As the preferred riser system for deep-sea oil and gas resource extraction

steel catenary riser (SCR) has a large impact on the depth of burial and fatigue life of the pipeline in the touchdown zone due to its interaction with the seabed soil body. According to the nonlinear soil resistance-intrusion depth p-y curve of pipe soil interaction

it is simplified as a three segment linear elastic soil stiffness attenuation model

and the analytical solution of initial penetration static equilibrium of catenary riser on seabed is obtained based on the nonlinear Pasternak foundation model. Compared with three-dimensional finite element and five model test cases

it is found that conventional Winkler foundation model overestimates the pipeline vertical deformation and bending moment of soil

which verifies the rationality and applicability of the analytical solution based on nonlinear Pasternak foundation model; the increase of seabed shear strength Su0 significantly improves the stiffness of three-stage linear elastic soil and reduces the pipeline verticaldeformation. In addition

according to the changes of water depth H

riser laying angle ?

pipeline outer diameter D

pipeline elastic modulus E and material density ?

the physical and mechanical properties of pipeline penetrating soil are compared and analyzed. The results show that with the increase of vertical pipe laying angle ?

the pipeline vertical deformation will be reduced

while the bending moment and shear force will be increased. When the angle exceeds 82o

it is prone to yield failure. With the increase of pipe outer diameter D

the soil vertical resistance

vertical deformation

bending moment and shear force in touchdown zone will be increased simultaneously. When the outer diameter exceeds 0.4 m

it is easy to yield. The larger the elastic modulus E is

the smaller the pipeline vertical deformation is

the greater the bending moment and shear force are

when the elastic modulus exceeds 275 GPa

it is easy to yield. When the density of pipeline material is higher

the pipeline vertical deformation is larger

the bending moment does not change obviously

but the shear force increases

and when the density exceeds 14 850 kg/m3

it is easy to yield. The above conclusions can provide a theoretical basis for the preliminary design of catenary riser of offshore pipeline.