上穿公路隧道爆破对下方供水隧洞的振动影响研究

Influence of Blasting Vibration of Lower Water Supply Tunnel on the Excavation of Upper Tunnel

新建的大望山公路隧道从既有沙湾供水隧洞上方穿过,形成空间隧道交叉,高程上它们最小距离21.5 m,并且交叉段公路隧道和供水隧洞围岩分别为IV级和V级,岩性较差。上穿隧道爆破开挖会对下方供水隧洞的稳定造成一定影响,需对其进行具体的研究,应用ANSYS/LSDYNA对其进行数值模拟是一种较为合适的方法。通过计算,结果表明:当上穿隧道掏槽爆破最大单响药量为8.0 kg时,下方供水隧洞拱顶单元X方向上的拉应力为0.12 MPa,比其它两个方向的拉应力大,第一主应力为0.13 MPa;隧洞拱顶质点垂直振动速度最大,约为2.8 cm/s,小于水工隧道规定的安全质点振动速度7 cm/s,不会造成供水隧洞的破坏;供水隧洞质点垂直振动速度峰值在拱顶处较大,沿隧洞断面向下逐渐减小,而水平振动速度峰值沿断面向下先增大后减小,垂直振动速度峰值在整个断面上都大于相应点的水平振动速度峰值。分析结果可用来指导上穿隧道的爆破施工及供水隧洞的监控量测。

The new highway tunnel goes through above the existed water supply tunnel,with which forms the cross tunnels in space. The minimum clear distance between the upper and lower tunnel is21. 5 m. A numerical simulation with ANSYS / LS-DYNA is conducted to evaluate the vibrations of the lower supply water by the blasting excavation explosion of the upper highway tunnel. The dynamic tensile stress in X direction of the vault in the water supply tunnel is 0. 12 MPa,the first principal stress is 0. 13 MPa. The maximal vertical vibration velocity of the vault in the water supply tunnel is 2. 8 cm / s which is smaller than 7. 0 cm / s required in projects. The vertical peak particle vibration is bigger than those in the other two directions,which is focus on the vault,and decayed downwards. The results can guide the excavation of upper highway tunnel and monitoring of lower water supply tunnel.