Analysis of Pullout Bearing Capacity of Enlarged Head Anchors and Soil Failure Modes Using Discrete Element Method

Jiayun Gao ^1,2 Yan Zhu ² Jie Jiang ^3* Sensen Yin ³ Jingchao Bi ² Shuilong Shen ¹

• ¹ School of Ocean and Civil Engineering, Shanghai Jiaotong University, Shanghai, China
• ² Shanghai Research Centre of Ocean & Shipbuilding Maritime Engineering, China Shipbuilding NDRI Engineering Co. Ltd, Shanghai, China
• ³ School of Civil Engineering and Architecture, Guangxi University, Nanning, Guangxi Zhuang Region, China

Enlarged head anchors are typically utilized to fully mobilize soil resistance, thereby achieving a greater retaining structure support force. This type of anchorage is widely employed in geotechnical reinforcement. However, previous studies have significantly lacked a micro-scale mechanical analysis of the soil failure mechanism during the pullout process of enlarged head anchors. In this study, the pullout tests of enlarged head anchors were conducted using the Discrete Element Method (DEM) to investigate the effects of different section inclinations of the enlarged head and confining stress on the pullout force of the enlarged head anchors. The results indicate that the load-displacement curves of the enlarged head anchors initially increase sharply and then slightly decrease before eventually entering a stable stage. The enlarged head anchor with a section inclination of 120° exhibited superior bearing capacity during pullout tests. An increase in confining stress was found to enhance the mobilization of the bearing capacity of the enlarged head anchor. At the smaller section inclination of the enlarged head, the bearing capacity primarily originates from the end resistance generated ahead of the enlarged head. As the section inclination increased, the frictional resistance along the anchor-soil shear interface progressively became the dominant contributor to the bearing capacity. At a section inclination of 120°, the formation of a stronger contact force chain structure ahead of the enlarged head was identified as the micro-mechanical cause for the mobilization of greater soil resistance.