Simplified Calculation Method And Finite Element Analysis Of Composite Lining Shield Tunnel For Water Conveyance

Water resources and quality in China have been greatly different in different areas for a long time.In order to promote social economic and solve the shortage problem of water resources in some areas,more and more composite lining shield tunnels for water conveyance are under construction.For the composite lining shield tunnel for water conveyance,the force model existed is a conservative design which often results in complex construction processes and investment increased.At the same time,there is still a lack of research on design calculation methods,which is commonly calculated according to the guidelines issued by the International Tunnelling Association(I.T.A)and the existing underground railways code in China.In addition,when finite element methods are used for calculation,the experience and uncertainty of the design are also increased.In order to solve the problems above,this paper proposes a simplified calculation method based on the existing elasticity theory and some reasonable assumptions,which can consider the joint forces of composite lining.In the calculation,firstly,the stiffness of the shield segment must be equivalent,then,the ?r(radial displacement)-p(internal water pressure)curve of each component of the composite lining should be calculated separately.After that,in the joint force analysis,the internal water pressure and stress results of each component can be obtained by the principle of deformation compatibility.As a result,the structure of composite lining shield tunnel for water conveyance can be optimized under the allowable material strength and deformation.The constructing and constructed projects of composite lining shield tunnel for water conveyance are calculated in this paper by using the simplified calculation method.The results accord with engineering practice well,indicating that as a simple and feasible engineering calculation method,it has a prospect of application.For the complex conditions which can not be considered by using the simplified calculation method in actual project,this paper also made some finite element analysis.These analyses improve the deficiencies of the simplified calculation method,and some preliminary conclusions based on the depth of the buried rock,the distance between the double tunnels,the damage of surrounding rock,the effect of self-compacting concrete and grouting layer and the characteristics of contact between components have been obtained by the finite element analysis,which provide references for engineering practice.