Method for determining stress tensor containing three-layer medium model

The invention provides a method for determining a stress tensor containing a three-layer medium model. Accurate acquisition of the stress state is of great significance in engineering practice. According to the sleeve core stress relieving method, the stress tensor is calculated by measuring the strain through a triaxial strain gauge. However, an analytic solution of stress calculation at present is based on a two-layer model, and the situation involving three layers of media cannot be calculated. The invention provides a method for calculating the stress tensor of a triaxial strain unit in a three-layer medium model. On the basis of numerical simulation, four equivalent elastic parameters of the three-layer model are searched by utilizing a genetic algorithm; the correction coefficient of the stress observation equation, namely the K value of the three-layer model, can be calculated by using the equivalent elastic parameters and the analytic solution of the double-layer model, so that the accurate and effect