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ASSIGNMENT NO.-1

SUBMITTED TO : SUBMITTED BY:

MS. UMA MALIK BAJRANG GUPTA

ROLL NO.-C09210

BRANCH-CIVIL

SEM.-6TH

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WHAT IS A SLOPE FAILURE?

A slope failure is a phenomenon that a slope collapses abruptly due to

weakened self-retainability of the earth under the influence of a rainfall or an

earthquake.

Generally, a slope failure can be defined as a downward movement of a large

amount of slope material. For this reason, slope failures are also referred to

as mass movements.Slope failures can occur suddenly in one easily recognized

movement, or almost imperceptibly over a period of many years.

A slope failure is classified based on how it moves and

the type of material being moved:

Creep:very slow movement of rock or soil downslope, often caused by

repeated freezing and thawing of soil moisture.

Falls: very rapid fall of rock and earth material from vertical or near vertical

slopes. Rockfalls are a common example.

Flows:slow to rapid movement of rock, soil, snow, or ice. Types of flows

include mudflows, earthflows, debris flows, and snow avalanches. Flows

typically have more mixing of material than other slope failures.

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Slides: slow to rapid movement of soil or rock. This category includes rock

slides, earth slides, and slumps. Slides often occur with little mixing of material.

Subsidence:slow to rapid collapse of rock or soil into underlying spaces.

Sinkholes in karst landscapes are a common example.

SLIDES

Slides, either in rock or soil, will have rotational or translational movement. The

behavior of the slide depends mostly on the type of material and whether that

material is:

(1) homogeneous (isotropic) material (similar properties in all directions), or(2) inhomogeneous (anisotropic) material with planes of weakness.

Caused by slope failure ofhomogeneous (isotropic) materials

(similar properties in all directions).

Caused by slope failure of

inhomogeneous (anisotropic) material

with planes of weakness.

Translational Movement

Imagine yourself sliding down a slide

at a playground. This is similar towhat occurs in translational rock- and

land- slides. Slides move in contact

with the underlying surface! The

"sliding surface" is commonly a

bedding plane, but may also be a

fault or fracture surface.

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Rotational Movement

The sliding of material along a

curved surface called a

rotational slide or slump. Acommon cause of slumping is

erosion at the base of a slope.

For example, coastal stormwaves erode cliff bases,

removing supporting material

(remember?). Slope failure

occurs. The slump block rotates

downward, producing a scarp

(cliff) at the top of the slope.

SLOPE FAILURE FACTORS

Gravity can be divided into components acting parallel to a slope and

perpendicular to the slope.

Failure is more likely to occur if the effect of friction on thepotential sliding

surface is reduced.

The physical properties of the slope materials such as cohesion between grains

may reduce the potential for slope failure.

The angle of repose is the maximum slope generated when loose

unconsolidated material is formed into a pile.

The addition of excess water may destabilize slopes by adding weight,

destroying cohesion between grains, and reducing friction.

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SLOPE FAILURE PROCESSES

Rock fall occurs when ice wedging loosens angularboulders from rocky cliffs.

Rockslides occur where sheets of rock move downslope on a planar slidingsurface such as a bedding plane or fracture surface.

A slump is the downslope movement of material on acurved surface.

Mudflows and debris flows represent a chaotic mixture of water and

unconsolidated slope materials.

Arid and temperate areas may be marked by rockfall and rockslides whereas

humid regions will show greater frequency of slumps, mudslides, and debrisflows.

WHERE DO SLOPE FAILURES OCCUR?

Slope failures can be triggered by weather events, geologic events, humanmodification of the landscape, or most commonly, some interaction of all

of the above.

Therefore, slope failures occur nearly everywhere slopes exist.

Mountainous regions, hilly regions, and coastlines have the greatest risk

of slope failures. Also, locations in active tectonic regions are prone to

slope failures triggered by earthquakes or volcanic activity.

Sinkholes form in karst landscapes, where water has dissolved underlying

bedrock, typically limestone or gypsum. The southeastern United States is particularly prone to sinkhole

formation; over 50% of the state of Kentucky is subject to these hazards.

Along the highways of the Rocky Mountains and coastal mountain ranges

of California, rockfalls cause transportation delays, vehicle damage, and

road damage every year.

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PRACTICAL EXAMPLES OF SLOPE FAILURE

1.Bukit Lanjan NKVE-2003

2.Slope failure along Lake Erie.

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3.Slope failure around Port-au-Prince

4. Landslide at Kobe

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CONSEQUENCES OF SLOPE FAILURES :

Whether on the surface or underground, unanticipated movement of the

ground can pose hazardous conditions which may lead to

Endangerment of lives.

Demolition of equipment.

The loss of property.

Losses to engg. Structures, railway formations, highway embankments,

canal banks, earth dams etc