基于含水劣化特性的隧道围岩时效变形数值计算

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。

Numerical calculation of time effect deformations of tunnel surrounding rock in terms of water degradation

Based on a visco-elastoplastic model considering the feature of water degradation effect of rock,its finite difference scheme is presented.Through program development for the model by C++ language,the FLAC3D dynamic link library file is obtained.To test the model effectiveness,it is shown that the model program can better simulate the instantaneous elastic deformation,attenuation creep,creep constant,water degradation and plastic deformation characteristics of rock.With the numerical calculation for an on-site tunnel geological model by the visco-elastoplastic model program,it is shown that the vault settlement,convergence and uplift deformation increase with the growth of moisture content,and the time that surrounding rock remains stable is shortened.Uplift displacement in saturated state is twice of that in natural moisture state;and the time that surrounding rock remains stable in saturated state is less than that in natural moisture state for about 40 days;so reasonable construction time for the second supporting is also greatly shortened.The calculation results are consistent with the measuring results in the tunnel site,which can explain the generation mechanism of large deformation disaster effectively.Both stability of rock-support system and reasonable time for the second supporting can be well predicted by the visco-elastoplastic model program presented above.