Study On Long-term Performance Evolution Law Of Typical Deep Excavation Channel Section Of South-to-north Water Transfer Project

The basic status quo of China's water regime is that there are more people and less water,and the distribution of space and time is uneven..The South-to-North Water Transfer Project is a major measure to optimize the spatial and temporal allocation of water resources in China.Since the official opening of water in 2014,the overall operation of the entire line has been stable,which not only guarantees the living water of urban residents along the line,but also significantly improves the ecological environment of the water-receiving areas.Social,economic,and ecological benefits.Since the middle line of the South-to-North Water Diversion Project has entered a longer operating period,it is in the deep side of the river course,the phenomenon of lining board bulging and cracking appears locally.For a long time,it will have a greater impact on the water transport safety of the South-to-North Water Transfer Middle Channel project.Based on this,this paper intends to use the Seepage-Stress-Damage(SSD)solution method to treat the channel "lining-foundation" as a whole coupling system structure,and treat the damage of the lining concrete and the seepage damage of the foundation The effects are closely related,and the fluid-solid coupling effect under rainfall infiltration is studied.The long-term effect is introduced,and then the lining structure is numerically analyzed,so as to provide support for more accurately studying the long-term performance evolution law of channel engineering.In this thesis,the seepage-stress-damage coupling analysis was performed in a typical excavation section of a deep foundation pit in the middle route of the South-to-North Water Transfer Project to study its long-term performance evolution.The main contents are as follows:(1)The coupling seepage-stress-damage coupling theory and its equations are described.The basic principles of the channel seepage calculation and the numerical simulation implementation method in ABAQUS are described,which provides the theoretical basis and technical support for the numerical simulation calculation of the long-term performance of the channel.(2)The fluid-solid coupling model in the ABAQUS finite element calculation software is used,combined with the rainfall infiltration process,to further develop the seepage boundary.Through channel engineering examples,the fluid-solid interaction of the channel under rainfall conditions is numerically simulated,and the changes of the seepage field and stress field of the channel are given.(3)Based on the non-localized theory of concrete materials and the theory of continuous damage mechanics,the gradient plasticity theory is introduced to develop the damage constitutive program,and a plastic damage coupling constitutive model for the nonlinear dynamic damage characteristics of concrete is established and applied to In the numerical simulation calculation of Seepage-Stress Coupling model,the long-term settlement of the channel and the changes of the seepage field are studied.(4)Based on concrete plastic damage model and permeable lining theory,a seepage-stress-damage coupling algorithm for channel lining is proposed.Based on the ABAQUS finite element software platform for secondary development,the utility program GETVRM was used to obtain the material damage,and the subprogram USDFLD was used to achieve the dynamic update of the material permeability coefficient with the damage.Analyze the process,study the evolution characteristics of lining stress,and provide a certain reference for the lining design of channel engineering.