The deep mixing technique, which blends in-situ soil with cementitious materials, is commonly used to improve ground stability. Deep mixing is widely applied in engineering, but understanding failure mechanisms is key to success. Failure in deep mixing columns, especially in embankment support, is influenced by factors like soil properties, design, and shallow stabilization layers. Failures are categorized as internal or external and occur progressively. A shallow mixing layer can improve column performance by synchronizing their response. This study reviews these failure patterns, focusing on the impact of shallow layers through laboratory tests and centrifuge experiments.