Abstract:

Site monitoring is made during the construction of Dunliang tunnel. Comparison and contrast are made, on basis of the monitoring results, among double side drift method, single side drift method and threebench method in terms of advantages, disadvantages and applicability. Conclusions drawn are as follows: Double side drift method has high safety coefficient, high applicability and obvious relaxcontrol effect, but has high cost; Single side drift method has little disturbance to the rock mass, but has slow construction advance rate; Threebench method has obvious advantages in construction advance rate, but has poor deformationcontrol effect in adverse geological conditions; Countermeasures, such as timely ring forming, footlocking bolts and good control of the distance between the tunnel face and the invert, have good effect in deformation control.

Key words: large crosssection, loess tunnel, double side drift method, single side drift method, threebench method