Study On Theoretical Calculation And Numerical Simulation Of Active Earth Pressure On A Cylindrical Retaining Wall Considering Spatial Arching Effect

The cylindrical retaining structure has good mechanical and deformationcharacteristics and is widely used in underground structures such as cylindrical shafts and circular foundation pits.The calculation of earth pressure is the key to the design of a cylindrical retaining structure.Therefore,it is of great significance to carry out the research on the active earth pressure on a cylindrical retaining wall.In this paper,the active earth pressure on a cylindrical retaining wall was theoretically deduced based on horizontal layer analysis method and energy method,and the numerical simulation was carried out by FLAC3D software.The main research contents and conclusions are as follows:（1）Based on the horizontal layer analysis method and considering the spatial arching effect,a calculation method of active earth pressure on the cylindrical retaining wall was established.In the active limit state,the inclination angle of the slip surface behind the cylindrical retaining wall was greater than that of the plane retaining wall,and the active earth pressure on the cylindrical retaining wall was smaller than that of the plane retaining wall.The active earth pressure on the cylindrical retaining wall increased with the increase of radius to height ratio（r₀/H）,and the height of the active resultant force action point decreased with the increase of radius to height ratio（r₀/H）.From the perspective of engineering application,the active earth pressure on the cylindrical retaining wall with r₀/H≥5 can be calculated as a plane retaining wall.According to the above method,the practical tables of active earth pressure coefficient and resultant action point height coefficient of cylindrical retaining wall were compiled,which could provide a theoretical basis for engineering design.（2）According to the hyperbolic relationship of the radial stress-strain in the triaxial test of unloading stress path,the relationship between the internal friction angle and the displacement of retaining wall was obtained by analogy.Considering the influence of the displacement,the calculation formula of non-limit active earth pressure on a cylindrical retaining wall was deduced.The displacement of retaining wall had a significant impact on the active earth pressure on a cylindrical retaining wall,and the active earth pressure decreased gradually with the increase of displacement.（3）Based on the energy method,the calculation formula of active earth pressure on a cylindrical retaining wall was deduced.For cohesionless soil,when r₀/H tended to infinity,the calculation method was consistent with Coulomb’theory.The greater the circumferential stress coefficient,the smaller the active earth pressure of circular retaining wall.The calculation formula based on energy method could calculate the active earth pressure on a cylindrical retaining wall with cohesive soil.（4）Based on the numerical simulation,the slip surface,ring arch effect and active earth pressure on a cylindrical retaining wall were analyzed.When the soil behind the cylindrical retaining wall reached a stable plastic flow state,an axisymmetric conical slip surface is formed.the inclination angle of the slip surface decreased with the increase of r₀/H.The main manifestation of ring arch effect was the change of circumferential stress value.The smaller r₀/H was,the greater the ring arch effect was.The circumferential stress coefficient obtained by numerical simulation was within 1and K₀,and decreased with the increase of radial distance.The active earth pressure distribution and resultant force of numerical simulation were in good agreement with the theoretical calculation.