纤维喷射混凝土硬化对隧道围岩的支护作用

侯伟¹，张露晨^2*，王子方¹，王鹏程³，王修伟³

1.山东高速基础设施建设有限公司，山东 济南  250013；

2.山东交通学院交通土建工程学院，山东 济南  250357；

3.山东大学齐鲁交通学院，山东 济南  250100

摘要：为解决喷射混凝土在隧道新奥法施工中易开裂、强度低、支护作用不清晰等问题，研制一种新型无碱液体速凝剂，测定净浆凝结时间和砂浆强度。在喷射混凝土中掺入聚丙烯粗纤维和无碱液体速凝剂，进行喷射混凝土力学性能试验研究；考虑纤维喷射混凝土硬化规律，采用离散单元程序法（universal distinct element code,UDEC）分析纤维喷层对隧道围岩的支护作用。研究结果表明：此无碱液体速凝剂能有效加快混凝土凝结时间，减少喷射混凝土后期强度损失；聚丙烯粗纤维可有效提高喷射混凝土的强度和韧性；纤维喷射混凝土随时间硬化，喷层有让压卸载作用，有利于稳定支护结构。掺入聚丙烯粗纤维和研制的无碱液体速凝剂有效提高了喷射混凝土的强度和韧性，能更好地发挥喷射混凝土衬砌结构对隧道围岩的支护作用。在高地应力、大变形隧道施工中，聚丙烯粗纤维喷射混凝土具有广泛的应用前景。

关键词：纤维喷射混凝土；隧道工程；无碱液体速凝剂；围岩支护；喷层硬化；UDEC

Supporting effect of fiber shotcrete hardening ontunnel surrounding rock

HOU Wei¹, ZHANG Luchen^2*, WANG Zifang¹, WANG Pengcheng³, WANG Xiuwei³

1.Shandong Hi-Speed Infrastructure Construction Co.,Ltd.，Jinan 250013, China；

2. School of Transportation and Civil Engineering, Shandong Jiaotong University, Jinan 250357, China；

3. School of Qilu Transportation, Shandong University, Jinan 250100, China

Abstract:To solve the problems, such as easy cracking, low strength and unclear supporting function, of shotcrete in procedure of tunnel construction by NATM, a new alkali-free liquid accelerator is developed. The paste setting time and mortar strength are measured. Polypropylene coarse fibers are added into shotcrete to carry out mechanical properties experimental study. Considering the hardening rule of shotcrete, using universal distinct element code (UDEC) method, the supporting effect of shotcrete on tunnel surrounding rock is analyzed. The results show that the alkalifree liquid accelerator can effectively reduce the setting time and decrease the later strength loss of shotcrete, the addition of polypropylene coarse fiber can effectively improve its strength and toughness. Considering the hardening process of fiber shotcrete with time, the shotcrete spray layer can relief pressure, which is conducive to the stability of support structure. Adding polypropylene coarse fiber and the developed alkali free liquid accelerator can effectively improve the strength and toughness of shotcrete, and can better support the shotcrete lining structure on the surrounding rock of the tunnel. Therefore, polypropylene coarse fiber shotcrete has a wide application prospect in tunnel construction with high in-situ stress and large deformation.

Keywords:fiber shotcrete; tunnel engineering; alkali-free liquid accelerator; surrounding rock support; spray layer hardening;UDEC