One of the methods of the earth retention the Soldier Pile wall and Lagging wall system (berlin wall).
Soldier Pile wall and Lagging wall System is actually a combination of:
- Soldier pile (concrete or steel piles): width double IPE, pipe, in situ concrete pile, and
- Lag such as: shotcrete or precast concrete, timber or steel sheet.
For trapping steel and concrete piles, about 25% of their length is considered as the root of the pile. In order to prevent local falls between the piles, in-situ or precast concrete surfaces, timber, etc. are used.
One of the common concrete surfaces in urban projects is concrete shotcrete which after excavation, a steel bar mesh is placed between the piles and then by shotcrete, a concrete surface is created between piles.
Precast concrete can be used for permanent stabilization and timber can be used for temporary stabilization.
To earth retention or prevent settlement in the vicinity of settlement-sensitive structures, the combination of Berlin wall method with nailing, anchorage or struts is also used.
History Soldier Pile wall and Lagging wall system (Berlin Wall)
The Soldier Pile wall and Lagging wall system (Berlin Wall) is one of the oldest methods of the earth retention. It has been successfully performed in major cities such as New York, Berlin and London since the 18th century. The reason for naming this method the Berlin Wall goes back to its use in the 1930s on the Berlin Underground train. The Soldier Pile Wall is often used interchangeably with the Berlin Wall.
Basic Design of soldier pile wall and lagging wall system
Specifications of 1 meter of concrete surface section plus specifications of pile materials divided by their distance are given to 2D Geo-Slope software and Plaxis 2D finite elements, and then the reliability coefficient and wall displacement are obtained. In 3D software such as Plaxis 3D, the whole wall is simulated and only the specifications of the materials are given.
Execution method of a of berlin wall method
- The Execution of piles:
In the case of using concrete piles, in situ concrete piles should be executed according to the executive plans. If metal piles are used, which are often wide double IPE, IPE or pipes, the piles are drilled first and then the roots of the piles are concreted.
Steel piles are then placed in the drilled locations. Of course, steel piles can also be made by compacting. The type of pile and the diameter of the pile depend on the load adjacent to the excavation and the soil characteristics.
2) Completing the wall between the piles:
After the execution of the piles, excavation begins and is excavated to the appropriate level for the execution of steel mesh or timber, and then to prevent local fall of the steel mesh and then shotcrete is done or timber is placed.
This process continues to the end of the excavation. In cases where the displacement near the excavation is relatively sensitive, the back of the timber should be filled with dense material. The thickness of timber or concrete surface depends on the type of soil, the distance of the piles, etc.
The forces are transmitted to the concrete or steel piles (Soldier Piles) by concrete or timber and then they are tolerated by concrete or steel piles in the form of a cantilever and cause an excavation static. If concrete or steel piles alone are not able to withstand these forces, use a combination of this method with other stabilization methods such as nailing, anchorage, struts and pressure on the piles are tolerated.
For structures designed in the final limit state (LRFD), the service life of timber is about 75 years. Therefore, timber is not acceptable for structures that have a service life of more than 75 years.
The following American highway regulations are used to design timber:
“Lateral Support Systems and Underpinning” (Report No. FHWA-RD-75-130)
According to this regulation, for 3 different soil types, the conditions of timber are presented:
Applications of berlin wall method
- Suitable for excavations where the water level is below the floor level of the excavation
- Suitable for excavations around which there are no settlement-sensitive structures
Advantages of Applications of soldier pile wall and lagging wall system (Berlin Wall)
The following are some of the advantages of the Berlin wall and lagging wall system.
over other methods of stabilizing the excavation:
- Suitable price compared to other methods of stabilization
- Easy and fast execution
- No need for special equipment
The following are some of the disadvantages of berlin wall compared to other methods of stabilizing the excavation:
- No recommendation for permanent stabilization
- No recommendation for high water level
- Low stiffness compared to stabilized walls in other ways
Related contents:
Federal Highway Administration (FHWA)
Aarsleff , Berliner walls
Deep Excavation , SOLDIER PILE WALLS
Bauer-Egypt , Berlin Walls
Finesoftware , Soldier Pile Wall
Federal Highway Administration (FHWA)
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