Experimental And Theoretical Research On Optimization Of Stope Structure Parameters In Sublevel Openstope With Subsequent Filling Method

The open-pit into underground mining of the Yongping copper mine is in progress. According to the design, the underground mining adopt the method of downgoing filling. And the extraction of No. Ⅱ orebody is under conducting with sublevel openstope with subsequent filling method. Due to the original design is a plan, the specific implementation needs to combine with the practical situation of engineering stability of pillar and related parameters optimization of mining technology, to satisfy the requirement of practical productionSo this paper optimize the stope structure parameters to improve the stability of the stope and decrease exploitation losing by collecting information, crime scene investigation, laboratory test, theoretical analysis, numerical calculation and so on. The main research content is as the following:(1) The information about geology, geological structure, characteristics of structural face, orebody occurrence characteristics, hydrogeology and so on has been gotten in Yongping copper mine.(2)By means of in-situ investigation and laboratory rock mechanics test, the systematic research of the ore rock characteristic was carried out, combined the result of rock mechanics and adopted the Generalized Hoek-Brown Criterion to reduce rock mechanics parameters to obtain the strength parameters of the main ore rock under the pit in the Yongping copper mine.(3) Tailings were brought to lab to test moisture content, and made standard samples of cement filling body, what’s more, we did the uniaxial compressive strength test, brazilian split and tensile test, angle mould pressure-shear test with the cemented tailings specimen whose curing time is 28 days and the proportion of the lime and sand is 1:4、1:10 to obtain the strength parameters of the cement filling body.(4) Simplify the level pillars under loose medium to the clamped- clamped beam under uniform load, on the premise of Yangsen theory, the bearing mechanism of the level pillars under loose medium was analysed, and the universal calculation formula of loose medium load in the upper of level pillars was derived. By means of the rock tension instability criterion, the least reservation safety thickness calculation formula of the level pillars under loose medium was derived. Then, calculated the theoretical solution of the least reservation safety thickness of level pillars was calculated by according to the basic data which obtained from the engineering practice and test.(5) The three-dimensional model of stope in research region was established by using ANSYS software, and then adopted FLAC3D software to analyze the stability of the level pillars under the condition of static force and blasting load to obtain the numerical solution of level pillars’s optimum dimensions.(6) Fixed the optimum dimensions of the level pillar in the copper mine by synthetic theoretical analysis and numerical calculation.(7) To reduce the permanent loss of the level pillars, numerically simulated the bottom of the room which transfer from the original design loose medium filling to cemented filling whose proportion is 1:4, and optimized the distribution and height of the cemented filling.(8) Using the method of numerical simulation to prove and optimize some stope structure parameters such as the size of room and ore pillar、stoping sequence, the distribution and height of cemented filling in the spacer pillar.