Study On Bearing Capacity Of Deep Water Shallow Foundation In Soft Clay

As one of the common structural forms of hydraulic engineering and offshore engineering,shallow foundations whose depth is less than the width or diameter of the foundation can be used as the foundation of towering fans,offshore oil platforms and various modules of deep-sea oil and gas resources production system to adapt to the complex topography and harsh environment of the seabed.In this paper,the limit analysis and numerical calculation methods are used to study the ultimate bearing capacity of foundation under different load unidirectional action modes of square shallow foundation and circular shallow foundation with different opening forms,and a new structural form of concrete trapezoidal shallow foundation is proposed.The research contents and main achievements are summarized as follows:The research results of theoretical research,model test and numerical calculation on shallow foundation and cylindrical foundation of anti-subsidence plate are comprehensively summarized and compared.Based on the upper bound solution method of limit analysis,the three-dimensional mechanical field of soil failure was established,and the upper bound solutions of vertical bearing capacity of shallow circular foundation with square holes and shallow circular foundation with circular holes were derived.The calculation methods of vertical and horizontal bearing capacity of shallow foundation in the current code and the calculation methods of bending and torque bearing capacity of shallow foundation not included in the code are summarized.Based on finite element software ABAQUS,the three-dimensional finite element models of square shallow foundation and circle shallow foundation with holes were estiablished,the bearing characteristics of square shallow foundations and circle shallow foundations with different opening rates,different number of holes and different opening shapes in heterogeneous undrained saturated soft clay were calculated under the independent action modes of vertical load,horizontal load,bending moment load and torque load.The influence of opening rates,number of holes and opening shapes on the ultimate bearing capacity was analyzed.Suggestions on optimal structure form for different loads in practical engineering were put forward.Based on finite element software ABAQUS,the two-dimensional finite element models of trapezoidal shallow foundation were established,the bearing capacity characteristics of single function mode were calculated which based on different sizes of trapezoidal shallow foundation in saturated soft clay in vertical load,horizontal load and bending moment load.By the means of dimensionless and normalized processing,the influences of the foundation inclination α and foundation depth-width ratio d/B on the bearing capacity were analyzed and the bearing capacity calculation formulas on the foundation bearing capacity were put forward.