盾构隧道联络道爆破施工优化

Optimization of Blasting Construction for Connecting Passage of Shield Tunnel

针对盾构隧道间联络道爆破对既有盾构隧道结构造成的不良影响,对隧道的爆破施工方案进行优化,并利用有限元数值模拟软件建立数值模型,分析不同爆破位置对隧道管片稳定性的影响。模拟结果表明:当联络道掌子面与管片距离为0时,在隧道管片上出现较高的应力集中,盾构隧道管片是极不稳定的;将桶形掏槽调整为渐进式螺旋掏槽,并增加崩落眼的延时间隔数量,主应力值降低较明显,最大降幅63.45%,开挖轮廓内外的螺栓应力分别降低了77.23%、72.36%,降低后的应力均小于螺栓的屈服强度。位移仅为2.6 mm,较优化前降低了27.78%,由此可知此时管片是安全的。

In view of the adverse effects of link tunnel blasting on the existing shield tunnel structure,the blasting construction scheme of the tunnel was optimized,and the numerical model was established by using the finite element numerical simulation software to analyze the influence of different blasting positions on the stability of tunnel segment.The simulation results show that a high stress concentration appear on the tunnel segment when the distance between the link tunnel face and the segment is 0,meanwhile the shield tunnel segment is extremely unstable.When the barrel cutting blasting is adjusted to progressive spiral cutting blasting and the number of delay intervals of caving holes is increased,the main stress value is reduced obviously,with a maximum reduction of 63.45%,meanwhile the bolt stress inside and outside the excavation profile is reduced by 77.23%and 72.36%,respectively.The stress after reduction is smaller than the yield strength of the bolt.The segment displacement is only 2.6 mm,which is 27.78%lower than that before optimization,so it can be seen that the segment is safe.