Jong-Ho Shin

Hydraulic Significance of Fractured Zones in Subsea Tunnels

This article presents the effect of fractured zones on subsea tunnels. Generally, a subsea tunnel is designed to support high water pressure so that the hydraulic condition is of fundamental interest. In cases where fractured zones exist along the tunnel route, attention should be paid to it at the design stage. However, there is not much information about the hydraulic influences on the fractured zones. Pore water pressure and inflow rates are the main hydraulic factors to be considered in the design. In this article, the hydraulic effects on the fractured zones of a subsea tunnel under construction and during operation have been investigated using a numerical method and small scale model tests. The Vardø tunnel, which is a subsea tunnel in Norway (Grønhaug and Lynnegerg, 1984), is used for the numerical modeling. Based on the analysis results, the significance of fractured zones in subsea tunnels is identified.

Performance evaluation of pin-holed pipe anchor for fractured zone in subsea tunnel

ABSTRACT The presence of a fractured zone at a tunnel face can threaten the stability of the tunnel by causing water leakage and degradation of the soil strength. In this case, to stabilize the tunnel face, the pore water pressure is generally reduced and the loss of soil particles is prevented by installing drainpipes. The installation of drainpipes, however, can cause the concentration of flow channels and other ground instability problems. In this paper, a novel pin-holed pipe anchor is proposed to overcome the problems occurring in subsea tunnels. The pin-holed pipe anchor is a pipe-type support member designed to reinforce the ground while simultaneously enabling flow into the tunnel. Here, the design requirements of the pin-holed pipe anchor were examined through material tests, and the structural–hydraulic characteristics of the pin-holed pipe anchor were investigated through a model test. Furthermore, the applicability of the pin-holed pipe anchor to an actual tunnel was evaluated by numerical analysis of actual tunnels. Through selection of an appropriate perforated drainage area and bonded length, the pin-holed pipe anchor contributed to the improvement of the structural and hydraulic stabilities of the tunnel.

An experimental study on the static behavior of advanced composite materials drainage pipe member for an undersea tunnel

In order to design an advanced composite materials drainage pipe structures for an undersea tunnel, mechanical properties for the lamina types of the structural member must be predetermined. It is also reported that the size effect of the specimen is significant. In this study the tensile tests for the lamina types of the structural member are conducted at the room temperature () and the seawater temperature (). In addition, the mechanical properties are predicted by theory based on the rule of mixtures and elasticity solution technique. The predicted mechanical properties are compared with test results obtained by a test method. In the design of an advanced composite materials drainage pipe structural members for an undersea tunnel, the used mechanical properties must be applied at the room temperature with considering the modified factors. These are to be offered the datum for the design an advanced composite materials drainage pipe structures for an undersea tunnel.

Review on the buoyancy effect of the multi purpose double-deck tunnels during operation

ABSTRACT: Double-deck tunnels beneath the groundwater table have relatively large volume and commonly constructed as watertight tunnels. In this case, it requires to secure stability of the tunnels for buoyant force. Generally the contact fo rce between lining and ground is sufficient to resist the buoyant force. However in the long-term the contact force could be reduced because of structural deterioration. In this study the effect of long-term buoyant force acting on the double-deck tunnel is investigated. The result s has shown that the buoyant force has increase d invert deformation and stress. It is indicat ed that the contact resilience between lining and ground needs to be kept during tunnel operation.Keywords: Double-deck tunnel, Lining, Buoyant force, Stress-pore pressure coupled analysis, Ground stiffness 초 록: 지하수위 아래에 건설되는 복층터널은 비교적 대단면이며 비배수 터널로 건설되는 특징을 가지고 있다. 지하수위 하부에 위치하는 터널은 지하수로 인해 발생하는 부력으로부터 터널의 안정성 확보방안이 필요하다. 일반적으로 터널 라이닝과 지반사이의 경계면에서의 결합력은 부력에 대해 충분한 안정성을 발휘한다. 그러나 장기적인 시간이 경과하면 구조물의 열화로 인하여 결합력이 감소할 수 있다. 본 연구에서는 장기적인 관점에서 부력으로 인한 복층터널의 영향을 조사하였다. 그 결과 부력으로 인해 터널 하단부분에서 변형과 라이닝에 작용하는 응력이 증가하였다. 본 연구로부터 운영중 터널의 라이닝과 지반사이의 결합력을 유지시킬 수 있는 방안이 필요함을 알 수 있다. 주요어: 복층터널, 라이닝, 부력, 응력-간극수압 연계해석, 지반강성Copyright ⓒ2015, Korean Tunnelling and Underground Space Association

A study on the characteristics of multi load transfer ground anchor system

In order to identify a load transfer mechanism of ground anchors, the behavior of multi load transfer ground anchor systems was investigated and compared with those of compression type anchors and tension type anchors. Large scale model tests were performed and stress-strain relationships were obtained. The load transfer mechanism of ground anchors was also investigated in the field tests. Finally, numerical analyses to predict the load-displacement relationships of anchors were conducted. It is concluded that the load transfer characteristics of MLT anchors are mechanically much more superior in the pull-out resistance effect than those of existing compression and tension type anchors. From the results of research work, we could suggest that the max pull-out capacity of anchor capacity to each the soil condition. Also, the MLT anchors can be used to achieve both structural enhancement and economic construction in earth retaining or supporting structures.