Dissertation > Industrial Technology > Mining Engineering > Mine the pressure and support > Rock pressure and rock movement > Wellbore to pressure

Study on the Mechanism of Collapse of Mix & Vrtical-pit Shaft in YIXIN Coal Mine

Author LuYouZhong
Tutor GaoYongTao
School Beijing University of Science and Technology
Course Geotechnical Engineering
Keywords coal mine vertical-pit shaft Mechanism of Collapse numerical compute
Type PhD thesis
Year 2008
Downloads 283
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The background of the project research is based on the mechanism of collapse and the technique of anchoring & grouting mix &vertical-pit shaft that happened in YIXIN coal mine which belongs to HEGANG Mining Industry Group in HEGANG in HEILONGJIANG province on October, 2004. According to the advanced numerical compute optimal theory and combination test of engineering, the author takes the elaborate, embedded research and quest.(1) A collapsed-body programming have been produced which based on FLAC3D of the ANSYS’interface, as well as, a three-dimensional model has been built up, and we combine the numerical simulation make a first judgment on the reasons of collapsing of the pit-shaft,as well as we can judge and analysis the state of rock mechanics from the results .(2) As lacks of maintain & protection for a long time, it caused decayed rock & water seepage of rock body, the strength has been reduced, esp. cranny-water’s pressure may increase the speed that the pit-shaft lost the stabilization and then would collapse. So we used dimensional method make a deduced analysis of cranny-water’s pressure, and proposed the effect of rock body’s structure that influenced by non-water pressure & vertical fracture rock body’s face pressure of cranny water.(3) On the basis of the pit-shaft and wall of well’s characters that mobility and the flexible rocks have, we made the relevant programming, and improved the Burger’s creep’s model of the FLAC3D, taking a numerical simulated study .The results told us that creep which means potential inducement and breakage have a more important effect on the pit-shaft when collapses. Elasto-plastic rock contrast with the results of creep,the results show that, at t = 0, rock the key point for the elastic-plastic 3.57 mm horizontal displacement, and consider ways to improve the creep model for the displacement of 4.25 m ,an increase of 19.1%, elasto-plastic depth to the displacement of 7.85 mm, and consider ways to improve the depth of creep model to 10.07 mm displacement, an increase of 28.3%, elasto-plastic vertical displacement of 13.62 mm, and consider ways to improve the creep model for the vertical displacement 19.74 mm, an increase of 44.9%. Thus, improved creep model to improve the accuracy of many of the results, creep instability of the shaft wall collapse important impact. This shows that the improved creep model calculated the results more precise, and more accurately reflect a meltdown in the shaft wall instability mechanism of creep. So the collapse of the shaft wall rock creep site of important significance, but also for similar projects can provide a certain degree of reinforcement design basis.(4) Based on the fact that there exists certain proportion of siltized intercalations that interior wall rock the residual strength or almost the residual strength in the rocks of the surface of coal-mining silos, support vector machine’s theory is introduced for the first time in the research, anticipating the residual strength of the siltized intercalations of the project background through a mean of Support Vector Machine(in short for SVM). With the help of the convinnient function of Matlab optimized toolbox, we worked out the Matlab programme of corresponding optimized equations, and through the mean of machine-study , we constituted a non-linear SVM connection between the residual strength of siltized intercalations and all factors that affect, to predict the residual strength of newly-formed siltized intercalations. The outcome shows that soft siltized intercalations play a certain damaging role in the destabilization and collapse of the surrounding rocks of silos.

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