Study On Mechanism And Prevention Methods Of Rockburst In Erdaogou Gold Mine

As metal mines gradually entering into the deep mining, rockburst hazard has become more and more serious, and its prevention has also become a major technical issue which is in the urgently need to be resolved. To this end, according to the deep mining conditions of Erdaogou Gold Mine, this thesis studied the mechanism of rockburst and thus explored the rock burst prevention measures and control technology in order to protect the security of the mine deep mining production.Erdaogou Gold Mine is one of the typical mines beset by rockburst hazard in China, and its orebody is steeply inclined and extremely thin mined by short-hole shrinkage method and resuming-fill method. With the mining depth increasing, the phenomenon of rockburst hazard has become more and more serious. At present, there are multiple stopes forcing to stop mining because of rockburst hazard. Rockburst stopes appear frequently, which seriously affect the normal operation of the mine production. In order to solve the problem of rockburst hazard in stopes, this thesis carried out the research work as follows:(1) The position of rockburst stopes in the deposit and the lithological situation of rockburst zone were analyzed and counted. It was found out that rockburst always occurred in the stopes where was affected by the wedge of hanging wall and also occurred in the zones where hardness and integrity of surrounding rock changed rapidly. Thus, on the basis of position, lithological conditions and face state of rockburst, three necessary conditions of rockburst were summarized, namely the high-stress, high strain energy savings of surrounding rock and the sudden release of high strain energy.(2) In the process of stope mining, deformation process of the roadway which located under the stope was measured by the method of roadway deformation monitoring. Then the pressure distribution curve was obtained. Based on the curve, after a series of analyzing, the author gained that the main high stress which led to stope rockburst was vertical stress that mainly came from the additional force of wedge of hanging wall.(3) Combining with actual conditions of rockburst stope and appling the method of mechanical analysis, the author established the model of wedge hanging wall and the model of pressed sheet buckling of stope surrounding rock, and then revealed the formation process of the stope rockburst and its main features.(4) According to rock burst proneness theory, the author built the rockburst criterion index system suitable for Erdaogou Gold Mine and analyzed the initial stope of rockburst by the method of numerical simulation. Hence, the critical index value was obtained, and the process and the law of rockburst was showed simultaneously.(5) Based on the principle of controlling and transforming necessary conditions of rockburst, the author proposed the methods of preventing rockburst as follows:On one hand, using the methods of stress relieving and goaf filling can eliminate the high stress pressed on the stope. One the other hand, using the methods of drilling and rock bolting can change the high strain energy savings of surrounding rock and the sudden release of high strain energy. Then, according to the combination of the two aspects, rockburst prevention system suitable for all kinds of rockburst proneness stope will be formed.(6) According to the orebody condition, process and method of pressure relief for preventing rockburst was discussed, and the optimization method of size of pressure relief project was given.(7) According to these research results, test program of pressure relief of 1511# rockburst stope was designed. The test results showed that recurrence of rockburst was effectively controlled in the mining process of hanging wall stope, but when mining the footwall stope, rockburst occurred again. The reason was that high stress in the footwall stope was unloaded incompletely because of the unexploded rock pillar in pressure relief project. In order to ensure the mining safety of rest stope, the methods of drilling for relieving and softening the surrounding rock were proposed. What's more, the mining of rest test stope was expected to be successfully completed in the future.Analysis shows that rockburst prevention technology proposed in this thesis which was the method combining eliminating the high stress, softening the surrounding rock and controlling sudden strain energy release togheter can highly adapt the ore and rock conditions of Erdaogou Gold Mine and effectively control the occurrence of stope rockburst. In this thesis, combining the actual mine, the author summarized the rockburst occurred conditions and prevention methods which can provide a new way to prevent the occurence of rockburst in deep mining of metal mines.