Study On Deformation And Failure Mechanism Of Rockfall Hazards And Monitoring And Early Warning

Rockfall of geological disasters are relatively frequent disasters of a natural disaster, according to the China Geological Environmental Information Network statistics, disasters occur each year around rockfall 2000, the huge human and economic losses every year since rockfall disasters. In order to mitigate the loss rockfall disaster. Domestic and foreign scholars have done a lot of research and rockfall disaster prevention practices, has made more research. But the rockfall of disasters occur with strong uncertainties, sudden and concealment, the current method of monitoring and early warning mechanisms and study the causes of the rockfall is still not deep enough disaster system, continue to strengthen the rockfall of the deformation and failure mechanism and disaster monitoring and early warning of Research is very necessary and important.In this paper, Guizhou and Sichuan typical rockfall hazard as the prototype of typical rockfall disaster area two field research, summed up a common model for deformation rockfall disaster, and by means of physical simulation experiment to study the rockfall of deformation and failure of disasters characteristics and mechanisms reveal the main factors of instability and failure rockfall. On this basis, for all types of rockfall characteristics, the mechanical analysis of rock mechanics, fracture mechanics, warning criterion established various types of typical rockfall disaster. By analyzing the rockfall deformation test- time curves, the establishment of a collapse hazard occur at different scales of time prediction models and methods. Through this study, the main results obtained are as follows:(1) Based on the typical rockfall disaster site survey on the southwest region, with rockfall of rock mass structure, lithology, deformation and failure mechanisms of evolution and development as the basis, the rockfall divided into three categories(Toppling type, Sliding type, Falling type) and seven sub-categories: Toppling, Toppling crushed type, Sliding, Toppling slide, Izod formula(crack overturning), dislocation type.(2) According to the basic characteristics of rockfall hazard and disaster-induced rockfall of the environmental factors, the rockfall the whole process of design and development of three-dimensional physical simulation test platform. Test body model box size 3m(height) × 3m(length) × 2m(width), the inclination can be adjusted as needed, equipped with loading systems, multi physical test systems, systems and rain water level lifting system to achieve different working rockfall simulation conditions.(3) Type of Toppling crushed, toppling slide and Izod formula conducted a series of physical simulation test, analysis of the various types of rockfall deformation and failure characteristics, processes and genetic mechanism. The results showed that: Toppling slide style and toppling crushed style rockfall deformation curve- time with a typical three-stage deformation features, but the Izod rockfall deformation-deformation features a three-stage time will not be significant enough.(4) According to the characteristics and mechanism of deformation and failure of rockfall, and analyzes the internal and external factors affecting the rockfall deformation and failure, and in order to determine the various types of typical rockfall targeted monitoring contents, monitoring instruments and techniques. Combined with the actual monitoring results Guizhou rockfall disaster, we analyzed the characteristics of monitoring instruments and applicable conditions.(5) Combined with various types of rockfall features and content monitoring, critical crack width were established criterion and critical head fracture criterion the toppling slide of rockfall, The critical crack width and crack critical head criterion Toppling rockfall, The critical crack width head toppling crush style rockfall and rockfall the critical crack width head connected with rock, Izod rockfall critical crack width criterion and dislocation style rockfall connectivity rate criterion.(6)Through the rockfall deformation- Saito contrast curve characteristic time curve landslide analysis found that both showed a three-stage deformation features(initial deformation, constant deformation and deformation acceleration), and both have obvious differences, rockfall deformation curve in the initial stages of deformation curve was "S" type; at constant deformation phase slope of the curve is relatively small, indicating that the rockfall in constant deformation stage is relatively slower than the landslide deformation; accelerated deformation phase deformation curve steep, indicating instability rockfall having rapid, sudden. For this deformation curves, using the proposed method of inverse velocity model equations can better fit the quantitative characterization and accelerated phase deformation curves.(7)According to rockfall deformation- time curves, different time scales proposed prediction models and methods, may be short-term forecasting model rockfall : inverse-velocity method and Di Takashi Saito model; deformation due to rockfall accelerated phase of rapid and unexpected, its acceleration time deformation stage before the entire time the ratio of deformation stage have been satisfied landslide golden number 0.618, the ratio of 0.8 to 0.9, whereby the long-term forecast can rockfall disasters. Finally, according to characteristic curve deformation monitoring, warning criterion and early warning models and methods were established all kinds of rockfall. Comprehensive method for determining alert levels.