岩爆区与富水洞段隧道湿喷混凝土配合比设计研究

为使喷射混凝土在强度、回弹、一次喷射厚度等方面达到理想的效果,解决锦屏山隧道支护技术难题,采用室内试验和现场试验对岩爆区与富水洞段湿喷混凝土的配合比设计进行了深入研究。研究结果表明:通过引入新型纳米级材料和硅灰,喷射混凝土一次喷射厚可达30～50 cm,2 min内终凝,与岩石的黏结力是普通混凝土的7～8倍以上;2 h内强度可达到1 MPa(普通喷混凝土10 h左右才能达到此强度),28 d强度可达到40 MPa,后期强度(90 d)也比普通喷混凝土增加快,达到44.7 MPa;减水率达到30%、泌水率比不超过17%,流动性提高,能够有效地改善混凝土拌合物的黏聚性和保水性,并且坍落度损失率低于12%,回弹率小于10%。该配合比在岩爆区能有效地抑制岩爆的发生,且在富水区能及时终凝达到封堵水的作用。研究成果对深埋特长隧道的设计和施工具有参考价值。

Study on concrete mix proportion of grouting parameters and process in tunnel with rock burst and water-rich

In order to achieve the ideal results in terms of strength，rebound，and primary thickness of shocrete，and solve the technical problems of support for the Jinpingshan tunnel，the mix proportion design of the wet spraying in the rock burst area and the water-rich section is studied by the laboratory and field test. The results show that by introducing a new type of nano materials and silica fume，the primary thickness of shotcrete can be up to 30 ～ 50 cm，final setting is 2 min，and the cohesive force with the rock is 7 ～ 8 times higher than that of ordinary concrete． The strength can reach 1 MPa within 2 h ( about 10 h for ordinary shotcrete) ，the strength can reach 40 MPa in 28 d，and the later strength ( 90 d) also increases faster than ordinary shotcrete to reach 44. 7MPa. The water reduction rate is 30% ，the bleeding rate is less than 17% ，and the fluidity is improved. It can effectively improve the cohesiveness and water retention of the concrete mixture，the slump loss rate is less than 12% ，and the rebound rate is less than 10% . The mix proportion can effectively suppress the occurrence of rock burst in rock burst area and reach the final strength in time for blocking water in the water-rich area. The research results are of reference value for the design and construction of the deep-buried long tunnel.