基于围岩渗透影响范围的隧道外水压力计算方法模型试验研究

Research on the evaluation method of the hydraulic pressure on tunnel lining according to the range of seepage field

采用大型隧道渗流模拟试验系统,分析围岩渗透系数、初始水头高度、隧道排水率等因素对围岩渗流场分布、隧道背后水压力的综合影响,给出围岩渗透影响范围、隧道背后水压力的计算公式,并采用数值计算软件对其进行验证。研究表明:隧道排水会对隧道周边局部范围内围岩渗流场产生影响(即围岩渗透影响范围);围岩渗透系数、初始水头高度、隧道排水率均会对围岩渗透影响范围产生影响;围岩渗透影响范围分别与围岩渗透系数、隧道排水率呈正相关关系,且渗透系数对于围岩渗透影响范围的影响较大;围岩渗透影响范围与初始水头高度呈线性正相关关系,且围岩渗透影响范围系数仅与排水率、渗透系数有关,而与初始水头高度无关;围岩渗透影响范围系数、排水率和渗透系数三者呈二次曲面关系;同时,得到了隧道背后平均水压力计算公式;围岩渗透影响范围、隧道背后水压力公式计算结果与FLAC数值模拟计算结果吻合良好,证明提出的公式正确、合理。研究方法与成果对高水压地区隧道结构抗水压设计、施工具有一定的参考指导作用。

With the large testing system for tunnel seepage,experiments were carried out to analyze the influence of the rock permeability coefficient,the initial height of water head and the rates of drainage on the distribution of seepage field in surrounding rock and the water pressure on lining. The calculation formulas for the influencing range of seepage field and water pressure of lining were presented. The obtained results were verified by numerical simulation. The influencing range of seepage field is affected by the permeability coefficient of surrounding rock,the initial height of water head and the rate of tunnel drainage. The analysis of the correlation between the above factors and the influencing range of seepage field by the single variable method proves that the greater the permeability coefficient and the rate of tunnel drainage,the larger the influencing range of seepage field. The effect of permeability coefficient on the influencing range of seepage field is greater than that of the rate of tunnel drainage. There is a linear positive correlation between the influencing range of seepage field and the initial height of water head. The influencing range of seepage field coefficient is related to the rate of tunnel drainage and permeability coefficient,but has nothing to do with the initial height of water head. The influence range of seepage field coefficient,the rate of tunnel drainage and permeability coefficient satisfy the quadratic surface equation. The average water pressure on lining,the influencing range of seepage field and the rate of tunnel drainage also satisfy the quadratic surface equation. The calculation formula for the average water pressure was obtained. The above formulas are in good agreement with the numerical results.