Reliability Assessment of Geotechnical Structures on Soils improved by Deep Mixing Method II: Reliability Analyses and Estimation of Target Reliability Index

Abstract

The objective of this research is to probabilistically assess the stabilities of the structures on Soils improved by Deep Mixing Method (SDMM) using reliability method. This paper addresses the implementation of component (FORM/SORM) and system reliability analyses to the stability problems of SDMM. The reliability analyses are performed for six design sections of the geotechnical structures, i.e., quay wall and breakwater, which were actually constructed in Korea. Six failure modes of both external and internal stabilities of SDMM are formulated into the limit state functions in the study. In the component reliability analysis, the failure modes of the internal stability have more influence on the stability of SDMM than those of the external stability. System reliability index has been obtained mostly from the internal stabilities of either toe compression or short wall shear stress. From the sensitivity analysis, the stability of SDMM is highly influenced by the compressive strength of DMM improved soil and the wave pressure. Target reliability index of SDMM is obtained by comparing the results of the reliability analyses with the values both from the transformation of safety factors and from the literature surveys. The target reliability index assessed in this study would be an important reference in Load and Resistance Factor Design (LRFD) design of SDMM.