MAT AND PILE FOUNDATION NOROZ FIAZ MALGHANI
MAT AND PILE FOUNDATION
NOROZ FIAZ MALGHANI
Mat/Raft Foundation
A mat foundation is a thick reinforced concrete slab supporting arrangement of column's or walls in a row and transmitting the load into the soil. It is use to support storage tanks, industrial equipment's , chimney's and various structure.
WHY IT IS USED The spread footings cover over 50% of the foundation area because of large
column load. The soil is soft with a low bearing capacity. When the expenses of deep foundation is higher than raft foundation. Walls of the structure are so close that individual footings would overlap
TYPES OF MAT FOUNDATION
Flat plate mat Plate thickened under column's Rigid frame mat Piled mat Two way beam and slab Plate with pedestal
PRESSURE DISTRIBUTION IN MAT FOUNDATION
A mat supported on strong bed rock transmit the load in a relatively area column's. The pressure distribution on raft/mat foundation as shown in fig.If the mat rests on stiff or compact soil, the mat distribute the load to the sub soil in larger area as shown in fig.If the mat rests on weak soil the pressure distribution on the mat tends to be uniform as shown in fig
PROCEDURE 1. SOIL TEST2. SHORE PILE CONSTRUCTION3. EXCAVATION4. REINFORCEMENT5. CC LAYER CONSTRUCTION6. LEVELING & DRESSING7. COLOUMN POSITIONING8. FORM WORK9. CONCRETE WORK10. CURING
SOIL TEST
Bearing capacity of soil Classification of soil Moisture content Ground water level Appropriation and depth of mat
SHORE PILE CONSTRUCTION
Shore piles support the surrounding loads and prevent the surrounding soil from breaking in at the time of construction
PLACING OF REINFORCEMENT
A batch of horizontal reinforcement placing; Another batch of reinforcement placement to to complete the
bottom mesh; Columns rod placement; Vertical rod placement over bottom mesh to hold the upper
mesh; Upper mesh placement
FORM WORK Form work is a mold or open box, like container into which fresh concrete is
poured and compacted. When the concrete is set, the form work is removed and a solid mass is
produced in the shape of the inner face of the form work. The top of the form work is normally left open. False work is the necessary support system that hold the formwork in the
correct position.
TYPES OF FORM WORK
Timber form work Plastic form work Steel form work
CASTING Start from one end Layer basis casting Side basis casting
LEVELING
After casting the whole mat area leveling is essential to be ensured That the thickness of the mat slab is same all over the area.
TYPES OF CURING Shading concrete work Steam curing Ponding method Sprinkling of water Covering concrete surface with gunny bags
ADVANTAGES OF MAT/RAFT FOUNDATION
Raft foundation is economic due to combination of foundation& floor slab Require little excavation Can cope with mixed and poor ground condition It reduces different settlement.
DISADVANTAES OF MAT FOUNDATION It require specific treatment for point loads. Edge erosion occur if not treated properly
PILE FOUNDATION
Pile foundation is a special kind of deep foundation, where the depth of the foundation is much greater than the width of the foundation
Today, pile foundation is much more common than any other type of deep foundation
USES It is used where the soil is compressible, It is used where the soil is water logged It is used when stratum of required bearing capacity is at greater
depth
MAJOR USES OF PILES : To carry vertical compression loads, To resist uplift loads To resist horizontal or inclined loads
CLASSIFICATION OF PILES1. BASED ON THE FUNCTION End bearing pile Friction pile compaction pile Sheet pile Batter pile Tension pile fender pile and dolphins
2. BASED ON THE MATERIAL& COMPOSITION Concrete pile Timber pile Steel pile Composite pile: concrete& timber concrete& steel3. BASED ON THE METHOD OF INSTALLATION; Driven pile cast-in situ pile Driven and cast-in-situ pile
SELECTION OF PILES
FACTOR GOVERNING THE SELECTION OF PILES
They are: Length of the pile in relation to the load and type of soil, Characters of the structure, Availability of the materials, types of loading, Factor causing deterioration, Ease of maintenance, Estimated cost of types of pile, taking into account the initial cost, life expectancy and
cost of maintenance Availability of funds.
Prepared By NOROZ FIAZ MALGHANI CIVIL ENGINEER