• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4201-4207
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• 2015

In this study, the performance of underground water pipeline system affected by earthquakes is examined by using data acquired after MW 6.2 February 22, 2011 earthquake in Christchurch, NZ. Water pipeline repair rates, expressed as repairs/km, for different types of pipe are evaluated inside the areas of which liquefaction induced by permanent ground deformation was observed and assessed relative to differential settlement and lateral ground strain, calculated from high resolution LiDAR data acquired before and after each seismic event. The earthquake performance of underground water pipeline systems associated with permanent ground deformation is summarized in this paper. The results show that highly ductile polyethylene water pipelines has a high earthquake performance.

• Geomechanics and Engineering
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• v.21 no.2
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• pp.171-178
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• 2020

Mountainous areas cover more than 70% of Korea. With the rapid increase in tunnel construction, tunnel-collapse incidents and excessive deformation are occurring more frequently. In addition, longer tunnel structures are being constructed, and geologically weaker ground conditions are increasingly being encountered during the construction process. Tunnels constructed under weak ground conditions exhibit long-term deformation behavior that leads to tunnel instability. This study analyzes the behavior of the bottom region of tunnels under geological conditions of long-term deformation. Long-term deformation causes various types of damage, such as cracks and ridges in the packing part of tunnels, as well as cracks and upheavals in the pavement of tunnels. We observed rapid tunnel over-displacement due to the squeezing of a fault rupture zone after the inflow of a large amount of groundwater. Excessive increments in the support member strength resulted in damage to the support and tunnel bottom. In addition, upward infiltration pressure on the tunnel road was found to cause severe pavement damage. Furthermore, smectite (a highly expandable mineral), chlorite, illite, and hematite, were also observed. Soil samples and rock samples containing clay minerals were found to have greater expansibility than general soil samples. Considering these findings, countermeasures against the deformation of tunnel bottoms are required.

• Geomechanics and Engineering
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• v.33 no.5
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• pp.439-451
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• 2023

The construction of shield tunnelling in urban sites is facing serious risks from complex and changeable underground conditions. Construction problems in the sand-clay mixed ground have been more reported in recent decades for its poor control of soil loss in tunnel face, ground settlement and supporting pressure. Since the limitations of observation methods, the conventional physical modelling experiments normally simplify the tunnelling to a plane strain situation whose results are not reliable in mixed ground cases which exhibit more complicated responses. We propose a new method for the study of the mixed ground tunnel through which mixed lays are simulated with transparent soil surrogates exhibiting different mechanical properties. An experimental framework for the transparent soil modelling of the mixed ground tunnel was established incorporated with the self-developed digital image correlation system (PhotoInfor). To understand better the response of face stability, ground deformation, settlement and supporting phenomenon to tunnelling excavation in the sand-clay mixed ground, a series of case studies were carried out comparing the results from cases subjected to different buried depths and mixed phenomenon. The results indicate that the deformation mode, settlement and supporting phenomenon vary with the mixed phenomenon and buried depth. Moreover, a stratigraphic effect exists that the ground movement around mixed face reveals a notable difference.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.170-175
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• 2003

The ASCE formula of pipeline' soil interaction force is the basis of semi-analytical relationship for buried pipelines subjected to longitudinal permanent ground deformation due to seismic induced liquefaction. However, since the ASCE formula has been developed based on the stiffness of non-liquefied region, it is needed to modify for the varied stiffness of liquefied region. With this object, the consideration of decreasing effect of soil stiffness in liquefied region is made: i.e. the spatial distributions of pipeline. soil interaction force in liquefied region. It means that the improved formula can reflect various patterns of permanent ground deformation more realistically. Through the comparative analyses using both the improved and ASCE formula, the applicability of the improved, the limitation of the existing formula and semi-analytical relationship are discussed.

• Geomechanics and Engineering
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• v.4 no.2
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• pp.91-103
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• 2012

Focusing on the effect of excess pore pressure dissipation on liquefaction-induced ground deformation, a series of 1-g shaking table tests were conducted in a rigid soil container by use of saturated Toyoura sand, the relative density of which was 20-60%. These tests were subjected to the sinusoidal base shaking with step increased accelerations: 100, 200, 300 and 400 Gals for 2-4 seconds. Shaking table tests were done using either water or polymer fluid with more viscous than water, thus varying the sand permeability of model tests. Excess pore pressures, accelerations, settlements and lateral deformations were measured in each test. Test results are presented in this paper and the effect of sand permeability on liquefaction and liquefaction-induced ground deformation was discussed in detail.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1343-1350
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• 2005

In this study, the whole deformation conditions of domestic old tunnels and reinforcement methods for deformation tunnels were investigated and analysed, and the present conditions, occurrence cause and reinforcement methods of cavity behind the tunnel lining were investigated and analysed comprehensively. The deformation causes of domestic old tunnels could be classified in three kinds : change of earth pressure operating tunnel ground, material problem of concrete lining, mistake of design and construction. As a result of analysis, the tunnel deformation was occurred by not specific cause but various cause As a result of investigation for 455 domestic tunnel data, more than 70% of the tunnel deformation was related to leakage and the other deformation cause also accompanied leakage mostly. An applied reinforcement method was related to leakage and flood prevention measures, but application of reinforcement method for boundary area between tunnel and ground and tunnel periphery which influence on the tunnel stability was still defective. The cavity of domestic old tunnel occupied about 16% of the total tunnel length and about 68% of cavity was located in the crown of tunnel, and besides, the occurrence cause of cavity was analysed to design, construction and management cause. The filling method for cavity using filling material was comprehensively appling to cavity behind tunnel lining.

• Geotechnical Engineering
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• v.14 no.1
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• pp.81-92
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• 1998

Coal ash from thermal power plants has been produced in large quantity and discarded uselessly, However, it is possible to supply construction material properly by utilizing the coal ash as construction material. In this study, the applicable model and its applicability for deformation analysis of coal ash fill and reclamation ground are studied. Camflay model gives complete constitutive law which illustrates deformation and pore water pressure while soil is loaded under the various stresses at drained and undrained conditions. The merit of proposed model which is acquired from laboratory tests is that only a few soil parameters are available. The whole parameters of Camflay model are obtained by typical mechanical test and CV triaxial test on the sample with optimum mixing ratio( i.e. fly ash : bottom ash=5:5) Then the results from proposed numerical analysis are compared with laboratory results. The differences between laboratory test and numerical analysis are negligible. Parameters deter mined from laboratory tests are useful as a basic data for deformation analysis of coal ash reclamation ground using Camflay model.

• The Transactions of the Korea Information Processing Society
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• v.13 no.9
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• pp.468-473
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• 2024

Excavation work in urban areas can induce ground deformation, which may damage nearby infrastructure. Such ground deformation can result in displacement of paving blocks near the construction site. Accurate measurement of these displacements can serve as an indicator for assessing the potential risks associated with ground deformation. This paper proposes a robust and efficient method for paving block displacement measurement using a 3D laser line sensor mounted on an Unmanned Ground Vehicle (UGV). The proposed method consists of two stages: 2D projection based object detection and measurement through the CPLF algorithm. Experimental results demonstrate that the CPLF algorithm is more efficient compared to the PLF algorithm, achieving an error of 1.36 mm and a processing time of 10.76 ms, confirming that the proposed method ensures robust online measurements with high accuracy in real-world environments with various types of paving blocks and environmental factors using a 3D laser line sensor on a UGV.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.887-903
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• 2017

Lots of shallow tunnels are constructed in the mountainous areas where the stress distribution in the ground around tunnel is not simple, also the impact of stress conditions on the longitudinal load transfer characteristics is unclear. The tunnel construction methods and the ground conditions would also affect the longitudinal load transfer characteristics which would be dependant on the displacement patterns of tunnel face. Therefore, in this study, the slope of the ground surface was varied in $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$, and the longitudinal load transfer depended on the deformation conditions of tunnelface (that were maximum deformation on the top, constant deformation, and maximum deformation on the bottom), and the stress distribution at tunnelface. As results, when the tunnelface deformed, the earth presure on the tunnelface decreased and the load at tunnel crown increased. The load transferred on the crown was influenced by the earth presure on tunnel face. Smaller load would be transfered to the wide areas when the slope of ground surface decreased. When the slope of ground surface became larger, the longitudinal load transfer would be smaller and would be concentrated on tunnelface, In addition, the shape of the transferred load distribution in the longitudinal direction was dependant on the deformation shape of tunnelface. The deformation shape of tunnelface and stress conditions in longitudinal sections would affect the shape and the magnitude of the load transfer in the longitudinal directions.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.57-64
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• 1999

In order to decide critical vibration level on structural damages induced by near blasting, deformation of existing cracks in structure was investigated and ground vibrations were measured. New criteria to evaluate blasting damage to structure are proposed considering daily deformation of cracks in structures. Results from 2 brick houses in fishing village show that new design criteria far more than current are required to cause structural damage for brick houses.