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The application of backfill mining method in deep mines is becoming more and more common, but the accompanied hydration heat of cemented tailings backfill (CTB) exacerbates the thermal damage in the depths. This study establishes and validates the wind temperature prediction model of excavation roadway containing CTB heat sources according to the simulation results and field measurements. The results show that the hydration heat of CTB has an important influence on the wind temperature in excavation roadway, and the use of ventilation to alleviate it is effective. The wind temperature increases gradually with the distance between the measurement point and air duct. The overall mean absolute percentage error (MAPE) between the theoretical calculated values and the simulated values of the established wind temperature prediction model of excavation roadway containing CTB is 0.08 %, which verifies the accuracy and validity of the model. The wind temperature prediction model can be used to guide the development of appropriate ventilation and cooling programs at the site, providing a guarantee for personnel health and safe and efficient mine production.

Aiming at forecasting and preventing remnant coal spontaneous combustion in goaf, this thesis conducts determination on the spontaneous combustion tendency of coal seam, simultaneous thermogravimetry and differential scanning calorimetry(TG-DSC) analysis on coal samples, optimization on index gas of spontaneous combustion, and division of spontaneous combustion “three zones” with O2 concentration as the indicator. The conclusions are as follows: the spontaneous combustion period of remnant coal is 1–3 months, so the coal seam is easy to spontaneous combustion. CO and C2H4 are selected as the index gas for forecasting spontaneous combustion in No.12 coal seam and No.12-up coal seam because of their regular evolution tendency in concentration changing with coal temperature and easiness in detecting. As to the spontaneous combustion “three zones” divided by O2 concentration, the depth and width of both heat dissipation zone and left side oxidation zone in the goaf is slightly increased when the “Y” type ventilation is adopted, comparing with the “U” type ventilation, and the asphyxiation zone is extended to about 200 m behind the workface. Pressure balance method and ground fissure sealing are proposed for spontaneous combustion prevention and extinction, which offers some practical experiences for adjacent mine or similar coal seam.

In order to deal with the thermal hazard in deep engineering, it is proposed to control the temperature of workface with the constant temperature zone as cold source and deep gushing water as refrigerant. Cooling effect of the water in borehole network which were arranged in constant temperature zone was studied based on similar experiment and numerical simulation. The results show that: The environment temperature has an effect on model cooling, and the higher cooling temperature difference when covering insulation layer. Therefore, conformed to the actual properties of the constant temperature zone and the cooling effect better, an insulation layer was covered on the model and the conjunction. By dimensionless analysis it can be obtained that the water cooling rate TV and rock heating rate Tb are 0.28 °C (m s)−1 and 0.06 °C·min−1, respectively. The initial temperature, peak temperature, sag temperature and stable temperature of the water flow in the borehole obtained by similar experiments and simulations are similar. The temperature change curves of all measuring points shared similar tendency. This thesis provides a reliable reference for the application of the constant temperature zone in deep gushing water cooling recycling in Xiadian gold mine.

There are many influencing factors for deep thermal environment, which will interact with each other. The analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) are introduced to construct the evaluation model. Based on the comprehensive evaluation of the underground heat source and its thermal contribution rate, some suggestions on thermal stress control are put forward. The results showed that the average thermal contribution rates of surrounding rock, air self-compression, equipment, and personnel were 56.28%, 27.44%, 15.23% and 1.04%, respectively. SSD and HSI (heat stress index) of −652 m and deep workface are far higher than the maximum heat overload tolerated by human body. The nine evaluation indexes show that the degree of heat stress increases significantly with the increasing of depth. Among them, temperature, surrounding rock heat release and dress sensitivity are the main influencing factors of thermal environment evaluation. The severity of thermal stress was determined by comparing the difference in standard score and standard deep thermal environment parameters. Therefore, corresponding cooling technology is adopted to provide a new approach for deep thermal environment treatment. Keywords: Deep thermal environment, Thermal contribution rate, AHP, FCE, Index system

In order to obtain the impact factors of hydration heat of cemented tailings backfill, different evaluation indexes were selected and analyzed. The results showed that the hydration of cement was violent in the early stage of reaction. The heat release increased with the increasing of the cement-sand ratio and the slurry concentration. In the middle and late stage of the reaction, the hydration heat was mainly generated by the hydration of the cement, and the heat release increased with the increasing of the dosage of cemented powder. According to the probability statistics, 13 evaluation indexes were selected, among which the evaluation index called slurry concentration > cement-sand ratio > dosage of cemented powder occurred for 9 times. Nine evaluation results were analyzed and screened to obtain the highest and lowest heat production levels. The optimization of evaluation index is of great significance to reduce the hydration heat of filling and optimize the mixture ratio as well as improve the deep thermal environment. Keywords: Cemented tailings backfill, Hydration heat, Evaluation index, Dosage of cemented powder, Cement-sand ratio, Slurry concentration

For the high-temperature thermal hazards faced by deep underground engineering, it is proposed that water flow borehole with corresponding specifications and quantities were arranged in the constant temperature zone to form a borehole network. Water in deep underground engineering was led to the borehole network for cooling and recycling. The reasonable spacing of boreholes was studied by using ANSYS FLUENT to achieve an optimal cooling effect. The results show that the main factors influencing the cooling of the constant temperature zone in Xiadian gold mine are water velocity v, borehole diameter Ф, borehole length L and rock thermal conductivity λ. The optimal parameters are water velocity v = 0.5 m/s, borehole diameter Ф = 80 mm, borehole length L = 40 m and rock thermal conductivity λ = 4.1 W (m °C)−1. According to the optimal solution, the maximum temperature influence radius in the cooling process is r = 0.5 m. When the distance between any two boreholes is 2.5 times the maximum temperature influencing radius, that is 1.25 m, the temperature variations between boreholes will not affect each other. Cooling effect is good and layout area of the borehole network is small. It makes full use of existing resources, and provides a reliable reference for energy conservation and consumption reduction. Keywords: Constant temperature zone, Deep gushing water, Water velocity, Borehole diameter, Borehole length, Rock thermal conductivity

As museums usually target large numbers of visitors with great diversities, it is important for museum professionals to have a well-rounded understanding of the visitors as well as an approach to categorize them so that curation strategies can be applied accordingly and effectiveness achieved. This article presents a study of the exhibition “Dippy Returns” at the Natural History Museum in London. By performing on-site observation, we categorized visitors-by their movements and interactions with the exhibits-into four types: Horse Riders, Treasure Hunters, Picky Eaters, and Deep Divers. We also interviewed a curator of the exhibition to understand intended visitor experiences from the museum’s perspective. We believe that the categorization can help museum professionals better understand on-site visitor behaviors from the perspectives of both interactions and movement, which responds to the trend for museum exhibitions nowadays to deploy a diversity of activities and more flexible visiting routes. The categorization could serve as a common language that curators and designers can use to communicate their expectations and improve visitor experiences with exhibitions. [ABSTRACT FROM AUTHOR]

In the context of exploiting extensive recoverable coal reserves situated beneath buildings, water bodies, and railways, the application of paste backfill mining has gained prominence. This study addresses the unique requirements of mines characterized by substantial mining heights and the need for long-distance slurry transportation. It focuses on optimizing the composition of paste backfill materials suitable for such demanding conditions. Investigations indicate that increasing the slurry concentration to 79% optimally balances various factors: it reduces the slump degree and bleeding rate while enhancing the material's strength and reducing the setting time. Similarly, an optimal 7% incorporation of cementitious materials into the backfill composition is identified. This proportion not only augments the backfill body's strength and the slurry's slump degree but also minimizes the bleeding rate and shortens both the initial and final setting times. Such a composition ensures efficient transportation performance, effective control over the overlying rock strata and surface movement, and facilitates the extensive disposal of mine-related solid waste. This study underscores the criticality of precise backfill material formulation in ensuring structural stability and environmental sustainability in mining operations. [ABSTRACT FROM AUTHOR]