| The main characteristic of ore-drawing under the waste is large amounts of waste rock and ore contact directly and causing excessive growth indexes of ore loss and dilution in the process of drawing. Practices has proved that artificial roof can play a role of isolate waste rock, but it rarely used in the caving method, and also the action of artificial roof in ore-drawing under the waste is lack of further experiments and theory studied. On the basis of summarized and analyzed a large number of literature and the action characteristics of metal mesh flexible roof and concrete rigid roof, the concept of "wire rope-concrete-flexible artificial roof" was proposed. The roof is consist of wire rope (mesh), reinforcement mat (small grid) and concrete, protocolled laid the roof on the top of ore block overall and formed the overburden, and then caving under the roof. The roof’s boundary without fixed and moved down with ore interface gradually in the process of ore drawing, it can be realized the drawing-mode of separation of ore and waste. It is allowed the concrete fracture into block structure and taken full advantage of tensile strength of wire rope and steel fabric to bear the loading, make the roof appeared the deformation characteristics of "partial rigid, entirety flexible". The mechanism of the "wire rope-concrete-flexible artificial roof" in the process of ore-drawing was studied in this thesis:First, the simplified mechanical model of "wire rope-concrete-flexible artificial roof" was established and its deformation characteristics conditions were analyzed; Secondly, the action process of "wire rope-concrete-flexible artificial roof" was showed by ore-drawing simulation experiments; Then, the stress state of "wire rope-concrete-flexible artificial roof" in the process of drawing was analyzed with numerical simulation and carried out contrast analyzed. The work in this thesis is summarized as following:1. The concept of "wire rope-concrete-flexible artificial roof" in ore-drawing under the waste is first put forward in this thesis, it basically has following characteristics:(1) It is allowed the concrete fracture into block structure at action point of resultant force; (2) Due to the effect of bonding of the rebar and concrete, the concrete block is connected as a whole; (3) Take full advantage of tensile strength of wire rope and steel fabric to bear the load.(4) The characteristic of "flexible" of the "wire rope-concrete-flexible artificial roof" is a relative concept.2. The simplified mechanical model of "wire rope-concrete-flexible artificial roof" was established and its deformation characteristics of "partial rigid, entirety flexible" was analyzed based on the soil arch theory, soil theory, mechanics of materials, structural mechanics, and mechanics of elasticity. And then the deformation characteristics of roof was verified with ore-drawing simulation experiments, the results shows that the deformation characteristics of "partial rigid, entirety flexible" can be realized if the strength of "wire rope-concrete-flexible artificial roof" was meet the requirement of deformation conditions.3. The accumulated mass draw of isolated draw-point with flexible artificial roof was 4.4 times the mass drawn under the waste, and the recovery rate of multiple draw-point was increased by 20% or so, it present that the flexible artificial roof has obvious effect on improve the recovery rate of ore. In isolated draw test, the maximal displacement of roof has good linear relation with the mass draw:S1=0.00456Qf, the relationship between average deflection and mass draw was fitted by an equation of D=46.7941n(Qf)-397; in multiple draw-point test, the displacement of roof and mass draw also showed a good linear relationship:SM=0.00406Qf.4. In isolated draw test, the equivalent height of maximum pressure is 44.4% of the overburden layer thickness; in multiple draw-point test, the equivalent height of maximum pressure is 60% of the overburden layer thickness in the end, and it’s 20% in the middle. In a word, the dynamic pressure is less than the static pressure.5. The particle flow and stress state of flexible roof were analyzed by particle flow code. (1) On the ore body tilt direction, ore particles trajectory on the parallel to the lower plate boundaries, the trajectory, velocity vector and displacement vector of roof is in the same direction with particles trajectory, it showed that the roof was coupling move with particles. (2) The vertical stress of flexible roof in the process of drawing overall remained relatively stable in a certain range fluctuation; for the maximum tension of flexible roof was appear in section which contact with the medium instead of the section in the largest bending deformation degree. (3) Tension of flexible roof in the process of drawing was less than that at end of drawn, and tension of flexible roof in multiple draw-point test was less than that in isolated draw test.In this paper, the mechanical model and the deformation characteristics calculation of the "wire rope-concrete-flexible artificial roof" have been established at condition of ore-drawing under the waste in the steeply dipping ore-body, it is conducive to understand the action mechanism of the "wire rope-concrete-flexible artificial roof" in the process of ore-drawing, and it is also provide a certain theoretical guidance for the application.
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