Study On Stress And Deformation Characteristics Of Expansive Soft Rock Tunnel Of Surrounding Rock And Support Structure

Because embedded expansive soft rock expansibility,disintegration,rheological property,easy to disturbance and other characteristics,and under the influence of tectonic stress,the tunnel surrounding rock after excavation construction appear large deformation bias phenomenon,not only damage to the stability of surrounding rock,combined with the construction of supporting structure in the process of the overall damage.Paper based on mountain of Wofo tunnel engineering,through field monitoring,indoor model test,the theoretical analysis and numerical simulation,the method of combining the of swelling soft rock tunnel surrounding rock and support structure deformation characteristics were studied.1.The large deformation of surrounding rock tunnel definition,types,definition,mechanism and influencing factors of research,for in the particular geological conditions and deformation characteristics of surrounding rock and supporting structure theory analysis,and combined with field monitoring data,get high in-situ stress soft rock under the condition of large deformation analysis of bias tunnel surrounding rock and supporting structure deformation characteristics.2.Construction mechanical effects for the study of the surrounding rock and supporting structure,based on the analysis of initial geostress field and surrounding rock stress theory,the engineering practical calculation method for the flaws of the surrounding rock pressure is discussed,and the engineering practical calculation method for surrounding rock pressure of differences and engineering site monitoring data obtained were analyzed,and infers the elastic-plastic state of deep weak rock in linear Mohr-coulomb strength criterion and nonlinear Hoek Brown-strength criterion under the stress state of the plastic zone,the radius of plastic zone and the plastic area.3.Through the analysis of the interaction mechanism of surrounding rock and supporting structure,stratigraphic characteristic curve and supporting characteristic curve in the^u-pi coordinate plane different combination,get low tunnel excavation in close formation characteristic curve after a period of time using the flexible retaining the most reasonable.In combination with field monitoring data,by the large deformation of bias tunnel surrounding rock and supporting structure characteristics,the supporting timing and supporting stiffness retaining structure is not reasonable to cause serious damage.4.Adopting geomechanics model test,the test study on the bias of soft rock tunnel,under the condition of different lateral pressure,the surrounding rock and supporting structure along the axis of rotation to simulate a bias phenomenon,through the model similarity criterion is bigger than to determine the model test of surrounding rock deformation,and through the surrounding rock deformation and contact pressure of surrounding rock and lining structure and lining structure stress analysis,understand the soft rock under the condition of bias force deformation law of surrounding rock and supporting structure,and get under the condition of bias tunnel construction key monitoring area.5.Through numerical analysis,choose Moore-cullen elastoplastic constitutive model,simulation step method is used for the field construction,under the certain condition of horizontal tectonic stress,the deformation characteristics of surrounding rock and supporting structure is analyzed,it is concluded that the surrounding rock condition and the influence of the horizontal tectonic stress of surrounding rock and supporting system relations,and analyzes characteristics of displacement deformation and plastic zone distribution.Results show that under the condition of large deformation bias,deformation of retaining structure is most evident in the inverted arch and side wall,and at the side of the surrounding rock is better to bolting exert a certain compressive stress,damage to support.6.For complex surrounding rock under the condition of surrounding rock stress of elastic and plastic analysis,large deformation is put forward bias tunnel retaining structure design concept and the basic requirements.Through compound system of combined support and the layer 2 early to simulate the large deformation of bias tunnel surrounding rock stability analysis.