| Green technique in undersea mining is an orientation in the development of mining engineering industry. At present, the exploitation of undersea coal resources yielded a rich harvest. However, the research work of metal mine in this field is in its infancy. Financed jointly by the National Basic Research Program of China, the Key Science and Technology Project of Shangdong Gold Group CO.,LTD, and Key Technologies Research and Development Program of China, this article deals with the key technology of undersea mental mining. On the premise of the basic research of rock mechanics, reasonable layers of protection, frame stope structure parameters, strata monitoring and early warning and mine water system are discussed in this article.As regards the basic research of rock mechanics of undersea mining, it is important to know the bed of the existence of ore body, morphology of orebody, the geological condition and in-situ rock stress rule. Then, indoor rock mechanics testing and field testing of rock structural plane are carried out, and6evaluation index of RMR evaluation method was selected as a basis for evaluation of rock mass quality in Xinli mining area. Rock mechanics parameters of different quality levels were obtained by the use of Hoek-Brown criterion. All these works provides the research basis for underground engineering layout, stope stability analysis and parameter optimization, etc.The research of reasonable layers of protection in undersea mining focuses on the thickness. According to Mindlin plate theory and Winkler foundation theory, irregularly shaped protective layer model was established. And differential cubature method was used for the solving and programming of solving program DCFMP. As the criterion of reasonable protection layer, maximum tensile stress criterion is applied in the determination of reasonable protective layer thickness of the18panel in Sanshandao mine. The final recommendation uniform thickness of the protective layer is22.16m (the safety factor is1.8). It is also found that there was a significant correlation between reasonable protective layer thickness and area. A regression equation was then obtained and it provides a more convenient way for the determination of reasonable layers of protection.As far as the frame stope structure parameters is concerned, maximum principal stress of different frame stope structure parameters are first calculated. Then the system strain energy maximization objective function for stress constraint was established. In the cases, where response surface function is to be performed, it is better to use the nonlinear optimization techniques where the response surface functions have been calculated. The size of point column and the span are then known. They are respectively4×4m and12m. Based on Kirchhoff plate theory, irregular roof pillar model between the middle parts are established. The top pillar model and numerical analytical solution are also be found by the Galerkin method and coordinate mapping technology. Based on an overall analysis of factors in economic, safety and filling performance, an objective function is build. And the top pillar of the9panel in Sanshandao mine is optimized. The optimal unified thickness is7.16m. Stability analysis of surrounding rock of different excavation sequence within the panel mining stope of ore block was conducted using Stress-strain strength reduction process of any point in strength reduction FEM and safety factor method under the condition of Mohr-Coulomb criterion. And the mining sequence of the"two stope panels"is applied for the mine. Its safety factor range is2.5to3.5, which does not meet the conditions for instability ore.The monitoring data of the three exclusive observations chamber A, B, C in hanging wall rock is used in the research of strata monitoring and early warning. On the basis of the use of wavelet transform, estimation of abnormal tendency and smoothing treatment of the strata displacement monitoring data is carried out. Time series AR model was used for short-term monitoring forecasts. The error between the predicted and measured values of different wavelet decomposition level and forecast step was analyzed. Prediction error can be controlled within1%, and3-6is the best estimate step. At the same time, by comparing each determining method of the warning indicators in geotechnical engineering, the ratio of the deformation rate of vt in a single selected sampling time before and the average strain rate of20-80d, as threshold warning indicator, was used for the monitoring of security status discrimination. Studies show that the early warning system that can analyze the deformation of seabed mining rock, and it also provide guidance for safe operation of undersea mental mine.In the research of underground water system, thirteen physico-chemical indicators and two isotopic indicators were surveyed at100fissure water samples and13characteristic water samples in Xinli, a deposit of Sanshandao gold mine (Jiaodong peninsula, PRC). Firstly, principal components analysis (PCA) was used to extract four principal components (the contribution rates of information are48%,25%,10%and7%, respectively). This article has presented an in-depth look at the characteristics of hydrochemistry indicators of each main component. The four principal components are identified as the process of concentration and dilution of seawater, phyllic and carbonate process, the process of potash feldspathization and carbon dioxide dissolution process by comparing relevant geological reports. Then, based on an analysis of the PCA,100water samples were grouped into spatially continuous four water classes using the fuzzy c-means (FCM) clustering method. The article also takes advantage of graphic technology. It visually shows the spatial distribution of the four clusters. And then the characteristics of hydrochemistry of each cluster are analyzed, which verified the related hydrogeological report. The four clusters are deep saline water, shallow saline water, bedrock brine and mixed wastewater. Finally, a searching analysis of the results of PCA and FCM get to the movement and evolution system for groundwaters-in the pit. These factors include sources of water, flow path, mixing zone, local fissure zone and impact of mining.This research paper has focuses on the problem of how to carry on safe mining for undersea mental deposits. It not only based on the forefronts but it also closely bound up with engineering practice. Therefore, it is a prospective study with characteristics of great application value. |
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