Deformation properties of diaphragm wall due to deep foundation pit of subway station in Ningbo soft soil
According to the field measured data of a deep foundation pit of subway station of Ningbo rail transit, the paper studies the varieties of deformation rate and cumulative deformation along with excavation time, and estimates the proportion of deformation under different construction phases based on 450 monitoring data of 4 deep foundation pits. The result shows that the main deformation of diaphragm wall due to deep foundation pit of subway station in Ningbo soft soil happens in the third and the forth phases, and these two conditions should be the key point of hierarchical control.
Characteristics of ground surface settlement during excavation
The objective of this paper is to study the characteristics of ground surface settlement during excavation. Ten excavation cases in Taipei with good-quality construction and field observation data are selected to study the characteristics of excavation behavior. The location of maximum lateral wall deflection, magnitude of maximum lateral wall deflection, relationship of maximum lateral wall deflection and maximum ground surface settlement, location of maximum ground surface settlement, and apparent influence range are thus established based on the actual excavation cases. Finally, an empirical formula is proposed to predict the ground surface settlement profile at the center section of an excavation, where the behavior may be characterized by plane-strain conditions. Key words : excavation, surfac settlement, wall deflection, plane strain, empirical formula.
SURFACE SETTLEMENT ADJACENT TO BRACED OPEN CUTS
A semigraphical procedure is developed to predict the settlement gradient of the surface adjacent to a braced open cut. A review of existing methods for defining the zone of influence for underpinning discloses that present methods are not verified by field observations. The theoretical background used in developing the solution is presented. The soil mass behind the bulkhead is treated as a semi-elastic quarter-section that is stretched when the bulkhead moves towards the open cut. A typical example based on an observed open cut in Chicago clay show good correlation between the predicted and the measured settlements.