Large Deformation Finite Element Analysis Of Bearing Capacity Of Anchor Plate Considering Strain Softening

Most of the research results about the bearing capacity coefficient of anchor plate have not considered the strain softening of soil. In practical engineering, the anchor plate foundation is not only subjected to static loads, but also to cyclic loads such as wind,waves and current. Under cyclic loading, the plastic strain of the soil will accumulated and strain softening is produced, leading to the decrease of the bearing capacity of anchor plate. In the process of rotation and adjustment of anchor plate, strain softening will occur on the soil around anchor plate because it undergo great deformation. After the rotation and adjustment of anchor plate,the reduction of the bearing capacity of it is a problem worthy of further research. The offshore platform is generally anchored by multiple anchor plates, when an anchor plate is unstable to be pullout for some distance(strain softening will occur in the soil around anchor), the bearing capacity of anchor plate in this condition is of great significance to evaluate the stability of the whole offshore platform. The influence of strain softening on the bearing capacity of anchor plate is accompanied in many engineering problems. So, further research on the bearing capacity coefficient of the anchor plate considering strain softening is required.Firstly, the T-bar bearing capacity coefficients without considering strain softening was calculated by CEL (Coupled Eulerian-Lagrangian), a large deformation finite element method. The results by CEL are in good agreement with the results of existing plastic theoretical solutions and RITSS (remeshing and interpolation with small strain,in which the large deformation finite element analysis is realized by remeshing technique and stress interpolation technique on the basis of small deformation finite element). So, the reliability of the CEL calculation model is verified. Based on the ABAQUS finite element platform, the second development is carried out to compile strain softening subroutine to calculate T-bar bearing capacity coefficient considering strain softening. The results by strain softening subroutine are in good agreement with the results of RITSS So,the reliability of the strain softening subroutine is verified. Analysising the degree of softening and flow mechanism of soil around T-bar, it can be found that strain softening not only reduces the shear strength of soil, but also changes its flow mechanism. The combined effects of these two factors lead to the decrease of the bearing capacity coefficient of T-bar. So, the effect mechanism of strain softening on the bearing capacity coefficient of T-bar was revealed.Secondly, the effect of strain softening on strip anchor plate and square anchor plate was studied by CEL. The development law of resistance displacement curve of strip anchor plate under the action of strain softening is analyzed. The softening degree of the soil around the anchor plate and the changing law of the flow mechanism are studied. The effect of strain softening on the bearing capacity coefficient of anchor plate is revealed. The formula of bearing capacity of strip anchor plate and square anchor plate under different softening parameters are obtained.Finally, as it is very difficult for soft clay in deep water to obtain high-quality sample, so the parameters related to the strain softening of soft clay (strain softening parameters) can not be obtained directly from tests. Simulating marine soft clay with British import kaolin clay,centrifuge model test of T shaped penetrometer (T-bar) and strip plate anchor were carried to investigate the effect of strain softening on bearing capacity of anchor plate.Two mutually independent methods are proposed to evaluate the strain softening parameters of clay according to the resistance of T-bar. According to the strain softening parameters and strip plate anchor resistance, the bearing capacity coefficient of strip anchor plate considering strain softening is obtained.