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.

Borosilicate glass is renowned for its applications in Micro-Electro Mechanical Systems (MEMS), lab-on-chip devices, micro-pumps, and micro -valves due to its transparency, chemical resistance, and high strength-toweight ratio. The current study emphasizes the creation of crack -free micro-cavities in Borosilicate glass using Electrochemical Discharge Micro Machining (ECD mu M). Key parameters, such as voltage, electrolyte concentration, and nitrogen gas flow rate, have been optimized to influence material removal (MR) and tool wear (TW) through L20 experiments and the Response Surface Methodology. A modified Blackwidow Optimization (mBWO) strategy is introduced, iteratively addressing contrasting responses. Optimal outcomes, registering 2.206 mg of MR and - 1.372 mg of TW, were attained at settings of 119.66 V, 11.867 wt%, and 4.95 lit/min for voltage, electrolyte concentration, and nitrogen gas flow rate, respectively. The m-BWO demonstrated superior efficacy when compared to the Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Firefly Algorithm (FF), and Cuckoo Algorithm. When juxtaposed against Grey Rational Analysis (GRA), its performance was notably superior. This strategic optimization has the potential to decrease electrolyte preparation costs in MEMS and Nanotechnology, while also endorsing eco-friendly machining practices that mitigate water and soil pollution.