Measuring the in situ deformation of retaining walls by the digital image correlation method

• This study uses DIC method to monitor the deformation of a retaining wall.
• The preparation procedures for the in situ experiment are recommended.
• The results clearly indicate the deformation pattern of the retaining wall.
• The environmental factors that affect the measuring precision are investigated.

In this study, the digital image correlation (DIC) method was used to monitor the full-field deformation of a retaining wall. Two retaining walls located in mountainous areas of Taiwan were investigated. The first, Fushan slope, was characterized by substantial long-term deformation, and the second, Bulao slope, was located beneath an expressway and was severely damaged by Typhoon Morakot. This paper first describes the preparation procedures for in situ applications of the DIC method. Various environmental factors such as fog, rain, light direction, and spot mark clarity affected measurement precision, and consequently produced monitoring images that were unsuitable for further analysis. The DIC analysis results clearly indicate the deformation pattern of the retaining walls. The proposed method is accurate and effective for performing long-term monitoring of retaining walls, and the results can be used to accurately predict the tendency, location, and quantity of retaining wall displacement. Therefore, the proposed DIC method can be implemented to prevent disasters caused by landslide.