1、翻译部分英文原文MINE STABILITY WITH APPLICATION OF SUBLEVEL CAVING SCHEMESA. M. Freidin, S. A. Neverov, A. A. Neverov, and P. A. Filippov UDC 622.831.1The paper expounds results gained in mathematical modeling of stress state of a rock mass under mining by sublevel caving with areal-frontal and frontal ore
2、drawing schemes. Stability of underground excavations in the course of applying the compared methods is evaluated in terms of the Sheregesh deposit. The authors recommend on supporting the openings at the ore drawing-off level.Technology, stress state, modeling, stability INTRODUCTIONThe feature of
3、the current ore mining technologies is the maximally simplified mining methods and the philosophy of highly intensive mining with using mobile equipment unites and sets. For instance, equipage of underground mines in Canada, Sweden, Australia, USA includes more than 95 % of advanced mobile machinery
4、 both for primary and secondary mining operations 1.Mining conditions at thick iron ore deposits (e.g., Sheregesh deposit) and at mid-grade ore deposits are most suitable for application of the method of sublevel caving with frontal ore drawing, the efficiency of which is proved world-wide 2. This t
5、echnology ensures qualitative and safe mining at any complex deposits; it is advantageous for high productivity and intensity of works, needlessness of ore chutes, pull holes, manholes, undercut levels, simplicity, flexibility and culture of the method. Though there are same drawbacks, too, e.g., hi
6、gh ore losses and dilution, mining in dead-ended stopes, which worsens working conditions and requires extra expenditures for ventilation. The presence of these disadvantages needs for new structural schemes to be developed for the method of sublevel caving.METHOD OF SUBLEVEL CAVING WITH AREAL-FRONT
7、AL ORE DRAWINGThe researchers of the Institute of Mining SB RAS have developed a modification of the method of sublevel caving with areal-frontal ore drawing specially for thick and very thick steep pitching ore deposits with the aim of eliminating the above drawbacks of the frontal drawing but keep
8、ing the advantages of the sublevel caving (Fig. 1).The studies 3, 4 highlight in detail the features and efficiency of this innovative technology. The proposed modification, as compared with the “classical” frontal drawing, offers an additional driving of haulage inclines between haulage crosscuts i
9、n order to drawing ore over the whole area of a broken layer and ventilate stopes at the expense of all-mine airing 5, 6. Hereby, it is possible to benefit from greater completeness, better quality and higher safety of ore mining.Fig. 1. Method of sublevel caving with areal-frontal ore drawing: 1 ha
10、ulage roadway; 2 haulage crosscut; 3 haulage inclines; 4 broken ore layer; 5 air driftBased on the studies 3, 4, the technological parameters to gain the highest extraction indices were determined. Depending on a sublevel height of 15 m and 20 m, the distance between the haulage crosscuts is 12.0 m
11、and 14.0 m, the haulage inclines (considering an ore layer for frontal drawing scheme) are spaced at 12.0 12.5 m and 13.5 14.5 m, respectively. The broken layer thickness is 0.45 0.50 of the sublevel height. It was found that the optimal regime of ore drawing is by batches from a haulage incline (ov
12、er the broken layer area) and from a haulage crosscut at a ratio 2:1. Comparing the areal-frontal and frontal ore drawing schemes showed the better parameters of the first one: ore losses reduced by a factor of 1.4 1.5, ore dilution decreased by a factor of 1.5 1.7, while the quality of clean ore ex
13、tracted before the dilution increased by a factor of 1.5 1.6. Safety of the method of sublevel caving with areal-frontal ore drawing is determined by operational stability of underground opening for their whole service life. Worse stability of haulage crosscut, inclines and drifts confines the appli
14、cation field of the proposed method, yet not approved in the world mining practice. For that matter, it is necessary to evaluate from the view point of rock mechanics the determined technological parameters of the presented method and to develop measures for higher stability of underground openings.
15、PROBLEM STATEMENTThe study object is to develop a comparative rock mechanics evaluation of underground opening stability for the areal-frontal drawing scheme as against the frontal drawing. The stress-strain state of a rock mass is calculated by the finite element method for the conditions of the Sh
16、eregesh deposit located in Gornaya Shoria 7.We used a 3D model of an isotropic linearly deformable homogeneous rock mass (Fig. 2). Mining depth is 600 m. The calculation domain boundary conditions depended on stress state in the area of stoping, considering the overlying mined-out space. The calculation involved the following principal stresses: horizontal stresses across the orebody strike were z= 3.0 g H ,
