신뢰성 기법에 의한 연약지반의 압밀 및 침하해석

Abstract

본 연구에서는 항만 부두 준설토 투기장 축조공사 구역의 지반조사결과 및 문헌연구를 통하여 신뢰성 있는 지반정수를 산출한 후 토질정수의 불확실성을 고려한 신뢰성 해석법을 도입 해석하여 실제 시공되는 배수재의 타설 간격에 대한 신뢰성 해석을 수행하여 안정성을 높이는데 목적이 있다. 또한 주변지반이 연약한 점성토에 시공된 구조물은 지반의 강도가 작고, 침하 등의 변형이 크기 때문에 지반개량공법을 적용할 경우 지반의 압밀 및 침하 특성 해석을 확정론적 해석과 함께 지반정수의 불확실성을 고려한 신뢰성 해석을 실시하여 구조물기초와 개량된 연약지반의 안정성을 높이고자 하였다.

또한, 통상 불확실성을 고려해 연약지반에 과다설계 적용을 최소화함으로써, 공사비적인 측면에서 경제성 향상에 큰 효과가 기대된다.|In this thesis, reliability analysis was done on the characteristics of consolidation and settlement in the inner temporary dike where a weak ground improvement construction was applied. Through the analysis, PBD optimal space of placement was established, and it was examined if outer arc obtains stability against the residual settlement with the change of consolidation period. As for the range and method of this study, a consolidation settlement was calculated through the consolidation of underground foundation and settlement analysis, and the data were analyzed in average, variance, and distribution. In reference to analyzed data, the study aimed to proceed the reliability analysis on the optimal space calculation of drains and the permissible residual settlement according to the consolidation period through various application methods and to achieve the stability for the optimal space of placement and residual settlement. When the consolidation analysis on the foundation ground was done through this study, the following conclusions were obtained as a result from conducting the stability analysis on the effect of space of drains, the effect of consolidation time, and the residual settlement and differential settlement. When applying the space of drains as 1.0m, 1.2m, and 1.5m for the objective ground, from the result of analysis on the probability of reaching a target consolidation, the space 1.0m showed 99.9% ~ 100% in all sections, meaning that it is an overestimated construction, and as the space 1.2m obtained a reliability of over 95% in all areas, it showed a stability relatively. Also, when the space 1.5m was applied, as it showed low reliability of 80.22 ~ 84.52%, 50.26% ~ 71.32% by each section, it may be concluded that it is better to apply the drain distance of less than 1.5m for areas in which the probability to reach the target consolidation is lower than 95%. Also, as a result of analysis on the reliability of differential settlement with nearby area, it exceeded the permissible differential settlement slope (1/600), showing a possibility of occurrence of differential settlement close to 0%. When construction was done with a drain space which satisfied 95% probability of reaching a target consolidation in each divided area and the occurrence of a residual settlement was within the range which did not exceed 10cm, it was shown that there was almost no possibility of the occurrence of differential settlement which was above the permissible differential settlement slope.