To elucidate the wear mechanisms of the scraper in shield tunneling through sandy pebble strata, this study aims to achieve high efficiency and low wear during the tunneling process. We evaluate the operational parameters and tool wear characteristics of a 9-m diameter spoke-type shield machine used on the Beijing Daxing Airport Line. The analysis focuses on the wear values of the scrapers and rippers, wear of the scraper in different wear forms, and scraper wear relative to the position of the rippers obtained from the field. The study yielded the following conclusions. The wear values of scrapers on different spokes vary significantly owing to ripper protection. The wear of the scrapers can be categorized into six types: tooth chipping, local damage of teeth, wear of side teeth, wave-type of wear, wear on intermediate teeth, and flat wear, with the majority exhibiting wear on the side and intermediate teeth. The 0 degrees spoke maintained the initial shape of the scrapers, making it more suitable for tunneling in sandy pebble strata. Based on the differences in the relative positions of the ripper and scraper, a model is proposed to determine the ripper plowing influence area. It was found that this area depends on the geological conditions of the soil; thus, the influence angle of ripper plowing in the considered sandy pebble strata is determined to be between 35 degrees and 50 degrees. The results obtained in this study provide a theoretical reference for optimizing scraper layouts in shield construction, even when operating under varying geological conditions.

Traditional robotic grippers encounter significant challenges when handling small objects in confined spaces, underscoring the need for innovative instruments with enhanced space efficiency and adaptability. Erodium cicutarium awns have evolved hygroresponsive helical deformation, efficiently driving seeds into soil crevices with limited space utilization. Drawing inspiration from this natural mechanism, we developed a biomimetic thin-walled actuator with water-responsive helical capabilities. It features a composite material structure comprising common engineering materials with low toxicity. Leveraging fused deposition modeling 3D printing technology and the composite impregnation process, the actuator's manufacturing process is streamlined and cost-effective, suitable for real-world applications. Then, a mathematical model is built to delineate the relationship between the biomimetic actuator's key structural parameters and deformation characteristics. The experimental results emphasize the actuator's compact dimension (0.26 mm thickness) and its capability to form a helical tube under 5 mm diameter within 60 s, demonstrating outstanding space efficiency. Moreover, helical characteristics and stiffness of the biomimetic actuators are configurable through precise modifications to the composite material structure. Consequently, it is capable of effectively grasping an object smaller than 3 mm. The innovative mechanism and design principles hold promise for advancing robotic technology, particularly in fields requiring high space efficiency and adaptability, such as fine tubing decongestion, underwater sampling, and medical endoscopic surgery.