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| Analysis of the Geologic Origin of Large Deformation of a Tunnel of Chengdu - Lanzhou Railway in Meizoseismal Areas |
| SONG Zhang1，DU Yu - ben1，TAO Yu - jing2，YUAN Chuan - bao2 |
| (1. Geological Innovation Studio of China Railway Eryuan Engineering Group Co. Ltd， Chengdu， Sichuan 610031，
China; 2. China Railway Eryuan Engineering Group Co. Ltd，Chengdu，Sichuan 610031，China) |
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Abstract Abstract ： Research purposes ： Based on the geological background of the complicated geological condition such as the
intricate and active tectonic condition，extremely significant seismic effect，high tectonic stress field property，and soft
and crushed formation anthology，which is under construction for the Chengdu - Lanzhou railway，the larger deformation
phenomenon of tunnel which possessed the characteristic of soft and crushed surrounding rock in meizoseismal areas is
relatively common. Based on the analysis of the survey，test data and deformation monitoring data，this article analyzed
and researched the genetic mechanism of larger deformation of soft and crushed rock tunnel in meizoseismal areas from
several aspects such as the engineering geological condition， formation anthology，tectonic，underground water，
earthquake and stress field in engineering geological perspective.
Research conclusions ：( 1 ) The section of larger deformation is located in the domain of influence of Pengxian -
Guanxian fault zone in front of Longmen mountains fault in Wenchuan “ 5. 12" seismic area， with the extremely significant cracked and crushed surrounding rock effect. ! 2" The larger deformation was mainly shown as the
deformation failure with the settlement of primary lining crown, splitting, clearance - intrusion and spilling of tunnel
side wall, steel torsion and so on. (3) The deformation section was strongly influenced by Longmen mountain fault
structure and Wenchuan "5. 12" earthquake, joint fissure of rock mass is developmental, the geologic origin mechanism
of larger deformation failure could be summarized that ： the soft and cashed surrounding rock was the material basis of
larger deformation, the intricate high stress field was the mechanics condition of larger deformation, and the action of the
bedding lateral pressure caused by discontinuities and the groundwater softening further heightened larger deformation.
We should enhance the management of monitoring measurement of primary lining, feed back and analyze timely the
monitoring data of deformation to estimate scientifically and accurately the formation mechanism of larger deformation.
(5 ) The analysis methods and conclusions can be widely applied in the survey and construction of the larger deformation
of soft and crushed surrounding rock tunnel in similar geological condition in meizoseismal areas.
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Received: 24 June 2016
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2016, Vol. 33 
