黄土隧洞支护结构设计方法探讨

采用ANSYS软件，对宝兰铁路二线码头隧道的双层模筑复合式衬砌试验断面进行建模分析，应用有限元强度折减法，求得隧洞的围岩的安全系数，应用有限元法按土体与结构共同作用原理求衬砌的安全系数。黄土隧洞设计须满足的两个要求：初步建议初期支护后土体围岩的安全系数不小于1.15～1.2，初期支护安全系数不小于1.3；二次支护后衬砌结构的安全系数大于2.0～2.4，确保工程施工与运行安全。对求得的围岩和衬砌安全系数进行评价分析，形成黄土隧洞支护结构设计的定量方法。

Exploration of design methods of support structure in loess tunnel

Sections of double layer compound liner test of second-line terminal tunnel for Baoji-Lanzhou railwag are modeled and analyzed by using ANSYS software, safety factors of the surrounding rock are calculated by strength reduction finite element method, and safety factors of the liner are calculated by applying finite element method based on the combined effect of soil and structure. The loess tunnel design must meet the two stable requirements: according to the preliminary proposals, the safety factors of the surrounding rock can't be less than 1.15 to 1.2; at the same time, the safety factors of the initial liner can't be less than 1.3 after the initial support; the safety factors of the liner are greater than 2.0 to 2.4 after the second liner so that the construction and operation security can be ensured. Evaluating and analyzing the safety factors of the surrounding rock and the liner, quantitative methods of designing loess tunnel support structure are formatted.