Study On Formation Mechanism And Development Law Of Tunnel Cracks

When engineers deal with tunnel diseases at home and abroad,combined with the characteristics of tunnel diseases,structural stress and the surrounding geology,climate and hydrology information,the paper analyzes the causes of disease,evaluauates the safety grade of tunnel,and finally formulates the corresponding reinforcement scheme,which is more systematic and comprehensive,and deserves in-depth study and research.In this paper,the influence of the interaction force of tunnel surrounding rock and supporting structure on lining cracks is deeply studied based on the theoretical derivation,combined with the knowledge of rheology mechanics,elastic plastic mechanics and fracture damage mechanics,the internal forming mechanism and fracture development law of the disease are studied and analyzed systematically.finally,the reasonable maintenance cycle of lining cracks is determined by the combination of tunnel maintenance code,and corresponding maintenance measures are put forward.The main contents of the thesis are as follows:1.this paper analyzes the research status of tunnel lining cracks at home and abroad,puts forward the problems encountered by the current fracture research institute,combined with the rheological mechanics and fracture mechanics knowledge,studies and analyzes the formation mechanism of tunnel lining cracks based on the rheological theory.2.to establish the elastic foundation beam model of the lining structure and establish the elastic foundation beam model,use the elastic-plastic mechanics knowledge to establish the control differential equation of tunnel lining,according to saint Swai principle,deduce the excellent equation that the crack spacing corresponding center angle should meet,calculate the tunnel lining crack spacing under external load,and then determine the expression of tunnel lining crack width in the conditionof equal space.3.discuss and take value of surrounding rock parameters,using the dynamic relationship between support structure and surrounding rock force with time,analyze and deduce the interaction force between typical ? and ? surrounding rock and supporting structure,combined with the expression of tunnel lining crack width,get the relationship between the crack width of tunnel lining under typical ? and ?surrounding rock.4.combining the relevant tunnel maintenance norms with the relationship between the crack width of tunnel lining under typical ? and ? surrounding rock,the maintenance cycle of tunnel lining cracks is analyzed and the corresponding maintenance measures are formulated.Finally,some useful conclusions are obtained.the results are as follows:1.Beam on elastic foundation model,the study of tunnel lining crack spacing and width are derived and established the lining according to the governing differential equations of curved beam on a elastic foundation together,determine the outside under the load of tunnel lining crack width and spacing of expression.2.In a typical ?,? surrounding rock as an example,study the different parameters of interval tunnel surrounding rock support-rock interaction force with time changing law of the tunnel and the interaction of surrounding rock of tunnel lining with time increasing,surrounding rock stability in the end.And the elastic modulus of surrounding rock and surrounding rock supporting force is inversely proportional to the size of the each other.3.In a typical ?,? class surrounding rock as an example,study out of the tunnel lining under different surrounding rock elastic resistance coefficient of crack width,namely tunnel lining crack width increasing over time,about 10 years around the tunnel will exceed the standard value of 3 mm,and the elastic resistance coefficient of surrounding rock and tunnel lining crack width is inversely proportional to,ultimately determine the maintenance cycle according to the rules.