Wang Meng, Yu Qunding, Xiao Yuanjie, Li Wenqi
School of Civil Engineering, Central South University, Changsha 410075, China.
Urban Rail and Underground Engineering Design and Research Institute, China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063, China.
Materials (Basel). 2022 Aug 31;15(17):6005. doi: 10.3390/ma15176005.
Tunneling rock wastes (TRWs), which are often open- or gap-graded in nature, have been increasingly recycled and reused for sustainable construction of unbound permeable aggregate base (UPAB) courses with high porosity and desired drainability. However, there is still a lack of sufficient understanding of long-term mechanical stability of such TRW materials subjected to repeated applications of moving wheel loads. This paper aimed to characterize and predict resilient modulus (M) behavior of the TRW materials used in unbound permeable aggregate base applications. To achieve this goal, five different UPAB gradations were designed based on the gravel-to-sand ratio () concept. In order to study their M behavior, the laboratory repeated load triaxial tests were conducted under different combinations of confining pressure and deviator stress as controlled by the levels of the shear stress ratio (SSR). The prediction accuracy of fourteen classical M prediction models was comparatively analyzed, from which the improved M prediction model incorporating gradation and stress variables was proposed for TRW-derived UPAB materials and further validated by external database accordingly. The results show that under the same value and confining pressure level, the higher the SSR is, the greater the final M values are, and the more significant the effect of on M is. Under the same SSR level, the increase of confining pressure alleviates the effect of on M. There appears to exist an optimal value of around 1.6-1.8 that yields the best M behavior of the TRW-derived UPAB materials studied. The improved M prediction model was verified extensively to be universally applicable. It can potentially contribute to balancing long-term mechanical stability and drainability of TRW-derived UPAB materials through gradation optimization. The findings could provide a theoretical basis and technical reference for cost-effective and sustainable applications of UPAB materials derived from TRWs.
隧道岩石废料（TRW）在性质上通常为开级配或间断级配，目前已越来越多地被回收再利用，用于可持续建设具有高孔隙率和理想排水性能的无结合料透水集料基层（UPAB）。然而，对于此类TRW材料在移动车轮荷载反复作用下的长期力学稳定性，仍缺乏足够的了解。本文旨在表征和预测用于无结合料透水集料基层的TRW材料的回弹模量（M）特性。为实现这一目标，基于砾砂比（）概念设计了五种不同的UPAB级配。为研究其M特性，在不同围压和偏应力组合下进行了室内重复荷载三轴试验，这些组合由剪应力比（SSR）水平控制。对14种经典M预测模型的预测精度进行了比较分析，在此基础上提出了结合级配和应力变量的改进M预测模型，用于TRW衍生的UPAB材料，并通过外部数据库进行了进一步验证。结果表明，在相同的 值和围压水平下，SSR越高，最终M值越大， 对M的影响越显著。在相同的SSR水平下，围压的增加减轻了 对M的影响。对于所研究的TRW衍生的UPAB材料，似乎存在一个约为1.6 - 1.8的最佳 值，可产生最佳的M特性表现。改进后的M预测模型经过广泛验证，具有普遍适用性。它有可能通过级配优化，有助于平衡TRW衍生的UPAB材料的长期力学稳定性和排水性能。这些研究结果可为TRW衍生的UPAB材料经济高效且可持续的应用提供理论依据和技术参考。
