Abstract
Based on a tunnel through slope of Yongji highway project, relying on ABAQUS geotechnical numerical analysis software, using the appearance of plastic penetration area for instablilty criterion, choosing 11 typical influential factors as independent variables to tunnel stability, the orthogonal test array L50(511) is used to analyze sensitivity of influence factors under evaluating indexes of safety factor to the tunnel stability and the maximum principal tensile on the inner surface of surrounding rock. Research results show that: there are some certain differences between calculation results of safety factor and maximum principal tensile, but overall presentation represents favorable consistency, and the sensitivity of influence factors to the stability of tunnel through unfavorable geological slope can be preferably annlyzed by orthogonal test. The influence of the cohesion of rock c, the horizontal distance d between tunnel centerline and slope toe, the inclination angle of slope α are significant. Comprehensive consideration of safety factor and maximum principal tensile of tunnel circumference is more perfect than one-sided safety factor when performing the analysis of tunnel stability. The research results of this paper can provide reference to design, construction of similar tunnels.
Highlights
China is a mountainous country, with mountainous areas accounting for about two thirds of the land area[1]
After the implementation of the western development strategy, a large number of railways and highways were built in the mountainous areas in the central and western regions, and some lines were restricted by plane lines, natural geographical environment and other factors, so they often had to pass through the bad geological slopes in the form of tunnels
As can be seen from table 4, continuous penetration in the plastic zone is taken as the tunnel instability criterion, and the ranges of the influencing factors with the safety factor as the test evaluation index are in turn as follows: c>φ>γ>α>d>p>q>Δh>r>μ>E
Summary
China is a mountainous country, with mountainous areas accounting for about two thirds of the land area[1]. Adverse geological engineering geological conditions of slope area are much more complicated, the shear strength parameters (Cohesion and Internal friction angle), bulk density, poisson's ratio and elastic modulus, tunnel central line and the slope toe distance, the tunnel bottom section size and height of slope toe, Tunnel section size and Tunnel support force factors such as the sensitivity of the influence on the stability of surrounding rock of tunnel engineering is unclear These factors are random and uncertain, sensitivity to the effect on the stability of the tunnel are different, and the orthogonal experiment method is a more efficient processing level of multi-factor optimization experiment design method, orthogonal experiment design in multiple factors level sensitivity analysis can be less desired, scientific experiments and statistical effect[6].
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