Research On The Mechanical Properties Of Semi-rigid Joint Of Immersed Tube Under Differential Settlement

At present,there are quite many researches on the joint form of immersed tube tunnel in broad and abroad,but few researches on the mechanical properties of semi-rigid joint of immersed tube tunnel.When complex differential settlement occurs underwater,the shear key of semi-rigid pipe joint is very important for the safety of immersed tunnel.In this paper,the mechanical properties of the shear key of semi-rigid pipe joint under differential settlement are studied based on the underwater immersed tunnel of Hong Kong Zhuhai Macao Bridge.Based on the project of National Natural Science Foundation of China(Project No.: 51708368)and the project of Hebei Natural Science Foundation of China(Project No.: e2018210145),this paper aims at the joint mechanics of the prestressed steel of the semi-rigid pipe joint of the immersed tunnel The influence mechanism of performance is not clear.The mechanical properties of semi-rigid pipe section joints under the action of prestressed reinforcement are studied by theoretical analysis,numerical simulation and indoor model test.The conclusion that prestressed reinforcement has a positive effect on the stress of pipe section joints is drawn,which is very important for the safety maintenance of semi-rigid pipe section in the future Significance.First of all,through the theoretical analysis of the load effect of immersed tube tunnel,focusing on the load factors of the greater stress on the joints of immersed tube tunnel,the two cases of uneven stiffness and uneven back silting of the longitudinal foundation are selected to study the impact on the semi-rigid pipe joint structure,with the bending and direct shear conditions as the main research object.Secondly,ANSYS software is used to simulate the mechanical properties of semi-rigid pipe joints under the action of differential settlement.By making indoor physical test model and elaborately designing the test platform,a scale of 1:10 is selected to carry out the physical model test of semi-rigid pipe joints.At the end of the experiment,the numerical model and the physical test results are compared and analyzed,and the stress characteristics of the shear key and the contact part of the joint are obtained.Finally,according to the guidance of three-dimensional numerical model and indoor physical model test,detailed analysis is carried out to reach the optimal conclusion,and other complex stress conditions that may appear in the future are prospected.This study has guidance and reference significance for the mechanical properties and practical engineering design of the semi-rigid pipe joints of immersed tunnel under the differential settlement in the future.