3D Deformation Characteristics of Composite Structure in Ultra-Deep Pipe Jacking Working Well

Taking the pipe jacking project of an ultra-deep buried power tunnel in Foshan City as the background, the method of combining on-site monitoring and numerical simulation is used to study the deformation law of the composite support structure of the pipe jacking working well during the construction process. The results show that the numerical simulation results are basically consistent with the actual monitoring values; with the construction of the inner support and the lining wall in the excavation stage, the combined effect of the composite structure effectively restrains the horizontal displacement of the wall from increasing into the well. The influence of the displacement of the upper wall gradually decreases; while in the jacking stage, the wall moves out of the well within the range of the jacking reaction force, and the vertical and lateral horizontal deformation of the wall outside the well increases with the increase of the jacking reaction force; by analyzing the vertical and lateral horizontal deformation laws of the back wall of the working well, it is shown that the overall deformation is a curved surface that “bulges” out of the well; finally, it is suggested that the closer the distance to the action center of the jacking reaction force, the smaller the spacing between the inner supports, and the section size should be larger, in order to improve the support efficiency and overall stability of the working well structure.