ASSALAMUALAIKUM & GOOD MORNING DON’T EVER HURT OTHER PEOPLE’S FEELING

EARTH RETAINING STRUCTURE EARTH RETAINING STRUCTURE CAN BE CLASSIFIED TO 2 TYPES THAT IS: Externally Stablilized Systems i) In- Situ Walls ii) Gravity Walls B) Internally Stabilized Systems i) Reinforced Soils ii) In-Site Reinforcement

RETAINING WALL

FUNCTION To retain the soil at a slope that is greater than it would naturally assume, usually at a vertical or near vertical position.

DESIGN The designed retaining wall must be able to ensure the following : Overturning doesn’t occur Sliding doesn’t occur The soil on which the wall rests mustn’t be overloaded The material used in construction are not overstressed.

DESIGN CONSIDERATION In order to calculate the pressure exerted at any point on the wall, the following must be taken in account: height of water table nature & type of soil subsoil water movements type of wall material used in the construction of wall

The effect of 2 forms of earth pressure need to be considered during the process of designing the retaining wall that is: Active Earth Pressure “ It is the pressure that at all times are tending to move or overturn the retaining wall” Passive Earth Pressure “It is reactionary pressures that will react in the form of a resistance to movement of the wall.

ACTIVE EARTH PRESSURE It is composed of the earth wedge being retained together with any hydrostatic pressure caused by the presence of groundwater. This pressure can be reduced by: The use of subsoil drainage behind the wall Inserting drainage openings called weep holes through the thickness of the stem to enable the water to drain away.

PASSIVE EARTH PRESSURE This pressure build up in front of the toe to resist the movement of the wall if it tries to move forward. This pressure can be increased by enlarging the depth of the toe or by forming a rib on the underside of the base.

GROUNDWATER BEHIND A RETAINING WALL

DEFINITION OF GROUNDWATER Groundwater can be defined as water which is held temporarily in the soil above the level of water table.

EFFECT OF GROUNDWATER TO RETAINING WALL have adverse effect to the design and stability the water behind the wall could increase the active pressure on the back of the wall It will reduce the soil shear strength that would lead to reduction of soil bearing capacity The water will reduce the frictional resistance between the base and the soil and also reduce the possible passive pressure in front of the wall

It can be concluded that the existence of groundwater behind the retaining wall could lead to failure of retaining wall. Therefore, ways must be found to drain the groundwater out from behind the wall. Normally, weep hole will be installed in the retaining wall where it will penetrate the retaining wall and drain the area immediately behind the wall.

Adequate spacing between the weepholes allow uniform drainage from behind the wall. Weep holes should have filter material between the wall and the backfill to prevent fines migration, weephole clogging, loss of backfill and caving

EARTH RETAINING STRUCTURE SPECIFICALLY ON “GRAVITY WALL”

GRAVITY WALL There are many types of gravity wall such as the followings: Massive Gravity Wall Crib Wall Cantilever Gravity Wall

GRAVITY WALL

It’s construction only need simple materials and moderately skilled labor But the required volume of material is very large because there’s steel reinforcement is used. Eventhough it need moderately skilled labor but the construction process is very labor extensive.

MASSIVE GRAVITY WALL Often made of mortared stones, masonry or reinforced concrete It resist the lateral forces from the backfill by virtue of their large mass These walls are very thick, so the flexural stresses are minimal and no reinforcement is needed.

CRIB WALL Another type of gravity retaining structure It consists of precast concrete members linked together to form a crib The zone between the member is filled with compacted soil

CRIB WALL

CANTILEVER GRAVITY WALL STEM 8 IN WIDE CONCRETE BLOCKS SOIL REINFORCING STEEL 12 IN. WIDE CONCRETE BLOCK Large Flexural Stresses At Base Of Stem REINFORCED CONCRETE FOOTING TOE HEEL

CANTILEVER GRAVITY WALL It is a refinement of the massive gravity wall concept These wall have much thinner stem and utilize the weight of the backfill soil to provide most of the resistance to sliding and overturning These walls require much less construction material because the crossection of this wall is much smaller.

It have a large flexural stresses which requires the use of reinforced concrete or reinforced masonry It must be carefully constructed & requires skillful labor less expensive than mass gravity walls most common type of earth retaining structure.

COUNTERFORT WALL

GABION WALL

EARTH RETAINING STRUCTURE SPECIFICALLY ON “IN-SITU WALL”

IN-SITU WALL Different from gravity walls There are many types of In-Situ wall such as the followings: a) Sheet Pile Walls b) Soldier Pile Walls c) Slurry Pile Walls

SHEET PILE WALLS Sheet piles are tine, wide steel piles Driven to the ground using pile hammer Series of sheet piles in a row form a sheet pile wall It’s usually necessary to provide lateral support at 1 or more levels above the ground that can be done using 2 ways that is internal braces or tieback anchor

Tieback Anchors are tension members drilled into the ground behind the wall The most common type is a grouted anchor with a steel tendon

Wall With Tieback Anchors WALER GROUTED TIEBACK ANCHOR SHEET PILE WALL SOIL Wall With Tieback Anchors

SHEET PILES

SHEET PILE WALLS

SOLDIER PILE WALLS Consist of a vertical wide flange stell members with horizontal timber lagging. Often used as temporary retaining structures for construction excavation

SOLDIER PILE WALL

SLURRY WALLS It’s a cast-in-place concrete walls built using bentonite slurry The contractor digs a trench along the proposed wall alignment and keeps it opem using the slurry The reinforcing steel is inserted and the concrete is placed using pumps / tremie pipe As the concrete fills the trench, slurry exits at the ground surface.

SLURRY WALL

SLURRY WALL

HOPEFULLY YOU UNDERSTAND THIS CHAPTER SYUKRAN JAZILAN = DOMO ARIGATO GOZAIMASU