Theoretical Research On Non-limit Earth Pressure Of Flexible Retaining Wall Based On Rotary Line Slip Surface

Calculation of earth pressure on retaining walls is an ancient subject in geotechnical engineering,as a common supporting structure in foundation pit engineering,the flexible retaining wall has an important influence on the design of the foundation pit supporting structure.The traditional earth pressure theories are all based on the rigid retaining wall when the soil beside it reach the limit state to calculate earth pressure,the results cannot accurately reflect the magnitude and distribution of earth pressure in actual engineering,especially for flexible retaining walls which has low stiffness and can deform under the effect of earth pressure,there are some flaws in its calculation theories.Based on the existing research,the paper takes model experiments and actual foundation pit engineering as the background,and studies the calculation of earth pressure of flexible retaining walls under non-limit conditions.The main contents and results are as follows:(1)By Summarizing the research status of classical earth pressure theory and earth pressure theory of flexible retaining wall,and analyzing the stress state and slip surface of soil behind the retaining wall,the limitations of the classical earth pressure theory can be found.(2)Taking the flexible retaining wall of the deep foundation pit as the research object,using univariate cubic function to fit the arbitrary displacement curve equation of the flexible retaining wall,considering the relationship between the friction angle of the soil behind the wall and the external friction angle of the wall-soil contact surface under non-limit state,assuming that the potential slip surface of the soil behind the wall is the rotary line,applying the horizontal layer analysis method,considering the soil arching effect,the calculation formula of the non-limit earth pressure strength,the earth pressure resultant force and the resultant force point considering the displacement of the flexible retaining wall is derived.(3)Taking the model test as the basic example,and comparing with the results which are based on classical earth pressure theories and test.The results show that the range of potential slip surface calculated by the rotary line slip surface theory is smaller than that of the classic earth pressure theories,theoretical methods and experiments show that the active earth pressure is roughly R-shaped,and the passive earth pressure is roughly V-shaped,the resultant force position is higher than 1/3 wall height,which is obviously different from the classical earth pressure theories.Finally,the effect of the external friction angle ? on the earth pressure is studied by using the rotary line slip surface theory.(4)Applying theoretical research to actual foundation pit engineering projects,establishing a two-dimensional foundation pit model based on actual engineering by ABAQUS,by comparing and analyzing numerical simulation results and theoretical calculation results,it can be found that although there are some differences between the theoretical and analytical values,the overall distribution trend is the same,it reflects the rationality of the theoretical method to a certain extent.