# A Study on the Effects of Hob Temperature on the Rock-Breaking Characteristics of Sandstone Strata
## 1 Introduction  
In the context of rapid economic development, the exploration and utilization of underground spaces are becoming more exhaustive, bringing forth a spectrum of complex challenges. One of the critical issues encountered is the wear and damage of tools during shield machine tunneling operations. A notable factor contributing to this challenge is the high temperature of the hob during rock cutting, which significantly influences the mechanical properties of the rock formation and subsequently alters the damage patterns. Considering the high costs and practical limitations of direct experimental studies to address hobbing-related problems, numerical simulation has emerged as a pivotal approach for conducting in-depth analysis and improving our understanding of these issues [1]. Extensive research has been conducted on rock destruction patterns, particularly focusing on the study of rock cracks [2; 3]. One contribution in this field was made by [PERSON] et al. [4], who conducted a detailed study on the fracture toughness of granite in the temperature range of 20 \({}^{\circ}\)C to 500 \({}^{\circ}\)C. Their research revealed critical insights into the fracture toughness of granite and the acoustic emission properties of the rock during the damage process under high-temperature conditions. Similarly, [PERSON] et al. [5] embarked on conducting an in-depth study centered around the mechanical properties of rocks under the influence of low peritectic temperatures. Their work encompassed a range of properties, including Poisson's ratio, the modulus of elasticity, fracture toughness, and compressive strength. They successfully deduced the damage mechanism of rock mechanical properties as influenced by temperature variations and time. Further, [PERSON] et al. [6] made noteworthy advancements in understanding granite's mechanical parameters at both room temperature and elevated temperatures. Their approach integrated basic mechanical testing with acoustic emission and microelectron microscopy observations, leading to a comprehensive analysis of thermal damage in rocks. Based on the mechanical parameters derived from these physical tests, they constructed a granite model and completed a numerical simulation study of thermal rupture in a state devoid of lateral stress. Another innovative approach was undertaken by [PERSON] et al. [7], who employed the acoustic emission method to investigate the damage process of rocks under different temperature conditions. Their study provided valuable insights into the fracture characteristics of granite in the temperature range of 20 \({}^{\circ}\)C to 50 \({}^{\circ}\)C. In the realm of applying advanced computational techniques, [PERSON] et al. [8] explored the potential of deep recurrent neural networks and convolutional neural networks for vibration-based ground recognition at mining sites. Their work represents a significant stride in applying machine learning and artificial intelligence in geological studies. Complementing these approaches, [PERSON] et al. [9] utilized the thermodynamic coupling module in PFC\({}^{\text{2D}}\) to analyze rock fracture phenomena and the pattern of crack expansion in temperatures ranging from 10 \({}^{\circ}\)C to 120 \({}^{\circ}\)C. This study provided a nuanced understanding of the thermal effects on rock fracture behavior. [PERSON] et al. [10] ventured into the domain of microwave-induced thermal damage in mineral particles using discrete element particle flow. Their model, comprising calcite as the matrix and galena as embedded particles, underscored the crucial influence of particle size on the simulation results. This finding highlighted the necessity of carefully adjusting and calibrating parameters in particle flow software to accurately simulate and predict the behavior of mineral particles under thermal stress.