Abstract: This paper proposes a horizontal displacement monitoring method based on structural analysis of a typical braced excavation for deep foundation. Using translation of coordinates, the temporary coordinate system for excavation monitoring is converted to an independent coordinate system with the datum point located at a corner of the foundation pit.  Monitoring results show that accumulated critical value of the horizontal displacement is 30mm. This method which is suitable for the more complex surrounding environment of the rectangular or nearly rectangular pit should not be used for circular pits or pits with other irregular shapes.

Key words: Excavation Engineering, Independent Coordinate System, Free Stationing, Displacement Monitoring