Strain Wedge Theory And Numerical Analysis Of Large Diameter Laterally Loaded Piles

With the world energy shortage and environmental degradation caused by traditional energy use becoming increasingly prominent,China has put forward the 30 / 60 climate target.In order to achieve the goal of carbon neutrality,it is expected that China will vigorously develop renewable energy such as wind power generation in the next five years,and the extensive use of clean energy will be a basic national policy of China.Single pile foundation has become the most widely used foundation form for wind turbines in shallow water because of its simple foundation form,simple installation and low cost.However,the construction of offshore wind farms in China is in the initial stage,and there is no mature design code for offshore wind power foundation.With the gradual increase of the scale of wind turbines,the diameter of single pile foundation is becoming larger and larger.The emergence of large-scale wind turbine brings challenges to the design of large-scale single pile.The traditional design method based on small-diameter single pile may no longer be suitable for large-diameter single pile.The design method of single pile under horizontal load is more strict.The complex cyclic load form and the single pile beyond the traditional pile diameter need to study its horizontal load characteristics.In order to meet the relevant needs,this paper studies the deformation characteristics of large diameter rigid pile and flexible pile in sand and clay under horizontal load by theoretical derivation and finite difference numerical simulation:(1)Based on the previous research results,this paper summarizes and analyzes the deformation behavior of horizontally loaded piles and traditional calculation methods,respectively expounds the advantages and disadvantages of traditional calculation methods,and introduces cases to verify the applicability of m-method and p-y curve method in large diameter piles.(2)The analysis method of strain wedge model is introduced in detail,and the hyperbolic stress-strain model and the strain wedge method considering the vertical shear stress of pile side are modified.The analysis method of strain wedge model is improved and supplemented.The finite difference method is used to solve the horizontal displacement of single pile,and the strain wedge model method in sand and clay is proposed respectively.The calculation procedure of single pile horizontal displacement in sand and clay is improved.(3)Mohr Coulomb constitutive model and plastic hardening with small strain constitutive model are used to simulate rigid pile and elastic pile in sand and clay under horizontal load respectively.The results show that although there is a certain error between the modified strain wedge model and the numerical value,the calculation result of horizontal displacement in rigid pile is too large,and the horizontal displacement of flexible pile is too small,but it is closer to the numerical simulation value than the traditional strain wedge.(4)Based on the three-dimensional numerical model,the horizontal loading characteristics of different pile diameters are analyzed.The sensitivity of horizontal response characteristics of large-diameter piles to soil stiffness(related to different shear wave velocities)and its own stiffness(related to pile diameter ratio)in sand and clay is further studied.