of a swelling pressure test on soil is to determine the swelling pressure of expansive soil when it is not allowed to undergo any volume change. The volume change is arrested or the soil is not allowed to swell in order to test this. The test determines the intrinsic swelling pressureRead more

    The objective of a swelling pressure test on soil is to determine the swelling pressure of expansive soil when it is not allowed to undergo any volume change. The volume change is arrested or the soil is not allowed to swell in order to test this.

    The test determines the intrinsic swelling pressure of the expansive soil. The test is conducted on a consolidometer. More details are explained in IS 2720(Part 41):1977.

    The swelling pressure is dependent on the:

    • Clay Content in the soil
    • Moisture content
    • Stress history
    • Drying and wetting cycles of soil
    • The nature of the pore fluid
    See less
    • 3
Asked: In:
AdityaBhandakkar
AdityaBhandakkar

AdityaBhandakkar

View Profile
User

What is the Average Density of Soil?

  1. nikeetasharma

    nikeetasharma

    View Profile
    nikeetasharma Guru

    As we know, Density = Mass / Volume Here, Soil density is defined in two well accepted concepts as particle density and bulk density. In the metric system, particle density can be expressed in terms of mega grams per cubic meter (Mg/m3). Thus if 1 m3 of soil solids weighs 2.6 Mg, the particle densitRead more

    As we know,
    Density = Mass / Volume

    Here, Soil density is defined in two well accepted concepts as particle density and bulk density. In the metric system, particle density can be expressed in terms of mega grams per cubic meter (Mg/m3). Thus if 1 m3 of soil solids weighs 2.6 Mg, the particle density is 2.6 Mg / m3 (since 1 Mg =1 million grams and 1 m3 =1 million cubic centimeters) thus particle density can also be expressed as 2.6 g / cm3.

    Particle Density :-

    The weight per unit volume of the solid portion of soil is called particle density. Generally particle density of normal soils is 2.65 grams per cubic centimeter. The particle density is higher if large amount of heavy minerals such as magnetite; limonite and hematite are present in the soil. With increase in organic matter of the soil the particle density decreases. Particle density is also termed as true density.

    Bulk Density :-

    The oven dry weight of a unit volume of soil inclusive of pore spaces is called bulk density. The bulk density of a soil is always smaller than its particle density. The bulk density of sandy soil is about 1.6 g / cm3, whereas that of organic matter is about 0.5. Bulk density normally decreases, as mineral soils become finer in texture. The bulk density varies indirectly with the total pore space present in the soil and gives a good estimate of the porosity of the soil. Bulk density is of greater importance than particle density in understanding the physical behavior of the soil. Generally soils with low bulk densities have favorable physical conditions.

    See less
    • 33
Asked: In:
DevilAVRT
DevilAVRT

DevilAVRT

View Profile
Beginner

Explain the construction & use of New Mark’s influence chart?

  1. Suyogmuralkar

    Suyogmuralkar

    View Profile
    Suyogmuralkar Beginner

    Hi devilart, This method is used to compute the vertical and horizontal stresses of any shape ,irregular geometry below any point outside or inside The chart as shown in the above figure essentially consists of n no. of radial lines and m no. of concentric circles.   To find out vertical stressRead more

    Hi devilart, This method is used to compute the vertical and horizontal stresses of any shape ,irregular geometry below any point outside or inside

    The chart as shown in the above figure essentially consists of n no. of radial lines and m no. of concentric circles.

     

    To find out vertical stress at any point below or outside the loaded area, Plan of the loaded area is drawn such that depth Z at which stress is being computed equals the length AB as shown on

    N = No. of blocks. Bina Nusantara.

    Further, the plan is placed over influence chart such that the point below which stress is required coincides with the center of chart Then count the number of influence area (N) covered by the plan

    See less
    • 4
Load More Questions