Abstract: Foyansi Tunnel is a large-angle oblique entry-exit tunnel structure with steep slope and dangerous rock mass.The location of the tunnel entrance crosses the Laziyu Bridge at the bottom of the ditch.The construction site is narrow and the construction safety risk is high.In order to prevent the collapse accident of dangerous rock slope，safety protection measures are set up in the transitional section of cross operation，and active protective net is applied to reinforce dangerous rock mass at the top of the cave.Considering the large angle of oblique intersection between the topography of the left tunnel entrance and the tunnel body，half arch protection is applied outside the tunnel，construction executed from the right tunnel to the left tunnel through the traveling cross-hole，the small guide tunnel is excavated backward，and then preliminary expansion is formed according to Three-bench Seven-step Excavation Method.According to the monitoring data of the construction process，the maximum displacement of tunnel is less than the specification.The effect is remarkable.The construction scheme effectively reduce the safety risk，the safety quality of construction is guaranteed.The paper provides reference for the similar construction difficult issues.

Key words: steep cliff, dangerous rock mass, crossing operation, oblique intersection, half arch protection, small pilot hole

摘要： 佛岩寺隧道为大角度斜交进出洞结构,洞口段坡体陡峭且分布有危岩体,洞口施工与沟底梯子峪特大桥施工交叉作业,施工场地狭小,进出洞施工安全风险较大。为防止边坡危岩坍塌事故,在交叉作业过渡区间设置安全防护措施,在洞顶施做主动防护网加固危岩体;左洞洞口地形与隧道洞身斜交角度大,在洞外施做半边护拱,从右洞通过车行横洞进入左洞,反向掘进小导洞出洞,然后按照三台阶七步开挖初步扩挖成型。通过施工检测数据可知,采用此方案后隧道位移最大值符合规范规定要求,效果显著。本次施工方案有效降低了交叉作业区域的安全风险,保障了洞口段施工的安全和质量。

关键词:  , 陡崖, 危岩体, 交叉作业, 斜交, 半边护拱, 小导洞