RESEARCH AND APPLICATION OF PVA CHOPPED FIBER SHOTCRETE
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摘要: 喷射混凝土具有凝结时间短、黏结强度高、支护效果好等优点,但目前喷射混凝土施工过程中普遍存在回弹率过大、喷射质量不达标等不足。以重庆红岩村隧道项目初支喷射混凝土为工程背景,采用现场试验和数值模拟方法研究了聚乙烯醇短切纤维喷射混凝土中纤维的最优掺量,以及对喷射混凝土回弹率和隧道洞室的稳定性、围岩变形等方面的影响。研究结果表明:一定量的聚乙烯醇短切纤维会降低隧道喷射混凝土的回弹率,其最优掺量为0.132%;相比于普通喷射混凝土,采用聚乙烯醇短切纤维喷射混凝土可使隧道洞室失稳时的竖向位移和水平位移减小,最大减小幅度分别可达2.0%和4.3%;喷射混凝土层最大应力较普通混凝土可增大14.3%。Abstract: Shotcrete has the advantages of short setting time, high bond strength and good supporting effect. However, there are many disadvantages in the engineering application of shotcrete, such as high rebound ratio and unqualified sprayed quality. This paper took the initial supporting shotcrete of Chongqing Hongyan Village tunnel project as the engineering background. The experimental and numerical simulation methods were used to study the optimum content of fiber in PVA chopped fiber shotcrete and its influence on the shotcrete rebound ratio, the stability of tunnel cavity and the deformation of surrounding rock. The results showed that a certain amount of PVA chopped fibers could reduce the rebound ratio of shotcrete, and the optimum amount of fiber was about 0.132%. Compared with ordinary shotcrete, the PVA chopped fiber shotcrete could reduce the vertical and horizontal displacements when the cavity was unstable, and the maximum reduction could reach 2.0% and 4.3%. The maximum stress of the fiber shotcrete layer could be increased by 14.3% compared with that of ordinary shotcrete.
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Key words:
- PVA chopped fiber /
- fiber concrete /
- shotcrete /
- tunnel engineering
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