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为了解新奥法修建大跨度公路隧道时围岩的支护机理,进而探讨支护设计原理和方法,进行了软弱围岩中大跨度隧道的三维有限元分析模型试验,以检验掌子面支护效应的存在与范围,初始地应力和围岩参数与计算对比的可靠程度以及围岩的破坏形态、部位和范围。试验结论认为,围岩的初始应力符合σ_x=(μ/1-μ)σ_y的关系,三维有限元分析毛洞的位移曲线与实测值吻合,掌子面支护效应最有效范围是距掌子面约0.7D(D-毛洞宽)范围内,围岩的峰值强度与残余强度之间有一个塑性软化变形的阶段,试验与计算结果相一致。
In order to understand the supporting mechanism of the surrounding rock during the construction of the long-span highway tunnel in the New Austrian law and to explore the design principle and method of the support, a three-dimensional finite element analysis model test of the long-span tunnel in the weak surrounding rock was conducted to test whether the face The existence and scope of the protective effect, the initial stress and the reliability of the surrounding rock parameters and the calculated contrast as well as the damage morphology, location and range of the surrounding rock. It is concluded from the experimental results that the initial stress of the surrounding rock is in accordance with the relationship of σ_x = (μ / 1-μ) σ_y. The displacement curve of the three-dimensional finite element analysis matches well with the measured value. The most effective range of the support effect There is a stage of plastic softening deformation between the peak strength and the residual strength of surrounding rock in the range of about 0.7D (D-furrow width). The experiment and calculation results are consistent.