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为了更加全面准确地定量评价高地应力黄土隧道的稳定性,介绍了考虑材料抵抗变形和抗力强度储备等力学性质的高地应力黄土隧道稳定性分析方法;通过Q3黄土试样的三轴试验结果规律,提出采用原状黄土双曲线应力-应变模型探讨高地应力黄土隧道稳定性储备;考虑原状黄土的抗力强度和抵抗变形能力耦合效用,构建反映围岩任一点稳定性状态的映射关系,探索黄土隧道的极限状态;采用卸围压方式类比黄土隧道开挖过程,进而研究黄土抗力强度和抵抗变形能力的变化,并根据Q3黄土试样的围压卸荷试验结果,拟合得到卸荷过程中强度、弹性模量和泊松比与围压的变化规律,从而计算黄土隧道安全系数;在此基础上,对山西平阳(平定—阳曲)高速公路某隧道进行了实例分析。研究结果表明:双曲线模型能得到更加真实的变形场,并能较好反映黄土隧道的稳定-失稳力学特征;本文方法所得隧道稳定性评价结果与现场监测结论较为一致。
In order to evaluate the stability of the high geostress tunnel in a more comprehensive and accurate way, the stability analysis method of the high geostress tunnel with considering the material resistance deformation and mechanical strength reserve is introduced. According to the triaxial test results of Q3 loess sample, This paper proposes to use the hyperbolic stress-strain model of undisturbed loess to study the stability of high-stress-strain loess tunnel. Considering the coupled effect between the strength of original loess and the resistance to deformation and deformation, a mapping relationship reflecting the stability of any surrounding rock is established to explore the limit of loess tunnel State. The excavation process of analogy loess tunnel with unloading confining pressure was conducted to study the change of loess resistance strength and deformation resistance. According to the unloading test of Q3 loess, the strength and elasticity Modulus and Poisson’s ratio and confining pressure, so as to calculate the safety factor of loess tunnel; on this basis, an example is given to a tunnel in Pingyang-Pingyang-Yangqu Expressway in Shanxi Province. The results show that the hyperbolic model can obtain a more realistic deformation field and better reflect the stability-failure mechanics characteristics of the tunnel. The tunnel stability evaluation results obtained by this method are in good agreement with the field monitoring results.