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在京福高速公路南平连接线NLA3标段的上洋隧道右洞进口右侧YK12+932～YK13+077段,有一深挖路堑,开挖后边坡最高达55米,共设有6级台阶,离坡顶边缘不远处有一高压输电铁塔,受其限制,原设计图坡率较陡,第1至6级边坡的坡率分别为1:0.33、1:0.5、1:0.75、1:0.75、1:1,第1级台阶采用挡土墙防护,2至6级台阶分别采用不同长度的压力分散型预应力锚索防护。边坡上覆盖残坡积层及砂土状强风化层、顺线路走向的构造结构面极其发育,边坡稳定性差。在2002年7月中旬完成所有坡面开挖,进行最后一级边坡形成及挡墙基坑开挖过程中,发生YK12+993-YK13+045段坡脚松动,坡
In the Beijing-Fuzhou Expressway Nanping Link NLA3 section of the tunnel on the right entrance to the right YK12 +932 ~ YK13 +077 section, a deep dig cutting, excavation slope up to 55 meters, with a total of 6 steps, from the Within a short distance from the top of the top of the hill, there is a high-voltage transmission tower. Due to its limitation, the slope of the original design is steep. The slope rates of the 1st to 6th grade slopes are 1: 0.33, 1: 0.5, 1: 0.75 and 1: 0.75 respectively , 1: 1, the first level of the retaining wall protection, two to six steps were used in different lengths of pressure-dispersed prestressed anchor cable protection. Covering the residual slope plies and sand-like strong weathering layers on the slope, the tectonic surface along the line is extremely developed and the stability of the slope is poor. During the completion of all slope excavations in mid-July 2002, during the last stage of slope formation and excavation of the retaining wall, YK12 + 993-YK13 + 045 section foot loosened and slope