Study On Deformation Mode Identification And Monitoring Forecast For Tunnel Rock Mass

With the rapid development of tunnel construction, the stability of rock mass in underground space has become an important part of the underground construction.However,many factors due to the serious shortage of rock parameters of the tunnel, mechanical parameters of design loads and other technical parameters during the design stage,such as the unpredictable and the complexity of underground engineering,as well as the constraint and limit of exploration techniques.So,we can not get a clear understanding of the rock deformation modes and the mechanism.Therefore,we must combine the construction site geological conditions, monitoring and measurement and analysis of geological prediction in the tunnel construction process,to revise the design parameters,optimize support mode and adjust the construction program.The paper is research on Daguang high-speed tunnel and the main contents and results are presented as follow:(1)We can have a basic knowledge and judgment of deformation modes and failure modes of rock mass through the description of the geological site and analysis of engineering geological conditions, combined with the eleven kinds of typical rock deformation modes summarized by a large number of engineering examples.(2)By Geological Survey, combined with meticulous description of the tunnel face,used methods of joint occurrence pole distribution, rose diagram and density map to count and analyze occurrence of twenty strip joints, predicting the rock parts which may occur deformation and failure by the way of the change interval dominant joint’s attitude, trend and tendency.(3)Combined with surface monitoring,macro-responsing the deformation mode and failure mode of rock mass is plastic deformation of swelling;through preliminary identification of deformation and failure mechanisms, the writer real-time monitored displacement deformation of various parts of tunnel rock mass changes over time used subsidence monitoring of tunnel cave vault and the level of convergence monitoring of neighboring rock mass,predict deformation mode and failure mode of tunnel rock mass with comprehensive variety of factors accurately.(4)Through linear regression analysis and correlation test to monitoring data,the paper obtained the error range of monitoring data was1.47mm,and the correlation coefficient was0.99,which can prove the monitoring data is reliable and the rock deformation is sustained.(5)The paper introduces the applications of the total station and strain gauges in rock deformation monitoring in detail,including technical parameters, measuring point (?), data acquisition and processing analysis and so on.We can get the rock displacement and the stress variation coused by the excavation of different parts by the way of analyzing the project examples about the rock stress and bolt stress.(6)The paper combined with engineering projects study focused on the image features interpretation of adverse geological in different types and interpreted process and conclusion analysis of two technical methods,which used integrated geological prediction method such as radar and tunnel seismic tomography(TST) to detect the front of tunnel face.Combining the two methods concluded that the case of front rock mass was the same to the front actual situation after excavation.