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Practical experience of roadheader

Jul. 31 , 2019

Practical experience of roadheader shared by rocking tunnel boring machine supplier.

The practical experience and lessons of roadheader can be summarized as follows:

A. The long tunnel is constructed with dual shield TBM, which has the advantages of fast, safe, simultaneous tunneling and lining. This conclusion is confirmed by TBM construction of wanjiazhai Yellow River diversion project.

Through the cooperation among owners, design, construction and supervisors, experience is summed up and lessons are drawn. From the unsatisfactory construction quality of the 6#, 7# and 8# tunnel in the main trunk to the satisfactory construction quality of the 7# tunnel in the joint section, the following satisfactory indicators are achieved:

(1) excavation error control to the horizontal ±150mm, vertical (that is, vertical) ±50mm.

(2) the wrong installation platform of pipe segments is 90% controlled within the range of 5mm, and the joints of pipe segments are basically qualified.

(3) bean gravel backfill and cement grouting basically achieve full fill filling, a complete.

(4) tube joint pointing smooth, uniform, no fine crack, bonding tight.

EBZ260A Rock Tunneling Boring Machine

(5) pipe piece production, installation without obvious damage or other quality defects.

(6) set records for the highest daily and monthly TBM footage at 113m and 1645m respectively.

B. The TBM construction of long tunnel must be carried out with geological advance prediction, otherwise, bad geology will not only delay the progress of the project, but also make the project passive.

C. When the long tunnel is constructed with TBM and the diameter of the tunnel is not large (for example, in this project, nangan D= 4.30m ~ 4.20), great attention should be paid to the traffic safety of light rail vehicles inside the tunnel to avoid casualties. Five people died and two were injured in the traffic accident inside the cave under the TBM construction of wanjiazhai Yellow River diversion project.

D. When using double shield TBM to carry out tunnel construction, it is necessary to train the segment installers before taking up their jobs, or hire operators with segment installation experience, otherwise, the quality and progress of the initial segment installation cannot be guaranteed.

E. The rock powder generated during the TBM rock tunneling machine with loading with double shields is deposited within the scope of 120° at the bottom of the tunnel, and the rock powder is very dense under the main engine's self-pressure. It is difficult for cement grouting to fill into the rock powder layer, forming a weak layer whose strength is lower than that of the bean gravel layer after grouting.

F. All the 6 TBM used in the Yellow River diversion project of wanjiazhai are double-shield type, which can only observe the small window at the bottom or side of the shield to understand the surrounding rocks, making the geological mapping work very difficult, which is the shortcoming of double-shield TBM.

G. Double shield TBM and prefabricated segment lining are used for tunnel construction, which is only applicable to water conservancy and hydropower projects without pressure diversion. Of course, road and rail tunnels do not carry water, and this type of TBM works well.

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