Sheet pile meaning: Any retaining structure that meets the following conditions is called a sheet pile.
A) A metal, concrete or … member is compacted to the ground.
B) A member has a thin cross section and low weight so that it does not play a role in the stability of the excavation.
Sheet pile has a wide range of applications. Examples include the use of this method in marine bulkheads, retaining walls in confined spaces, and cofferdam. A cofferdam
is used to dry the construction site of structure foundations such as bridge bases, ports, underground structures, piers and dams. Cofferdams are usually rectangular or circular in shape.
Sheet pile is done with different materials. The selected materials depend on different variables that resistance and environmental conditions are two important variables in the selection of sheet pile materials. The designer must consider the corrosion of the materials and their effects on the main structure. Sheet pile method can be used for permanent and temporary retaining structures. Most permanent structures are made of steel or concrete. Under normal conditions, despite the high operating life of concrete, it has a relatively high initial cost compared to steel. Of course, the useful operating life of steel is also high with a suitable design. Concrete sheet piles are more difficult to install than steel sheet piles. If sheet pile is used as a permanent retaining structure, cathodic protection must be used to prevent corrosion.
The sheet pile is an optimal and cost-effective method for concrete retaining walls and secant concrete walls. In the sheet pile method, concrete does not need to be trapped and excavation can be started after the sheet pile. Therefore, the project execution time is less than similar methods.
History of the sheet pile method
From ancient times, wooden beams have been used to create a retaining wall or dam. However, the new sheet pile method is not more than 100 years old. It can be said that since the 1970s, the type and materials of this method have undergone major changes.
Types of sheets in the sheet pile method
Wooden sheet pile
Wooden sheet piles are used to temporarily stabilize shallow, short walls with light overhead. Of course, in such walls, if water penetration is an important and vital factor, a wooden sheet pile is not a good suggestion.
How to connect wooden sheet piles is in different ways, including the groove and tongue. The following figure shows the different types of connection of wooden sheet piles:
Concrete sheet piles:
Reinforced concrete sheet piles are precast and are usually connected to each other by groove and tongue. It is commonly used for permanent stabilization of river embankments, channels and other water structures.
Metal sheet pile:
Steel is one of the common materials for making sheet piles, which has the following advantages:
- Acceptable resistance
- Proper dewatering
- Possibility to increase the length by welding and screws
- Possibility of connection by interlocking
Metal sheet piles used for temporary stabilization may be removed after the project is completed and used for other purposes. Of course, sometimes they will stay in the ground forever.
Conventional metal sheet pile sections can have different shapes, some of which are mentioned below:
1) Z-type Sheet Piles:
The shape of these sections is like the Z. The locking position of these sheet piles to each other is away from the neutral wire to ensure the transfer of the shear and increase the resistance to weight ratio. This type of sheet pile is the most common type of sheet pile in North America and can be used for many applications.
2) Flat Web Sheet Piles:
The function of this type of sheet pile is different from other sheet piles. Most sheet piles hold water or soil by flexural strength and flexural stiffness. But flat web sheet piles make circular or arched gravity cells. These cells are held together by the tensile strength of the locks. The tensile strength of the lock and the allowable rotation of the lock are the two main design features of this type of sheet piles. These types of cells can be large in diameter and high in height and can withstand high pressures.
3) U-type Sheet Piles:
U-shaped steel sheet piles, like Z-shaped sheet piles, block water or soil from entering the excavation area. The only difference between U-shaped sheet piles is that, unlike Z-shaped sheet piles, they are locked on a neutral wire. Placing these sheet piles in the center of the wall surface reduces the efficiency of this section and reduces the characteristics of this section due to problems in cutting transmission.
4) Pan type Sheet Piles:
The pan type sheet pile is cold rolled and is smaller than other metal sheet piles and is used for low and light overheads. These sheet piles are often used for drainage streams, retaining walls of residential houses and golf grounds.
sheet pile design
Flexural strength and flexural stiffness are the primary considerations for the design of the sheet pile method. The flexural stiffness of the sheet piles is given as input to 2D and 3D software and is designed based on the available overhead and soil specifications, sheet and its distance.
Stages of Sheet pile method installation
1) Compacting or drilling: In order to stabilize the excavation, the excavation should be sheet pile in around according to the soil conditions. If the soil is hard and it is not possible to drill it, it should be drill first and then the sheet should be placed inside the drilled borehole.
2) Excavation: After compacting the sheet piles to the appropriate depth specified in the surveys, it is time to excavate. Excavation is done up to the floor level of the excavation.
3) Horizontal foothill: Depending on the soil conditions and the depth of the excavation, it is possible to place the horizontal members at different levels as a foothill to limit the displacement.
Also, due to soil conditions and the depth of the excavation, it is possible to combine this method with other stabilization methods such as anchorage to limit displacement.
Applications of sheet piles method
- Marine bulkheads
- Cofferdam
- Retaining wall
- Permanent stabilization of river embankments
- Permanent stabilization of channels
- Permanent stabilization of water structures
- Drainage streams
Advantages of the sheet pile method
- High execution speed
- High degree of safety
Disadvantages of the sheet pile method
- Requiring special equipment
- Requiring specialized personnel
Related contents:
Federal Highway Administration (FHWA)
Aarsleff , SHEET PILING
Leave a Reply