Field monitoring and analysis of stresses for dual-purpose pile wall

The dual-purpose bored pile wall, which serves as a retaining wall in the construction period and the outside wall of the permanent underground structures, has been used in some projects. The stresses and load sharing features for this type of wall have been investigated, but field monitoring data are limited. The stresses in the dual-purpose bored pile wall for an excavation in Hongqiao District of Shanghai are monitored from the commencement of excavation to the completion of underground structures. The measured stresses agrees fairly well with the calculated results by the simplified method. In addition, most of the pore water pressures and earth pressures are undertaken by the bored piles during the entire monitoring period. Therefore, the load sharing assumption taken in the simplified method is considered to be reasonable. The dual-purpose bored pile wall has been proved to be feasible and can be widely used in similar excavations.