基于经济安全系数比的隧道穿越超浅埋大偏压段方案优化研究

在黄土高原地区,由于沟壑众多,在隧道选线过程中出现了一种最不利的地形条件,即隧道需穿越超浅埋大偏压地段。为了研究其经济、安全、可靠的穿越方案,提出经济安全系数比的概念及计算原理。对隧道穿越超浅埋大偏压段的方案先进行设计,然后采用有限元强度折减法和相关定额计算出各方案的经济安全系数比,并结合数值模拟方法对3种典型穿越方案下的隧道围岩应力、洞室变形和初期支护应力等进行计算分析。经过综合对比,得出按反压法设计的穿越方案最优。该方案既有利于超浅埋大偏压隧道的整体稳定,又有利于减少工程造价。

OPTIMIZATION RESEARCH ON TUNNEL CROSSING SCHEME THROUGH ULTRA-SHALLOW AND LARGE-BIAS SECTIONS BASED ON ECONOMIC SAFETY COEFFICIENT RATIO

There are many gullies in the loess plateau region.A most unfavorable topographic condition occured when tunnels passed through the gully region.It meaned that tunnels needed to pass through the ultra-shallow and large-bias sections.In order to obtain the economic and safe crossing scheme,the conception of economic safety coefficient ratio and its calculation principle was brought forward.Firstly,the tunnel crossing schemes through ultra-shallow and large-bias sections were designed.The economic safety coefficient ratio of each tunnel crossing scheme was calculated by the methods of strength reduction method and related quotas.Besides,the tunnel's rock stress,deformations and the primary support's stress were simulated and compared among the three tunnel crossing schemes.Finally,the counterweight fill method was considered to be the best crossing scheme,with which the ultra-shallow and large-bias tunnel was in the steady state during the construction period.Good results were achieved so as to offer reference for the future similar projects.