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湿喷混凝土技术逐渐被应用于高寒矿区破碎岩体巷道支护中,而温度对湿喷混凝土强度发展起着关键作用。针对吉林金英金矿寒区湿喷混凝土支护中遇到的喷层强度低、易开裂等问题,综合研究了温度、水泥掺量、水灰比对喷层强度发展响应规律,采用SEM对湿喷混凝土微观形貌进行观察。结果表明:温度低于10℃时,湿喷混凝土早期强度显著降低,温度高于16℃时,有利于后期强度增长;水泥掺量存在临界区间,掺量大于临界区间后,湿喷混凝土强度有显著增长;水灰比对不同龄期强度发展呈互补关系,低水灰比有利于早期强度提高,高水灰比更有利于后期强度的发展;温度是影响湿喷混凝土微观结构本质因素,内部初始孔隙率及骨料界面黏结强度裂化直接影响湿喷混凝土宏观力学性能;温度低于10℃时,骨料界面因热胀系数不同易产生微裂缝。通过优化配比、改进工艺,使金英金矿日喷射量达40 m3,湿喷支护返修率降低80%。
Wet sprayed concrete technology has been gradually applied to the roadway support of fractured rock mass in high-cold mining area, and temperature plays a key role in the strength development of wet shotcrete. Aiming at the problems of low strength and easy cracking of sprayed layer encountered in the wet shotcrete support in the cold area of Jinying Gold Mine in Jilin, the response of the sprayed layer intensity to temperature, cement content and water-cement ratio was comprehensively studied. SEM Wet sprayed concrete microstructure was observed. The results show that when the temperature is lower than 10 ℃, the early strength of wet shotcrete significantly decreases. When the temperature is higher than 16 ℃, the strength increases at the later stage. The content of cement is in the critical range. When the dosage is greater than the critical range, The water-cement ratio is complementary to the strength development at different ages, the low water-cement ratio is conducive to early strength, high water-cement ratio is more conducive to the development of late strength; temperature is the essential factor that affects the microstructure of wet- The initial porosity and aggregate interface bond strength cracking directly affect the macroscopic mechanical properties of wet shotcrete. When the temperature is lower than 10 ℃, the aggregate interface is likely to produce microcracks due to different thermal expansion coefficients. By optimizing the ratio and improving the process, Jinying gold mine has a daily discharge volume of 40 m3, and the wet-blast support and repair rate is reduced by 80%.