The earth pressure map is the foundation of the design of the steel sheet piles
retaining wall. The commonly used triangular earth pressure map is based on the assumption that the wall exits the soil to generate active earth pressure, while the extruded soil generates the passive earth Pressure. This simplified pressure map is to facilitate hand calculation, the calculation results tend to be conservative.
The correction of the triangular earth pressure map, which takes into account the movement of the wall, is usually done by software, which results in a decrease in pressure (soil arching) at larger displacements at smaller displacements of the wall (eg, the supporting Point).
If soil / pile interaction is considered, the earth pressure map can be further modified. This also requires more advanced software, the result of the amendment is to reduce the active earth pressure, passive earth pressure increases.
This is also the case when the base plate and the cantilever retaining wall are in contact with each other if the position of the wall support is relatively low. In this case, the bottom plate as a fulcrum, failure mode for the fulcrum of the upper Part of the wall to leave the soil direction offset, the fulcrum of the lower part of the wall to the soil body offset. This leads to a change in the active passive earth pressure below the fulcrum, which must be taken into account in the design .
The post-wall load-relief platform will reduce the active earth pressure at the lower part of the platform. Assuming that all the overloads and soil mass are borne by the load-bearing platform and transferred as vertical loads to the vertical load-bearing members , The wall pressure and bending moment will be lower.