Construction incidents, mechanisms and causes in Geotechnical Engineering have been closely reviewed for the safety assurance during design and construction stages. The safety assurance is clearly related to the observational method in which design is reviewed during construction and contingency actions are undertaken successfully to minimise any potential failures. The observational method has been extensively applied for the construction of subways underground structures, dams and many important Civil Engineering projects in the past 20 years. But the number of serious construction incidents are growing for the past several decades. Therefore present development of observational method and improvement techniques are introduced with some case histories.

The observational method using field measurement technique have contributed significantly to advancements in the state-of-the art of geotechnical engineering in the 20th century. Due to the rapid development in computer technology, Internet and GIS have become an integral part of civil engineering project management. This paper presents new technologies and development in observational method which have valuable implication on field measurement in geotechnical engineering. Systematic approach to planning monitoring program in geotechnical instrumentation is also presented. Finally, research needs in development and application of integrated design/construction management system in geotechnical engineering projects are discussed.

Field instrumentation has been important part of construction management in embankment on soft ground. Most of all, well organized plan, instrumentation, maintenance, analysis and feed-back to the construction procedure are the key to the successful construction. In this paper, We review problems of field instrumentation has been performed at road construction on soft ground. And then, several proposals to improve field instrumentation and management are suggested

Enormous instruments have been installed to measure movement and stresses during and after the construction of Seoul Subway. However, a number of problems have been noticed and reported, such as planning, calibration, installation, contract procedure etc. Some of them are presented and discussed in this paper in order to call an attention to these problems and provide a baseline for the future improvement.

By means of analyzing the problems in monitoring plan, design, installation, operation based on maintenance monitoring system installed in subway tunnel section, the methods of improvement were proposed for applying to subway monitoring maintenance effectively in future. The choice of the better monitoring system, the operating method of monitoring system, the confidence and continuity of maintenance monitoring, the performance of responsible monitoring supervision in the phase of the planning of monitoring and design were proposed. The problem and developed plan in the different monitoring systems, the calibration and correction of monitoring system, the analysis for the results and plan for maintenance in the phase of installation of monitoring system and operation were also proposed.

본 연구에서는 터널구조물의 안전상태를 평가하기 위하여 터널라이닝에 광변위센서 계측시스템을 적용하였다. 먼저 터널 라이닝 모델실험을 실시하여 광변위 계측시스템의 신뢰성을 검증하였고, 터널 현장적용을 통하여 계측시스템의 적용성을 검토하였다. 본 계측시스템은 터널구조물의 상시적인 안전관리측면에서 효과적이라 할 수 있으며, 계측결과의 평가와 정밀안전진단에의 활용에 대한 연구가 필요하다.