Abstract:

In order to guarantee the safety of urban artery, ground viaduct and underground pipelines, a series of technologies have been adopted during the construction of a super shallowcovered extralarge crosssection upright wall tunnel on Kangwanglu crossing underneath Liuhua Lake. The technologies adopted include: (1) A 70m long large pipe roof is constructed by horizontal guide pipe with high construction accuracy. (2) Thick steel plate is laid on road 45°of tunnel excavating contour. (3) Ground active underpinning is carried out for pile foundation of adjacent viaduct. (4) The CRD method with 6 parts is used, TSS grouting technology is used on tunnel face, and radial grouting and backfill grouting are carried out timely after primary supporting. (5) The first layer lining with moulded concrete is conducted before temporary support dismantling; the temporary support is dismantled when the first layer lining strength meets requirement; the waterproof layer is set on the first layer lining; and the second layer lining of arch wall reinforced concrete and tunnel structure is conducted. (6) The scaffold + template was used for tunnel structure, curved arch frame + combined steel template is used for first layer lining of arch wall, and formwork trolley is used for second layer lining of arch wall. At present, the right line construction has been completed, the maximum ground surface settlement (70.9 mm), the maximum crown top settlement (61.1 mm) and the maximum horizontal convergence (8.44 mm) are within control, and the points with maximum deformation are in tunnel. The results can provide reference for the construction of left line.

Key words: extralarge crosssection, tunnel, upright wall, mine tunneling method, shallowcovered and mining method, urban artery, multilayer composite lining structure