富水地层隧道施工深井降水技术

大西客专干庆隧道在1#斜井和2#斜井之间工区的施工过程中多次发生流砂、涌砂及涌泥现象,严重威胁隧道施工安全。通过现场抽水试验确定出等效地层的水力参数,并通过单井降水效应的数值分析,验证数值方法的适应性。采用数值方法对比分析了三种降水井布置方案的降水效果,确定了合理的降水方案,并分析了降水施工对地下水环境的影响。采用超前支护、分部开挖与及时支护,顺利完成了该段隧道施工。

On the Deep-Well Water-Lowering Construction Technique for Tunnels in the Rich-Watered Stratum

During the construction of the section between the first shaft and the second shaft of the Ganqing Tunnel of the Da-Xi Passengers-oriented Railway,the phenomena of drift sand,gush sand and gush mud happened time and again,which seriously threatened the safe construction of the tunnel.Through the site pumping tests to determine the hydraulic parameters for the equal-effect strata,and by means of analyzing the values of the water-lowering effect of a single well,the adaptability of the numerical method is tested.The water-lowering effects of three different well layouts are compared and analyzed,with the rational water-lowering scheme chosen and the effect of the water-lowering construction on the underground water environment analyzed.With the construction methods of the pre-support,excavating section by section and timely support adopted,the construction of the above-mentioned section of the tunnel is successfully completed.