Lu Yi, Li Cong, Zhang Xiaoyu, Huang Xiangyun, Zhao Zhongyin
School of Civil Engineering, Guangzhou University, Guangzhou 510006, China.
Earthquake Engineering Research and Test Center, Guangzhou 510006, China.
Materials (Basel). 2022 Aug 2;15(15):5319. doi: 10.3390/ma15155319.
The aim of this study is to assess the workability of an innovative rubber concrete to fill in the gaps in a shield tunnel construction. This grouting material includes porous sand, PVA (polyvinyl alcohol) fiber, cement, and rubber. One advantage of the material is its high toughness, which is good for the postfailure stage of an earthquake event. Evaluations were carried out on the physical properties in terms of the slurry density, consistency, fluidity, bleeding rate, consolidation shrinkage rate, setting time, and unconfined compressive strength (UCS) (i.e., 3 and 28 days). The toughness index was also introduced to evaluate the performance at the postfailure stage. The results demonstrate that the toughness index will increase as the rubber content increases. It increases from 1.0 at 0% to 1.7 at 80% rubber content (28 days' curing) and from 1.2 at 0% to 2.2 at 80% rubber content (3 days' curing). The increase in fiber content and fiber length will also increase the toughness index as the fiber will enhance the tensile strength of the matrix. The results show that when the fiber content increases from 0% to 1%, the toughness index increases from 1 to 7 (28 days' curing) and from 1.1 to 10 (3 days' curing). Similarly, if the fiber content or fiber length is above the optimum level, the UCS of the material will be compromised. The optimum fiber content is 0.8%, and the optimum fiber length is 6 mm to 9 mm. This study suggests that the balance of physical properties should be considered in designing a satisfactory grouting material based on the specific purpose of the engineering practice.
本研究的目的是评估一种创新型橡胶混凝土在盾构隧道施工中填补缝隙的可施工性。这种灌浆材料包括多孔砂、聚乙烯醇（PVA）纤维、水泥和橡胶。该材料的一个优点是其高韧性，这对地震事件的破坏后阶段有利。针对浆液密度、稠度、流动性、泌水率、固结收缩率、凝结时间和无侧限抗压强度（UCS）（即3天和28天）等物理性能进行了评估。还引入了韧性指数来评估破坏后阶段的性能。结果表明，韧性指数会随着橡胶含量的增加而提高。橡胶含量从0%时的1.0增加到80%时的1.7（养护28天），从0%时的1.2增加到80%时的2.2（养护3天）。纤维含量和纤维长度的增加也会提高韧性指数，因为纤维会增强基体的抗拉强度。结果显示，当纤维含量从0%增加到1%时，韧性指数从1增加到7（养护28天），从1.1增加到10（养护3天）。同样，如果纤维含量或纤维长度高于最佳水平，材料的UCS将会受到影响。最佳纤维含量为0.8%，最佳纤维长度为6毫米至9毫米。本研究表明，在根据工程实践的具体目的设计令人满意的灌浆材料时，应考虑物理性能的平衡。
