Study On 3D Deformation Rule Of Tunnel And The Application Of The Rule To Wushaoling Tunnel

Deformation behavior due to tunnel excavation is influenced by rock stress state, rock mass structure and other geological conditions. The deformation of ground adjoin to face is asymmetry transformation caused by 3-D stress. Tunnel excavation grounds often obviously appear geological variability, such as existence of worse geological structure and irregular distribution of soft, hard ground which complicate tunnel force behavior after excavation. For the factor of tunnel, obvious change about tunnel longitudinal displacement will occur when the different geological interface are excavated section.To investigate and use tunnel longitudinal displacement, some foreign researchers put forward some methods of dealing with tunnel 3-D displacement data and show us the idea about tunnel 3-D deformation. Displacement vector azimuth trend lines are used to forecast the geology state of ground around face and explore unfavorable geological condition status. At present, researches on tunnel 3-D deformation are short in our country. Up to now, study and application on tunnel longitudinal displacement have no datum to quote. Based on Wushaoling tunnel project, this article has investigated regularity of tunnel 3-D deformation and applied the conclusions on fieldwork. It can offer some references for analogous tunnel engineering to be constructed.Law of development of tunnel 3-D displacement is influenced by distribution of tectonic stress field. Changes of 3-D displacement located at F7 fault are very complicated in Wushaoling tunnel. Components of displacement are not even or symmetry. Parameters and construction methods of sections neighbored F7 fault are various due to construction technology. Inversion analysis method of tectonic stress field proves that direction of macro primary stress has an obvious angle with the axis of tunnel. Lining located at fault area is extruded in cross direction and the pressure on lining is asymmetric in longitudinal direction. It is favorable for anglicizing the distribution character of tectonicstress field to master the law of development of tunnel 3-D displacement.Deformation of the tunnels located at Wushaoling tunnel F7 fault and Siluric System phyllite ground belongs to large deformation of soft rock . It has obvious secular change feature and can be assorted into rheological deformation. The displacement of tunnel in this region is apparent. Direction of its longitudinal displacement development is opposite to the face. Severe destruction happened at tunnel large deformation area when in earlier construction days. Supported structures had rather large inward extruded deformation in cross direction and it also had apparent warping deformation. Some primary support steelwork was split, sheared and collapsed. Large acreage craze and partial longitudinal warping deformation appeared in secondary lining. Tunnel displacement reduced obviously after design parameters and construction measures were adjusted. Bearing capacity of supported structure was enhanced and tunnel large deformation was controlled effectively. Controlling measures of deformation could be available for similar tunnel construction in the future.Tests of tunnel 3-D deformation, analyses of influence and destructive action due to longitudinal displacement and its application for engineering structure and construction should be more emphasized day by day in tunnel constructing.Changes of rock structure in tunnel excavation ground influenced deformation performance. It could be reflected by the variable tunnel displacement caused by change of rock mass stiffness. So we can study the displacement of the excavated cavern to reflect the transformation trend of rock mass, furthermore, this method can be used to predict the transformation trend of geologic formation in front ground. It is feasible that trend lines of the displacement vector orientation of the places apart from face 1. OD or 1. OD inside are used to present reflection attribute and deformation attribute of the ground around face. But, this method is only in test stage and few experiences can be referred at present. The information of displacement due to tunnel excavation shouldbe analyzed and compared to geology of the real excavated ground. At the same time, other geological prediction methods can be used to predict the geologic status of the unexcavated ground around cavern.