DATA ACQUISITION SYSTEM BASED ON VIRTUAL INSTRUMENTS FOR PRE-STRESS CHARACTERISTICS OF EXPANDABLE BACKFILL MATERIALS AND COMPUTATIONAL SIMULATION

Category: ICETI 2017
Author: Qian Zhao-ming , Yuan Yan-bin, Zhang Sa-sa, Wang Yu-jie, Ren Gao-feng
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The applying proportion of filling mining method is increasing considerably in mines as it meets the demands of building "two-oriented" society. However, due to the influence of various factors, the backfill materials fail to contact the roof of goaf completely, causing the backfill materials can’t play its role fully. In the paper, the over burnt calcium oxide is injected into goaf as cementations materials together with the tailings. Those mixed backfill material will swell in a relatively short period of time and fill the goaf thoroughly. When the volume expansion is constrained by the boundry of the goaf, the backfill materials will exert stress on the surrounding rock. Firstly, stress data acquisition system based on virtual instruments was established when pre-stress measurement experiment was conducted, the goaf model was filled up with the expandable backfill materials (cement-sand ratio is 1:3 and concentration is 75%), which exerted 0.76MPa and 0.42MPa pre-stress on the roof and bottom of the stope respectively after its volume expansion was limited and stopped. Moreover, the computational simulation was carried out for mutual verification and the results show that: keeping the initial filling rate 0.85, the largest displacement and maximum stress in vertical direction of stope roof are 44.2mm and 17.3MPa respectively when using the ordinary portland cement as backfill materials, however, the corresponding figures are only 4.6mm and 12.1MPa when using the expandable backfill materials. In conclusion, the pre-stress measurement experiment facilitated by self-designed data acquisition system and computational simulation has proved that the expandable backfill materials are effective in controlling displacement and improving the stress distribution in surrounding rock.  

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