Design of steel sheet piles retaining structure, the designer can choose free support or fixed support. The difference between the two is the depth of the embedded deformation of the wall.
The free-standing retaining wall may be simplified as a vertical simply supported beam embeddedough deep to prevent translational motion but still capable of pivoting about the pile end as a hinge and a near-end support or rod as another Fulcrum. For a given condition , The required pile length for free-standing retaining walls is minimal, but the bending moment on the wall is the great.
The fixed steel sheet piles
supports the retaining wall to be equivalent to the vertical supporting cantilever beam. The increase of the embedding depth of the wall avoids the translation and rotation of the wall. The pile end can be assumed as a fixed end. The tie The solid end of the pile will produce a solid end torque to reduce the maximum bending moment on the wall, the corresponding need to increase the pile length. The solid-end confinement is assumed to be The basis for the design of the cantilever wall, and the stability of the cantilever wall is maintained by the fixed end.
For the fixed support retaining wall, as long as the support arrangement is reasonable, the wall can resist bending moment and shear force, there is no overall stability checking problem. In addition, it can also be empirically designed.
Particular care should be taken in selecting the design method. For example, a steel sheet piles retaining wall in a soft clay may not produce sufficient pressure to secure the pile end. It is advisable to assume free support in this case. When the embedded depth Of the wall is greater than the depth to maintain lateral stability, it is possible to cut off groundwater or to provide sufficient vertical bearing capacity, assuming that the fixed support is more appropriate. However, it is also a problem to hit the steel sheet piles To the design depth. The free support assumes that the piling length is the shortest. When the fixed support is assumed, it is necessary to ensure that the theoretical bending moment is not reduced.
When the steel sheet piles retaining wall is high, there are multi-channel support, the steel pile need to have enough pile length, in the design of solid-side support assumed, and the use of reduced bending moment calculation. Located below the center point of the retaining height, the assumptions in the analytical model do not apply in this case and therefore the pile length can not be calculated from the free or fixed bearing assumptions.