Application of Grey-ENN model to prediction of wall-rock deformation in deep buried tunnels

With the comprehensive effect of structure,stress distribution,groundwater,opening mode,etc.,displacement time series of the deep buried tunnels’ wall-rock display monotone increasing characteristics and nonlinearity.Based on the responding composition model,the displacement of tunnels’ wall-rock is decomposed into trend item and random item.The trend and random items of displacement time series are predicted by Grey-ENN model,which combines the advantages of GM(1,1) and ANN model.GM(1,1) can forecast the trend of increasing sequence,and ANN model can reduce error by self-adapting of network.Thus the correctness of prediction is assured due to avoiding the problem that forecast result is far away from real one by using GM(1,1) only.The Grey-ENN model is applied to predict the short-term convergence displacement of wall-rock in Baozhen Tunnel based on the in-situ displacement data.The reasonable convergence rule of tunnels wall-rock is achieved,which provides eference for choosing opportunity to do the second support.