Study On The Influencing Factors And Resilience Evaluation Method Of Shield Tunnel Structure Resilience In Loess Area

In recent years,the concept of "resilience" has been widely concerned in academic circles,and the research on resilience has gradually warmed up.Resilience is a kind of self-recovery ability and characteristic of a system,and it is also a common phenomenon in nature.The structural resilience of shield tunnel is an important index to evaluate the permanent stability of tunnel structure.It is of great scientific significance and engineering application value to study the influencing factors and evaluation methods of structural resilience of shield tunnel in loess area.Based on the in-depth analysis of the resilience theory,combined with the existing resilience evaluation framework,this paper analyzes the current performance evaluation index,and puts forward a quantitative evaluation method for evaluating the resilience of shield tunnel structure.By using ABAQUS numerical software as a quantitative analysis tool,the resilience characteristics of shield tunnel structure in loess area under different buried depth,different water content and earthquake action are studied,and the variation law of shield tunnel structure resilience in loess area with different influencing factors is obtained The enhancement law of structural resilience of shield tunnel with different steel fiber content and different length-diameter ratio is obtained.The main research results of this paper are as follows:(1)Under the action of upper surcharge,the resilience of shield tunnel structure gradually increases with the increase of buried depth,and the resilience of shield tunnel structure increases rapidly with the increase of buried depth in the early stage,but increases slowly with the increase of buried depth in the later stage;Under the same buried depth,the resilience of shield tunnel structure gradually decreases with the increasing of water content under the action of upper surcharge,and the resilience of shield tunnel structure in the early stage decreases slowly with the increasing of water content;In the later stage,with the increase of water content,the structural resilience of shield tunnel decreases rapidly,and in the stage of 18%-20%water content,the structural resilience of shield tunnel decreases rapidly.(2)Under the action of earthquake,with the increasing of buried depth,the resilience of shield tunnel structure decreases rapidly in the early stage,and decreases slowly in the later stage with the increasing of buried depth,and the change of resilience of shield tunnel structure tends to be flat after the buried depth is 20m;Under the same buried depth,the structural resilience of shield tunnel increases and decreases with the increase of water content under earthquake,and increases before the water content is 15%and at the stage of 18%-20%,while decreases at the stage of 15%-18%and 20%-25%.In addition,the structural resilience of shield tunnel is at the water content of 20%(3)Under the action of upper surcharge,the resilience of concrete shield tunnel structure with steel fiber is greater than that without steel fiber;With the addition of the same steel fiber,the greater the content of steel fiber,the better its resilience;Under the condition of the same content of two kinds of steel fibers,the resilience of reinforced structure is better by adding steel fibers with large aspect ratio.(4)Under earthquake,the peak acceleration of shield tunnel structure is larger than that of ordinary concrete structure with different steel fiber content.The peak acceleration of steel fiber reinforced concrete structure is relatively small when the aspect ratio is small and the content is large;The resilience of concrete shield tunnel structure after adding steel fiber is greater than that of shield tunnel structure without adding steel fiber And the same kind of steel fiber is added,the greater the content of steel fiber,the better its resilience(in a certain range);Under the condition of the same content of two kinds of steel fibers,the effect of adding steel fiber with large aspect ratio on strengthening the resilience of the structure is better,and the effect of adding steel fiber with large content is better,but the improvement of structural resilience is not obvious.