The moss Sphagnum (peat moss) is ecologically and economically important. There is a paucity of physiological and developmental studies on Sphagnum because of the lack of an axenic culture system for its whole life cycle. A culture system has been established for the Sphagnum gametophore, but not the protonema (juvenile vegetative stage after spore germination). Therefore, the aim of this study was to develop a protonema culture system for Sphagnum. Sphagnum squarrosum gametophore tissue was disrupted and then cultured in liquid Knop medium. The regeneration of protonemata from the gametophore fragments was analyzed in detail by microscopy. We observed a developmental balance between filamentous and thalloid protonemata, and growth competition between the thalloid protonema and the gametophore. On the basis of these findings, we established a relatively stable peat moss protonema proliferation method. Using this method, all the developmental stages of peat moss vegetative growth could be obtained through differentiation or regeneration. The method can provide abundant homogeneous Sphagnum materials at desired stages for physiological and developmental studies, and will be useful for large-scale Sphagnum vegetative proliferation. The regeneration analysis method will be useful for establishing protonema proliferation systems for other mosses.

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Open pit mines have a direct impact on the production efficiency and sustainable development of the enterprise by realm optimization. In the case of changing mining technology conditions and market demand, the original design realm of the mine needs to be optimized in time for the study. Therefore, based on the slope stability analysis, this paper changes the slope angle by changing the working platform size and step and section, and forms a total of four Programs I, II, III, and IV. Geostudio software was utilized to analyze the slope stability of four scenarios and obtain the slope safety coefficients under different scenarios, and the results show that Programs I, II, and III all meet the requirements of reasonable safety coefficients. Furthermore, the geological model of the slope in C profile in Program III was constructed, and the changes of slope stress and displacement during the step-by-step excavation process were analyzed, with a maximum of stress 3.5 MPa, total displacement 12.9 cm, shear should be incremental, plastic zone change is small, and the results showed that the slope structure parameters of Program III were reasonable. The geological drilling data of Jiguanshan molybdenum mine was processed with 3DMine software, the geological database was constructed, the ore body model was established, and the mine boundary optimization study was conducted, Program III was finally determined as the optimal option. The result of the boundary optimization improves the final slope angle by 1°, which can enable the mine to extract 13.334 million tons more ore, reduce the stripping ratio to 1.07m3/m3, and generate economic benefits of $116 million.

In order to reveal the instability law of open pit mine slope in high-cold and high-altitude area. Firstly, the slope structural plane is scanned by three-dimensional (3D) laser scanning technology, and the point cloud data is obtained to realize the intelligent identification of rock mass structural plane. The geometric parameters of rock mass are counted, and the physical structure model is established. Then, we carry out freeze-thaw cyclic tests on granite to obtain the corresponding mechanical parameters. Finally, according to the obtained mechanical parameters, we use RS2 finite element software to calculate the shear strength of structural plane and joint by generalized Hoek-Brown criterion and Barton-Bandis criterion, respectively, establish the geomechanical model, and use the finite element strength reduction method to calculate the safety factor of slope and judge the instability of slope. The results show that the physical and mechanical properties of granite deteriorate with the increase of the freeze-thaw cycle. Under the action of the freeze-thaw cycle, the pore water in the rock mass freezes and forms frost heaving force. The expansion of volume leads to the further development of joint fissures. The strength of rock slope decreases gradually with the increase of freeze-thaw cycle times, and the safety factor of slope decreases continuously. It shows that repeated freeze and thaw alternation makes the stability of mine slope worse and worse. The research results are helpful to prevent the occurrence of slope disasters in advance and are of great significance to effectively and safely manage the stability of slope, the treatment of open pit, and environmental treatment.

Due to the lack of relevant investigation research on the evolution of mining stress in high stope of metal mines, the understanding of how to ensure the safety during mining process is not clear at all. In this paper, by monitoring the mining-induced pressure of the surrounding rock in the 16-2# stope of Lilou Iron Mine, the evolution of the mining-induced pressure of the subsequent filling and mining method of the high-stage empty field is obtained. The study shows that there are three stages of pressure change in the second-step stope of Lilou Iron Mine: I (stress rising stage), II (stable stage), and III (pressure relief stage), and the mining stress in the surrounding rock is transferred from the top to bottom. The stress transfer model of stope is proposed, and the variation of vertical stress versus the depth is fitted; the four horizontal sections are fitted, respectively. By establishing the three-dimensional numerical model and distributed excavation simulation, the time-space evolution of mining stress is obtained and compared with the in-site measuring result. The two results show high consistency, and the effectiveness of numerical simulation is verified.

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