Abstract:

Taking the overlapped section between Nanning Metro Line No. 1 and Line No. 2 for example, the advantages of the construction scheme of “upper tunnel after lower tunnel” are analyzed so as to ensure the rapid and safe construction of overlapping tunnels. And then the key technologies, i.e. secondary consolidation, grouting reinforcement, support reinforcement of lower tunnel and driving parameter control, are studied based on site construction conditions; the reinforcement range of the overlapped section is given; and then the applicable conditions of two kinds of construction methods, such as integration of drilling and grouting and trolley + pneumatic drill, and two kinds of supporting methods, such as walking synchronous mobile support trolley and removable ring steel bracket, are analyzed. Finally, some suggestions on the control technology of driving parameter of shield tunneling are proposed in terms of driving parameters, shield altitude and synchronous grouting.

Key words: shield tunneling, overlapping tunnels, secondary consolidation, grouting reinforcement, support reinforcement of lower tunnel, driving parameter control