Effects of Active Axial Force Adjustment of Struts on Support System during Pit Excavation: Experimental Study
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 150, Issue 5
Abstract
Given their high cost, servo steel struts typically are used only in specific sections of foundation pits in which nearby buildings are sensitive to excavation-induced deformation. Servo steel strut adjustments affect the mechanical behaviors of adjacent ordinary-steel-strut-supported areas. However, the plane strain assumption is used in current designs, ignoring this influence. To propose a more reasonable design, the effects of servo steel strut adjustments should be examined. In this study, a model support system with adjustable strut axial forces was constructed (scale: , under ), and several groups of tests with different adjustment schemes were conducted. The lateral earth pressure, lateral wall deflection, and strut axial forces were monitored and analyzed. The results indicated the following: (1) the first level of struts is not suitable to be actively adjusted because this can increase the maximum lateral wall deflection; (2) increasing the strut axial forces can lead to redistribution of lateral earth pressure along the horizontal direction, which can be divided into two areas with different characteristics, and whereas the lateral wall deflection decreases in both areas, the lateral earth pressure increases in the area adjacent to the adjusted strut and decreases in the other area; and (3) a transition section can be designed between the servo-steel-strut-supported area and the ordinary-steel-strut-supported area, within which strut adjustment diminishes as one approaches the ordinary-steel-strut-supported area. However, the horizontal length of the transition section should exceed a threshold value, which is approximately 3 times the horizontal strut distance, to effectively mitigate the axial force reduction in ordinary steel struts.
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Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
This research was supported by the National Natural Science Foundation of China through Grant no. 52278456.
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Information & Authors
Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 150 • Issue 5 • May 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Mar 27, 2023
Accepted: Dec 12, 2023
Published online: Feb 26, 2024
Published in print: May 1, 2024
Discussion open until: Jul 26, 2024
ASCE Technical Topics:
- Axial forces
- Construction engineering
- Construction methods
- Continuum mechanics
- Displacement (mechanics)
- Dynamics (solid mechanics)
- Engineering materials (by type)
- Engineering mechanics
- Excavation
- Forces (type)
- Geomechanics
- Geotechnical engineering
- Lateral pressure
- Materials engineering
- Metals (material)
- Pressure (type)
- Soil dynamics
- Soil mechanics
- Soil pressure
- Solid mechanics
- Steel
- Structural engineering
- Structural mechanics
- Structural members
- Structural systems
- Struts
- Walls
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