Written Test3 Flashcards
What is failure ?
A state when the element can no longer be used as intended,
cannot be rehabilitated
What is Strain ?
– The relative elongation/compression of an element
What is Shear Strain ?
The change in angle between two line elements originally at right
angles
What is viscoelastic materials ?
Time dependence Materials , The behaviour often changes as time progresses . ( CREEP )
What is Deformation
The physical combination of strains and shear strains or the change in volume and shape
Principal Strains ?
– For every point in a body there is a coordinate system
directed such that the strain state can be
characterized by the normal strains only
– These normal strains are then denoted principal
strains
What is invariants ?
Ki is independent of the chosen coordinate system They are used to transform strains between coordinate systems
What are compatibility Equations ?
Strain relations used to ensure that the deformations
is compatible with displacements and are continuous
Constitutive Equations ?
Mathematical relations between stresses and strains
- the material models
Geomechanical Sign conversion
Displacements are positive when acting in the coordinate axes
positive directions
– Normal strains are considered positive at compression
Settlement ?
Surface Deformations
• Elastic and plastic deformations ?
– Reversible and permanent
What is Elasticity ?
Describes the behavior of material in which after
discontinuing the applied stress the entire
deformation remains reversible; the relationship
between stress and strain is usually linear.
What is Plasticity ?
Describes a behavior of material which can deform
continuously without failure under stresses
surpassing the one necessary to cause yielding.
• Relate to the concept of residual strength
What is Young Modulus
E is the stiffness or ”deformation resistance”
of the material
What is Poisson’s ratio
ν is the relationship between the
axial and tangential strain for a
given axial stress
K ?
Bulk Modulus
G ?
Shear Modulus
Laboratory Tests ?
– Uniaxial compression test
– Sound velocity test
Field Tests ?
– Plate loading test
– Dilatometer measurement
– Seismic measurement
How will you determine young modulus in Uniaxial Compressive Test
Tangential Young’s modulus, (Et) is
calculated when the stress level is equal to
about 50% of the uniaxial compressive
strength.
Average modulus (Eav) is calculated from the slope on the linear part of the stress‐strain curve
what are the 2 basic assumptions of the Dilatometer Test
- Tested volume must be free of joints to avoid
hydraulic fracturing and joint opening
• Is independent on the prevailing stresses!
impoving the slope stability ways ?
Changing Geometry
change water conditions
Installing Reinforcments
Dmage preventions ( smooth plasting and pre split )
Controlling rock falls ( catch benches , fences , nets )
Slope monitoring methods ?
*Geodetical Methods ( prisms and base station ) + base movement.
• Extensometer or Inclinometer
(failure surface)
• Vertical boreholes (groundwater)
stability is determined in footings on rock surfaces ?
– bearing capacity
– unacceptable settlements
– Slope stability
How to measure deformation in site ?
Extensometer measurments
Convergence Measurment
Geodetic Measurments
