Wang Zhiwei, Ma Weibin
Railway Engineering Research Institute, China Academy of Railway Sciences Corporation Limited, Beijing, China.
Sci Prog. 2022 Apr-Jun;105(2):368504221098886. doi: 10.1177/00368504221098886.
Due to the complexity of tunnels, accurate prediction of their loosening pressures in layered jointed rock strata is a very difficult engineering task. To recognize loosening patterns and estimate loosening pressures, numerical tests were employed in areas where tunnels were excavated in layered jointed rock strata. A total of 12 influential factors, including joints, tunnel depth, and strata, were considered in each of the numerical models. Three loosening patterns were found in the numerical testing: a ringent trumpet-shaped boundary, an arch-shaped boundary, and a closing-trend trumpet-shaped loosening zone. Empirical expressions for the loosening zone boundaries were further established and, in the form of the 12 influential factors, considered in the simulation. Given the boundary function, the loosening pressures were further deduced, which were categorized according to loosening pattern, i.e., ringent trumpet shape or arch shape, and the excavation condition of whether or not the embedded depth was deeper than the soft layer. Two case studies were used to test this method. The newly-proposed method was found to perform better than existing methods, with loosening pressure values that were slightly larger than, but very close to, actual measured field data.
由于隧道的复杂性，在层状节理岩层中准确预测其松动压力是一项非常困难的工程任务。为了识别松动模式并估算松动压力，在层状节理岩层中开挖隧道的区域进行了数值试验。每个数值模型中总共考虑了12个影响因素，包括节理、隧道深度和地层。在数值试验中发现了三种松动模式：张开的喇叭形边界、拱形边界和呈闭合趋势的喇叭形松动区。进一步建立了松动区边界的经验表达式，并以12个影响因素的形式在模拟中加以考虑。根据边界函数，进一步推导了松动压力，并根据松动模式（即张开的喇叭形或拱形）以及埋深是否大于软层的开挖条件进行了分类。通过两个案例研究对该方法进行了检验。结果发现，新提出的方法比现有方法表现更好，其松动压力值略大于实际现场测量数据，但非常接近。
