Abstract:

To improve the efficiency and safety of tunnel boring machine(TBM) construction in complex geology of Z tunnel in a plateau railway with a total length of 31.085 km, the complex geology of Z tunnel and its effect on TBM construction are analyzed, and the key technologies of TBM construction in complex geology are summarized in the form of option comparison table for the first time based on the experience of TBM tunnel construction over the world. According to the applicable geological conditions of each technology, three options, preferred, optional, and inapplicable, are marked, which is more convenient for comparative analysis and selection. Furthermore, in view of the complex geology of Z tunnel, six key technologies are put forward to guarantee the smooth TBM construction under the conditions of fault fracture zone, rockburst, and large deformation of soft rock. The technologies adopted include: (1) The prereserved advance holedrilling technology, which can be used to construct advance anchor bolts, advance grouting, advance small conduits, and advance pipe sheds, as well as reinforce the broken surrounding rock and prevent strong to extremelystrong rockbursts. (2) The controlled blasting and stress releasing technology with the support of rockburst prediction method of microvibration monitoring, drilling holes with advance or anchor drilling machines, which can weaken the rockburst grade and reduce the harm. (3) Convenient and emergency shotcreting, which is different from conventional shotcreting, adopts polymer materials instead of concrete, and the shotcrete manipulator is installed on the gear ring of the steel arch installer to realize mechanized construction, which is convenient and safe to operate. (4) The steel pipe, which has a good supporting effect on severelybroken geology, and the auxiliary propulsion oil cylinder can be used to realize the continuous slow construction of TBM, so as to avoid longterm shutdown. (5) Combined support system of radial anchor cable and steel arch or steel pipe, which can control large deformation of soft rock. (6) Largescale expanding technology with reserved expanding cutter, which can realize larger expanding amount in large deformation tunnel section and prevent TBM shield from jamming. Most of the above technologies are new, the actual application effect needs to be constantly summarized and improved in the construction practice.

Key words:

 , plateau railway, open tunnel boring machine, complex geology, prereserved advance reinforcement, controlled blasting, stress release, emergency shotcreting, steel pipe, largescale expanding