Study On Residual Displacement And Control Index Of Pile Foundation In A Slope Under Seismic Loading

The motorways in western China are mostly in the form of full-high bridges or half-way half-bridges,and the pile structure is widely used in the lower structure.However,the seismic design method of pile foundations in residual soil slopes still lays behind its practice.Therefore,ifs of great significance to study the seismic response of residual soil slope piles under seismic loading.In view of these,In this paper,according to the national natural science fund project "Mechanism and prevention to failure of pile in slope induced by lateral movement of residual soil in mountainous terrain"(51478051),the shaking table model test of the centrifuge of the pile of residual soil slope was carried out.The open-source software OpenSees was used to the test,and the test results were compared with the numerical results.On this basis,the influencing factors of the pile foundation of residual soil slope under the El-Centro wave with the maximum acceleration amplitude of 0.4809g are analyzed.The main conclusions are as follows:(1)The shaking table test of the centrifuge and the numerical calculation of the OpenSees of the finite element software showed that the trend of the test results and the simula-tion results were basically the same and the results were in good agreement.The maximum residual horizontal displacement,residual bending moment and residual earth pressure of P3 and P4 piles appear at the top,near the soft and hard interface and at a certain depth near the surface,and the maximum value of them increases with increasing the seismic wave acceleration amplitude.(2)Changing the slope degree has a significant effect on the final settlement of the surface of the slope shoulder and the final horizontal displacement of the slope top;changing the internal friction angle of the sand has more influence on the final horizontal displacement of the slope top than the final settlement of the surface of the slope shoulder;the influence of the variation of pile diameter on the final horizontal displacement of slope top is less than the impact on the final settlement of the surface of the slope shoulder;the effects of sand gravity and elastic modulus of pile foundation on the final settlement of the surface of the slope shoulder and the final horizontal displacement of slope top are small.(3)In the shallow sand,each influencing factor has significant deterioration of the dynamic shear modulus of the sand shear stress-strain hysteresis loop at the position of the slope shoulder A,but it’s basically not degraded in the deep sand;the influencing factors have obvious degradation of the dynamic shear modulus of sand at various depths at the slope top B.The maximum shear strain of sand at the position of the slope shoulder A is decreasing along the depth,but the maximum shear strain of sand at the position of the slope top B is decreasing first and then increasing along the depth.(4)The influencing factors have different effects on the internal forces and displacements of the slope pile foundation;the two influencing factors of slope degree and pile diameter have significant influence on the final residual moment,earth pressure and horizontal displacement of the pile body;the two influencing factors of the internal friction angle of sand and pile elastic modulus have little effect on the final residual moment and earth pressure of the pile body,but have a great influence on the final residual horizontal displacement of the pile body;the influence of sand gravity influencing factor on the final residual moment,earth pressure and horizontal displacement of the pile can be ignored.