Deduction Of Active Earth Pressure Calculation And Wall-soil Interaction Experiment Of Deep Foundation Pit Before Disaster

In deep foundation pit engineering,the soil is often in the non-limit state,and when the displacement of retaining wall exceeds the limit state,it will cause disaster of the foundation pit.Some scholars have conducted research on the non-limit earth pressure before the critical displacement of deep foundation pit,but the theory of earth pressure beyond the critical displacement to the state before the disaster is rarely reported.Therefore,the whole process before the disaster is taken as the research interval,the active earth pressure and wall-soil interaction were studied by means of theoretical analysis and experimental research,which further supplements the relevant research on the earth pressure in the pre-catastrophic state.In order to provide a theoretical basis for the calculation method of active earth pressure before the disaster,the calculation model of non-limit active earth pressure under the space-time dimension before the disaster was established by using the theoretical derivation method.Took the whole process before the disaster as the research interval,based on the characteristics that the soil will transform to a fluid-like state before the disaster,the soil was compared to a fluid.According to the momentum equation of fluid motion and the rheological model of soil,the calculation method of active earth pressure in the space-time dimension before the disaster is deduced.This equation solves the problem of coupling the time dimension and space dimension of earth pressure before the disaster.The change of earth pressure before disaster is closely related to the friction between wall and soil.In order to complete the change law of friction between wall and soil in the whole process before the disaster,the development law of friction between wall and soil before the disaster was studied by combining theoretical research with experimental research.The shear test device of wall-soil friction was designed and developed,and the shear test of wall-soil interface friction angle was carried out before the disaster.Through the analysis of the test results,the change law of wall-soil interface friction was obtained.From the point of view of tribology,the theoretical model of wall-soil interface friction is established,and the friction mechanism of the wall-soil interaction before the catastrophe is revealed in combination with the test results.From the perspective of wall soil interaction,the setting of alarm value is reexamined.According to the variation law of wall soil friction angle,the early warning domain of deep foundation pit displacement is established,and the safety of deep foundation pit before disaster is effectively evaluated.