The attitude control of the shield machine is mainly realized by the telescopic pushing jack and the control of the elongation of the over-excavation cutter. Due to the complexity of the curve line of the transition curve section, the attitude of the shield machine is often difficult to control. In view of the above problems, based on the over-excavation mode and plane attitude analysis of the shield machine, the reasonable over-excavation mode of the shield machine is determined to be the inner half-circle over-excavation, and the difference between the inner and outer pushing strokes and the maximum elongation of the over-excavation cutter is calculated. In the calculation process, a two-dimensional plane is used to simplify the jacking jack of the shield machine, and only the influence of the jacks at the left and right ends on the attitude of the shield machine is considered. Finally, the calculation formulas of the jacking stroke difference and the maximum elongation of the over-excavation cutter of the shield machine in the straight-line transition curve section and the transition curve section are obtained. Taking the construction data of a project into the above formula, it is concluded that the push stroke difference between the inner and outer sides of the straight line into the transition curve section and the maximum elongation of the over-excavation cutter is in a quadratic parabola relationship with the tunneling distance of the shield machine, and the transition curve section. The research can provide a scientific basis for the plane attitude and over-excavation control of the shield machine when the shield machine is over-gentle curve.

In response to the problem of shield tunneling prone to lateral elliptical deformation exceeding the limit under the action of overlying soil, a 1:10 scale model shield tunnel is designed, the influence of overburden soil on the deformation of the existing shield tunnel is studied by experiment. The results show that: (1) As the thickness of the overlying soil layer increases, the maximum increase and change in soil pressure at the top of the tunnel, followed by the bottom, and the minimum on both sides. (2) Significant vertical soil pressure concentration occurs after the thickness of the overlying soil layer on the tunnel is greater than 0.4 m. As a result, the increase in vertical soil pressure is greater than vertical soil pressure concentration does not occur. (3) Under the action of soil cover on the tunnel, due to the vertical soil pressure being greater than the horizontal soil pressure, the tunnel undergoes transverse elliptical deformation. (4) At the location of the tunnel, the lateral soil pressure coefficient of the stratum gradually increases with the increasing thickness of the overlying soil layer. And after reaching a certain degree of thickness, the growth rate of lateral soil pressure coefficient significantly decreases. The results provide reference for the control of existing shield tunnels and the distribution of additional soil pressure around them.

It is difficult to control the plane posture of shield tunneling machines during construction on small radius curved sections. In actual construction, construction person mainly determine the main parameters based on experience, and there is currently no relevant theoretical basis. This article analyzes the plane posture of shield tunneling machines and proposes a reasonable plane state for shield tunneling machines, that is, the cutter head of the shield tunneling machine passes through curved sections close to the outer boundary; When obtaining a reasonable plane posture of the shield tunneling machine, the relationship between the inner and outer jack travel of the shield tunneling machine can be obtained. During construction, as long as the pushing amount of the inner jack is controlled, the pushing amount of the outer jack can be obtained; A reasonable calculation method for the maximum over excavation amount of the shield machine under different top pushing amounts in the plane state of the shield machine is obtained; It is proposed to only perform over excavation on the inner side of the curve, without over excavation on both the upper and lower sides, and a calculation method for the extension of the over excavation knife at different angle positions is obtained. The results have laid the theoretical foundation for intelligent control of shield tunneling posture in curved sections.