GEOLOGICAL STRUCTURE DAMAGE ANALYSIS OF DA XIANGLING-NI BASHAN EXTRA-DEEP AND OVER-LENGTH TUNNEL ROCKMASS

Understanding of geological features are the key issues and difficult problems in the extra-deep and over-length tunnel,Combination the Da Xiangling-Ni bashan extra-deep and over-length tunnel Investigation,this paper Study the use of geological structural damage to study and analyze the geological characteristics of the deep tunnel wall rock.The Da xiangling-Ni bashan deep-buried(1660m)and over-length(94946m in left, 10007m in right)tunnel located in Intersections of three major tectonic system,which are Da xiangling NW-trending tectonic belt,Longmen moantain NE-trending tectonic belt and Chuan-Dian NS-trending tectonic belt,the faults is very developed,Different structural positions,as well as the composite effect of different tectonic systems,causing structural damage characteristics significantly different in different regions.Geological structure damage factor are defined to describe the geological structure damage,mainly by tectonic location and intensity of tectonic deformation influence coefficient,degree of development of secondary faults influence coefficient,degree of development of joint influence coefficient and the degree of development of micro-cracks of rock influence coefficient.Based on the Da xiangling-Ni bashan tunnel geological information analysis and combination with some other tunnels survey data,put forward the structural damage grading and evaluation methods.The tunnel area are divided into strong structural damage zone,secondary strong structural damage zone and weak structural damage zone,and carry detailed research and analysis of the damage characteristics of each zone.Based on structural damage study,can develop the tunnel exploration program,study of tunnel surrounding rock geological characteristics,qualitative analysis of stress field characteristics of the tunnel and rock burst prediction,analysis the water-control structures and qualitative forecast the tunnel water gushing problem.