Horizontal Displacement of Urban Deep Excavated Walls Supported by Multistrands Anchors, Steel Piles, and In Situ Concrete Piles: Case Study

Abstract

Deep excavations are commonly used in urban areas due to the extreme increase in ground worth. Stability and displacement of adjacent structures are two main design criteria in stabilized excavated walls. In this paper, one of the largest excavations in urban areas in Iran, the Farmanieh Project, is examined as a case study. The minimum and maximum depths of the excavation were about 26 and 45 m, respectively. Three different support systems including multistrand anchors, steel piles combined with multistrand anchors, and concrete piles combined with multistrand anchors were used. Owing to the limitation of lateral movement of adjacent buildings and urban facilities, the displacement of the excavated walls was controlled by precise instruments during and after the construction procedure to compare actual displacement and numerical analyses predictions. The results showed that if the construction procedure, including delays during the excavation procedure and vibration of construction machinery during drilling, the groundwater level, and soil properties were not properly taken into account, numerical analysis could be misleading in predicting wall displacement during deep excavations. Therefore, considering the factor of safety against displacement is as important as the factor of safety against failure.