Study On Stress Prediction Criteria And Application Of Rock Burst In Deep Buried Chamber

In recent years, many roads or rail tunnels of long lines and great depth have emerged in our country, and with fulfilling the demand of mineral resources development, as mining operations continue to the underground, many mines have entered the deep mining. With the increasing depth of excavation or mining cavern engineering, this geological condition can easily form the phenomenon of high geo-stress, and can easily trigger a rockburst of geological disasters in the brittle rock.Rockburst often happens under a very complex mechanism, because of the randomness of its location, the slowing of its gestation process and the sudden of its occurrence; it brings great harm to production safety and engineering reliability. Therefore, the studies of the rockburst mechanism and forecasting model have great significance to reduce the loss of life and property and to guide engineering practice.At present, the research on the mechanism of rockburst have not yet formed a unified understanding at home and abroad, and it is difficult to form unified, accurate and practical prediction methods based on different theories. The research of rockburst has become one of the worldwide underground engineering geology disaster problems. In this paper, the rock stress field is a key line, through theoretical analysis and with engineering practice. The study consists of the following aspects:(1) The elastic strain energy accumulation and dissipation are two necessary conditions of rockburst, and both of them have important links with the surrounding rock secondary stress field. This paper relies on mechanical mechanism of rockburst tension-shear mixed failure in the rock mass failure, and uses Griffith-Moore strength theory as the basis of rock failure under different stress state in the form of judgment.(2) Surrounding rock will enter the plastic status under the high-level stress, so the accuration of the rock elastic-plastic stress field becomes the point to the study of rockburst. This paper uses the new-methods which solve plastic mechanical problems and the important conclusions of the two types of stress field in the special boundary conditions as the theoretical basis, and calculates the underground cavern surrounding rock stress field by the finite element method. The accurate stress distribution and variation with depth changing is revealed, and a comparative analysis with the calculation results based on the classical elastic-plastic theory has been made;(3) According to Griffith-Mohr strength theory and combining with the existing critical stress of the rockburst, I derived a new formula for the critical stress of the rock burst and analyzed its applicability;(4)Based on the critical stress of the rockburst, I deduced the critical depth under the complex power of the state of rock explosion and analyzed its influencing factors.(5) This paper calculated the tunnel surrounding rock stress field by new methods with the example of Changling tunnel engineering.Then I used the popular stress criterion of rockburst to predict rockburst piecewise, and judged the practical value of the new method of plasticity.