基于有限元极限分析的双孔隧道稳定性分析

为进一步探讨在考虑土体内摩擦角情况下,双孔隧道在支护反力及地面超载共同作用下的相互作用规律及稳定性分析,首先,基于有限元极限分析法,采用MATLAB平台编制了相关计算程序;此外,为减少各参数之间的交叉影响,引入无量纲分析方法;然后,将本文模型的计算结果与已有成果进行对比,验证了本文分析方法的合理性;最后,在此基础上求得各影响因素下的隧道稳定性参数(N_s),并绘制了无量纲分析图表。结果表明:(1)N_s随φ的增大逐渐增大,且当φ较大时,在N_s未达到稳定值之前,对其产生显著影响;(2)N_s随S/B的增大而增大并趋于稳定;(3)φ的存在与否对N_s随着γB/c的变化产生相反的规律,且随φ的增大,γB/c的变化对临界间距比(S/B)的值影响减弱;(4)临界间距比随H/B的增大不断增大;(5)S/B和φ是影响隧道破坏模式的关键因素。

Stability of Dual Hole Tunnels Based on Finite Element Limit Analysis

In order to further investigate the laws of interaction and stability of dual hole tunnels under the combined action of supporting reaction force and ground overloading when considering the cohesive-frictional angle in soil, firstly, the calculation program was compiled by MATLAB based on the finite element limit analysis. In addition, the dimensionless analysis method was introduced, which can reduce the mutual influence among various parameters. Then, the method and model proposed in this paper were verified by comparing the results reported by the previous investigations. At last, on this basis, the tunnel stability parameter (N_s) was calculated by the finite element limit analysis under various influencing factors and the dimensionless analysis charts were drawn. The results reveal that: (1) the value of N_s increases with the increasing of cohesive-frictional angle (φ), and when φ is larger, it has a significant effect on N_s before it reaches a steady value; (2) the value of N_s increases with the increasing of S/B, until it reaches a stable value; (3) the value of φ which is zero or non-zero will produce the opposite laws of N_s with the change of γB/c. And with the increasing of φ, the effect of γB/c on the critical spacing ratio weakens gradually; (4) the value of critical spacing ratio increases with the increasing of H/B; (5) the values of S/B and φ are the key factors to affecting tunnel failure mode.