Mechanical Behavior And Control Technology Of Multiple-Source Damage On Section Between Bridge And Tunnel

Abstract:Section between bridge and tunnel is a complex combination of bridge, tunnel with its surrounding rocks, the side or front slopes and the protection works nearby the entrance etc., which has a wide application both at home and abroad. It is very common on highways in mountain areas either west China or south China, which has a remarkable characteristic that all parts nearby have effects on each other causing many kinds of multiple-source damages and complex mechanical behaviors. Especially on bridge and tunnel connected project in weak surrounding rocks (such as grade IV or V surrounding rock), some key parts have much more significant effects on each other, with a characteristic that kinds of multiple-source damages, diseases and mechanical behaviors are certainly caused by coupling influences of each other. But according to the current comparatively little investigation situation at home and abroad, it is easily seen that little research has been done on multiple-source damages, mechanical behaviors or responses or diseases laws on some key parts of bridge, tunnel, surrounding rocks or soils nearby, but most of related researches or studies have little consideration of the influences among each other (bridge, tunnel and surrounding rocks) or influences caused by vehicle loads especially heavy load or overload at long time and so on.With wide application and rapid development of the bridge and tunnel connected project, more and more problems or influence factors will come across, which will not only bring new demands to its design or construction method but also bring things into consideration that some particular influences affect the operation, management or maintenance works of those existed projects.Aiming at problems mentioned above, supported by the major research project of Guizhou province (No.200904) and the transportation scientific research project of Hunan province (No.200928)-"Study on Mechanical Behavior and Control Technology of Multiple-Source Damage on Section between Bridge and Tunnel", main research work of this dissertation based on model tests and theoretical researches can be summarized as follows:(1)The characteristics, mechanism and main influence factors of multiple-source damage and mechanical behavior on bridge and tunnel connected project are discussed based on the discussion and analysis on its application and main features which cause kinds of multiple-source damages and mechanical behaviors.(2) A preliminary study has been performed on the characteristics of multiple-source damages and acting mechanism among some key parts of bridge and tunnel connected project, the characteristics of mechanical behaviors and the inducements along with its mechanism and developing law of some damages or diseases that easily seen on some parts of the bridge, tunnel or surrounding rocks during the construction or operation period on the basis of indoor model tests under multiple load cases. And some suggestions on how to control or reduce several kinds of damage or diseases have been provided according to the test results.(3) The elastoplastic damage model has been discussed together with the constitutive relation equations and the damage evolution equations, based on the summary and analysis on the damage characteristics of various materials and the detailed description of the constitutive relation of the elastoplastic model. Then several constitutive models and their detail forms of kinds of concretes, rock and soil masses which are suitable and in common use for researches on section between bridge and tunnel have been discussed along with some analysis on their characteristics and applicability, according to certain damage theories, massive research results and reference materials.(4) Some simplified numerical simulation and analysis method on multiple-source damage and mechanical behavior of bridge and tunnel connected project and a simplified calculation method on the bridge abutment with piles with the consideration of damage effects have been put forward based on theories or analysis methods such as the elastoplastic damage model, the fatigue damage accumulation model, etc. Secondary development of the numerical simulation software and the elastoplastic damage model are carried out which suitable for the damage analysis or calculation for concrete or rock and soil mass of bridge and tunnel connected project in weak surrounding rocks along, along with the implementation methods or the detailed analysis steps of each program, for the purpose of practical engineering application or uses for simplified analysis.(5) Series of models for finite element analysis on characteristics or law of multiple-source damage and its mechanical behavior of bridge and tunnel connected project have been created according to certain simplified numerical simulation and analysis method. Some specific influences along with variations of some multiple-source damages and mechanical behaviors under different vehicle load considering impact on beam, abutment with pile foundation, tunnel lining and surrounding rocks near the entrance in the bridge and tunnel connected project under circumstances of different part in different damage grade, which are summarized through systematical calculations of different finite element models and analyses of the results.(6) Systematical analyses and studies on some key influence factors of kinds of multiple-source damages and mechanical behaviors of some certain parts of in bridge and tunnel connected section in weak surrounding rocks under different kinds of vehicle loads (especially heavy load or overload ones considering impact) have been performed through systematical analyses and calculations of finite element models under different cases. And then some control technologies or reasonable treatments on how to reduce or control some certain damages, unfavorable mechanical behaviors or engineering diseases in bridge and tunnel connected projects have been investigated and and put forward according to some related theories and FEA results.