可考虑任意围岩压力分布形式的隧道衬砌计算分析

以大型通用软件ANSYS为平台,采用静力等效原则,把压力转化为相应的节点荷载,解决了隧道围岩压力与节点位置相关又不与衬砌结构垂直的输入问题.利用ANSYS的参数化高级设计语言,编制了适合任意三心圆拱衬砌断面和不同围岩压力分布形式的隧道衬砌内力和偏心距的通用计算程序.这为隧道设计提供了很大的方便.以武广客运专线双线浅埋隧道为例进行了计算分析.结果表明:对于埋深较浅的隧道,如果拱顶围岩压力按均布进行计算,结果会产生较大误差.围岩压力仅按均布设计的隧道,拱腰易出现开裂;围岩压力仅按马鞍型设计的隧道,拱顶易出现开裂;最好采用多种围岩分布形式进行隧道设计与验算.

Calculation analysis of tunnel lining considering arbitrary surrounding rock pressure distribution

Based on the large-scale universal software ANSYS,the input problem that surrounding rock pressures of tunnel are associated with node location but not perpendicular to the lining was solved using static equivalent principle to transform the pressures into corresponding nodal loads.A general program using APDL(ANSYS parametric design language),which is applicable to arbitrary lining sections of the three-centered circular arch with different surrounding rock pressure distributions,was developed for the calculation of the tunnel inner forces and eccentricities.The work provides great convenience to the tunnel design.An illustrative example of the shallow embedded tunnel of Wu-Guang special passenger transport double line is given to demonstrate the usage of the proposed procedure.The results show that,for relatively shallow embedded tunnel,a big error would occur if the surrounding rock pressure of the vault is regarded as uniformly distributed.When the tunnel is designed solely according to uniformly distributed surrounding rock pressure,its hance will be prone to fracture and when the tunnel is designed solely according to U-shaped surrounding rock pressure,its vault will be easy to crack.So it is better to adopt several different kinds of distribution of surrounding rock pressure in designing tunnel and checking computations.