裂纹方向对隧道稳定性影响规律的研究

采用模型试验和数值模拟方法,研究单轴压缩载荷下带裂纹直墙拱形隧道在不同的裂纹面与隧道垂直边墙之间的夹角?时围岩损伤破坏规律。试验采用水泥砂浆制作成具有不同夹角?的直墙拱形隧道模型,养护30 d后进行加载。数值模拟采用混凝土损伤塑性模型,计算出隧道周边各点的应力和裂纹尖端的应力强度因子,与模型试验结果吻合较好。结果表明,拱肩处的裂纹会降低隧道的整体稳定性及强度,在裂纹尖端及侧壁产生很大的应力集中,但随着?角度的变化,强度降低的程度有所不同;当?=60?和?=130?时,裂纹对其整体稳定性及强度的影响最大,其裂纹尖端的应力集中现象最为明显,而且破坏应力峰值仅为无裂纹模型的40.9%和41.8%。

Study of effect of cracking orientation on tunnel stability

In order to investigate the effect of cracking orientation on the stability of tunnel surrounding rocks, experimental and numerical studies were implemented. In the experiment, cement mortar models with different cracking orientations were made and loaded after cured room temperature for 30 days. In the numerical simulation, the concrete damaged plasticity was adopted. The stresses at the points around the tunnel and the stress intensity factor of crack tips were calculated; the results were in good agreement with the experimental results. The results show that cracks in the spandrel can reduce the stability and strength of tunnels, and induce a great stress concentration at the crack tip and the sidewall of tunnels; but this phenomenon exist in differences due to the angle between cracks and sidewalls. When =60° and =130?, cracks produce the most serious effect on the stability and strength of tunnels; and the peak of damage stress are only 40.9% and 41.8% of that of tunnels without cracks.