Abstract: With the construction of a large number of transport infrastructure in China,tunnel engineering is inevitable,especially in the western region.In the tunnel,the stability of the roof wedge is one of the harms existing in the construction.It is of great significance to monitor and predict the wedge to ensure the safety of the tunnel construction and the later period.Through prediction,timely and effective measures are taken to eliminate risks and avoid economic losses and casualties.The influence factors of tunnel wedge instability are complex and difficult to quantify and are uncertain,which accords with the characteristics of grey system.This paper applied the grey system theory to the prediction of tunnel wedge deformation,and established the G(1,1) single point prediction model of tunnel wedge deformation based on the original monitoring data.The accuracy of the model was verified by an engineering example.In the prediction model,the posterior error ratio C is 0.1195 and the frequency of small error P is 1.The results show that the precision of the prediction model reaches a higher level,and the prediction results can guide the actual construction very well.

Key words: Grey prediction, Grey theory, Single point prediction model, Tunnel, Wedge