This work conducted laboratory tests considering the coupled freeze–thaw (FT) and variable‐frequency–variable‐amplitude cyclic loads on granite containing two fissures and a circular hole. The analysis is dedicated to reveal the deformation and energy rate characteristics. Testing results show that increasing FT cycle and loading level both accelerate rock damage. The rock subjecting to high FT cycle behaves much larger damage rate in terms of volumetric strain and dissipated energy. The warning strength is defined according to the volumetric strain rate and dissipated energy rate which can early issue a warning than the crack damage stress point. In addition, the rock instability precursor is proposed by monitoring the incremental rate of the radial strain and volumetric strain; drastic damage occurs when the volumetric rate exceeds the radial rate. Three typical crack coalescence modes of double shear coalescence, single shear coalescence, and single tensile coalescence were revealed.
The instability of rock mass induced by the deterioration and failure of rock bridge is often encountered in hard rock engineering. Under engineering disturbance, a steep and gentle stepped sliding surface is prone to forming along the rock bridges between the intermittent rock joints, which directly controls the rock mass instability modes. In order to reveal the influence of fissure angle on the fatigue deterioration and energy evolution mechanism of stepped double-flawed hard rock, the multilevel cyclic loading mechanical test were carried out on flawed marble samples with fissure angle of 10°, 30°, 50°, and 70° angles. The testing shows that rock strength, fatigue lifetime, peak strain and dissipated energy increase with increasing fissure angle and the increase rate of them becomes sharply in the high cyclic level. In addition, the increase of dissipated energy accelerates with the increase of cyclic loading level, and shows a sudden increase trend in the last cyclic loading stage. When the joint fissure angle is 10°, the dissipated energy is the smallest and the dissipated energy is the largest at 70°. Moreover, a damage evolution model based on dissipated energy is established to describe the characteristics of damage accumulation. The model is in good agreement with the experimental data and reflects the nonlinear characteristics of damage accumulation.
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.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.