Considerable evidence is available that slope failure in homogeneous soils usually occur on curved failure surface. In many circumstances ( for example zoned dames and foundations on weak strata), stability analysis using plane failure of sliding is more appropriate and yields excellent results.
Failure of infinite slopes, we can analyze using several techniques,
(1). Using planer failure surface (transnational slides)
- Culman method
(2). Using curved failure surface (rotational slides)
- Circular failure surface
1. Circular arc method
2. Stability number method
3. Method of slice (widely use, base the many softwares)
4. Morgestern and Bishop method
5. Cousins charts
- Non - Circular failure surfaces
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Saturday, October 27, 2018
Wednesday, October 24, 2018
Slope Stability
If the ground surface is not horizontal, a component of gravity will tend to move the soil downwards.
How slope failure will occur : If the driving force can overcome the resistance offered by the surrounding material along a rapture surface, slope failure will occur.
Slope stability analysis involves comparison of the developed shear stress along the most likely rapture surface and the shear strength of the soil.
How slope failure will occur : If the driving force can overcome the resistance offered by the surrounding material along a rapture surface, slope failure will occur.
Slope stability analysis involves comparison of the developed shear stress along the most likely rapture surface and the shear strength of the soil.
Tuesday, October 23, 2018
Slope Failure - Land slides
Slope failures
Slope failure describes a wide variety of processes that result in the downward and outward movement of slope - forming materials including rock, soil, artificial fill or a combination of these processes. the various types of landslides can be differentiated by the kinds of material involved and the mode of movement.Types of slope failures / movements
1) Slides2) Falls
3) Topples
4) Flows
5) Lateral spreads
(1). Slides
There are two major types,
- Rotational slides
The surface of rupture is curved concavely upward and the slide movement is roughly rotational about an axis that is parallel to the ground surface and transverse across the slide.
Lateral Earth Pressure - Part 03
Sloping back fills - Cohesive
For this there are 3 methods,(1). Extended Ranking Theory
If the soil have both cohesion and friction Rankine method was extended by Mazindrani and Ganjali.Active Case
Ka n we can observe from the table using alpha and phi ' and c'/gamma z, z is the height of the fill
Lateral Earth Pressure - Part 02
Cohesion less Back fills
For Cohesion less back fills,(1) Active state,
(2) Passive state,
Without water table - as usual method (please go through part 01)
With water table - Need to draw horizontal pressure distribution and water pressure diagrams. sum of those two diagrams equal to the final diagram. (using final diagram we can find final force and the line of action)
If there is a surcharge, on top of the ground it is also need to draw diagram for that and add up all diagrams to get the final.
If there is a surcharge, due to that this diagram need to add,
Lateral Earth Pressure - Part 01
If the wall AB is static, if it does not move either to the right or to the left of its initial position. The soil mass will be in a state of elastic equilibrium, that is the horizontal strain is zero. ( at rest condition - there is no lateral deformation.
The ratio of the effective horizontal stress to the vertical stress is called the coefficient of earth pressure at rest - K0
The ratio of the effective horizontal stress to the vertical stress is called the coefficient of earth pressure at rest - K0
Monday, October 22, 2018
Stress Distribution of Soil (Layered Soil Medium)- Part 04
Stress distribution through layered soil mediums
Burmister developed the chart given below to estimate the vertical stress distribution through a two layer medium. the chart is developed to estimate the vertical stress below the center lines of a circular loaded area and the thickness of a layer 1 is assumed ti be equal to the radius of the circular loaded area.
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