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Abstract of the Article

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Influence of Tunneling in Soft Soils on Response of Footings Loaded Dynamically in Vertical Direction

Author:
[ Mahmoud Ghazavi ] - Assistant Professor, Civil Engineering Department, Isfahan University of Technology, Isfahan, Iran

Abstract:

The development in urban areas may lead to the construction of shallow tunnels. The presence of such tunnels may cause tunnel-soil-foundation interaction. In other words, the tunnel construction may alter the response of already-constructed supporting foundations, resulting in changes in machine operations. Such changes may affect the operational behaviour of in-service machines, which are supported by dislocated foundations. In this paper, a two-stage analysis for changes in the response of footings loaded dynamically in axial direction due to tunnelling in clayey soils is performed. A recently developed mathematical model is first used to determine the free field movements of the ground in the vertical direction due to tunnelling. The estimated free field vertical movements are then are imposed on the footing soil and the response of the footing is calculated under several vertical dynamic loads. In the analysis of the footing, for each dynamic load the well-known equilibrium equation is established and explicitly solved. It is shown, through a parametric study, that the effects of tunnelling on the footing response is of great importance and depends on tunnel geometry, tunnel placement relative to the footing, ground loss ratio, and footing geometry. It will also be shown, depending on the placement of the tunnel relative to the footing, that interaction of tunnel-soil-footing can alter the footing response. A parametric study shows that beyond a certain distance between the tunnel axis and the footing, the interaction vanishes.

Keywords:

Settlement, Soft soils, Tunnelling, Winkler type analysis, Shallow foundations, Dynamic analysis