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Journal of Engineering and Applied Sciences

Year: 2019  |  Volume: 14  |  Issue: 23  |  Page No.: 8676 - 8685

A Case Study of the Ground Collapse Mechanism Due to Excavation-Induced Groundwater Level Disturbance

Y. Han, J. Kim, H. Jang, H. Sohn and K. Yoo

Abstract

Cities are now experiencing accidents with unpredicted ground collapses adjacent to the existing properties. Such ground collapses, caused by natural or artificial factors, may harm the assets in dense urban areas. This study discusses the ground collapse induced by groundwater level disturbance in an excavation site. The subsurface condition was characterized by geophysical methods; ground loosening region around the excavation site was detected and analyzed by Real Time Kinematic (RTK), Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT). To overcome the unreliability or ambiguity problems in the interpretation results, interpretations of the ERT and GPR data are compared and then, integrated for detection of the water leakage in this case study. The survey results showed a wide range of adjacent ground was loosened due to groundwater drawdown. A numerical analysis in MODFLOW was carried out to simulate the groundwater flow on the site. Finally, it can be concluded that the soil erosion due to water leakage and the positive groundwater discharge was the main contributing factor of the collapses. The initial ground improvement plan of high pressure grouting, therefore had to be replaced by low pressure grouting to avoid any further soil erosion that would eventually lead to potential collapses on the adjacent site.

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