铁路隧道喷射混凝土回弹率测试及优化

为控制隧道喷射混凝土回弹率,进行了现场测试,分析了主要影响因素,并设计实施了优化方案,取得了显著效果。结果表明,拱墙回弹率整体偏高,5个工作面回弹率小于35%,5个工作面回弹率处于35%～45%,3个回弹率超过45%,拱部回弹率大幅高于边墙回弹率;围岩等级、岩面水况、施工工艺及混凝土配合比等因素会不同程度地影响回弹率,其中围岩等级及断面大小是主要客观因素;相比优化前试验工作面拱墙整体回弹率平均降低7.7%,拱顶回弹率平均降低9.7%,尤其对于软弱围岩,拱顶回弹率平均降低11%以上。

EXPERIMENTAL INVESTIGATIONS ON MEASURING AND REDUCING THE REBOUND RATE OF SHOTCRETE INRAILWAY TUNNELS

In order to control the rebound rate of tunnel shotcrete, field tests were carried out, the main influencing factors were analyzed, and the optimization scheme was designed and implemented, and remarkable results were obtained.The results show that the rebound rates of 5 faces are less than 35%, and the rebound rates of 5 faces are between 35%~45%, and the rebound rates of 3 faces are more than 45%. The arch rebound rate is significantly higher than the wall rebound rate. Rock grade, water conditions of rock surface, the construction technique and concrete mix ratio will affect the rebound rate. Furthermore, by optimizing the shotcrete material proportion and improving construction standards, compared to the results before optimization, the arch-wall rebound rate decreases by 7.7%, the arch rebound rate decreases by 9.7%.