隧道半断面帷幕注浆施工技术

Construction Technology of Curtain Grouting in Half Section of Tunnel

小南塬隧道黄土冲沟淤积坝段地层软弱且地表常年积水,地下水上升至隧道洞顶设计高度,隧道开挖过程中易发生涌水、突泥等灾变。针对小南塬隧道岩体破碎和涌水量大的工程特性,提出采用半断面帷幕注浆加固设计方法对不良地层进行加固并对加固效果进行分析。结果表明:隧道单孔/米注浆量为2.74 m^(3)/m,浆液填充率为94.8%,达到充填裂隙和固结围岩的作用;P-Q-T(P为注浆压力,Q为注浆量,T为时间)曲线表现为前期的注浆压力小、吸浆量大到后期注浆压力大、吸浆量减弱的变化规律,说明注浆效果良好;现场检查孔成孔效果良好,水泥浆液纹路清晰,未发现坍孔、涌水、涌突泥等灾变现象;上半断面帷幕注浆对掌子面变形的控制效果最好,而对仰拱隆起影响较小。

In the loess gully deposition dam section of the Xiaonanyuan tunnel,the ground is weak and the surface is stagnant all the year round.The groundwater rises to the designed height of the tunnel roof,and there are risks of water gushing,mud bursting and collapse in the tunnel excavation.In view of the engineering characteristics of rock mass fragmentation and large water inflow in Xiaonanyuan tunnel,it was proposed of half section curtain grouting to reinforce the bad stratum and the reinforcement effect was analyzed.The results show as follows.The grouting amount of single hole/m is 2.74 m^(3)/m,and the filling rate of grout is 94.8%,which can fill cracks and consolidate surrounding rock.The P-Q-T(P:grouting pressure,Q:grouting quantity,T:time)curve showes that the grouting pressure is small and the grouting amount is large in the early stage,and the grouting pressure is large and the grouting amount is weak in the late stage,indicating that the grouting effect is well.It has been checked that the hole into intact,cement slurry veins clear,no slump,water,sand,mud and other adverse phenomena.The curtain grouting of the upper half section has the best control effect on the deformation of the palm surface,but has little effect on the uplift of the invert.