In shield tunnel construction, the tightening torque of shield segment bolts is a crucial parameter, which is directly related to the connection quality of tunnel segments and the stability of the structure.
First, the determination of tightening torque needs to consider multiple factors. Among them, the material and specification of the bolts are important basic factors. Bolts of different materials have different strengths and elastic moduli, and the tightening torque they can withstand will also be different. For example, high-strength bolts usually require a larger tightening torque to exert their best performance, while ordinary bolts are relatively small. At the same time, the specification parameters such as the diameter and length of the bolts will also affect the size of the tightening torque. Generally speaking, bolts with larger diameters require a larger tightening torque to ensure the firmness of the connection.
Secondly, the material and structural characteristics of the segments will also affect the tightening torque. Segments of different materials have different hardness and elasticity, and their degree of coordination with bolts will also vary. For example, concrete segments are relatively hard, and an appropriate tightening torque is required to ensure a tight connection between the bolts and the segments, while not being too large to avoid damaging the segments. In addition, factors such as the structural shape and thickness of the segment will also affect the distribution and transmission of the tightening torque, which needs to be comprehensively considered when determining the tightening torque.
Furthermore, the actual engineering situation is also an important basis for determining the tightening torque. Different shield tunnel projects have different geological conditions, construction processes and use requirements, which will affect the tightening torque of the segment bolts. For example, in cases where the geological conditions are complex and the tunnel is subjected to large forces, it is necessary to appropriately increase the tightening torque to improve the connection strength of the segment; while in some projects with high requirements for tunnel deformation, it is necessary to control the tightening torque to avoid cracks in the segment due to excessive extrusion.
In order to determine the appropriate tightening torque, a series of tests and analyses are usually required. Through laboratory tests, bolts and segments of different materials and specifications can be combined and tested to measure their connection strength, deformation and other parameters under different tightening torques, so as to determine the optimal tightening torque range. At the same time, the stress conditions of the shield tunnel segments can also be analyzed with the help of numerical simulation and other means to optimize the distribution and size of the tightening torque.
In summary, the tightening torque of shield segment bolts needs to comprehensively consider multiple factors such as bolt material and specifications, segment material and structure, and actual engineering conditions. The appropriate value should be determined through testing and analysis to ensure the connection quality of the shield tunnel segments and the stability of the structure.
