那邦水电站引水隧洞渗流分析

Seepage Analysis of Headrace Tunnel of Nabang Hydropower Station Project

在分析那邦水电站引水隧洞水文地质条件的基础上,根据实测渗流量,以代表剖面反算得到围岩的平均渗透系数。各工况渗流场计算分析表明,Ⅲ类围岩洞段在没有衬砌的条件下,地下水位线不会因外水内渗而明显降低,发电流量不会因内水外渗产生较大损失,渗流量和围岩渗流梯度均处于可接受的范围内,为取消Ⅲ类围岩洞段衬砌提供了依据。

According to in-situ seepage quantity measurement, the average permeability of surrounding rock is got by inversing the seepage data of typical cross sections of long headrace tunnel in Nabang Hydropower Station project based on hydrogeological condition analysis. The calculation results of seepage field in different operation conditions indicate that, for tunnel sections with Class-Ⅲ surrounding rock, the underground water level will not have a obvious lower and the diversion flow will not have a greater loss as seepage water from surrounding rock to tunnel or tunnel to surrounding rock when no lining in tunnel. The seepage quantity and the seepage gradient of surrounding rock are within acceptable range, which support to cancel the linings of tunnel sections in Class-Ⅲ surrounding rock area.