Study on the Labor Intensity and Labor Time of Construction Personnel in High Temperature and High Humidity Tunnel

When the tunnel passes through the fracture zone of the high-temperature hot spring fault, construction personnel will encounter a challenging environment characterized by high temperature and humidity. The construction process involving drilling and blasting is complex, leading to high labor intensity. Regrettably, existing research has overlooked the impact of high-humidity environments on tunnel personnel. To ensure the safety and well-being of construction workers in such conditions, this study establishes revised labor intensity grades for tunnel construction personnel operating in high-temperature, high-humidity environments. Additionally, it develops a human body predicted heat stress correction model based on changes in energy metabolic rates. Furthermore, recommendations are provided regarding safe continuous working times for tunnel construction personnel under these conditions. Field tests were conducted within a hot tunnel environment to validate these findings. Results indicate that when temperatures exceed 30 ℃ and humidity surpasses 70%, labor intensity levels for tunnel construction personnel increase by approximately one grade for every 4 ℃ rise in temperature or 10% increase in relative humidity. When temperatures exceed 38 ℃ with relative humidity exceeding 90%, or when temperatures exceed 40 ℃ with relative humidity over 70%, operations should be halted by construction personnel as per safety guidelines. Notably, field test results demonstrate that the error margin of the human heat stress correction model remains below 5%.