Research On The Interaction Mechanics Model Between Frozen Soil And Lining Of Trapezoidal Channel Based On Elastic Foundation Beam Theory

As an important water delivery structure for irrigation area construction and water diversion projects,canals are of great significance to water conservation in irrigation areas,economic and social development of water-receiving areas,and ecological protection of river basins.The channel project built in the northern cold region is affected by the seasonal frozen soil,and the channel lining often suffers from cracking,dislocation,bulging,hollowing out and even overall slump,etc.,which reduces the water running function of the channel and causes serious leakage,which restricts the project benefits.For the design of channel frost heave in cold regions,the current code only provides an empirical method to determine the cross-section form depending on the channel scale and the free frost heave amount of the foundation soil,and the theoretical design method is insufficient.It is urgent to establish the frost heaving failure analysis theory of channel engineering in cold region,including failure criterion of freezing-thawing failure and section design method,so as to ensure that the frost heaving design of channel has rules to follow.Therefore,this paper systematically establishes the failure criteria of strength,stiffness and stability of water conveyance channels in cold regions based on the characteristics and mechanism of cascading failure of strength,stiffness and stability of channel freeze-thaw failure.According to the stress characteristics of canal frost heave,the calculation method of frost heave foundation coefficient of canal lining is proposed.On this basis,based on the theory of elastic foundation beams,the frost heave mechanics of cast-in-place lining trapezoidal canals with higher accuracy are established from the two aspects of the foundation soil frost heave continuity and the lining-frozen soil tangential effect.model;for the precast concrete lined trapezoidal channel widely distributed in the cold region,a frost heave mechanical model considering the effect of joints is established;the above three mechanical models of frost heave elastic foundation beam can give the calculation formula of the frost heave displacement and internal force of the channel lining.The theoretical basis and technical means are provided for the design of channel engineering in cold regions.The research contents and results of this paper are as follows:(1)Using two methods of field and literature investigation,the characteristics of freezethaw failure of the channel in cold regions are summarized and analyzed,and it is pointed out that the freeze-thaw failure is a chain failure process of strength,stiffness and stability.At the same time,combined with the evolution law of canal lining stress and deformation,a judging system for canal freeze-thaw damage is established,which provides a theoretical reference for canal design and evaluation in cold regions.(2)According to the stress characteristics of channel frost heave,combined with the free frost heave amount of the foundation soil and the results of the double-layer foundation method,the calculation method of the frost heave foundation coefficient of the channel lining is proposed.Compared with the frost heave foundation coefficient obtained by taking the general foundation as the research object in the past,the calculation method in this paper is more suitable for the cold region channel,which lays a theoretical foundation for the value of the foundation coefficient.(3)Considering the frost heave continuity of the foundation soil,based on the generalized Winkler elastic foundation beam theory,the frost heave mechanics model of the cast-in-place lining trapezoid channel is established,and the calculation method of the frost heave displacement and internal force of the lining is given by the finite difference method.The model can consider the limit equilibrium state of lining failure and the release of normal frost heave force by the lifting displacement of the lining,and the results are more realistic.(4)A tangential spring,which can consider the tangential interaction between the frozen soil and the lining and is coupled with the normal spring,is introduced,and a mechanical model of the canal frost heave elastic foundation beam considering the tangential interaction between the lining and the frozen soil is established.Based on the calculation method of freezing force,the analytical solutions of the frost heave displacement,internal force and section normal stress of the channel lining are given,and the model is verified based on the field measured data and finite element simulation.The role of lining frost heave.The mechanical model can give the values of lining deformation and section normal stress,and assist designers in structural design from strength,stiffness and stability indicators.(5)Considering the effect of caulking between slabs,based on the mechanical model of cast-in-place lining canal,the mechanical model of the prefabricated trapezoidal canal with frost heave elastic foundation beam was established.The safety of the channel is evaluated in terms of shear strength and joint shear strength.Combined with the field measurement,the mechanical model is verified,and the difference between the internal force and deformation of the prefabricated lining and the cast-in-place lining is discussed,and the influence of the length of the prefabricated plate on its safety is analyzed.