This paper investigates the pullout behaviours of horizontal rectangular plate anchors under inclined loading in sand using three - dimensional finite element (3D-FE) analysis. An advanced bounding surface plasticity model incorporating the critical state framework is developed to capture the stress-strain relationship of sand. The model is firstly validated against various analytical solutions and centrifuge test data. Then, a series of FE analysis is conducted to consider the effects of plate anchor aspect ratio, initial embedment depth, sand relative density and inclined loading angle on the pullout capacities. Results show that shallow anchors develop failure zones reaching the soil surface, and vertical pullout capacity exceeds that under pure vertical loading when the load is slightly inclined. For deep anchors, failure zones are confined below the surface, and horizontal pullout capacity exceeds that under pure horizontal loading when the load is slightly inclined. The transitional embedment depth depends on anchor aspect ratio and sand density. A modified analytical solution is proposed to estimate the vertical pullout capacity of plate anchors from shallow to deep depths. Failure envelopes established from probe tests provide practical guidance for assessing rectangular anchor failures under various inclined loadings.

The pull-out capacity of plate anchor is significantly impacted by the embedment loss during keying, necessitating its prior estimation. The soil surrounding the anchor undergoes considerable disturbance during keying, but the soil softening induced by accumulated shear strains was neglected in almost all the existing numerical studies. In this paper, an elastic-perfectly plastic model with strain-softening was combined with the integraltype nonlocal method to overcome the mesh dependency in large deformation finite element simulations. The biaxial compression tests were simulated firstly and the keying process of strip anchors were reproduced by varying anchor width, thickness, loading eccentricity, undrained shear strength and sensitivity. It was observed that the ultimate embedment loss increased nearly linearly with soil sensitivity, a trend that was especially pronounced at lower loading eccentricity ratio. The generalized equations for evaluating the ultimate embedment loss were proposed and their reliabilities were verified by the existing centrifuge tests.

Various anchors are used to withstand uplift forces for offshore and onshore structures on which research is going on for almost the last six decades. In the present study, it has been attempted to obtain the responses of inclined anchors based on numerical studies. Uplift capacities of model anchor plates having dimensions of 0.025 m x 0.025 m, 0.050 m x 0.050 m, and 0.075 m x 0.075 m with embedment ratios of 1, 2, and 3 and inclination angles 30 degrees, 45 degrees, and 60 degrees with vertical, have been obtained under cyclic loading with 0.2 Hz, 0.5 Hz frequency and 0.002 m, 0.005 m amplitude. The soil bed has been made of locally available clay and the anchors are of mild steel. The numerical analysis has been carried out by ABAQUS, considering all relevant parameters of soil, plate size and inclination angle, and embedment ratio of anchor and also for different frequencies and amplitudes of loading. The variation of ultimate pullout capacity has been studied by varying these parameters. It has been observed that the ultimate capacity under pullout increases significantly with increase in the dimensions of the plate, the embedment ratio, and also the angle of inclination of the anchor with vertical.

Constructing infrastructures such as traffic and railway gantries, transmission towers, and near-shore sea walls on soft soils, demands specially designed foundation systems capable of withstanding pull-out forces. Plate anchors are crafted for such environments. It consists of a steel plate embedded in the soil and connected to the external structure through a tie-rod. These anchors have become increasingly prevalent in engineering projects designed to withstand the pull-out forces from the superstructure. The present study investigates the vertical pull-out response of embedded anchors, subjected to cyclic disturbances, using three-dimensional finite element analysis. Advanced constitutive models, including the Soft Soil (SS) model and Hardening Soil model with small-strain stiffness (HSsmall), are employed to study the non-linear and time-dependent response of soils under monotonic and cyclic pull-out loads. The numerical analysis indicates that, in addition to soil type and anchor size, the placement and nature of loading, influence the anchor capacity. It was noted that under cyclic loads, anchors buried in saturated soft soils display a non-linear hysteresis response and a degradation in pull-out resistance with loading cycles. This reduction in anchor resistance with an increment in the loading cycle is noted when the anchor is subjected to higher cyclic stresses. A series of numerical investigations were carried out to analyse the impact of reinforcing the soil above the anchor with geotextile. This approach aimed to address the challenges associated with soft soils and enhance the performance of anchor-soil foundation systems under different loading scenarios. The results highlight the substantial role of geotextile reinforcement in enhancing anchor stability and resistance against vertical pull-out and cyclic disturbances. Reinforcing the soil above the anchor plate amplifies the pull-out resistance up to 45%, in contrast to anchors placed in unreinforced soil. In addition, the anchors exhibit improved performance under cyclic loads, with an enhancement in cyclic pull-out resistance up to 29%, without causing additional degradation of the soil's shear strength under repeated cyclic loading. This improvement in cyclic pull-out resistance is attributed to the resilient cyclic characteristics of geotextile reinforcement.