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基于一种可考虑含水劣化特性的岩石黏弹塑性模型,推导得到了该模型的有限差分格式,并采用C++语言进行程序设计获得了FLAC3D二次开发的动态链接库文件。通过简单模拟试验对程序进行有效性检验表明,模型程序可较好地反映岩石的瞬时弹性变形、衰减蠕变、等速蠕变、含水劣化和塑性变形等特性。通过采用黏弹塑性模型程序对实际的隧道地质模型进行数值分析表明:与自然含水状态相比,围岩处于饱和状态时隧道的拱顶沉降、周边收敛和底鼓位移都出现明显增大,饱和状态下隧道底鼓值约为自然含水状态下的2倍,围岩自稳时间较自然含水状态时减小了40 d左右,严重缩短了二次衬砌的合理时间范围。计算结果与隧道现场实际情况较吻合,有效揭示了隧道大变形灾害的产生机制。运用该黏弹塑性模型程序可较好地分析围岩-支护体系的稳定性,并预测隧道二次衬砌的合理施作时机。
Based on a rock viscoelastic-plastic model that can consider the characteristics of water degradation, a finite difference scheme of the model is deduced and the dynamic link library file of secondary development of FLAC3D is obtained by C ++ programming. The validation of the program by simple simulation shows that the model program can better reflect the characteristics of instantaneous elastic deformation, attenuation creep, constant creep, water deterioration and plastic deformation of rock. The numerical analysis of the actual tunnel geological model by using the viscoelastic-plastic model program shows that compared with the natural water-bearing state, when the surrounding rock is saturated, the vault settlement, the surrounding convergence and the displacement of the bottom drum of the tunnel are obviously increased, and the saturation Under the condition of tunnel bottom drum value is about twice that of natural water, and the self-stabilization time of surrounding rock is reduced about 40 d when compared with that of natural water, which shortens the reasonable time range of secondary lining seriously. The calculated results are in good agreement with the actual conditions at the tunnel site, effectively revealing the mechanism of large deformation disasters in tunnels. The viscoelasto - plastic model program can be used to analyze the stability of surrounding rock - support system and predict the reasonable timing of tunnel lining.