Abstract:

The XiKou tunnel (3 140 m) and KuangFu tunnel (2 360 m) are the shallowcovered tunnels of the HauTung railway electrification project, inner width is 11.3 meters, two railway lines and two maintenance walkways at each side are arranged. The cutandcover method of tunnel construction was mainly adopted, but the underground drilling method was used at 4 sections of passing through the north and south dikes of ShouFeng stream (75 m & 85 m) and the north and south dikes of MaTaiAn stream (170 m & 120 m) between the crossriver tunnels. The overburden of drilling tunnels is about 6~18 m in thickness, passing though the gravel layer, and the excavated profile is 13.7 m wide and 131.3 m2 in area. The New Austrian Tunneling Method (NATM) was used for these sections mentioned above. Due to the shallowcovered soil, the arch action can’t form, therefore, the ground improvement and pipe roofing method should be executed before excavating. The construction procedure was grouting from groundsurface, installing pipe roofing, excavating and temporary supporting by steel ribs, shotcrete, and rock anchors, at last constructing concrete inner lining. These cases were successfully completed.

Key words: shallowcovered, cutandcover, pipe roofing, gravel layer