Study On Stability And Design Parameters Of Surrounding Rock In Filling Mining Of Gently Inclined Thick Large Ore Body Based On Three-dimensional Geological Model

China’s iron ore production has been unable to meet the needs of economic development,and it is urgent to increase the production of underground mines.The safe and efficient mining of gently inclined and thick ore bodies,which are widely distributed in China,has always been a hot research topic at home and abroad.Taking the mining of gently inclined and thick ore bodies in Gujiatai iron mine as the engineering background,this paper addresses the problem of large differences between numerical calculation models and real mine geological forms,and low reliability of numerical simulation results.A method combining SURPAC program and FLAC^3Dsoftware was used to achieve refined three-dimensional geological modeling,and to analyze the stability changes and impact range of surrounding rocks in different excavation stages.For locations with significant roof subsidence,the optimal position of artificial concrete pillars was selected to control roof subsidence.Finally,the mining danger zone was determined based on the numerical simulation results,and a remote real-time monitoring system was installed on site.The main research contents of this paper are as follows:（1）Collecting and organizing geological data of Gujiatai iron mine,establishing a geological database of Gujiatai iron mine using SURPAC software,and creating a more realistic three-dimensional geological model of Gujiatai iron mine.By studying the file data formats of SURPAC software and FLAC^3Dsoftware,establishing the corresponding conversion relationship between the two program block unit data,and developing PYTHON programs,the complex geological model was successfully converted into a numerical calculation model that FLAC^3Dsoftware can recognize.（2）After the excavation of the first stage of the ore body,the surrounding rock subsidence mainly occurred in the roof and the upper plate surrounding rock at the-65m level,and the subsidence was mainly concentrated between the 3#～4#vertical survey lines.The filling body of the mining room has a low pressure-bearing capacity,and the pressure stress gradually transfers to the surrounding rock outside the mining room.The stress borne by the pillar increases with the increase of excavation level,forming a stress concentration zone at the-65m level.The roof and upper plate surrounding rock produce a mixed plastic zone of shear and tension,and a shear plastic zone appears between the plate and the pillar,but it does not develop into the surrounding rock.The second artificial pillar in the first stage mining room had the most significant effect in reducing roof subsidence and reducing the volume of plastic zone,followed by the first artificial pillar,and the third artificial pillar had the smallest effect.（3）The second stage ore body and the horizontal isolation pillar mining have a relatively small impact on the filling body and roof of the first stage mining room.The subsidence of the roof is mainly transferred to the upper plate surrounding rock at the-65m to-100m level,and the subsidence area is mainly concentrated between the2#to 4#vertical survey lines of the upper plate surrounding rock,and the subsidence impact gradually expands.With the excavation of the lower second stage ore body and horizontal isolation pillar,the stress reduction zone develops towards the upper plate surrounding rock,and the stress reduction zone on the 2#vertical survey line of the left wing of the ore body extends to a depth of 119m.The maximum stress value on the pillar between the plates still occurs at the-65m level,and the stress value increases to 20.03MPa.The mining of the second stage ore body and horizontal isolation pillar has a relatively small impact on the development of the plastic zone of the roof of the first stage mining room,and a shear plastic zone appears at the pillar between the plates and extends to the deep upper plate surrounding rock.The first artificial pillar in the second stage mining room has the largest reduction in surrounding rock subsidence and plastic zone volume,followed by the second artificial pillar,and the third artificial pillar has the smallest effect.（4）Based on the results of the three-dimensional simulation calculation of the mining area,the mining hazard zone is determined,and remote real-time monitoring equipment is installed in combination with the geological conditions on site.The monitoring curves of the multi-point displacement meter and the pressure gauge show that the subsidence of the surrounding rock of the roof at different levels is slowly increasing,but the surrounding rock is currently relatively stable.The pressure of the filling body is on the rise,but the value is far lower than the compressive strength of the filling body,and the filling body is relatively safe.