隧道进口危岩体滚落特征分析及防护措施

通过软件计算，对某隧道进口危岩体滚落运动速度、运动轨迹等进行分析，提出针对性防护措施。结果表明:隧道进口段滚石滚落至B点的速度约为45 m/s，滚落至C点的速度约为25 m/s。假设每块滚石的重量达到100 kg时，滚石滚落的总动能最大值达到120 kJ，在BC段上滚动的总动能最大值为80 kJ。处治方案主要在危岩体下设置拦石（水）沟、堆积缓坡设置被动防护网、两隧道洞门上垫层和端墙加厚、两隧道洞门前设置柔性棚洞共4部分防护工程对危岩体进行防护，保证隧道施工及运营安全。

Analysis and Treatment of Falling Rock Characteristics of Dangerous Rock in Tunnel Entrance

Through the software calculation, the rolling velocity and trajectory of dangerous rock mass at the entrance of a tunnel are analyzed and studied and corresponding protective measures are put forward. Research suggests that the speed at which the rolling stones fall from the tunnel entrance to point B is 45 m/s, and the speed at which they roll to point C is 25 m/s. Assuming that the weight of each rolling stone reaches 100 kg, the maximum total kinetic energy of the rolling stone falls to 120 kJ, and the maximum kinetic energy of rolling on the BC slope is 80 kJ. The treatment plan is to set up a rock barrier (water) ditch under the dangerous rock mass, a passive protective net on the accumulation slope, a cushion on the two tunnel doors and a thickening of the end wall and a flexible shed hole in front of the two tunnel caves. The four-part protection project is set up to protect the dangerous rock mass and ensure the safety of tunnel construction and operation.