In view of the lack of quantitative indices in the adaptability evaluation of the shield,the geological conditions of downdip mining face with deep large mining height and soft rock in the Huainan area is considered as the research background.The load-bearing stability model of the"shield-shifting ram"of four-leg and two-leg shields is established,and the standard forms of critical load and the judgment criteria of the shifting ram participating in the mechanical balance of the shield are obtained.Moreover,a double quantitative evaluation index is introduced to measure the adaptability of the shield to roof and floor,and the four-leg large mining height shield of ZZ18000/33/72D suitable for the coal mine is developed.Then,theoretical analysis,numerical calculations and field tests are carried out to investigate the adaptability of the two types of shields.The results show that the greater the adaptability index between shield and roof and the smaller the adaptability index between shield and floor,the stronger the corresponding adaptability of the shield.The ZZ18000/33/72D typed large mining height four-leg support exhibits significant advantages over the two-leg support in terms of adaptability to the roof,bottom pressure ratio,and control of the safety valve.The critical load curve of the ZZ18000/33/72D support is better suited to the roof load characteristics of the specific scenario.The shield has good adaptability to the roof and floor,no large-area sidewall and roof fall affect the safety and mining of the coal,and the base does not sink into the floor.The study provide s quantitative reference for the adaptive design and evaluation of shields.
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