路堑边坡开挖对邻近既有隧道影响研究

设计中的承德迎宾大道路堑边坡邻近既有京承铁路21号隧道，边坡开挖后会对既有隧道产生不利影响。根据现场试验取得的围岩及隧道衬砌的力学参数，对边坡开挖进行了静力学和动力学数值分析，研究了路堑边坡可开挖的最大范围及爆破振动对隧道的影响。结果表明：当路堑二级边坡坡脚距离隧道中心线距离大于等于30 m时，边坡开挖后隧道衬砌内力虽有增加，但仍可保证结构安全。进行边坡爆破开挖时，如考虑3倍的安全系数，当京承铁路21号隧道衬砌振速小于1.5 cm/s时，隧道衬砌内产生的动拉应力小于衬砌极限抗拉强度，可按此控制指标进行现场监测。

Research on influence of excavating road trench slope on adjacent existing tunnel

The Yingbin Avenue trench slope being designed is adjacent to the existing Jingcheng railway 21th tunnel, the tunnel will suffer a bad affection when the slope be excavated. A numerical analysis of statics and dynamics according to the rock and lining parameters from the field test has been undertaken. This paper studies the maximum extension of slope which can be excavated and the influence of tunnel on slope blasting vibration. The result indicates while the distance between the base of second slope and tunnel center line is larger than 30 m, the inner force of tunnel lining will increase but the structure still in safety state when the second slope be excavated; and when we excavate the slope by blasting method, if we consider a triple safety factor, and while the vibration velocity is smaller than 1.5 cm/s, the dynamic tension stress of the 21th tunnel lining is smaller than its ultimate value; and therefore we can undertake field monitoring by the reference control vibration velocity.