Study On The Mechanical Deformation Characteristics Of Inclined Retaining Piles In Foundation Pit

With the continuous enhancement of China’s comprehensive strength,the process of urbanization has been rapidly developed,land resources are increasingly scarce,underground space has been widely developed and utilized,and deep and large foundation pits continue to emerge.Foundation pit support piles are mainly vertical piles.In recent years,inclined pile support types have emerged for soft soil layers and foundation pits with limited construction space.From the perspective of practical application,compared to vertical piles,under the same conditions,inclined retaining piles are more conducive to controlling soil deformation and effectively reducing the bending moment of the retaining pile shaft.At present,inclined retaining piles are widely used in Tianjin area,while other areas are still in the initial stage of application.Its calculation mode and method need to be improved,and its mechanical deformation behavior needs further in-depth research.In this paper,indoor model tests and numerical simulation methods are used to analyze the stress and deformation characteristics of inclined retaining piles in foundation pits.The specific research contents are as follows:(1)A large number of references at home and abroad were consulted and summarized from indoor model tests and numerical simulation experiments.(2)Study on indoor model test scheme.Determine material parameters through the principle of similarity,select appropriate test materials and testing instruments,and determine test conditions,test procedures,and data processing methods.(3)The indoor model test study on the mechanical deformation characteristics of inclined retaining piles in foundation pits mainly includes the effects of different inclination angles(0°,10°,15°,and 20°)of the retaining piles and different arrangement methods(pure straight piles,pure inclined piles,and a slanted straight pile in the oblique vertical alternating direction)on the inclined retaining piles in foundation pits.The test results show that when the ratio of excavation depth to pile length is 0.57,and the inclination angle of the support pile increases from 0 ° to 20 °,the bending moment of the lower half of the pile,the soil pressure on the pile side,the horizontal displacement of the crown beam,and the settlement of the soil outside the pit decrease by 55.3%,23.7%,57.2%,and 49.5%,respectively,compared to the vertical pile.This indicates that the greater the inclination angle of the support pile,the more obvious the support effect.When the ratio of excavation depth to pile length is 0.57,and the inclined pile is 20 °,the bending moment of the pile shaft,the horizontal displacement of the crown beam,and the maximum settlement of the soil outside the pit of an inclined straight pile are reduced by 67.1%,64.9%,and 87%,respectively,compared to the pure inclined pile arrangement.(4)Using ABAQUS software,the mechanical and deformation characteristics of inclined retaining piles in foundation pits were numerically simulated.Under different pile length to excavation depth ratios and different inclination angles of the retaining piles,the mechanical and deformation characteristics of the inclined retaining piles,such as bending moment,horizontal displacement,and soil settlement outside the foundation pit,are analyzed.