Case of Slope Collapse and Reinforcement of a Cut Retaining Wall Applied to the Colluvium Layer in the Limestone Zone

To make up a vertical shaft site, a panel-type retaining wall was installed after the slope was cut. However, deformation occurred in the constructed panel-type retaining wall. While emergency restoration was achieved by installing a counterweight fill across the front of the first-tiered retaining wall, a trend of increasing ground displacement was observed, necessitating urgent reinforcement work. This study was conducted to identify the cause of the deformation of the cut retaining wall and establish appropriate reinforcement measures to prevent further deformation. The complex geological characteristics were identified as the primary cause of the wall deformation. The bedrock at the site is limestone, with a layer of colluvium approximately 10 m thick distributed over it. The colluvium is a mixture of weathered limestone, clay, clayey sand, and shale. A comprehensive analysis was conducted, taking into account not only the topographic and geological conditions but also rainfall conditions, design conditions, and construction conditions. Additional ground investigations were conducted during the research phase, and the results were used to adjust the bedrock line and re-evaluate the ground parameters of the colluvium. To assess slope stability in both its current and post-reinforcement states, a slope stability analysis was conducted using the Slope/W program. A step-by-step reinforcement plan was proposed, considering on-site conditions, to ensure slope stability during construction and use.