Mechanical Properties of the Shield Tail Brush and Its Pressure Distribution Acting upon the Segment

Shield tunnels are widely used in underground transportation. The shield tail brush is an important component of the shield machine, but also can exert an adverse influence on the segment as it can induce considerable and uneven pressure thereon. Therefore, it is necessary to consider the tail brush pressure in calculations on the segment. However, there are few studies on the calculation method of this pressure. As a consequence, this study carried out laboratory tests on the tail brush, and revealed the two-stage nature of its pressure-compression curve, which can be fitted well by a line together with a polynomial function. In addition, formulas describing the tail brush pressure distribution along the circumference were derived by theoretical analysis. Furthermore, by summarizing the distribution law, simplified formulas for the tail brush pressure acting upon the segment along the circumference and lengthwise due to vertical shield posture adjustment were established. The results can be used in calculations on the segment to improve the segment design and provide guidance for shield tunnel construction.