For San-Xin gold and copper mine, deep blasting large block rate is high resulting in difficulty in transporting the ore out; secondary blasting not only increases blasting costs but is more likely to cause the top and bottom plate of the underground to become loose causing safety hazards. Based on the research background of Sanxin gold and copper mine, deep hole blasting parameters were determined by single-hole, variable-hole pitch, and oblique hole blasting tests, further using the inversion method to determine the optimal deep hole blasting parameters. Meanwhile, the PSO-BP neural network method was used to predict the block rate in deep hole blasting. The results of the study showed that the optimal minimum resistance line was 1.24–1.44 m, which was lower than 1.6–1.8 m in the original blasting design, which was one of the reasons for the higher blasting block rate. In addition, the PSO-BP deep hole blasting fragmentation prediction model predicts the block rate of the optimized blasting parameters and predicted a block rate of 6.83% after the optimization of hole network parameters. Its prediction accuracy is high, and the blasting parameter optimization can effectively reduce the block rate. It can reasonably reduce the rate of large pieces produced by blasting, improve blasting efficiency, and save blasting costs for enterprises. The result has wide applicability and can provide solutions for underground mines that also have problems with blasting large block rate.

As environmental requirements become more stringent, the liquid carbon dioxide blasting system is one of the non-explosive blasting technologies that, with low tensile stress energy, will replace the chemical explosive blasting technology, and the impact pressure characteristic of high-pressure fluid is a crucial factor in the process of rock breaking. To further investigate the impact and pressure attenuation characteristics of high-pressure fluid during the phase transition of liquid carbon dioxide blasting system, the pressure curves of high-pressure fluid in liquid carbon dioxide blasting systems at different distances were measured in the laboratory. Based on the mechanism analysis of phase transition kinetics, the initial jet velocity of the four experiments was calculated, and the rationality of results was verified by the Bernoulli equation. The general expression of the positive phase pressure–time function was proposed, and the idealized impact pressure curve can be divided into five stages. The impact pressure field of the liquid carbon dioxide blasting system can be divided into three areas at different distances: the explosive jet impact zone, the jet edge zone and the shock wave action zone, and the pressure–contrast distance fitting equation of the liquid carbon dioxide blasting system were obtained.

Decision-making is very important in many fields, such as mining engineering. In addition, there has been a growth of computer applications in all fields, especially mining operations. One of these application fields is mine design and the selection of suitable mining methods, and computer applications can help mine engineers to decide upon and choose more satisfactory methods. The selection of mining methods depends on the rock-layer specification. All rock characteristics should be classified in terms of technical and economic concerns related to mining rock specifications, such as mechanical and physical properties, and evaluated according to their weights and ratings. Methodologically, in this study, the criteria considered in the University of British Columbia (UBC) method were used as references to establish general criteria. These criteria consist of general shape, ore thickness, ore plunge, and grade distribution, in addition to the rock quality designation (ore zone, hanging wall, and foot wall) and rock substance strength (ore zone, hanging wall, and foot wall). The technique for order of preference by similarity to ideal solution (TOPSIS) was adopted, and an improved TOPSIS method was developed based on experimental testing and checked by means of the application of cascade forward backpropagation neural networks in mining method selection. The results provide indicators that decision makers can use to choose between different mining methods based on the total points given to all ore properties. The best mining method is cut and fill stopping, with a rank of 0.70, and the second is top slicing, with a rank of 0.67.

A carbon dioxide (CO₂) blasting system is a reusable non-explosive blasting product that can be used in many engineering applications. To investigate the influences of thermodynamic properties of liquid CO₂ and its explosion energy during the phase transition, the pressure within the blasting tube was measured in a laboratory for a liquid CO₂ blasting system. Based on the measured pressure curve, the CO₂ blasting process can be divided into three stages: pressure rising stage, pressure release stage and pressure recovery stage. The evolutions of temperature, pressure, phase transition and explosion energy of the CO₂ blasting system were analysed in detail in this work. The results show that the variation rate of temperature increases as the initial density of CO₂ decreases. The effect of initial CO₂ density on its isochoric heat capacity is also significant as the lower the initial density, the higher the peak specific heat capacity at the critical temperature. Based on the Span and Wagner CO₂ equation of state and the thermodynamics of explosions, a method is proposed to calculate the explosion energy of CO₂ blasting systems. This method produces more accurate and realistic results.

The ornamental stones industry has grown progressively in Egypt as the demand has increased for Egyptian decorative stones in indoor and outdoor building spaces. Choosing the most suitable ornamental stone for each purpose and taking the right decisions related to aesthetic and practical performance can be a challenge causing a lot of confusion for homeowners and contractors. Thus, there is a need to define what decorative style you are trying to achieve in order to properly choose the most suitable decorative stone. In this research, some Egyptian ornamental stones were evaluated by combining the analytic hierarchy process (AHP) and the technique for order preference by similarity to ideal solution (TOPSIS). The optimized AHP–TOPSIS comprehensive decision model was implemented on natural materials relevant to ornaments and the finishing purposes of indoor and outdoor buildings. Ten rock types from four Egyptian sites were studied, examined, and analyzed. According to the quality index scheme, grey granite is an ideal ornamental stone that meets indoor and outdoor purposes. Grey granite and black marble have a performance score (Pi) of 0.78 and 0.71, respectively. Serpentine and pink granite were ranked third with a Pi = 0.68. These results provide stakeholders with strategic indicators to select different natural ornamental stones based on the total points assigned to all rock specifications and costs.

Carbonate building materials and engineering constructions are exposed to severe seasonal environmental fluctuations and result in a full or partial disintegration, especially in cold regions, and employment of nondestructive methods for evaluating the durability of building materials subject to frost weathering is gaining great significance. This research aims to obtain reliable relationships between unconfined compressive strength decrease and nondestructive parameters variations of limestone types under frost conditions and provide useful information regarding their durability in order to ensure the long-term viability or sustainability of these materials used for constructions against frost conditions. In this study, five important types of Chinese limestone used as construction materials were subjected to 50 frost cycles. Unconfined compressive strength, compressional wave velocity and spatial attenuation, and porosity were obtained at the end of every 10 cycles. As a result of progression in frost cycles, the increase and decrease rates were determined at the end of every 10 cycles, and the relationships between them were obtained to predict the loss ratios of unconfined compressive strength (RDσc). Results indicated that at the end of 40th cycles, there was a high correlation between RDσc and spatial attenuation loss with an R² of 0.8584. Furthermore, there was also a strong relationship between RDσc and compressional wave velocity decrease after the end of 20th and 50th cycles with an R² of 0.9089 and 0.9025, respectively. Therefore, these relations are reliable to provide useful information for durability and viability of studied samples under frost conditions and support the use of the ultrasonic measurements. It can also be successfully used for pre-estimation of unconfined compressive strength loss of studied limestone types against frost weathering without any tests.