Performance Evaluation of Anchored Diaphragm Walls under Service Loads

Document Type : Research Article

Authors

Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran

Abstract

Nowadays, RC or combined diaphragm walls are vastly used for deep excavation. This type of retaining structures consists of some piles, which are tied-back using the anchors and anchored from their toe to the ground. Concrete or wood plates were used between them. In order to evaluate the effects of some parameters on wall deflection and its internal forces, several models of combined diaphragm walls were selected and analyzed using FLAC software. Before developing the models, Lim and Braiud (1999) case study was modeled with FLAC2D and results were compared with the experimental results indicating acceptable accuracy of the modeling. The numerical model simulated the soldier piles with beam elements and the anchors with cable elements. The soil model used is a modified hyperbolic model with unloading hysteresis. The complete sequence of construction was simulated including the excavation and the placement and stressing of the anchors. The numerical model was calibrated against an instrumented case history. Then a parametric study was conducted. The parameters which was evaluated were: distance and stiffness variation, the bonded and un-bonded length of the anchors, the angle of the anchors and the first raw anchor location. By comparing the different parameters it was observed that the variation of the flexural stiffness of the soldier piles and variation of the bond length of the anchors contained the highest and lowest effect on the maximum horizontal displacement of the wall, respectively. Other analytical results consisting wall deflection vs. geometric characters of the wall were presented and discussed.

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