Since the settlement of the underground ground occurred in Seok-Chon Underground Roadway in Seoul from August 2014, the social interest of ground stability has increased. Thus, in this paper, We introduce not only the legal counterplan about the ground settlement but also a result of study on how many new materials can be used in the repairing of ground settlement.

In this study, The correlation between drainage clogging of drain tunnel and leakage of lining was analyzed. As a result of analysis, the position of clogged drainage hole, leakage and efflorescence location are similar. When repairing leakage of lining, the maintenance method should be selected considering the clogging of tunnel drainage.

Underground cavern is caused to be the cause of most sewer pipe fracture. this is the main cause of the land subsidence. This study suggests method for hazard assessment of land subsidence according to the underground cavern position and size.

The crack propagation on lining is compared for 10 years with previous length of crack in PISD(Precise Inspection for Safety and Diagnosis) depending on the width from 0.2mm to 1mm. Analyzed crack on horseshoe single tunnel is increasing in proportion to square time and linear increment. In this proposal, the extent of crack propagation can be estimated during the elapsed time. The tendency of crack can also be used in evaluating the life cycle of tunnel.

Infrastructure of the Korean construction industry has been rapidly aging in spite of the major qualitative growth over a short period of time for the last fifty years and interest in the social needs for maintenance has been increasing. Consequently, the paradigm of the domestic infrastructure maintenance market is changing and the needs of users are gradually increasing. According to the results of the domestic maintenance survey and analysis, first-class and second-class public structures specified by the 'Special Act on the Safety Control of Public Structures' are showing remarkable results and effects through the enactment and improvement of related laws. In this study, a survey was conducted for the domestic maintenance market and its status and ensuing reactions regarding policy were proposed for future improvement.

Although researching and developing of safety and maintenance on domestic facilities are important, there is little recent on a comprehensive and integrated survey of actual condition. Therefore this study asserts the necessity of the survey process of actual condition by period planning(short-term, middle-term, long-term). The purpose of this study is to investigate current situation and to suggest the whole process method, and to establish survey process of actual condition on domestic infrastructure facilities and buildings.

the government and the National Assembly of the Republic of Korea enacted and proclaimed the 'Special Act on the Safety Control of Public Structures' (hereinafter referred to as the 'Special Act') through the legislation process by Assembly members on January 5, 1995, in order to prevent disasters and calamities through facility safety inspections and proper maintenance. But nevertheless the result of the 'Special Act on the Safety Control of Public Structures' clearly exist, methodical analysis and effect of 'Special Act on the Safety Control of Public Structures' have not proposed since last 20 years. So question about the infrastructure of safety is brought up consistently. After that, the government has been creating new trends of facility maintenance since it deeply realized the significance of systematic inspection and maintenance of major public structures.

Scanning technic is implemented with the underground structures: subway, tunnel, shaft, drainage path, spillway, and slurry wall. Both optical and laser scanning system have been conducted to the precise inspection of diagnosis and safety. Image and 3D coordinate from scanning can be utilized in monitoring scope and fundamental database of maintenance. There is a high possibility that the scanning will prevail on inspection and diagnosis.

The in-depth inspection and maintenance process is based on the ‘Special Act on the Safety Control of Public Structures’ and accompanied specific guide. They prescribe the evaluation standard for physical condition and safety on structures. Recently we are faced with the threat coming from the aging of structures and external condition such as climate change. In this study, sustainable and long-term maintenance strategy is derived.

서울지역 28개 지하구조물에 대한 정밀안전진단 결과를 활용하여 제안된 균열집중구간 및 탄산화 기반 한계상태함수를 산정하여 우선적인 보수구간을 선별하고자 하였다. 상태평가를 위해 분할된 503개 쉬트에 대한 균열밀도는 로그정규분포, 탄산화 및 피복은 정규분포의 현장조사 결과를 얻었다. 각 구간별 실시한 강도, 초음파속도, CO2농도, 철근부식도, 염화물함유량 등을 고려할 수 있도록 환경지수를 도입하여 합리적인 보수 우선순위를 제안하고자 하였다.

Reinforced concrete structures are deteriorated in a few decades due to various causes, such as carbonation. Therefore it is important to evaluate the accurate carbonation depth in order to secure the durability of the structure. In this paper, carbonation depth by drilling excavation and splitting core sample are compared. Also, the procedure for estimating the appropriate repair zone is proposed, with the result of carbonation depth and steel bar detection.

Tunnel scanner is the most powerful and applicable technic for tunnel inspection. The enlargement or diminishment of defects is compared and analyzed by the scanning images. The pattern of crack is classified with the direction, shape, and location depending on the original lining and reinforced lining.

Infrastructure has been managed by precise diagnosis and repair․rehabilitation. Generally, more than 0.3mm cracks are repaired by injection method regardless of the time of repair and location of crack. In this papar, considering the feature of crack variation at three tunnels, it suggested that current diagnosis and repair methods should be improved.

The more durability of structures has been concerned, the more attention of maintenance has been given. Durability index is introduced to evaluate the state assessment in the precise safety of diagnosis in this paper. Two field data have been implemented to this proposal method. The priority of maintenance is also suggested using by this application.

Tunnel built in the late 1970 is currently being used by maintenance. For the maintenance of the tunnel, tamping materials filled backside cavity occurred during construction. In this paper, By investigating the filling state of backside cavity, It is to evaluate the filling effects of backside cavity and the adequacy of the repair and reinforcement.

과천터널은 서울지하철 4호선 연장구간으로서 사당에서 금정역까지를 말한다. 이러한 장대터널 전 구간에 대해서 새로운 터널유지관리시스템을 적용하기에는 한계가 있어 약 40m 구간의 박스터널 구간을 선정하여 새로운 터널유지관리시스템을 적용하였다.

유류탱크 구조물을 대상으로 기 실시한 유류탱크 정밀안전진단 결과를 중심으로 구조적 문제점을 도출하고 이를 근간으로 내구년수를 결정하는 기법에 대하여 제시하고자 하였으며 추가로 구조적 개선사항도 제안하였다. 정밀안전진단 결과 폐기된 유류탱크를 분석하면 시공년도와는 상관없이 시공, 유지관리 등의 정도에 따라 상이한 것으로 분석되며, 탱크형식별로는 매립형의 건전성이 가장 취약한 상태이다. 또한 손상원인별로 분석한 결과 강재 부분에 대해서는 강재의 두께, 용접 불량이 가장 많은 상태이며, 기초의 영향에 따른 부등침하의 원인도 다수 조사되었다. 또한, 유류탱크의 수명은 일반적으로 30년 정도를 예상수명으로 관리하고 있으며 연구 결과 내구년수는 30년으로 추정 할 수 있었다.