深埋隧道涌水量数值计算中的试算流量法

TRIAL METHOD FOR SIMULATING TUNNEL DISCHARGE

首先,建立隧道涌水的水文地质概念模型:若隧道施工中没有采取堵水措施,贯通后,忽略轴向补给,可以将隧道涌水的三维问题降为剖面二维;当深埋隧道的几何尺寸远远小于渗流场岩体的规模,可以将其处理为一个点井。建立隧道涌水的数学模型,离散后按类比方法先大致确定隧道涌水量的数量级,代入模型试算,如果水位不能降落到隧道底板或形成了稳定的漏斗,数据收敛快且和初始、边界条件不矛盾时,可按一定的步长对初定涌水量进行修正,然后,反复试算,直到水头降落到底板标高或形成稳定降落漏斗后大量出现异常值时,可认为隧道围岩的给水能力已经发挥到了极限,此时的涌水量和解析法计算结果互相验证后,可以作为隧道涌水量的预测值给出。工程实例计算表明,该方法和其他方法计算的结果比较一致,但其适应性更强,能够更加深入和全面地反映隧道涌水的过程,可以推广使用。

During the construction of a tunnel, if no measure is adopted to prevent groundwater discharge, the movement of groundwater along tunnel axis can be ignored and the seepage movement of groundwater can be simplified to 2D movement in section after completion of the tunnel. If the size of a deep tunnel is far less than that of its surrounding aquifer, it can be treated as a point-well in section. Trial calculation is performed by putting a value of discharge, estimated by analogy, into the numerical model and by repeated increases or decrease in a certain step until the groundwater table reaches the stable state. Then a trial discharge can be obtained. The discharge of a deep tunnel in southwest China calculated by the trial method accords well with results of other methods and its significance of hydro-geology is more clear, when used together with experimental and analytical method. The value of discharge can be calculated more precisely, and this indicates that it can be used practically.