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采用有限单元法代替传统的综合折减系数法,对某导流隧洞的渗透水压力进行了计算分析.计算表明对于完整衬砌结构,当围岩渗透系数远大于衬砌渗透系数时(1000倍以上),隧洞对山体地下水位的影响甚小,外水压力折减系数可以达到0.87以上,当围岩渗透系数与衬砌渗透系数相当时(1~10倍),隧洞对山体地下水位有较大扰动,外水压力折减系数在0.3以下.同时计算表明衬砌施工冷缝张开时排水效果显著,能显著降低隧洞周边的渗透水压力,但造成局部渗透水压力梯度明显增大.
By using the finite element method instead of the traditional method of comprehensive reduction coefficient, the seepage water pressure of a diversion tunnel is calculated and analyzed.The results show that for the complete lining structure, when the permeability coefficient of surrounding rock is much larger than the permeability coefficient of lining (more than 1000 times) , The influence of the tunnel on the groundwater table is very small and the reduction coefficient of the external water pressure can reach over 0.87. When the permeability coefficient of surrounding rock is equivalent to the permeability coefficient of the lining (1 ~ 10 times), the tunnel has a great disturbance to the groundwater table of the mountain, The reduction coefficient of external water pressure is less than 0.3. Simultaneously, the calculated results show that drainage effect is obvious when the lining cracks open, which can significantly reduce the permeable water pressure around the tunnel, but cause the gradient of local permeable water pressure to increase obviously.