Artificial-Crack-Behavior Test Evaluation of the Water-Leakage Repair Materials Used for the Repair of Water-Leakage Cracks in Concrete Structures
There are no existing standard test methods at home and abroad that can verify the performance of water leakage repair materials, and it is thus very difficult to perform quality control checks in the field of water leakage repair. This study determined that the key factors that have the greatest impact on the water leakage repair materials are the micro-behaviors of cracks, and proposed an artificial-crack-behavior test method for the performance verification of the repair materials. The performance of the 15 kinds of repair materials that are currently being used in the field of water leakage repair was evaluated by applying the proposed test method. The main aim of such a test method is to determine if there is water leakage by injecting water leakage repair materials into a crack behavior test specimen with an artificial 5-mm crack width, applying a 2.5 mm vertical behavior load at 100 cycles, and applying 0.3 N/mm2 constant water pressure. The test results showed that of the 15 kinds of repair materials, only two effectively sealed the crack and thus stopped the water leakage. The findings of this study confirmed the effectiveness of the proposed artificial-crack-behavior test method and suggest that it can be used as a performance verification method for checking the responsiveness of the repair materials being used in the field of water leakage repair to the repetitive water leakage behaviors that occur in concrete structures. The study findings further suggest that the use of the proposed test method makes it possible to quantify the water leakage repair quality control in the field.
A Case Study on the Effects on Underground Structure due to Changes in the Groundwater Level and Ground Stress
, 2015ABSTRACT : Recently, land subsidence and sinkhole are generated due to a change in the groundwater level in the city. For this reason, the necessity for management of stable underground water level is on the rise. In this study, it was conducted for the underground structure that passes through the lower of bus transfer center construction site to examine the influence on the stability for underground structures to changes in the groundwater level and effective stress, the coupled finite element analysis and structural analyses were performed to evaluate stability for underground structure. It is to secure stability for underground structures according to underground water level declines. In this way, effective construction management will be made by previewing and forecasting the influence on the ground behavior and adjacent structures due to changes in the groundwater level.Keywords : Groundwater level, Effective stress, Land subsidence, Bus transfer center, Underground structures요지 : 최근 도심지에서는 지하수위 변화에 따른 지반침하 및 싱크홀이 다수 발생함에 따라 안정된 지하수위 관리에 대한 필요 성이 대두되고 있다. 본 연구에서는 지반의 지하수위 및 유효응력의 변화가 지하철구조물의 안정성에 미치는 영향을 파악하기 위해 버스환승센터 조성 구간 부지 하부로 통과하는 지하철구조물을 대상으로 연구를 수행하였다 . 지하철구조물의 안정성 평가를 위해 수행된 연계해석 및 구조해석 결과 지하수위 저하에 따른 구조물의 안정성은 확보되는 것으로 평가되었다 . 이와 같이 도심지 터파기 시공 전 지하수위 변화에 따른 지반거동 및 인접구조물에 미치는 영향을 사전에 검토하고 예측하여 효율적인 공사관 리가 이루어져야 할 것이다.주요어 : 지하수위, 유효응력, 지반침하, 버스환승센터, 지하철구조물
Beyond East–West: Marginality and National Dignity in Finnish Identity Construction
Since the end of the Cold War it has become common for Finnish academics and politicians alike to frame debates about Finnish national identity in terms of locating Finland somewhere along a continuum between East and West. Indeed, for politicians, properly locating oneself (and therefore Finland) along this continuum has often been seen as central to the winning and losing of elections. For example, the 1994 referendum on EU membership was largely interpreted precisely as an opportunity to relocate Finland further to the West. Indeed, the tendency to depict Finnish history in terms of a series of “Westernizing” moves has been notable, but has also betrayed some of the politicized elements of this view. However, this framing of Finnish national identity discourse is not only sometimes politicized but arguably is also too simplified and results in blindness towards other identity narratives that have also been important through Finnish history, and that are also evident (but rarely recognized) today as well. In this article we aim to highlight one of these that we argue has played a key role in locating Finland in the world and in formulating notions of what Finland is about, what historical role and mission it has been understood as destined to play, and what futures for the nation have been conceptualized as possible and as providing a source of subjectivity and national dignity.