In order to achieve the purpose of early warning, a scientific and reasonable evaluation system of early warning is required to be established. Based on multi-source information obtained by monitoring surrounding rocks, this paper proposes three parameters as early warning indicators, namely, rock displacement, deformation rate and acceleration for deformation. First, it made a quantitative analysis and evaluation of the monitoring data, and used a variety of data smoothing methods or wavelet analysis for the diagnosing of monitoring data to determine the criteria for the safety of surrounding rocks. Then, it gave a consideration to the genetic mechanism of rock deformation and combined it with mathematical and statistical methods to establish a forecast model of monitoring data, thereby getting a system for monitoring, warning and evaluating the ground pressure. It has extremely important theoretical and practical significance for correctly predicting rock failure, effectively preventing accidents, and successfully warning accidents.
Currently, the warning reference for rock safety mainly includes the permissible ultimate displacement, displacement rate, displacement acceleration, deformation ratio and other judging bench marks. It's hard to use only one single index as a reference to judge the safety of surrounding rock and supporting structure. Sometimes the peripheral displacement goes beyond the reference value of displacement control, but no damage occurs to the supporting structure; sometimes the deformation rate is large, but still far less than the reference value of surrounding displacement control, and no structural damage has occurred; sometimes the rock deformation has not yet reached the reference value of displacement control, but the supporting structure has became instable. Within a certain period of time, the damage of rock will accelerate the destruction (Lian 2012).
