• Geotechnical Engineering
• /
• v.13 no.2
• /
• pp.101-124
• /
• 1997

Adjacent ground surface settlements by deep excavations are analyzed by field observations in the areas where excavations are performed in sandy soils or weathered soils underlain by rocks, First, the magnitude and the distribution of ground surface settlements, which are developed before main excavation activities (e. g., diaphragm wall installation and center pile installation) , are measured and analyzed. Secondly, the magnitude and the distribution of ground surface settlements by main excavation are measured and analyzed. And the results are compared with the predictions obtained by the empirical methods. Through case studies performed on the excavation sites where adjacent ground surfaces or structures are damaged by excavation activities, upper limit location of ground surface cracks are investigated.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.10 no.1
• /
• pp.145-153
• /
• 1990

The relationship between ground surface settlements and wall displacements associated with excavation is analysed by the results of model test of anchored sheet-piles in loose sand. The effect of wall restriction at the toe, anchor slope, wall rigidity, and excavation level on settlement of ground surface and wall displacement are considered for model test. The results of model test are compared with the theory and the results of field measurement of braced wall. The results of analysis are shown by fitted regression equations that may be used for prediction of ground surface settlement adjacent to anchored sheet-piles. It is found that wall displacement and ground surface settlement associated with excavation are different from the supporting methods.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.2
• /
• pp.23-32
• /
• 2001

A soil wall reinforced by soil nailing is excavated in the typical soil conditions which are consisted of weathered soil, weathered rock and soft rock. The resulting nail loads computed are compared to loads measured by utilizing strain gauges during construction. The wall deflection at two locations are related to construction events and specific soil conditions, providing an understanding of the behavior of soil nailed walls. The load distribution along the nail indicated relatively high loads close to the wall. The mobilized load on the nail is proportional to the wall deflection showing the maximum value at the surface of the wall. The construction monitoring for this project provided valuable information in understanding the behavior of soil nailed walls.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.2
• /
• pp.19-28
• /
• 2006

Long-term field observations were performed in three excavation sites in order to investigate the displacement behavior of adjacent ground during overall excavation procedure, where the depths of deep excavations were 15 m$\∼$29 m. In this study, ground settlements and lateral displacements of braced wall measured during installation of retaining wall and removal of bracing were specially focused to evaluate the behavior quantitatively according to three-stage-divided procedure, i.e. pre-excavation, main excavation, and removal of bracing. Through field measurements on three excavation sites, lateral displacements induced during removal of bracing are approximate to 40$\%$ of the amount found during main excavation stage and additional adjacent ground deformation during post-excavation procedure ranges from 18$\%$ to 33$\%$ of that found during main excavation stage, based on the settlement volume. In conclusion, it was quantitatively identified in this study that the deformations of adjacent ground during pre- and post-excavation stage were not negligible.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.7
• /
• pp.99-104
• /
• 2007

The deep soil mixing, on ground modification technique, has been used for many diverse applications including building and bridge foundations, port and harbor foundations, retaining structures, liquefaction mitigation, temporary support of excavation and water control. This method has the basic objective of finding the most efficient and economical method for mixing cement with soil to secure settlements through improvement of stability on soft ground. In this research, the experiments were conducted on a laboratory scale with the various test conditions of mixing method; the angle of mixing wing, mixing speed. Strength and shapes of improved soil of these test conditions of deep mixing method were analysed. From the study, it was found that the mixing conditions affect remarkably to the strength and shapes of improved soils.

• Journal of the Korean Geosynthetics Society
• /
• v.16 no.4
• /
• pp.231-240
• /
• 2017

Recently, there have been frequent occurrences of ground sink in the urban area, which have resulted in human and material damage and are accompanied by economic losses. This is caused by artificial factors such as soil loss, poor compaction, horizontal excavation due to the breakage of the aged sewage pipe, and lack of water proof at vertical excavation. The ground sink can be prevented by preliminary restoration and reinforcement through exploration, but it can be considered that it is not suitable for urgent restoration by the existing method. In this study, a model experiment was carried out to simulate the in-ground cavities caused by groundwater flow for developing non-excavation urgent restoration in underground cavity and the range of the relaxation zone was estimated by detecting the around the cavity using a relaxation zone detector. In addition, disturbance region and relaxation region were separated by injecting gypsum into cavity formed in simulated ground. The shape of the underground cavity due to the groundwater flow was similar to that of the failure mode III formed in the dense relative density ground due to water pipe breakage in the previous study. It was confirmed that the relaxed region detected using the relaxation zone detector is formed in an arch shape in the cavity top. The length ratio of the relaxation region to the disturbance region in the upper part of the cavity center is 2: 1, and it can be distinguished by the difference in the decrease of the shear resistance against the external force. In other words, it was confirmed that the secondary damage should not occur in consideration of the expandability of the material used as the injecting material in the pre-repair and reinforcement, and various ground deformation states will be additionally performed through additional experiments.