上穿输水隧洞公路隧道爆破开挖安全控制研究

针对某小净距近接公路隧道上穿既有输水隧洞的空间位置关系,结合萨道夫斯基公式,对隧道的爆破开挖方案进行优化,并利用Midas GTS数值模拟方法建立计算模型,分析不同开挖区段三种工况下爆破振动对输水隧洞结构安全的影响。研究结果表明:各工况最大振速是由隧道下台阶爆破导致的,为4.33 cm/s,小于根据《爆破安全规程》确定的输水隧洞7 cm/s的最大振速;而最大拉应力及最大压应力分别是0.75 MPa和1.51 MPa,均出现在下台阶爆破施工时,分别小于C25混凝土的设计强度值。通过现场实测得到的最大振速为3.428 cm/s。由此可知,根据设计的爆破开挖方案施工不会影响输水隧洞的安全稳定。

Study on Safety Control of Blasting Excavation of High Tunnel Upcrossing Water Conveyance Tunnel

To determine the spatial position relation of a highway tunnel passing up the water conveyance tunnel with small distance,the blasting excavation scheme of highway tunnel was optimized with Sadov's vibration formula, and the numerical simulation method of Midas GTS was used to establish the calculation model which analyzed the influence of blasting vibration on the safety of water conveyance tunnel structure under different excavation condi-tions.The results showed that the maximum vibration velocity was 4.33 cm/s caused by the blasting of the lower step of the tunnel and the value was less than the maximum vibration velocity of 7 cm/s according to the Safety Regulation for Blasting.The maximum tensile stress and the maximum compressive stress was 0.75 MPa and 1.51 MPa,respec-tively,lower than the designed strength value of C25 concrete in the next step blasting construction.The maximum vi-bration velocity was 3.428 cm/s by field measurement.It could be seen that the construction of the blasting excava-tion scheme would not influence the safety and stability of the water conveyance tunnel.