Pp Landslide

8/7/2019 Pp Landslide

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EARTH PROCESSBFT 1123

TITLE : LANDSLIDESITI NUR LIYANA ADZMAN (B10A239)SHARIPAH SAKINAH BT ABD AZAM (B10A227)

ALINA BINTI SHAHBUDIN (B10A232)SHARENE ANG EE SHIN (B10A226)


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Mass wastingMass wasting

y Any downslope movements of soil androck under the direction influence of

gravityy Divided into 3 categories :a) Slide (landslides)

b) Flowc) Fall


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LANDSLIDELANDSLIDE


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DEFINATIONDEFINATIONy The term "landslide" describes a wide

variety of processes that result in thedownward and outward movement of slope-forming materials including rock,soil, artificial fill, or a combination of these under the influence of gravity.


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Massive landslide at Bukit Antarabangsa


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C auses of landslideC auses of landslide

Landslides occur when the stability of a slopechanges from a stable to an unstable condition.

A change in the stability of a slope can be caused bya number of factors, acting together or aloneIt is usually possible to identify one or more

landslide causes and one landslide trigger.


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Natural causes of landslides include:

1. groundwater (porewater) pressure acting todestabilize the slope2. loss or absence of vertical vegetative structure ,

soil nutrients, and soil structure (e.g. after a

wildfire)3. weakening of a slope through saturation by

snowmelt, glaciers melting, or heavy rains4. earthquakes adding loads to barely-stable slope


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HU MAN A CTIVITIES

Landslides are aggravated by human activitiesdestabilize the already fragile slopesinclude: deforestation, cultivation and construction

a. vibrations from machinery or traffic blastingb. earthwork which alters the shape of a slope, or which

imposes new loads on an existing slopec. in shallow soils, the removal of deep-rooted vegetation

that binds colluvium to bedrock

d. Construction, agricultural or forestry activities (logging)which change the amount of water which infiltrates thesoil.


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TYPES OF LANDSLIDETYPES OF LANDSLIDE


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Anatomy of a LandslideAnatomy of a Landslide


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SLIDESLIDE

1)1) Rotational slideRotational slideThis is a slide in which the surface of rupture is curved concavely upward and theslide movement is roughly rotational about

an axis that is parallel to the ground surfaceand transverse across the slide.


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2) T ranslational slide2) T ranslational slide

The landslide mass moves along a roughly planarsurface with little rotation or backward tilting.


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FALLFALLy Falls are the simplest type of mass movement.y Occur when a mass of rocks detaches from a cliff

and falls to the bottom.

11 ) ) RockfallRockfall


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2)2) T oppleT oppleToppling failures are distinguished by the forward rotationof a unit or units about some pivotal point, below or lowin the unit, under the actions of gravity and forces exertedby adjacent units or by fluids in cracks..


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FLOWFLOW

y A flow is any slope failure where waterconstitutes major component of thematerial and major controlling factor inits behavior.

y Main agent of flow :

-> Water


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1)1)a)a) Debris flowDebris flowRapid mass movement in which a combination of loose

soil, rock, organic matter, air, and water mobilize as aslurry that flows downslope.

Commonly caused by intense surface-water flow, due toheavy precipitation or rapid snowmelt, that erodes andmobilizes loose soil or rock on steep slopes.


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can include anything from the smallest mud particles toboulders, trees, cars, and parts of buildings.occur when rainThe faster the water flow, the more the water can pick up


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b)b ) DebrisDebris avalancheavalanche

This is a variety of very rapid toThis is a variety of very rapid toextremely rapid debris flow.extremely rapid debris flow.


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H ave a characteristic "hourglass" shape.

The slope material liquefies and runs out, forming a bowl ordepression at the head.

The flow itself is elongate

Usually occurs in fine-grained materials or clay-bearing rocks onmoderate slopes and under saturated conditions.

3) Earth flow & Mud flow3) Earth flow & Mud flow

> mainly made of the smallest mud and silt particles.Extremely heavy rain, or a sudden thaw can triggerthese types of flows.


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4) Mud Flow4) Mud Flowy Consisting of material that is wet enough to flow rapidly

and that contains at least 50 percent sand-, silt-, andclay-sized particles. In some instances, for example inmany newspaper reports, mudflows and debris flows are

commonly referred to as "mudslides."


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CreepCreep

The imperceptibly slow, steady, downwardmovement of slope-forming soil or rock.caused by shear stress sufficient to producepermanent deformationtoo small to produce shear failure.


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It's just a slow adjustment of soil and rocks that is sohard to notice unless you can see the effects of themovement. These effects would be things likefenceposts shifted out of alignment, or telephonepoles tipping downslope.

Since the process is so slow, it can only bemonitored in terms of flow over longperiods of time.


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Lateral SpreadsLateral Spreadsy Distinctive because they usually occur on very gentle

slopes or flat terrain.y The failure is caused by liquefaction, the process

whereby saturated, loose, cohesionless sediments(usually sands and silts) are transformed from a solidinto a liquefied state.

y Usually triggered by rapid ground motion, such as thatexperienced during an earthquake, but can also beartificially induced


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L andslides in MalaysiaL andslides in Malaysia

L andslides in Malaysia are regular natural disasters inMalaysia which happen at the hillsides.

C auses :

Deforestation due to uncontained developmentof hillslope areas are partly the cause of amajority of landslides in Malaysia. There weresome instances where the development projectsat hill sites were abandoned for a considerable

period, affecting the maintenance of the slopescould causing them to collapse .


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