• Journal of Power System Engineering
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• v.3 no.4
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• pp.57-62
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• 1999

The microaccelerometer using a tunnelling current effect concept has the potential of high performance, although it requires slightly complex signal-processing circuit for servo-system. The paddle of micro accelerometer is pulled to have the gap width of about 2nm which almost allows the flow tunnelling current. This paper demonstrates at capacitor of microaccelerometer the use of the coupled thermo-electric analysis for voltage, current, heat flux and Joule heating then tunnelling current flows. Two electrodes are applied to the microaccelerometer producing a unform difference of temperature gradient and electric potential between the paddle and the substrate.

• Journal of Korean Tunnelling and Underground Space Association
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• v.6 no.4
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• pp.357-365
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• 2004

Tunnel portals are often located in areas where the risk of rock fall and/or detachement of rock fragments from rocky slopes is high. In this case it is necessary to design the portals so as to protect the road (i.e. using an artificial tunnel) or to instal structures that are able to intercept falling blocks on the slope. This paper deals with the design problems of these structures and includes a special analysis of net fences which have undergone a remarkable technological improvement over recent years.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.311-318
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• 2002

A GIS-based tunnelling risk management system (GIS-TURIMS) has been developed in this study, The developed system uses ArcView 8.2 as a basic platform and the built-in interface (VBA) has been used to perform first-order simplified analyses for prediction of tunnelling-induced ground movements and building damage assessment. The main emphasis in this study was to develop a working framework that can be used in the perspective of tunnelling risk management. The developed system is capable of carrying out computationally intensive analyses for ground movement prediction as well as building/utilities damage assessment with fully taking advantage of the GIS technologies. This paper describes the concept and details of the GIS-TURIMS development and implementation

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.679-686
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• 2002

A substantial portion of the cost of a tunnelling project in urban environments is, therefore, devoted to prevent ground movement. Therefore, prediction of ground movements and assessment of risk of damage to adjacent buildings has become an essential part of the planning, design, and construction of a tunnelling project in the urban environments. An internet-based tunnelling-induced ground movements and building damage assessment system (IT-TURIMS) was developed and implemented to Daegu Metro Subway Line tunnel construction project in Korea. This paper describes the concept and implementation of IT-TURIMS. Practical significance of tunnelling risk assessment is also discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.86-95
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• 2010

Ground movements during tunnelling have the potential for major impact on nearby buildings, utilities and streets. The impacts on buildings are assessed by linking the magnitude of ground loss at the source of ground loss around tunnel to the lateral and vertical displacements on the ground surface, and then to the lateral strain and angular distortion, and resulting damage in the building. To prevent or mitigate the impacts on nearby buildings, it is important to understand the whole mechanism from tunnelling to building damage. This paper discusses tunneling-induced ground movements and their impacts on nearby buildings, including the importance of the soil-structure interactions. In addition, a building damage criterion, which is based on the state of strain, is presented and discussed in detail and the overall damage assessment procedure is provided for the estimation of tunnelling-induced building damage considering the effect of soil-structure interaction.

• The Korean Journal of Pain
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• v.1 no.1
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• pp.59-63
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• 1988

Recently, epidural tunnelling was introduced for the convenience of keeping a catheter inserted for a long period of time. We had 15 cases in which used epidural tunnelling for the treatment of intractable pain mainly in terminal cancer patients. Epidural puncture with cannulation was carried out in the same technique as used for epidural anesthesia. After the subcutaneous epidural tunnelling was done from the site of the epidural entry to the anterior chest, just under the slim using a tunnelling device, the catheter was threaded through the tunnelling needle at the site of the outlet, was fixed and the tip of the catheter was connected to a filter. Five ml (2 mg) of saline diluted morphine can be given at home as needed when intractable pawn occurs. This long-term treatment of intractable pain by morphine injections through the epidural cannula place by subcutaneous tunnelling, is very convenient for the patient's daily routine and a better alternative in such a situation. Our technique, its advantages and problems were described in this paper.

• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.870-875
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• 2001

Objectives : Anterior tunnelling technique consist of anterior cervical fractional interspace decompression without fusion. This method provides sufficient space for adequate neuroforaminal decompression but avoids the need for fusion or fixation. We report early clinical results of 32 cases that underwent anterior tunnelling operation for treatment of cervical radiculopathy. Methods : This method is identical to conventional approach until the exposure of anterior cervical body and bilateral retraction of longus colli is made. A vertical window is then made at the vertebral bodies and disc space lateral to the insertion site of the longus colli. The window is deepened with drilling that follows a tunnelling fashion down to the compressive lesion. We analyzed clinical results from 32 patients who treated between December 1998 and August 2000. Results : Satisfactory results were obtained in 87% of the patients. Two patients required revision surgery. None revealed surgical spinal instability on last follow-up. Conclusion : Anterior tunnelling operation is an acceptable surgical option for the treatment of cervical radiculopathy. Its advantages are short hospitalization, minimal postoperative discomfort, and technical feasibility.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.199-210
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• 2012

The effects of tunnelling in weak weathered rock on the behaviour of a pre-existing single pile and pile groups ($3{\times}3$ and $5{\times}5$ pile groups) above a tunnel have been studied by carrying out three-dimensional (3D) elasto-plastic numerical analyses. Numerical modelling of such effects considers the response of the single pile and pile groups in terms of tunnelling-induced ground and pile settlement as well as changes of the shear transfer mechanism at the pile-soil interface due to tunnelling. Due to changes in the relative shear displacement between the pile and the soil at the pile-soil interface with tunnel advancement, the shear stresses and axial pile force distributions along the pile change drastically. Based on the computed results, upward shear stresses are induced up to about Z/L=0.775 from the pile top, while downward shear stresses are mobilised below Z/L=0.775, resulting in a reduction in the axial pile force distribution with depth equivalent to a net increase in the tensile force on the pile. A maximum tensile force of about $0.36P_a$ developed on the single pile solely due to tunnelling, where $P_a$ is the service axial pile loading prior to tunnelling. The degree of interface shear strength mobilisation at the pile-soil interface was found to be a key factor governing pile-soil-tunnelling interaction. Overall it has been found that the larger the number of piles, the greater is the effect of tunnelling on the piles in terms of pile settlement, while changes of the axial pile forces for the piles in the groups are smaller than for a single pile due to the shielding effect. The reduction of apparent allowable pile capacity due to tunnelling-induced pile head settlement was significant, in particular for piles inside the groups.

• Geomechanics and Engineering
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• v.11 no.4
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• pp.553-570
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• 2016

A series of three-dimensional (3D) parametric finite element analyses have been performed to study the influence of the relative locations of pile tips with regards to the tunnel position on the behaviour of single piles and pile groups to adjacent tunnelling in weathered soil. When the pile tips are inside the influence zone, which considers the relative pile tip location with respect to the tunnel position, tunnelling-induced pile head settlements are larger than those computed from the Greenfield condition. However, when the pile tips are outside the influence zone, a reverse trend is obtained. When the pile tips are inside the influence zone, the tunnelling-induced tensile pile forces mobilised, but when the pile tips are outside the influence zone, compressive pile forces are induced because of tunnelling, depending on the shear stress transfer mechanism at the pile-soil interface. For piles connected to a cap, tensile and compressive forces are mobilised at the top of the centre and side piles, respectively. It has been shown that the increases in the tunnelling-induced pile head settlements have resulted in reductions of the apparent factor of safety up to approximately 43% when the pile tips are inside the influence zone, therefore severely affecting the serviceability of the piles. The pile behaviour, when considering the location of the pile tips with regards to the tunnel, has been analysed in great detail by taking the tunnelling-induced pile head settlements, axial pile forces, apparent factor of safety of the piles and shear transfer mechanism into account.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.3
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• pp.333-339
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• 2015

In this paper, the surface settlement resulted from the shallow TBM tunnelling has been numerically simulated. TBM tunnelling is especially used in urban area to avoid serious vibration and noise caused by explosion in NATM. Surface settlement is one of the most important problems encountered in all tunnelling and critical in urban areas. In this study, face vibration of TBM excavation is considered to estimate surface settlement trend according to TBM extrusion. The dynamic excavation forces are calculated by total torque on the TBM cutterhead in mixed-face of soil and weathered rock condition with shallow depth. A 3-dimensional FDM code is employed to simulate TBM tunnelling and mechanical-dynamic coupling analysis is performed. The 3D numerical analysis results showed that dynamic settlement histories and trend of surface settlement successfully. The maximum settlement occurred at the excavation point located at 2.5D behind the face, and the effect of face vibration on the surface settlement was verified in this study.