Study On The Earth Pressure In Non-limit State Of Flexible Supporting Structure Under Consideration Of Displacement Effects

As a common supporting structure, flexible supporting structure is widely used in foundation pit engineering. It is of great significance for the design and construction of flexible retaining structure to determine the size and distribution of earth pressure. At present, there is a gap between the result of earth pressure of the flexible supporting structure obtained from the classical earth pressure theory and the actual situation. This paper introduced the derivation process of the classical earth pressure theory, summarized the problems existing in the classical earth pressure theory, analyzed the stress state of soils, proposed a design formula for non-limit earth pressure of flexible supporting structure with the influence of displacement. In this paper, the main results are as follows:(1) From the summary of classical earth pressure theory and the analysis of the soil stress state, it is discovered that the application of the classical earth pressure theory has limitations.(2) The horizontal displacement of flexible supporting structure is analyzed through polynomial regression; and a cubic polynomial is proposed to present the relationship between the horizontal displacement of flexible supporting structure and the depth of foundation pit, which is verified by the actual engineering data.(3) Combined with the stress path triaxial test, the function relationship between the value of the internal friction angle and the horizontal displacement of the flexible supporting structure is established by improving Mohr circle. Then, the expression of active earth pressure and passive earth pressure is deducted according to the horizontal layer analysis method. The earth pressure and horizontal displacement of flexible supporting structure calculation model is built up by inserting the function relationship into the horizontal layer analysis method, and the rationality of the calculation model is verified by laboratory experiment data.(4) Having applied the theory of earth pressure proposed in this paper to an actual project of deep foundation pit, the rule of earth pressure of deep foundation pit is discovered. The distribution of earth pressure of the flexible supporting structure is obtained by calculating and analyzing a two-dimensional model established by MIDAS/GTS. Comparing the simulated results with the theoretical calculation results, it is found that there are certain differences between them, but their general trend is the same, which reflects, to some extent, the rationality of the theoretical calculation.