Back Analysis of Mechanical Parameters of Surrounding Rocks Based on GA-BP Algorithm

A displacement back analysis algorithm was developed for deriving the mechanical parameters of surrounding rocks.Given the drawbacks of BP neural network(BPNN) such as easily getting stuck in local minima and over long training time,a genetic algorithm with global optimization ability was used to optimize the weights and thresholds of the BPNN.The parameters of surrounding rocks were designed in the initial domain by the uniform method,which reduced the iterative time and improved the forecast accuracy.Applying the method to the back analysis of the mechanical parameters of Luchunba railway tunnel,we introduced the parameters as obtained into the numerical model for computing.The results show that the errors of the calculated and measured values were-8.9% and 4.5%,respectively,which illustrates the reliability and applicability of the method.