Study On Bearing Capacity Of Subsoil Of Circular Foundation In Consideration Of Stress State

With the rapid development of the economy, the government pay more and more attention on oil strategic oil reserve policy and agricultural. In recent years, lots of oil tanks and silos have been built, so it is an emergency to deal with the bearing capacity of circular foundation. But the research on bearing capacity of circular foundation is still lacking. But traditionally, the formula of critical load p_1/4 is developed by assuming coefficient of earth pressure at rest K₀ equal 1 without consideration of stress state. It means that gravity stress field is similar to hydrostatic stress field, which soil is in a state of constant pressure in each direction. This incorrect assumption leads to an increase in lateral load. And then it will result in overestimating the bearing capacity of the foundation and lead to a dangerous result. So the uniform formula cannot be suitable for the bearing capacity of circular foundation. Firstly, numerical calculation has been taken to the study of bearing capacity of circular foundation with consideration of stress state and base shape in this paper; Then the existing formula has been corrected, we got the approximate formula. Last but not least, finite element simulation has been used to study bearing capacity of circular foundation with consideration of stress state. The main research contents are shown as follow:?1?With consideration of the complexity of mathematical problem, a self-developed program is used to solve this problem. In a state with K₀=1, expressions of additional stress are gotten at a very point in the circular foundation by using MATLAB. Then by adding additional stresses and gravity stresses, we can get the total stresses of the point. Therefore, principal stress at the point can be obtained by using elastic theory. And then, according to limit equilibrium based on Mohr-Coulomb failure criterion, equation of uniform circular load can be established. So equation of circular load p_1/4 can be obtained in the certain depth. Subsequently, the critical load p_1/4 can be obtained by inputting soil parameters. Also, the effects of parameters, such as cohesion, friction angel and coefficient of earth pressure at rest of the subsoil on critical load p_1/4 are studied.?2?The self-developed program has been used to obtain the critical load p_1/4 with consideration of stress state. By comparing result got from the existing formula, we can get coefficient of base shape. And then we can get their formulas through curve fitting. Lastly, we get the approximate formula for circular foundation with consideration of stress state.?3?Modeling analysis is made for circular foundation with the finite element software ABAQUS, the result of analysis can verify the self-developed program and approximate formula. Circular load p_1/4 which obtained in the self-developed program is applied on the bottom of the ground model during the simulation. So they can verify each other. Then 2 kinds of typical soil have been chosen to study the change rule of bearing capacity of circular foundation with the change of K₀.