Shotcrete is often subject to poor ductility and cracking problems, particularly under high stresses. In order to deal with these issues, the feasibility of adding polypropylene macrofibers to shotcrete was verified. To ascertain the supporting effect, dry shotcrete, wet shotcrete, and wet polypropylene macrofiber-reinforced shotcrete (WPMS) were used as samples. Furthermore, the mechanical response characteristics thereof in uniaxial compression tests were compared and analyzed by acoustic emission (AE) monitoring. The results showed that the three materials were brittle, but the ductility, residual strength, and bearing capacity of polypropylene macrofiber-reinforced shotcrete were significantly enhanced. The energy absorption value of plain shotcrete was higher in the cracking stage, while that of polypropylene macrofiber-reinforced shotcrete was greater in the postpeak stage, which showed that the polypropylene macrofiber-reinforced shotcrete had the characteristics of a high crack-initiation strength and toughness. Besides, the energy release from fiber shotcrete occurred after the peak stress rather than near the peak stress. The average energy absorbed by polypropylene macrofiber-reinforced shotcrete was significantly higher than that in dry shotcrete and wet shotcrete, which implied that polypropylene macrofiber-reinforced shotcrete could mitigate the brittle instability of a shotcrete layer. A constitutive model of damage statistics was established based on the test data. The comparison between the experimental data and the fitting results can reflect the characteristics of the total stress-strain curve of such shotcrete. The results provide a basis for the optimization of polypropylene macrofiber-reinforced shotcrete layers.

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湿法聚丙烯纤维增强喷射混凝土的压缩试验特性及本构关系

喷浆混凝土经常会出现延展性差和开裂的问题，特别是在高应力下。为了解决这些问题，验证了向喷射混凝土中添加聚丙烯大纤维的可行性。为了确定支撑效果，使用干喷射混凝土，湿喷射混凝土和湿的聚丙烯大纤维增强喷射混凝土（WPMS）作为样品。此外，通过声发射（AE）监测比较和分析了其在单轴压缩试验中的机械响应特性。结果表明，这三种材料都比较脆，但聚丙烯大纤维增强喷浆混凝土的延展性，残余强度和承载力得到了显着提高。在开裂阶段，普通喷射混凝土的能量吸收值较高，而聚丙烯大纤维增强喷浆混凝土在后峰期较大，这表明聚丙烯大纤维增强喷浆混凝土具有较高的开裂强度和韧性。此外，纤维喷射混凝土的能量释放发生在峰值应力之后而不是峰值应力附近。聚丙烯大纤维增强喷射混凝土的平均吸收能量明显高于干喷射混凝土和湿喷射混凝土，这意味着聚丙烯大纤维增强喷射混凝土可以减轻喷射混凝土层的脆性不稳定性。根据试验数据建立了损伤统计本构模型。实验数据和拟合结果的比较可以反映这种喷射混凝土的总应力-应变曲线的特征。研究结果为聚丙烯大纤维增强喷浆混凝土层的优化提供了依据。