Analysis On The Failure Mechanism Of Composite Ground Under Flexible Foundation

With the extensive applications of composite ground theory in important industries such as transportation, water conservancy, the failure mechanism of composite ground under flexible foundation is particularly important. In addition to bearing capacity and settlement calculations for composite foundation under flexible foundation, we should also analyze stabiltiy. Limit equilibrium theories are used to analyze the instability of the embankment. However, because of the instability of the embankment, the larger horizontal displacement of the soil and the diagonal trend of displacement at the foot of the slope occur. Therefore, part of the piles may bear the large bending moment and tensile stress, which may cause the pile flexural and tensile failure. In recent years, domestic and foreign research results show that the shearing failure of piles theory overestimate the stability of the embankment, which is unsafe. Therefore, to carry out the failure mechanism of the composite foundation under flexible foundation is not only theoretically valuable,but also useful in engineering applications.On the basis of research of flexible foundations, the ABAQUS software is used to establish the 3-D analytical model of the composite foundation, which doesn't consider the large deformation and consolidation of soils. This paper analyzed the force characteristics of piles in different location after loading step by step, discussed the distribution of bending moment, axial force and shear force and possible failure modes of piles. Then, the effects of pile diameter, modulus of soils between piles, pile modulus, cushion stiffness and the bearing stratum on the internal forces of piles are also analyzed.3-D analytical models considering the large deformation and consolidation of soils are established to analysis the influence of the large deformation and consolidation on the internal forces of piles.