不同类型明洞结构的可靠度对比分析

Reliability Analysis of Different Open Cut Tunnel

研究目的:随着铁路隧道设计技术的发展,相比安全系数法,概率极限状态法考虑的因素更全面,使安全评定更合理可靠。本文基于有限元软件ANSYS建模计算结构内力,并采用MATLAB编制H-L法的计算程序对不同工况下的可靠度进行计算,对比分析不同明洞结构的可靠度,探寻明洞可靠度与影响因素的关系,为明洞的相关研究提供参考。研究结论:(1)极限状态法能全面反映各因素的不确定性,充分反映结构的整体性,与安全系数法相比优势明显;(2)各时速下的明洞设计安全储备充足,双线参数较单线更加保守,但这一现象随时速的增加而不明显;(3)开挖部位和4 m以内的覆土厚度对明洞的可靠度影响不大,而结构的受力形式对可靠度的影响显著;(4)形成明洞的合理拱轴线,可极大地提高明洞的整体可靠度;(5)本研究结论可为明洞采用概率极限状态法设计提供参考。

Research purposes： With the increasing development of railway tunnel design technology,compared with the safety coefficient method,the probability limit state method can consider much more comprehensive factors to make safety assessment more reasonable and reliable.Combined with specific engineering case,based on the element software ANSYS modeling to solve structure internal force calculation,this paper used MATLAB to compose the H-L method program to calculate the reliability of the different open cut tunnels,compared the reliability of the different open cut tunnels and explored the relationship between its reliability and the influence factors,to provide reference for the research of related tunnel.Research conclusions：（1） Limit state design method can comprehensively reflect the uncertainty of every factor and the integrity of the structure,which is much better than the safety factor method.（2） The safety stock of the open cut tunnel structure in every speed is very enough now.The double-line tunnel＇s design parameters are more conservative than the single-line tunnel＇s,but this phenomenon becomes not obvious with the increase of speed.（3） Excavation site and thickness of covering soil below 4 m have weak influence on the reliability of the open cut tunnel structure,but the stress form have significant influence on it.（4） Making the reasonable arch axis can greatly improve the overall reliability of the open cut tunnel.（5） The research result can provide the reference for open cut tunnel design with the probability limit state method.