Research Of Extraction Of Security Pillar Under Filling Body Based On Energy Theory

For a long time,the study of rock mass stability mainly relies on empirical and semi-empirical methods,and some potential unsafe factors are difficult to reveal.With the increasing scale and complexity of the project,this experience-based method can not meet the actual needs of the development of the project,and it is difficult to effectively solve the stability problem in rock mass engineering.In geotechnical and underground engineering,rock mechanics problems are often encountered.It is necessary to determine the stress and displacement before and after excavation and their changes during excavation,so as to provide reliable quantitative basis for design and construction.However,the existing theories can only solve the stress and displacement fields around simple holes such as circle or ellipse.For the problems of holes with complex geometry,such as stope,the numerical simulation method can only be used to approximate the solution.In this paper,combined with Jiguanzui mining area of Sanxin Gold and Copper Mine-370 m horizontal filling body under the roof pillar mining project,different from the past through monitoring stress and displacement to optimize stope mining,but through energy analysis angle,to carry out stope analysis by energy method.In the research process,the mining parameters of 12 # stope are optimized by numerical simulation and field test,and a conclusion is drawn:(1)A comprehensive evaluation index based on energy release rate,local energy release rate,damage zone,displacement and stress for stability analysis of underground caverns under high in-situ stress is proposed,which overcomes the limitation of previous evaluation indexes in comprehensive prediction of various failure modes of surrounding rock under high in-situ stress.(2)Using ANSYS and FLAC3D software to simulate,the stress distribution and displacement strain change rule of isolation pillar in 12 # stope before mining were analyzed.The analysis shows that when the retaining wall orebody with smaller thickness is retained,the stress concentration at the retaining wall is concentrated and the maximum compressive stress is larger,which leads to the breakage of the retaining wall by fracturing,the release of the concentrated stress and the larger strain rate.As a result,the maximum horizontal displacement of the retaining wall orebody with smaller thickness is larger than the maximum level of the retaining wall orebody without retaining wall orebody.Displacement.When the thickness of retaining wall ore body is more than 0.6m or so,the thicker the thickness of retaining wall ore body,the smaller the maximum horizontal displacement of the mine room.(3)By comparing the numerical simulation and field test results of the optimum mining scheme for the top and middle pillars of-370 m section,it can be seen that the trend of displacement and stress changes of the two pillars are basically the same,and the change values are basically the same after the transformation of similarity ratio,which shows the reliability of the numerical simulation results,that is,the optimum mining scheme is adopted.The roof pillar and pillar are theoretically safe and reliable.At the same time,it is concluded that the excavation steps of the second floor room in the process of pillar stoping and the three-step stoping of the first floor in the process of pillar stoping are relatively unstable steps in the whole residual mining process.The safety monitoring of these two steps should be strengthened in the actual mining process of the mine.