In situ leaching (ISL) uranium mining involves intricate multi-scale dynamics spanning nine orders of magnitude, multi-physics coupling among hydraulic, transport, chemical, thermal, and mechanical fields, as well as strong nonlinearity arising from dissolution-precipitation feedback. This review systematically examines recent advances in three fundamental aspects of ISL uranium mining: characterization and evolution of porous media structures, multi-physics coupling mechanisms, and numerical simulation of reactive transport processes. Methodologies for pore structure characterization are outlined, dual fractal characteristics and their relationships with permeability are analyzed, and mechanisms governing pore evolution including dissolution-precipitation competition, particle migration, clay swelling, and gas blockage are elucidated. Seepage theories for multiple flow regimes are reviewed, reactive transport coupling models integrating five physical fields are examined, and reaction kinetics including rate laws, Arrhenius temperature dependence, and sorption models are summarized with dimensionless parameters characterizing dominant transport mechanisms. Multi-scale modeling approaches from pore-scale to field-scale are compared, major simulation platforms are evaluated with model selection criteria, and cross-scale correlation techniques including the embedded multi-scale method are discussed. Additionally, emerging applications of artificial intelligence technologies including machine learning surrogates, deep learning, physics-informed neural networks, and digital twins are highlighted for process optimization and environmental monitoring. Finally, key technical challenges and future research directions are identified.

Deep geological disposal repositories are regarded as the most effective and feasible solution for nuclear waste disposal. During the long-term storage process, the surrounding rock in the repository is exposed to high temperatures and hydrochemical environment of varying pH. To study the combined deterioration effect of high temperature and chemical corrosion on the mechanical properties of the surrounding rock of the disposal repository, this paper investigated the physical and mechanical properties of granite after high-temperature damage and chemical salt solutions treatment through uniaxial compression and AE experiments. A statistical damage constitutive model considering the combined initial damage due to heat and chemical effects and micro-element fracture damage during loading was established. At the same time, AE energy was introduced to characterize the damage degree. The results show that high temperature and the action of chemical salt solutions lead to a significant decrease in the quality and wave velocity of granite, as well as a reduction in the crystallinity of the minerals and a tendency for the crystalline structure to become looser. This results in a weakening of the brittle characteristics in the macroscopic mechanical properties of granite. High temperatures and chemical salt solutions reduce the compressive strength and elastic modulus of granite. 400 °C is the threshold for the effect of temperature. When the temperature effect exceeds 400 °C, the compressive strength of the rock drops sharply, and the rock failure changes from brittle deformation to plastic deformation. The established damage constitutive model can effectively describe the failure process of granite under axial loading after thermal-chemical damage. The theoretical stress–strain curve of the model is in good agreement with the experimental curve in terms of the trend, which verifies the validity and applicability of the model.

Pore clogging during acid leaching is a major factor limiting the leaching efficiency of uranium-bearing sandstone. However, the influence of suspended particles on pore structure evolution and clogging behavior during acid-rock interactions remains unclear. In this study, acid leaching experiments were conducted and analyzed using multiple techniques to monitor mineral composition changes, pore structure evolution, ion concentration dynamics, and the size distribution of suspended particles throughout the leaching process. These analyses elucidated pore-scale structural evolution and clarified the dominant mechanisms of pore clogging. Results showed that acid leaching progressively dissolved minerals in uranium-bearing sandstone, resulting in the formation of detached mineral fragments and newly formed solid particles. Simultaneously, dissolved species accumulated in the leachate, and partial recombination of ions resulted in the formation of secondary precipitates. The newly formed solid phases, detached mineral fragments, and reprecipitated materials, primarily composed of quartz, kaolinite, illite, and chlorite, existed as suspended particles that migrated with the leachate. When particle diameters became comparable to the dimensions of pores and throats, particles accumulated, resulting in bridge clogging and partially or completely blocking flow pathways. Under slow-flow conditions, dissolved and reprecipitated minerals deposited on pore surfaces, causing membrane clogging that further impeded percolation of the leachate. This study provides a theoretical basis for understanding pore clogging during acid-rock interactions and offers valuable guidance for optimizing declogging strategies in leaching to enhance uranium recovery.

Thermal and mechanical damage tests and uniaxial cyclic loading-unloading tests are conducted to investigate the effect of damage degree and temperature on the mechanical behaviour of sandstone under cyclic loading. The failure characteristics are analysed via acoustic emission (AE) monitoring and particle-flow code (PFC) simulations. The results indicate that the rock mass strength first increases and then decreases. The peak strain of samples increases with temperature, thus enhancing their ductility. The residual strain decreases gradually as the number of cycles increases. Additionally, the AE signal becomes more active with increasing temperature. The peak-frequency density ranges primarily between 100 and 200 kHz and shows a distinct discontinuity during cyclic loading. Shear failure predominantly occurs during the cyclic stage, whereas tensile failure is more common during the fracturing stage. The proportion of shear cracks increases with the damage degree. The simulation results show that stress reduction is typically accompanied by a rapid increase in the number of cracks. The failure process is dominated by tensile cracks, and the crack distribution angle is approximately 90 degrees. AE events are concentrated near the sample boundary, and the frequency distribution is approximately normal as the magnitude changes. The change trend of the b-value is consistent with that of the peak strength.

The damping ratio of rocks is essential for evaluating rock mass stability under dynamic loads. This study investigates energy evolution and damping characteristics through single cyclic loading–unloading uniaxial compression tests and acoustic emission (AE) monitoring on sandstone and granite, considering stress history. A strong linear relationship between cumulative AE energy and cumulative damage energy validates the theory of viscoelastic-plastic energy conversion in rocks. Additionally, the study discovered the linear energy damping (LED) law, characterized by a consistent linear relationship between damping energy and input energy, and a constant linear energy damping coefficient (LEDC) defined by linear fitting parameter A. Based on the LED law, two damping ratio calculation formulas ( λ_LED,i = (A_2 u_i + B_2 )/π (A_1 u_i + B_1 ) , λ_I - LED = A_2 /π A_1 ) were proposed. The results showed that the LED law enables the calculation of damping strain energy density at peak strength. The LEDC serves as an effective parameter for characterizing the damping capacity of various rock types λ_LED,i represents the evolution curve of the damping ratio, while λ_I - LED provides accurate estimates of the damping ratio at peak strength compared to traditional methods and reflects reliable stability. Stress history significantly affects the linear energy storage law fitting parameter B and the |B/A|. The research findings offer a novel method for calculating the energy relationship and damping ratio under ultimate stress states, enhancing the reliability of geotechnical engineering designs, and reducing disaster risks.

This study investigates the influence of built-in studs on the bond behavior in recycled aggregate concrete-filled steel tube (RACFST) composite structures through push-out experiments. The effects of stud number, position, and rows on RACFST bond strength and steel tube surface strain are systematically analyzed. Furthermore, the bond-slip behavior evolution mechanism is examined, and a constitutive equation is established. A novel interfacial modeling approach is developed via secondary development of ABAQUS software to comprehensively simulate RACFST interfacial bond-slip behavior. The results demonstrate that insufficient stud quantity compromises interface integrity, reducing bond strength, while increased stud count enhances composite stiffness and bond performance. Studs positioned nearer the free end extend the natural bond length participating in shear resistance, thereby improving bond strength. Internal studs promote stress redistribution within the composite structure, significantly improving collaborative performance. The proposed constitutive equation shows good agreement with experimental results, and the developed interface program accurately captures bond-slip curve trends. These findings facilitate RACFST applications and provide guidance for shear stud arrangement in RACFST structures.

To investigate the influence of pore structure evolution under physicochemical reaction stimulation on the variation of seepage pressure gradient in percolation systems. The study conducted seepage experiments under three different flow rates, employing computed tomography scanning to characterize sandstone samples during leaching. The relationship between pressure gradient and migration capacity of the leaching solution was established through the pore radius and fractal dimension obtained after three-dimensional reconstruction. The results indicated that minerals in sandstone were continuously dissolved and eroded during leaching, and the number of pores and throats increased with the leaching time. The pores were predominantly sub-nanoscale pores with a small proportion of micrometer-scale pores, while the throats mainly consisted of sub-nanoscale and nanoscale throats. The proportions of micrometer-scale pores, sub-nanoscale pores, and nanoscale pores were different under different flow rates, while throat channel distributions within the same range differed. Sandstone exhibited more effective leaching at flow rate of 0.8 ml/min, with the number of pores and throats increasing and the radius also expanding over time. Furthermore, the pore fractal dimension (Df) of sandstone increased with permeability enhancement, whereas the tortuosity fractal dimension (Dt) decreased with permeability increase. Based on reconstructed pore parameters, a predictive model correlating pressure gradient with mobility coefficient of leaching solution was established using mechanical equilibrium and fractal theory, demonstrating satisfactory model performance. The research provided a theoretical foundation for real-time adjustment of injection pressure based on pressure gradient monitoring when encountering pore clogging during leaching, offering significant practical implications for improving leaching efficiency.

In the case where tunnel anchor bolts are located in strata with limited surrounding rock boundaries, the response signals of the anchor bolts are affected by the tensile load and the transverse inertia effect, resulting in a decrease in the reliability of the non-destructive testing (NDT) results. To accurately assess the anchorage quality under these disturbances, a vibration energy loss model for anchor bolts after excitation was proposed. NDT experiments and numerical simulation studies were conducted on intact and defective anchor bolts under different conditions, analyzing the variation patterns of structural dynamic characteristics such as the first-order natural frequency, the first-order damping ratio, and the vibration energy loss under the influence of tensile load and transverse inertia effect. The results show that during the gradual increase of the tensile load, the first-order natural frequency first increases and then decreases; the first-order damping ratio exhibits an overall trend of an initial slight decline, followed by an increase, and then a subsequent decrease; and the rate of energy loss initially decreases and then increases. The presence of anchorage defects leads to a reduction in the first-order natural frequency, the first-order damping ratio, and the energy loss of the anchor bolt. As the transverse inertia effect intensifies, the first-order natural frequency initially increases and then decreases, the first-order damping ratio decreases, and the energy loss initially decreases slightly before increasing. The numerical simulation verifies the applicability of the theoretical model and explores the influence of defect location on energy loss. The results indicate that the closer the defect location is to the free end, the less the vibration energy loss of the anchor bolt.

Deep rock engineering (such as geothermal exploration, underground energy storage, radioactive waste storage) is often affected by external disturbances and high temperatures. Through characteristic stress identification, acoustic emission (AE) monitoring and numerical simulation, the deformation and fracture processes and degree of thermal-mechanical damaged sandstone are studied, and a simulation method considering thermal strengthening is proposed based on the two-dimensional particle flow code (PFC2D). The results show that: The axial peak strain of the sample shows fluctuations below 450 degrees C as temperature increases, and is followed by a rapid rise, whereas Poisson's ratio, after reaching its maximum at 150 degrees C, gradually decreases. With the increase of damage degree, the mean values of 6cc/6f and 6ci/6f first decrease and then increase, while the mean values of 6cd/6f have the opposite trend. With the increase of temperature, 6ci/6f of sandstone increases, while 6cd/6f remains at a certain level and fluctuates or decreases. Although the frequency band distribution and quantities of different rock samples are different, the frequency band number and the density within the frequency band have sudden changes before the samples are destroyed. The simulation results indicate that the porosity shows stress sensitivity and intergranular cracking dominates the failure process. The experimental and PFC simulation results agree well in terms of peak stress, failure mode and crack distribution, which verifies the applicability of the proposed thermal strengthening model.

Mineral dissolution and erosion during the leaching of uranium-bearing sandstone have profound effects on the evolution of pore structure and uranium leaching rate. X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) techniques were used to characterise mineral changes and pore structure evolution in samples. The results indicate that during the in situ leaching process, feldspar was transformed into clay minerals and quartz. Dolomite and calcite completely dissolved and formed a large amount of Ca2+, which increased the content of CaSO4. The CaSO4 and MgSiO3 precipitated particles formed in the reaction blocked the pores or migrated with the leaching solution, and the porosity of the sandstone initially decreased and then increased. Furthermore, the pores were divided into micropores, mesopores, and macropores, and combined with NMR fractal theory, it was found that the pore structure of sandstone exhibited multifractal characteristics. The obtained pore fractal dimension had a positive correlation with quartz, dolomite, calcite, and feldspar contents, whereas the other mineral components showed a negative correlation. This study provides a theoretical reference for understanding the mechanism of pore plugging and optimising the deplugging process in acid leaching for uranium extraction.

Cyclic disturbance has a significant effect on rock stability. It is very important to study the nonlinear behavior and failure precursor law of rock to evaluate stability and predict rock mass behavior. In this paper, uniaxial and cyclic loading and unloading experiments of three stress paths were carried out on sandstone and granite, alongside acoustic emission (AE) monitoring. Based on the maximum likelihood estimation method and least square method, the self-organized critical characteristics and AE b-value characteristics of rocks under different stress paths were studied and the nonlinear characteristics and failure precursor laws of rocks were explored according to the AE information before and after the critical point in the process of rock fracture evolution. The sudden change point of AE marks the precursor of self-organized critical behavior of rock from steady state to unsteady state, and the self-organization evolution of rock micro-cracks is affected by high energy AE events. The self-organized collapse phenomenon exists in the whole process of rock failure, from low energy collapse at the beginning to high energy collapse, and the scale gradually increases. The critical point is the region where b-value drops rapidly to the minimum value before failure and the region where b-value starts to fall before failure is the precursor characteristic region. As an important parameter of rock failure and collapse effect, b-value shows nonlinear dynamic behavior of spontaneous evolution, which is closely related to the self-organized critical behavior of rock failure.

Thermal–mechanical damage is an important problem threatening the safety of deep rock engineering. In this paper, the effects of coupling damage on the deformation and failure characteristics of rock mass were studied via cyclic loading damage, thermal damage and uniaxial compression acoustic emission (AE) tests, and the microscopic fracture process of the damaged rock mass was numerically simulated. Results showed that during heat treatment, the colour of the sample changed significantly, the mass, the P-wave velocity and the number of mineral species decreased. The peak strength and elastic modulus reach their maximum values at 600 °C and 300 °C, respectively, exhibiting a trend of initial increase and subsequent decrease. The rapid growth period of AE activity increased noticeably with increasing temperature, and the effect of energy accumulation became more significant at higher peak strengths. The failure mode was influenced primarily by the cyclic loading amplitude. In addition, an increase in the stress or temperature after crack initiation leads to a sharp increase in the damage within the rock. Temperature had a more significant effect on the generation of damage than stress. Stress-induced microcracks were concentrated in the weakly bonded particles, whilst temperature-induced microcracks were concentrated in the strongly bonded particles.

When the surrounding rock of tunnel anchor bars has boundaries, the signals obtained from non-destructive testing (NDT) of anchor rods will be simultaneously affected by size effects and pull-out loads, leading to potential misinterpretation of the test results. In order to accurately assess the anchorage quality of anchor rods under this interference, NDT and numerical simulations of anchor rods subjected to different anchorage quality were conducted under the influence of size effects and pull-out loads. A signal filtering method, which combines the infinite impulse response-finite difference method, was proposed for identify the impact of size effects. The study analyzed the variations in wave velocity and fundamental frequency of anchor rods with anchorage defects and intact anchor rods under the influence of size effects and pull-out loads. The results indicate that the IIR-FDM method, in comparison to the traditional wavelet method, provides better agreement between the calculated wave velocities and existing findings. With the increase of size effect, the wave velocity and amplitude ratio of the anchor rods decrease, and the fundamental frequency increases first and then decreases. As the working load on the anchor rods increases, the wave velocity initially decreases, then rises, while the fundamental frequency initially increases and then experiences a slight decrease. The presence of anchorage defect results in an increase in the wave velocity and amplitude ratio of the anchor rods, while causing a decrease in the fundamental frequency. This effect of defects on wave velocity and fundamental frequency is more pronounced at lower loads. The wave velocity after IIR-FDM processing has a small error with the simulated wave velocity, indicating the reliability of the processing method.

A series of numerical simulations of oblique-jet impinging onto concave walls are carried out to gain insight into the formation process of the liquid fuel film in a liquid film cooling thrust chamber. Moreover, the influence of jet and wall surface parameters on spreading the fuel film is investigated. The volume-of-fluid method is employed to capture the spreading process of liquid film formation after an oblique jet impacts the curved surface. Furthermore, the neural network model is developed to analyze the effects of jet diameter (0.2 mm <= d <= 0.6 mm), jet velocity (15 m/s <= v <= 20 m/s), impingement angle (15 degrees <=beta <= 30 degrees), equilibrium contact angle (45 degrees <=theta e <= 75 degrees), curvature radius (22.5 mm <= R <= 67.5 mm), and surface roughness (3.2 mu m <= Ra <= 16 mu m) on the fuel film's spreading length and maximum width based on Radial Basis Function. The results show that the liquid fuel film gradually stabilizes from upstream to downstream during spreading and the circumferential spreading of the liquid film is at its greatest when all the forces in the circumferential direction are in equilibrium. The jet diameter has the most significant effect on film spreading among jet parameters. Doubling the jet diameter at least doubles the film width and length. The effect of jet angle and velocity on film spreading is also magnified at larger jet diameters. Compared to other surface parameters, a change in the wall contact angle has the most marked effect on the spreading of the film. Lastly, the wall radius of curvature between 40 mm and 50 mm is more favorable for obtaining larger film lengths.

A protective scheme of quantum dense coding and quantum teleportation of the X-type initial state is proposed in amplitude damping noisy channel with memory using weak measurement and measurement reversal. Compared with the noisy channel without memory, the memory factor improves both the capacity of quantum dense coding and the fidelity of the quantum teleportation to a certain extent for the given damping coefficient. Although the memory factor can inhibit decoherence in some degree, it cannot eliminate it completely. In order to further overcome the influence of the damping coefficient, the weak measurement protective scheme is proposed, which found that the capacity and the fidelity can be efficiently improved by adjusting weak measurement parameter. Another practical conclusion is that, among the three initial states, the weak measurement protective scheme has the best protective effect on the Bell-state in terms of the capacity and the fidelity. For the channel with no memory and full memory, the channel capacity of quantum dense coding reaches two and the fidelity of quantum teleportation reaches one for the bit system; the Bell system can recover the initial state completely with a certain probability. It can be seen that the entanglement of the system can be well protected by the weak measurement scheme, which provides a good support for the realization of quantum communication.

In order to study the deformation and failure characteristics of rocks under different cyclic loading and unloading paths, three stress path tests were conducted, and acoustic emission (AE) monitoring was conducted simultaneously. The mechanical characteristics and AE characteristics under different stress paths were analyzed, and the influences of the different stress paths on the energy dissipation and deformation damage were investigated. The law of energy evolution considering viscoelasticity under different stress paths was obtained. The concept of ultimate damage energy and its calculation method was proposed. The results show that the "hardening effect" of sandstone and granite under the constant lower limit (CLLCL) is the most significant in maximizing the mechanical property. The CLLCL imparts a stronger elastic property to rocks than the variable lower limit (VLLCL) does, while the VLLCL causes more damage to rocks than the CLLCL. A significant linear relationship between the proportion of damage energy and the proportion of elastic energy was discovered. Based on this linear relationship, the ultimate damage energy can be calculated for sandstone and granite. The evolution of the damage variable based on damage energy was compatible with the real damage condition, which validates the ultimate damage energy calculation method. The research results lay a theoretical foundation for the design and construction of geotechnical engineering.

Smart distribution networks (SDNs) can integrate the flexible resources from source-network-load-storage (SNLS) to cope with the fluctuation due to a high proportion of distributed generation (DG). However, such SNLS resources are characterized by complex coupling relationships; their control authority may belong to different stakeholders. Challenged by the above, the laminar flow structure from the communication field is introduced for distributed optimal dispatching in SDNs. A day-ahead laminar dispatching method considering the effective interaction of SNLS resources is proposed. First, the applicability of the laminar flow structure is analyzed. An upper-layer dispatching model for the SDN and a lower-layer dispatching model for users with DG are established. Then, by introducing intermediate variables, the lower dispatching model is transformed into a quadratic programming problem and the upper dispatching model is transformed into a second-order cone relaxation programming problem. Selecting the tie-line power flow as the exchanged information in the boundary, the upper- and lower-layer models are alternately solved until the convergence criterion is met. Finally, an improved IEEE 33-bus system is experimentally analyzed. We find that the SNLS flexible resource dispatching scheme can be obtained with only a few iterations, and the DG consumption can be significantly improved.

氢氧火箭发动机燃烧室壁面热环境十分恶劣,头部气膜冷却是主要辅助冷却手段之一,圆孔头部气膜冷却是重要的设计方案.对圆孔型头部气膜进行了三维数值仿真研究,考虑推力室外部再生冷却的影响,通过全面数值实验分析了气膜流量占比、气膜孔直径和相邻气膜孔面积比等参数的影响,提出一种非均匀分布的圆孔头部气膜冷却方案.结果表明,在氢氧火箭发动机圆孔头部气膜冷却中,存在一个最佳吹风比使得头部区域冷却效果最好,最佳吹风比的值由气膜流量占比和气膜孔直径共同决定,最佳吹风比介于5.454～5.849之间;通过合理的非均匀圆孔气膜结构设计,控制相邻气膜孔面积比在0.6～0.8范围内,采用提出的非均匀气膜孔方案有利于提高燃烧室的整体性能.

The investigation of the failure mechanism is essential for the application of thermal barrier coating in the thrust chamber of liquid rocket engines. In this work, a four-layer thermal barrier coating system in a typical regeneratively-cooled thrust chamber was simulated by finite element method, and the interface morphology between layers was represented by an ideal cosinusoidal curve. A thermo-structural analysis, the boundary conditions of which were calculated by a fluid-thermal coupling method, was carried out to study the influence of the interface roughness and thermally grown oxide on the temperature and stress distributions under thermal cycles. Elasto-plastic deformation and creep behavior were also taken into consideration. The computed results reveal that the roughness parameters including interface amplitude and wavelength as well as the thermally grown oxide thickness have limited effects on the temperature distribution in the thrust chamber wall, but a significant impact on the residual stress distribution in thermal barrier coatings. As these parameters grow, the magnitude of residual stress generally increases, meanwhile, the dangerous regions transform in a complicated way. Much attention should be paid to the interface of thermal barrier coatings in thrust chambers.

The interferometric synthetic aperture radar (InSAR)-aided inertial navigation system (INS) is developed to introduce terrain elevation into registration, which gives out the accumulated error of INS. Unwrapped InSAR interferogram plays a key role in previous InSAR/INS frameworks, while airborne and side-looking assumptions are usually made. However, phase unwrapping is time-consuming, and high squint geometry with nonlinear trajectory is common for applications with InSAR/INS. In this article, a novel wrapped InSAR interferogram-based positioning method for the high-speed maneuverable platform is proposed. A novel back-projection-based InSAR (BP-InSAR) signal model for a slightly curved diving trajectory with a high squint angle is first presented. Then, the process that generates a phase gradient template from a given DEM is presented, considering both the estimated and measured trajectories. Error analysis is also made to discuss the performance of the proposed method in single dual-channel observation. Finally, a sequential maximum likelihood estimator based on error analysis is implemented to deal with the remained uncertainty in a single observation. Numerical experiments verify the proposed method and fully demonstrate its performance with curved trajectory and random errors in both position and attitude.