In order to understand the influence mechanism of grouting pressure fluctuations on pipe joints in large cross-section rectangular pipe jacking,this paper relies on a large cross-section rectangu-lar pipe jacking project in Nanjing,and uses research metho-ds such as theoretical analysis,engineering analogy,and numerical simulation to investigate the influence mechanism of grouting pressure fluctua-tions on the stress state of large cross-section rectangular pipe joint structures under local pressure sup-pression condit.The external loads of large cross-section rectangular pipe joints was calculated,and the concrete damage plasticity model built-in ABAQUS software was used for numerical modeling to study the damage evolution mechanism of reinforced concrete pipe joints under different grouting pressures.The results show that:(1)grouting load,as a variable load,has a significant impact on the stress dis-tribution of the pipe joint,such that the grouting pressure should be included in the design of the pipe joint;(2)For this project,the theoretical grouting pressure is 0.311 MPa.In view of the need to sup-press the carrying-soil effect,the grouting pressure should be appropriately increased,but it must be controlled within a reasonable range;and(3)From the perspective of damage evolution,when the grouting load reaches 0.6 MPa,the tensile damage to the top plate of the pipe joint has reached a high level.Therefore,0.6 MPa is used as the grouting pressure warning indicator for this project,while 0.9 MPa should be used as a control indicator for grouting pressure.
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