What is Piling?
Piling is a type of foundation for a building or structure that transfers loads deep into the ground beneath the structure, providing a solid foundation for the structure of engineering project. It is usually done in areas where the bearing capacity of the soil is low but the structure is multi-storied. It can be compared to a column in a structure that is placed deep into the ground.
Different types of piles according to use
(a) Bearing and friction pile
(b) Sheet pile
(c) Anchor pile
(d) Batter pile
(e) Fender pile
(f) Compaction pile
(g) Timber pile
(h) Concrete pile
(i) Simplex pile
(j) Composite pile
(k) Sand pile
(a) Bearing and Friction Pile:
A pile that transfers the load of the structure through soft soil or water to a solid layer with the required load-bearing capacity is called a bearing pile. This pile is placed directly on the solid layer inside the soil. Bearing piles can be made of wood or concrete. And in places where the soil is weak or soft to a great depth, the load is carried by the friction force generated between the soil surrounding the embedded pile and the pile surface. That is, the load is transferred through skin friction.
This type of pile is also called friction pile or floating pile. Friction pile is used where the bearing capacity of the soil does not increase with increasing depth or the rate of increase in bearing capacity is less than the increase in depth. This pile does not need to be driven into hard soil or rock.
(b) Sheet pile:
Sheet pile is never used as a vertical support. It usually acts as a barrier to horizontal movement of soil. It is used to act like a retaining wall. Where horizontal movement of soil occurs when soil is applied to it, sheet pile is used to prevent soil movement. Or sheet pile is used to enclose the soil in a specific area for a foundation and prevent it from being washed away by flowing water or water.
(c) Anchor pile:
Anchor pile is used to resist horizontal tension or other horizontal tensile forces of sheet piling wall.
(d) Batter pile:
A pile placed diagonally to resist horizontal or transverse forces is called a batter pile.
(e) Fender pile:
A pile used to protect a concrete deck or any other water-side structure from being hit by a ship or barge or any floating object is called a fender pile. This pile is usually made of wood.
(f) Compaction pile:
The pile used to increase the bearing capacity of granular soil is called compaction pile.
(g) Timber pile:
Timber piles are convenient for constructing light structures on wet and compressible soil. They are also less expensive. The load is spread by the friction force between the soil and the pile surface. Timber piles are generally used as friction piles. Wooden piles are made from trees such as shal, teak, deodaru, babul, khair, etc. Khair wood piles are used in coastal construction as they do not deteriorate in salinity.
Wooden piles are either square or round. The diameter of a round wooden pile is 30 cm to 50 cm and the size of a square pile is 30 cm to 50 cm. The length of a wooden pile should generally not be more than 20 times the size of the top of the pile. The bottom of the pile is narrow and a CI shoe is used at the bottom end for ease of installation. A ring with a steel plate is used to prevent damage to the top end of the pile during installation. However, the diameter or size of the ring should be at least 25 mm smaller than the head of the pile.
(h) Concrete pile:
In permanent structures, where additional load-bearing capacity is required, concrete piles are used. RCC piles, which are made by combining cement concrete with MS rod, are currently gaining popularity. Concrete piles can be mainly divided into three categories, such as-
1. Cast-in-situ concrete pile
2. Pre-cast concrete pile
3. Pre-stressed concrete pile.
1. Cast-in-situ pile:
A cast-in-situ pile is a pile made by digging a hole in the ground to a certain depth and then placing it in the ground. If a concrete pile is cast using only cement, sand, and gravel, it is called a plain concrete pile. If it is made with reinforcement, it is called a reinforced concrete pile.
Methods of casting concrete piles:
1. First, a hollow tube or hollow iron pipe casing is hammered into the ground. Then concrete is poured into the hole in the hollow tube. Such piles are 21 to 24 meters long.
2. Even after the concrete of the main pile is poured inside the casing pipe, the casing pipe is not lifted until the installation of other piles within a radius of 3 meters is completed.
3. Rods are not usually used in these concrete piles. However, if a concrete pile with rods is to be made, then the iron cage is first placed in the casing and then filled with concrete.
4. Care must be taken to insure the casing pipe for as long as possible.
(a) Cased east-in situ pile:
A steel shell is inserted into the soil in all types of soil. Then the mandrel is filled with concrete in the hollow shaft. The construction method of cased-in-situ pile is explained with the help of figure Raymond pile Mechanically Collapsible Mandrel Upper bag- 40 to 60 cm Lower diameter 20 to 30 cm Thin corrugated steel is shelled, the lower end of which is closed with the help of mandrel The shell is inserted into the soil to a specified depth. The mandrel is filled with concrete and the concrete is filled in the hole.
(b) Uneased-cast in situ pile:
In these piles, no special caning is used. However, skilled workers are required during construction. Such piles are made where there is no possibility of soil or water entering the hole when digging. First, the mandrel or shell is inserted into the soil by hitting it. Then, at the end, the concrete is filled and the shell is lifted some distance. In this way, this pile is made. Such piles can be made in different ways.
(i) Simplex pile:
A cast iron or steel rod is attached to the lower end of a 20 mm thick steel casing pipe and inserted into the soil to the required depth. If a rod is required, an iron cage is placed inside the casing pipe. Then, concrete is poured to a depth of one meter and rammed well, and the casing pipe is raised one meter. Concrete is poured to a depth of one meter again. And after ramming, it is raised one meter again. When the pipe is completely cast in this way, the pipe is lifted. Some of the end rods remain.
2. Pre-cast RCC pile:
In permanent structures, where additional load-bearing is required, pre-cast concrete piles are used. These piles are cast and cured at a convenient location away from the work site. Later, they are brought to the work site for installation. These piles are round, rectangular, square, octagonal in shape. The diameter of these piles is from 35 cm to 65 cm and the length is from 4.5 m to 30 m.
Construction method of Pre-cast RCC pile:
1. Formwork should be made according to the size and shape of the pile. If the number of piles is more, it is better to use metal formwork. Oil or soap solution is used before filling the formwork with concrete.
2. In addition to carrying the load of the structure, rods are used in the pile as per the design for the convenience of moving and placing the pile. However, generally, the longitudinal rods are 4 to 8 rods with a diameter of 20 mm to 50 mm, and the tie rods are 6 mm to 10 mm in diameter. The tie rods are used horizontally or in patches. The distance between the tie or spiral rods will be 80 mm to 100 mm within a distance of about one meter from the top and bottom of the pile. The distance between the middle part will be 300 mm. The concrete cover will be 50 mm. For the convenience of placing, cast iron shoes and steel straps are used at the ends of the pile.
3. Concrete should be poured into the formwork and rammed well with the help of a vibrator. Generally, concrete in the ratio of 1:2:4 and a maximum size of course aggregate of 19 mm is used. However, to make piles with a higher load-bearing capacity, concrete in the ratio of 1:1:3 is used. Since the upper part of the pile is damaged due to impact during pile installation, improved concrete in the ratio of 1:1:2 is used from 0.6 meters to 0.9 meters in length.
4. The formwork is removed after 3 days of pile casting. Then curing is done at the casting site for at least 7 days. Later, the pile is taken from the casting site to the curing tank and after curing for 4 weeks here, the pile is driven (driven). Pictures of different types of pre-cast piles:
(j) Composite pile:
A pile made of two different materials, one on top of the other. Most composite piles are made of a combination of concrete and wood. This pile combines the durability of concrete with the cost savings of wood. Wooden piles are used below subsoil water and concrete above subsoil water.
(k) Sand pile:
This pile is made by digging a hole in the ground and filling it with sand. This pile is used to strengthen the soil or to increase the load-bearing capacity as sand has a higher load-bearing capacity than soil. The hole is made by digging a hole with an auger or by closing the bottom end of a hollow pipe and inserting it into the ground with the help of pressure.
The diameter of the hole is between 20 cm and 40 cm. The excavated hole is then filled with sand and compacted firmly. The sand is kept wet during compaction. To prevent the pile from being damaged by lateral pressure or to protect the filled sand, 1 meter of cement concrete is filled on top of the pile. The pile can be made from 2 meters to 5 meters. The piles are usually placed under columns.
****** Caution in work**********
Pile work is very important and very sensitive. So pile work has to be done with some extra precautions, which an engineer must know and take care of.
You have to be very careful in pile work, because the worker can give you various excuses to get you out of the work, so do not pay attention to some things.
• > It is not enough to give 3 blocks in a cage, you must give blocks every 5-6 feet. The worker may say, "I worked on such and such a project and I gave 3/4 blocks there too." In that case, you must put pressure on them to give blocks every 5-6 feet and monitor them well.
• > You will need to provide the required diameter base ring (on which the main rod is tied to create the pile frame). Be sure to measure the base ring in mm before starting work.
• > Check carefully whether each main bar has equal distance/gap from each other.
• > If the spiral space/gap in the design is 5 or 6 inches, the mechanic will say sir, let's make the gap 7" or 8", but you must do the work according to the design. Measure whether the spiral space/gap is tick. If you make a mistake, do it again.
• > Alternately do the bending and welding. Many times it is seen that they only do the name welding which later runs out. Good quality welding must be on both sides of the joint. The amount of welding will also be more. Welding will also have to be done at the spiral joint.
• > When centering the pile point, they will say, "You can't do two or one inches here and there. You have to center it exactly. It will be fixed when you install the pile casing.
• > Many times, mud or sand accumulates at the bottom and the depth decreases, so you will have to do 1.5 to 2 feet of boring.
• > Before boring, be sure to measure the drill rod and mark it according to your needs.
• > Measure the trim pipe as much as you do the boring. In reality, it is more or less. It is seen that 5 trim pipes have to be added for 70 feet, but the length of 5 trim pipes is 80 to 80 feet, so they will want to add 4 pipes to make it loose. But 5 trim pipes have to be added.
• > After boring, you have to wash it well. However, if you wash for a long time, the sand or soil will break. You have to notice whether the sand or soil of that place is really like breaking?
• > The washed water will not come out fresh like a tube well, but You can see that the water is less in the water or there is no mud on your hands, if your hands look clean when you throw the water away, then the wash is done properly.
• > While lowering the pile frame, make sure that the block does not stick to the casing and break. And you
• > If the length of the pile is long, it is necessary to add more than one frame. In that case, you should pay attention to whether the laps are properly connected? At least three weldings will be done in each lap and the length of each welding will be 3 inches.
• > The level of the frame head should be kept equal according to the design.
• > If the head of the frame rod is below the ground level, then a block should be placed 3/4 feet between the head of the frame.
• > The ratio of sand, stone, cement should be kept correct while pouring. Many times, more sand and stone are added than the ratio to complete the pouring work quickly. This should not be allowed in any way. Many times, it is poured out of the machine before it is mixed well, so make sure that the mixing is correct.
• > The trimi pipe cannot be removed without filling it. In this case, no concession can be made. The trimi pipe cannot be opened until the top of the trimi pipe is above the casing or before one pipe is completely above the top.
• > It is always necessary to ask for pouring over.
• > Above all, every step of the piling work must be monitored seriously.
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