Estimating the Vulnerability Index of Buildings in Relation to the Excavation of Urban Tunnels

Document Type : Original Article

Abstract

Ground deformation due to the tunnel excavation process will inevitably have an impact on existing buildings and structures, and this phenomenon is unavoidable in urban tunneling. In this regard, the damage to buildings and surface structures depends on the type and condition of the building, the characteristics of the structure, and the amount of settlement caused by excavation. Therefore, due to the importance of the issue, it is necessary to estimate the risk of tunnel excavation in the area of buildings. In this paper, based on the experiences gained from the projects of Tehran Metro Line 7 and Qom Metro Line A, the categories and scores related to the effective factors in estimating the vulnerability index are reviewed and updated. For this purpose, the buildings that have suffered significant damage due to tunnel excavation in these projects are introduced. In other words, the damage to these buildings has sometimes exceeded the relevant forecasts. This is related to the error in estimating the vulnerability index of the building, because the amount of damage to the building is predicted based on the vulnerability index (for a specific amount of settlement). Therefore, by eliminating the existing shortcomings in determining the vulnerability index of the building, a more appropriate prediction can be made about possible future damages due to tunnel excavation. After introducing the damaged buildings in the studied projects, the main factors affecting the vulnerability of the buildings have been investigated and their scores have been adjusted. After that, the classification of each of the effective sub-factors according to the findings of the damaged buildings and with engineering judgment has been updated and the scores related to each category have been corrected if necessary. Moreover, to validate the proposed method in this study, the damage category of the studied buildings in Tehran Metro Line 7 and Qom Metro Line A projects was examined. In this regard, their damage category was determined based on the valid criteria of Rankin, which has been widely used in the analysis of damage status and stability of buildings, using the previous method and the method of the present study. By comparing the predicted damage categories and the actual damage category of buildings, the performance of the method presented in the present study was evaluated to determine the building vulnerability index. The results showed that the use of the new method significantly improves the accuracy of estimating the damage category of buildings.

Keywords

References

 
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Construction science and technology
Volume 2, Issue 2 - Serial Number 4
October 2021
Pages 21-32

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