Study On The Large Deformation Control Of The Weak Surrounding Rock In Tunnel

In the planning and design of the tunnel, more and more is the weak surrounding rocktunnel. Now due to the mechanism of large deformation and deformation control in the designand construction are not formed a complete theory system, therefore, the theory of largedeformation in weak surrounding rock, excavation methods and supporting control measureswere studied,and solve the large deformation disasters in weak rock tunnel excavationbecome more appears imminent.This paper is based on the Ying-Feng tunnel engineering, on the basis of relevant literature,analysis and summarize the concept and mechanism of weak surrounding rock largedeformation, the types of large deformation partition, large deformation definition andclassification, describe the terrain geology, rock properties, rock grading and largedeformation in the construction of Ying-Feng tunnel, and simulation and verification for thelarge deformation for the specific tunnel engineering geological condition by geotechnicalengineering software FLAC3D. Against the phenomena and engineering features of weakrock tunnel large deformation, Proposed two control technologies:①the control technologyof surrounding overbreak;②the control technology of prestressed anchor support.In the study of surrounding rock regularity overbreak to control the large deformation,With geotechnical engineering software FLAC3D, under the0.60m,0.65m,0.70m,0.75mfour kinds of surrounding rock overbreak, get stress from parts of the surrounding rock andtunnel structure, vertical settlement and convergence horizontal displacement of tunnel vault,hance and arch feet from three contout lines as overbreak contour, lateral contour of initialsupport, medial contour of initial support.Then comparatively study to analyze the feasibilityof the control scheme and reasonable overbreak of surrouding rock.In the study of the control technology of prestressed anchor support, under the variousgrades of the prestressed getting stress of surrounding rock and support structure, verticalsettlement and convergence horizontal displacement of two contout lines as lateral and medialcontour of initial support, anchor axial force, stress, etc. which is to validate the effect of largedeformation In the last, this paper makes a summary and comparative analysis the effect of the twocontrol schemes, Gives effective control scheme that through surrounding rock regularityoverbreak excavation to control the large deformation, and pointed out the unresolved issuesproblem of theoretical research and engineering practice of the weak surrounding rock tunneldeformation.