Abstract:

Water seeping from fissures is often encountered in the construction of tunnels of Metro works. Due to the nonuniformity of the fissure development and the small dimension of the fissures, it is difficult to perform grouting for the fissures. Therefore, it is very difficult to control the fissure water seepage. During the construction of Line 2 of Qingdao Metro, fissure water seepage occurs in the granite section. In the paper, the difficulties in the control of  the fissure water seepage in Line 2 of Qingdao Metro are summarized by means of analysis on the engineering geological conditions and the hydrogeological conditions; the grouting materials are optimized by field experiment, the grouting effect and the PQt curves are compared, and Type 800 microcement is finally adopted as the optimum grouting material; two grout stopping techniques, i.e., grout stopping at the orifice and grout stopping by plugs, are proposed, and the methods for the selection of grout stopping depth and grouting completion pressure are proposed; grouting hole arrangement methods and grouting parameters suitable for the fissure water seepage of Qingdao Metro are determined by means of engineering analogy and theoretical analysis. The study result has been used in the control of the fissure water of Qingdao Metro and satisfactory effect has been achieved. The paper can provide reference for similar projects in the future.

Key words: Metro tunnel, fissure water seepage, grouting, grouting material optimization, grout stopping method