Study On Mechanical Characteristics Of Segmental Lining Structure For Deep-buried Inclined Shaft Constructed By Shield

In recent years,In recent years,demand for transportation and energy construction in China continues to grow,the shield tunneling is widely used in areas such as transportation,hydraulic,coal mine,oil and gas.The construction conditions vary from shallow to deep,even involving over thousand meters deep underground space development.With the engineering development,a series of scientific and technical issues arise.However,it is a completely new field to construct deep underground engineering by shield and there are no existing specifications and engineering examples for reference.In the face of complicated conditions such as deep burial,rich water and complicated and changeable geological conditions,current researches on the mechanical characteristics of lining structures remain far from enough.This paper,subjects from deep and long inclined shaft constructed by shield,studies the mechanical performance and analysis method of lining structure of deep-buried mine inclined shaft constructed by shield.The results can provide leading thoughts and methods for many technical problems encountered in the expanding application of shield in deep underground space,and are of great importance.Supported by National Natural Science Foundation(Joint Research Program of Coal Mine)“Basic theory of lining structure design of coal mine roadway(inclined shaft)constructed by TBM(shield)under complex conditions” and National Science and Technology Support Program “Digital remote monitoring technology of long-distance inclined shaft in shield construction coal mine”,the literature investigation,theoretical analysis,numerical simulation,model test,as well as field test are carried out in this study based on the Shenhua Xinjie Taigemiao Coal Mine Inclined Shaft Project and Shendong Bulianta Coal Mine Inclined Shaft Project.Breakthrough has been made on the aspects of load deciding,the interaction between surrounding rock and support structure and countermeasures against high earth pressure and water pressure.The research achievements are directly applied to the first longdistance inclined shaft constructed by shield in the coal mine field in China——Shendong Bulianta Coal Mine Inclined Shaft Project,and provide technical reserves for another similar project to be constructed——Shenhua Xinjie Taigemiao Coal Mine Inclined Shaft Project,and can also provide important reference for the design and construction of similar tunnel engineering.The main work and achievements are as follows:1.By meanings of literature investigation and numerical simulation,the commonly used standards for the demarcation criterions of buried depth of inclined shafts are compared and analyzed to determine the demarcation principle of buried depth of deep and long inclined shaft constructed by shied,and the demarcation criterions of buried depth and the calculation formula of the loosening pressure of surrounding rock are proposed.Meanwhile,the applicable conditions of calculating the deformation pressure of surrounding rock by means of the convergence-confinement method(CCM)are clarified,and the calculation method is also introduced.2.Based on the elastic theory,an analytical solution for the stress and displacement is deduced to consider the interaction between the surrounding rock and double layered composite lining structure of inclined shaft constructed by shield.Moreover,based on MohrCoulomb yield criterion,the elastoplastic analytical solution of the interaction between the surrounding rock and double layered composite lining structure considering the seepage effect is also deduced.The solutions above can provide a theoretical basis for evaluating the effectiveness of the composite support system of segmental lining + compressible layer.3.Using “Shield Tunnel-Ground-Water Pressure Complex Simulation System”,similar model tests considering the interaction between shaft structure and ground were carried out against the characteristics of different types of complex strata with different mechanical properties including homogeneous stratum,two-layered strata and three-layered strata with the weak interlayer.The forces and deformation behaviors of segmental lining structure as well as the supporting effect of the composite support system of segmental lining + compressible layer were ascertained.4.The countermeasure to adopt the drainage segment in high water pressure section is put forward and based on which the numerical simulation model considering the fluid-solid coupling effect is established.By applying the orthogonal test method with the established model,the factors affecting the discharge and depressurization effect of the drainage segment were analyzed and compared to clarify the main influence factors and the major and minor relationship of them.The distribution characteristics of water pressure,as well as the discharge variation of the segmental lining under the depressurization effect of the drainage segment are verified,and the safety of the lining structure under the local low water pressure caused by the discharge and depressurization is tested.The effect of discharge and depressurization is also verified by field test.