火灾工况下两车道公路隧道承载力计算方法

Bearing capacity calculation method of two-lane road tunnel under fire conditions

常规下衬砌结构承载力的计算主要采用荷载结构法与地层结构法。但在火灾工况下,衬砌截面上每一点的温度分布不均,随厚度增大而降低,同时,材料的物理力学参数以及衬砌厚度也随着温度的变化而变化,而在常规计算方法中,计算参数的定义很难反映火灾工况下材料物理力学参数的实际变化。因此,本文提出一种能够反映火灾下材料物理力学参数实际变化的计算方法,同时将衬砌单元由常用的梁单元换成平面应变单元,然后根据实际情况对模型分层赋予属性并进行结构承载力计算,为以后火灾工况下公路隧道承载力计算提供借鉴。

Generally, the lining structure bearing capacity calculations are load-structure method and layer- structure method. But under fire conditions the temperature of lining cross section is different, and decreases with the thickness increasing. At the same time the physical mechanical parameters of materials and the thickness of lining change accoidingly. In conventional calculation method, the definition of the parameter calculation is difficult to reflect the actual changes on fire conditions. Therefore, a calculation method is provided, in which the lining is divided into several layers, the beam element commonly used is replaced by plain strain element and the property of model is given by layer. At last the calculation performed can provide a reference for bearing capacity calculation of road tunnel under fire conditions.