Study On Influence Of Cracking On Structure Safety Of Subway Tunnels

The subway system has the characteristics of fast and efficient,which can solve the urban congestion problem well,and its construction speed has been growing at a high speed.At the same time,as the subway operation time is getting longer and longer,the disease situation is more and more serious.In this paper,based on site investigation,widespread access to information and statistics,Beijing subway diseases on the basis of establishment of longitudinal cracks as the main research contents,and the model test and numerical simulation method,carried on the detailed analysis of research content,main research contents are as follows:(1)For Beijing metro line 1,line 2,line 5 and line 6,7 lines,line 8 and no.10 line and airport line 8 lines 103,obtained detailed statistics of interval disease situation,the overall disease condition,different method of construction of Beijing metro interval,and different lining structure crack distribution.The obtained data provide the basis for subsequent research content and condition.(2)Obtained the water:gypsum:carboxymethyl starch etherification= 0.65:1:0.01 ratio by the adoption of 1:10 model test method,through 26 groups of indoor mixture ratio test.The product can be a good simulation of C30 concrete under 1:10 scale features,satisfying the requirement on similarity and accuracy.(3)A set of test apparatus for loading and measuring of the structure is designed,and the test block is loaded by the method of jacking.Test shows that the device can well satisfy the test accuracy.Results from modelling and numerical simulation are matched which further verifies the feasibility of test apparatus and value of test results for reference purpose.(4)Using the method of model test,this paper studies the process of crack propagation and development to destruction in the process of graded loading.At the same time,8 kinds of working conditions were designed,and the influence of crack depth,length and width on structural bearing capacity was studied.(5)By the finite element software ABAQUS,the intact structure in the process of grading load crack evolution law has carried on the further analysis,design for 11 kinds of working conditions at the same time,studied the structure fracture crack location,depth,length,width,the bearing capacity of structure,and compared with the results of model test.(6)Using the results of model test and numerical simulation,the structural safety situation of the Huayuanqiao station-Bashiqiao station,Beihaibei station-Jintai road station of Beijing metro line 6 was analyzed,corresponding suggestions are provided.