李家峡水电站导流洞进口洞脸边坡处理及进洞措施

Side slope treatment of Lijlaxia diversion tunnel and measures to start tunnelling

李家峡水电站导流洞进口，地势陡峭，坡面自然高度达２００余ｍ。高程２１３０ｍ平台以下为８５ｍ高的洞脸边坡，该部分坡积物清除完后，意外地出现了ＮＳ向及ＮＥ向两组密集度很高的构造裂隙。这两组裂隙与岩层相互切割形成的不稳定体导致提前进洞失败。因此，如何在裂隙极为发育的薄层混合岩边坡上成洞便成了工程前期的头号技术难题。

The upstream side of the diversion tunnel in Lijiaxia Hydropower Station is a steep slope with a height of 200m. Below the terrace with an elevation of 2130m is a side slope with a height of 85 m,where the entrance of the tunnel was planed to be opened. After talus materials were removed,there were two grouped high density formation cracks in direction of NS and NE. The two grouped cracks cut the rock stratum to form a unstable rock body.Thus,how to cut a tunnel under these geologic conditions i& a number one problem.