Pullout Capacity Analysis of Horizontal Plate Anchors with Tensile Strength Cutoff

Abstract

The conventional Mohr–Coulomb (M-C) failure criterion is commonly used in existing studies to determine the ultimate pullout capacity of plate anchors buried in cohesive-frictional soils. However, this criterion overestimates the tensile strength of these soils by assuming a linear failure envelope (in both compression and tensile regimes) within the normal-shear stress space. In this study, the ultimate pullout capacity of horizontally buried plate anchors in cohesive-frictional soils was determined, accounting for the effect of tensile strength cutoff. The study proposed a series of semianalytical solutions utilizing the kinematic horizontal slice approach and investigated the ultimate pullout capacity of four different anchor shapes, including circular, square, rectangular, and strip anchors. The impact of nonassociated flow rule on the results was also examined. It has been observed that the results obtained using the M-C failure criterion with a tension cutoff are significantly lower than those obtained using the conventional M-C failure criterion. The difference between both results increases as soil cohesive strength increases and anchor burial depth decreases. These findings clearly demonstrate that eliminating tensile strength from the strength envelope leads to a more conservative estimate of plate anchor pullout capacity. The study emphasizes changes in anchor failure surfaces for various parameter combinations and provides results that are consistent with specific solutions reported in the literature. The study investigates using plate anchors to enhance the stability of both onshore and offshore structures, including transmission towers, guyed masts, chimneys, and mooring platforms. These structures often encounter significant vertical pullout forces. The research establishes a theoretical framework for calculating the ultimate vertical pullout capacity of plate anchors with various shapes (strip, rectangular, and circular) when buried in cohesive-frictional soils. A crucial aspect of this analysis involves incorporating the specified/limited value of tensile strength in cohesive-frictional soils when assessing the ultimate pullout capacity of plate anchors. This consideration is vital for ensuring a safe and conservative design, especially for structures subject to uplift forces. The findings provide valuable insights for engineers and practitioners, offering a reliable method to optimize the usage of plate anchors in the design of pullout-resistant structures.