Design And Implementation Of Dynamic Layout Algorithm For General Wedge Segment Of Tunnel

As an advanced form of tunnel lining,wedge-shaped segment is used more and more in shield construction.The dynamic layout of this type of segment has an important influence on the safety of shield tunneling and the forming quality of the tunnel.Dynamic typesetting is closely related to the deviation correction curve of shield machine.In this paper,the dynamic layout of the general wedge segment and the shield deflection correction curve are studied,including the following aspects:The factors involved in dynamic segment selection,such as segment geometry size,shield tail clearance,cylinder stroke difference,deviation of segment fitting center relative to design axis,and the relationship among them are analyzed.The attitude relationship between segment end face and shield is obtained by plane fitting for the stroke data of propulsion cylinder,and the position relationship between segment and shield is obtained by circle or ellipse fitting for the clearance data of shield tail.A set of vectors is defined to describe the relationship between segment and shield,segment and design axis.The relationship between the cylinder stroke difference between the front and rear ring segments,the shield tail clearance and the deviation from the design axis is derived.Combined with the relative relationship between shield and design axis,considering the shield tail clearance,hinge device,the minimum fitting radius of segment,the maximum allowable stroke difference of oil cylinder,the calculation formula of deviation correction curve is obtained.According to the deviation correction curve,the trend of the next several rings of shield and the data of the cylinder stroke difference introduced due to the deviation correction are obtained,which provides control suggestions for the shield operators.An objective function is designed to evaluate the dynamic layout results of segments.The function considers factors such as staggered joint assembly,cylinder stroke difference,shield tail clearance,deviation from the design axis,etc.By calculating the minimum value of the objective function sum of the next four ringsegments,the optimal layout scheme is obtained.The trend chart of fitting deviation of the four ring segments,the trend chart of shield tail clearance,and the trend chart of cylinder stroke difference are given to provide dynamic typesetting suggestions for construction personnel.The algorithm of dynamic layout of wedge segment and calculation of deviation correction curve of shield is written in Python.It has good effect in Qinghuayuan tunnel project of Beijing Zhangjiakou high speed railway.