无盖重固结灌浆在高瓦斯水工隧洞施工中的应用

Application of consolidation grouting technology without cover weight in construction of high gas hydraulic tunnel

针对夹岩水利枢纽及黔西北供水工程水打桥隧洞进口段围岩地质条件差、瓦斯浓度高、初期支护变形大且变形洞段长、安全风险高和工期严重滞后的情况,选取K0+700~K0+720和K0+740~K0+760作为试验段,采用不同的灌浆参数,在试验段无盖重固结灌浆完成后,通过对压水试验、钻孔取芯、灌前和灌后声波测试检查结果进行综合分析,确定了科学合理的灌浆技术参数。后续施工结果表明:通过提前开展无盖重固结灌浆,可显著提高围岩的整体强度和抗变形能力,降低煤层中的瓦斯溢出量,为变形段的拆除施工提供安全保障;将固结灌浆提前至衬砌施工前进行,可以减少后续灌浆施工与衬砌施工之间的相互干扰,加快施工进度。研究成果可为类似工程施工提供借鉴。

In view of the poor geological conditions of surrounding rock at the entrance section of Shuidaqiao Tunnel in Jiayan Water Conservancy Project,such as high gas concentration,large deformation of initial support,long deformation tunnel section,high safety risk and serious delay in construction period,different grouting parameters were used in the K0+700~K0+720 and K0+740~K0+760 test sections.After the completion of the consolidation grouting without cover weight in the test section,scientific and reasonable grouting technical parameters were determined through comprehensive analysis of the inspection results of water pressure test,borehole coring,pre grouting and post grouting acoustic testing.The results of subsequent construction showed that the overall strength and deformation resistance of the surrounding rock were greatly improved by carrying out the consolidation grouting without cover weight in advance,which also reduced the gas overflow in the coal seam and provided a safety guarantee for the demolition construction of the deformation section.With consolidation grouting carring out ahead of the lining construction,the mutual interference between the subsequent grouting construction and the lining construction could be reduced,and the construction progress would be speeded up.The research results can provide useful reference for similar projects.