Research On The Mechanical Characteristic And It's Influence Factors Of The Segmental-Joint Shear Key Of Offshore Immersed Tunnel

With the rapid development of coastal economy and bay area economy,the transportation industry has been rapidly promoted.Many large underwater tunnels have been built in China.Immersed tunnel is one of the common forms of underwater long-distance tunnel.Immersed tunnel can better use the space of tunnel and has no iMPact on the faireway.The Segment-type immersed tunnel can better adapt to the uneven settlement of foundation.The function of immersed tunnel joint is similar to "joint",which makes the immersed pipe tunnel adapt to the uneven settlement of the foundation without hunge internal force.At the same time,the immersed tunnel joint is the most vulnerable part of the immersed tunnel,and its mechanical properties directly affect the structural safety and waterproof of the tunnel.Immersed tunnel joints are divided into element joints and segment-joint joints.There are many researches on the element-joint joints at home and abroad,but few researches on the segment-joint joints.The shear key is an important component of the segment-joint.In this paper,the stess distribution and the fotor of stress-distribution of the shear keys have been researched by the model test and finite element analysis.The main work contents a nd results are as follows:1.Based on the hong kong-zhuhai-macao immersed tube tunnel,the mechanical properties of segmental joint shear key were studied.According to the similarity principle,the bending model test of shear key was determined,and the segment model was simplified correspondingly.Digital Image Correlation(DIC)was selected as the test measurement method.the results of tests show that the stress concentration of the Max.principal strain apppered the internal coners of shear keys and the stress concentration of the Min.Prinicipal strain appered the external of shear keys.It is possible to optimize the geometry of the shear key of Hong kong-zhuhai-macao immersed tube tunnel.2.The emulation model of the model test has been built to ana lyze the stress of shear key of the model test by the finite element software(ABAQUS).According the results of model test to difinte the stess boundary condition,the displacement boundary condition and the phycial model of the contact of the finite element emulation model by CoMParing the resuts of FEA and the model test.3.On the basis of the finite element emulation model,weather the stress distribution of shear keys would be optimiza byindividually changing the length of the shear keys and the external coners of the shear keys,the results show that the stess distribution of external and internal coners of the shear key would be improved by increasing the length o f shear key,and the external coners of shear key would be improved by changing the geometry-arc end Angle line end Angle of shear key.the arc end is better than the line end.4.Based on result of the sensitivity analysis of the factors,the geometry of shear key has been optimised through finite element analysis(ABAQUS),the result shows that when increasing the length of shear key and changing the external corners to arc corners,the sterss condition of concrete of internal corners and exte rnal corners of shear key would bee improved.