| The steep thick broken phosphate orebody of Kailin Group Yongshaba mine possesses some characteristics such as high-value and good quality, however the orebody mining exists following problems such as poor-safety, low-productivity and high-mining cost. For the difficulties mentioned above, the artificial roof downward sublevel cemented-method is applied to exploit it. The innovative technology of the method is adopting the new working procedure. First pre-building a high-intensity protective artificial top structure and increasing the sublevel height, and then using medium-leghth hole ore blast. Thus the application of the technology ensures safety and high-efficiency. The artificial roof protective structure is a key technology which directly affects whether the mining method can be successfully applied for this kind of steep thick broken orebody. Based on the complex and uncertainty of underground rock properties, geological conditions, as well as the mining construction process, it is necessary to research the bearing strength, construction method and the stability of the artificial roof structure. This paper makes a depth study on them and achieves following results:(1) The girder bearing and the hanging-bars suspension carrying two artificial roof bearing design programs are achieved and compared between construction difficulties and mining conditions in this study. Finally the hanging-bars suspension carrying artificial roof program is selected.(2) Artificial roof load calculation method under the filling body load or caving rock load is proposed and the conclutions that thin board mechanics model is suitable for artificial roof instability mechanism analysis and artificial roof design should focus on the bending tensile failure based on the weak board soft support structure are obtained.(3) The artificial roof strength design, reinforcement design and bolt bearing capacity design under the gravity and the upper loading is completed; and the artificial roof cost function is derived, and the artificial roof reasonable reinforcement ratio with different artificial roof thickness is calculated. According to the above results, artificial roof construction design and process design is made.(4) The artificial roof structure stability is analyzed by the ANSYS software, which indicates the metal mesh plays an important role in improving the artificial roof overall strength and load capacity and with the design roof-thickness0.8m and0.4m, reinforcement rate0.33%and0.325%can ensures the artificial roof stable and reliable.(5) The artificial roof construction experience is obtained by artificial roof site construction; and the artificial roof successfully is applied to the stope recovery test, nearly3000t ore is recycled. So the artificial roof creates good economic benefit. |
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