Challenge 12
Challenge 12
- Explain in detail about open foundation.
AIM:
HERE I AM GOING TO EXPLAIN DETAIL ABOUT OPEN FOUNDATION .
The 'open' refers to the fact that the foundations are made by first excavating all the earth till the bottom of the footing, and then constructing the footing. During the early stages of work, the entire footing is visible to the eye, and is therefore called an open foundation.
- OPEN FOUNDATION IS ALSO KNOWN AS SHALLOW FOUNDATION OR SPREAD FOOTING
- IT IS USED TO GIVE STABILITY TO THE STRUCTURE
- IT TRANSFERS LOADS FROM PIER TO GROUND.
- IT SHOULD BE RIGID ENOUGH TO TRANSFER ALL FORCES TO GROUND.
- THE OPEN REFERS TO THE VERY FACT THAT THE FOUNDATIONS ARE MADE BY FIRST EXCAVATING ALL THE EARTH TILL THE BOTTOM OF THE FOOTING THEN CONSTRUCTING THE FOOTING.
- DURING THE INITIAL STAGES OF WORK THE WHOLE FOOTING IS VISIBLE. AND IS THEREFORE CALLED AN OPEN FOUNDATION.
- THE IDEA IS THAT EVERY FOOTING TAKES THE CONCENTRATED LOAD OF THE COLUMN AND SPREADS IT OVER AN OUTSIZED AREA.SO THAT THE ACTUAL WEIGHT ON THE SOIL DOESNOT EXCEED THE SAFE BEARING CAPACITY OF THE SOIL.
- SUITABLE FOR BRIDGE OF MODERATE HEIGHT TO BE BUILT ON DRY GROUND WHICH IS SUFFICIENTLY FIRM TO SUPPORT THE BRIDGE STRUCTURE.
- BEST SUITED IN SITUATIONS WHERE THE HARD SOIL IS PRESENT WITHIN 1.5TO 3M BELOW THE BED LEVEL OF WATER COURSE AND WHEN THE SCOURING IS MINIMUM.
2.Explain in detail about the components of the Well Foundation.
AIM :
- Larger diameters might be extended to larger depths.
- Similar to piles they are shorter.
- If the soil (rock) with a large bearing capability is between 3-7 meters, it may be very effective.
- If the load is not very large, however, the upper 3-7 m soil is not suitable and it may be applied effectively.
- The price of construction is comparatively low on the bed level or lower side.
HERE I AM GOING TO EXPLAIN DETAIL ABOUT THE WELL FOUNDATION AND ITS COMPONENTS.
- Well foundation is a type of deep foundation
- It is provided for structures with foundation beneath rivers or other water bodies.
- It receives the load of the whole structure and transfers it to the ground
- Cassion are used to construct well foundations.
- They are prefabricated hallow box or cylinder.
- They are sunk into ground and filled with concrete.
- 3 type of caissons.
- open caisson
- box caisson
- pneumatic caisson
TYPE OF WELL
- Circular well'
- Rectangular well
- Double rectangular well
- Double octagonal well
- Double -D well '
- Twin Circular well
- Dumb Bell well
- Multiple Dredge Hole well
COMPONENTS OF WELL FOUNDATION.
- Cutting Edge
-
The lowermost portion of the well curb is leading edge.
It is operate to cut the soil throughout the sinking.
- Well Crub
- This transfers loads to ground through cutting edge while sinking;
- material are Timber and rcc
- Bottom plug
-
After the well is sunk to the required depth, the bottom of the well is plugged with concrete known as a bottom plug.
It is operated to transmit the load to the subsoil.
- Steining
- brick/stone masonary PCC or RCC materials are used .
- The design relies on the unit weight of well and skin friction
- Top plug
- Well cap
- It is constructed as a slab resting on the well.
- It transfers load of the pier to the well;
- This acts as an interim layer between the pier and well foundation to accommodatte pier.
- It is designed such that the pierr base is provided with a minimum all round offset.
- The centre of the cap coinncides witth the pier instead of the well to nulify th effects of shifts occurred during well sinking.