High pressure mechanics has set off a great wave of interdisciplinary researches among materials science and geosciences, providing solutions for the synthesis of novel materials with high challenge, improvement of mechanical properties of materials, and understanding of the seismic anisotropy and geodynamics in the inner of the Earth. Here we have reviewed recent research progress in high pressure mechanics, which includes diamond anvil cell combined with X-ray diffraction in a radial geometry, rotational diamond anvil cell induced shear strain, high pressure torsion-imposed shear strain, D-DIA induced plastic deformation and shock compression induced plastic deformation. These findings show the unique coupling effect of compression constraint and shear stress on tuning the structure, properties and mechanical behavior of materials, revealing the value and potential of high-pressure mechanics in research and application.

The pressure required for the metallization of solid hydrogen exceeds 400 GPa, thereby presenting a formidable challenge for its experimental preparation and characterization. Here, we systematically explore the structures and properties undergone by solid hydrogen under non-hydrostatic pressure conditions by first-principle calculations. Our findings reveal that solid molecular hydrogen can retain good structural stability under non-hydrostatic pressure conditions, which induces symmetry breaking and charge redistribution within the solid hydrogen lattice, facilitating the transformation of solid molecular hydrogen into metallic and superconducting states at lower pressures (e.g., pressures are lower than 300 GPa). This study proposes a new idea of introducing an anisotropic non-hydrostatic pressure environment for achieving metallic hydrogen at lower pressure.

Tellurium-based double perovskites offer the advantages of exceptional photoelectric properties, adjustable band gaps, and environmental friendliness, rendering them a promising class of light-absorbing materials. To further fine-tune the relevant attributes of these double perovskites, a comprehensive investigation of the structural-property relationship was conducted using a high-pressure diamond anvil cell (DAC) within in-situ high-pressure measurements. In this study, a representative tellurium-based double perovskite, Cs₂TeBr₆, was carefully investigated. The experimental findings reveal a notable structural transformation within the Cs₂TeBr₆ crystal lattice, transitioning from a cubic phase ($Fm \overline 3 m $) to a tetragonal phase (P4/mnc) in the pressure range of 0−51.0 GPa, which could be attributed to the tilting of the pressure-induced octahedron $\rm {TeBr}_6^{4-} $. Meanwhile, it is observed that the band gap of Cs₂TeBr₆ diminishes with increasing pressure under high pressure, exhibiting a turning point at approximately 14.0 GPa, coinciding with the onset of the structural phase transition. These findings contribute significantly to establishing the intricate correlation between the crystal structure and optical properties of Cs₂TeBr₆, thereby furnishing a valuable reference for precisely modulating the properties of tellurium-based perovskites.

The dynamic behavior of materials at mesoscales under intense dynamic shock loading has always been the research focus of dynamic compression science. Unfortunately, for a long time, due to the lack of in-situ dynamic multi-scale diagnostics, the progress has been slow. The emergence of advanced X-ray light sources typified by synchrotron radiation provides revolutionary opportunities and challenges for this problem. Significant breakthroughs have been made recently in terms of dynamic plastic deformation, damage failure, solid-solid and solid-liquid phase transitions of materials under shock loading. This paper focuses on the research progress of in-situ dynamic diagnostics based on synchrotrons and its applications, and briefly introduces the characteristics of synchrotron radiation light source, the combination with dynamic loading device, the development of related simulation calculation methods and the application of typical scientific problems from the perspective of physical requirements.

Ice giants such as Uranus and Neptune are numerous in the universe. Understanding the internal structure and local reaction processes of ice giants is of great significance for establishing a unified planetary evolution system. In recent decades, with the continuous development of simulation methods and experimental driving as well as diagnostic techniques, breakthroughs have been made in multiple physical problems related to the interior of ice giants, such as “superionic water” and “diamond rain”, which are no longer unpredictable. Starting from the physical issues related to ice giants, this article briefly introduces and discusses the theoretical and experimental research progress in high-pressure equations of state and microscopic physical processes under extreme conditions, as well as the development of related experimental platforms and supporting technologies. It also proposes prospects for the future direction of this field.

The effect of pressure on the glass transition temperature and the supercooled liquid region of amorphous selenium (a-Se), which was prepared through melting quenching, was investigated. The glass transition temperature $ {T}_{\text{g}} $ and crystallization temperature T_x were determined through the differential thermal analysis (DTA) during isobaric heating. The experimental results from piston-cylinder apparatus showed that both $ {T}_{\text{g}} $ and T_x increase with the increasing pressure in the pressure range of 0.1－1700 MPa. The glass transition middle temperatures $ {T}_{1/2,\text{g}} $ and extrapolated crystallization onset temperatures T_el,x were linearly fitted to pressure. The fitting results are ${T}_{1/2,\text{g}}\left(p\right)=322+0.046\,2p$ and ${T}_{\mathrm{e}\mathrm{l},x}\left(p\right)=398+0.030\,2p$, where the unit of temperature is K, and the unit of pressure is MPa. The smaller slope of T_el,x(p), compared with that of $ {T}_{1/2,\text{g}} $(p), induces the temperature range (T_el,x−$ {T}_{1/2,\text{g}} $) in the supercooled liquid region to be narrower with the increase of pressure. DTA data in the pressure range of 2000−4500 MPa was performed by using a cubic press. A slope change in T_x(p) curve is found. T_x increases with the increasing pressure within 0.1−1700 MPa, and the rate slows down when the pressure is above 2000 MPa. In the previous diamond anvil reports, a similar pressure dependence of T_x and T_g was observed, i.e., T_x and T_g both increase initially with the increasing pressure, and then become nearly constant above 1000 MPa. Since the slope changes in T_g(p) and T_x(p) curves occur nearly at the same pressure when the microstructure of a-Se changes, in view of the pressure of 2000 MPa corresponding to the inflection point of T_x(p) curve obtained in this study, it is speculated that the pressure of the inflection point of T_g(p) curve may be around 2000 MPa. The different pressures corresponding to the slope change obtained by the diamond anvil cell and the large-volume press may be related to the measurement method of T_g and T_x, as well as the pressure measurement error.

Carbon fibre reinforced composites have an important role in rail transportation, aerospace and other fields due to their excellent properties such as lightweight and high strength. However, as a surface structure material for high-altitude vehicles, carbon fibre reinforced composites suffer from mechanical property degradation and icing in low-temperature environments, which seriously affect their service safety. In this paper, a “carbon fibre-hand-torn steel” composite is designed using unidirectional carbon fibre prepreg and stainless steel ultra-thin belts, i.e. hand-torn steel, as the raw material, and a lay-up curing method is used to design a “carbon fibre-hand-torn steel” composite consisting of hand-torn steel with different cut shapes and carbon fibre lay-up. It is shown that the hand-torn steel not only improves the mechanical properties by improving the internal stress distribution of the composite, but also enables the temperature regulation of the composite due to the current-driven thermal effect of the hand-torn steel, which further improves the material strength and energy absorption properties. In addition, the cutting width of the hand-torn steel has an important influence on the regulation of the current path and its thermogenic effect, which is a key factor in optimizing the mechanical properties and de-icing function of the material. This paper provides guidance on the mechanical design and current-driven de-icing of carbon fibre-hand-torn steel composites, and is expected to have important applications in aerospace and other fields.

In order to study the dynamic response of the structure under explosion load in negative pressure environment, the negative pressure explosion experiments were carried out for the fixed supported steel plate, which is as a simplified unit of the protection project. The deformation law, and the ultimate strain and failure conditions of the fixed supported steel plate under different negative pressures were analyzed. The numerical simulation of the dynamic response of the fixed supported steel plate under negative pressure explosion load was carried out by AUTODYN, and the accuracy of the numerical simulation results was verified by comparing the experimental results. The results show that when the initial ambient pressure decreases, for the same burst distance, both the maximum deflection and the maximum velocity at the center point of the steel plate decrease. Under the negative pressure explosion load, the steel plate produces large plastic deformation, the oncoming surface forms a pit, and obvious tensile deformation occurs at the edges perpendicular to the boundary direction. The deflection changes in the edge zone are basically the same, and the maximum deflection at the center point decreases with the decrease of environment pressure. Through the bidirectional strain assumption, the dynamic limit strain of the steel plate is determined to be 0.269. The reflectance specific impulse formula of explosive blast wave under negative pressure environment was established, and the failure criterion based on rigid-plastic hypothesis and energy criterion were examined. The research results can provide a reference for the equivalent evaluation of the shock wave power of explosive air in negative pressure environment and the target damage assessment in plateau environment.

To further reveal the crack propagation law and failure characteristics of fissured sandstone with different moisture states, the uniaxial compression tests of steeply dipping fissured sandstone were carried out with different moisture states of dry, natural, and saturated. Acoustic emission (AE) and digital image correlation (DIC) techniques were used to analyze the effects of moisture state on the mechanical properties, AE characteristics, and crack evolution characteristics of fissured sandstone. The results show that water has a significant deterioration effect on the compressive strength, elastic modulus and peak strain of the fissured sandstone, and the mechanical parameters show a nearly linear decreasing trend as moisture content increases. The macroscopic failure mode of the fissured sandstone all exhibits H-type tensile-shear mixed failure under different moisture states, and the tensile cracks gradually increase with increasing moisture content, the secondary cracks also propagate mainly in the form of tensile cracks. As moisture content increases, the AE energy counts of fissured sandstone weaken gradually, the cumulative energy curve presents obvious stage characteristics and its distribution characteristics vary significantly with the moisture state. The combination of AE and DIC analysis methods is helpful to reveal the crack evolution law of fissured sandstone from the macro-meso perspective. The crack initiation and propagation orientation can be effectively predicted according to the strain localization zone, and the increase in moisture content speeds up the crack initiation rate and slows down the crack propagation rate in the later stage of loading. The results of micro-crack analysis based on the AE parameters are basically consistent with the macroscopic failure mode. The effect of moisture state on tensile and shear cracks in fissured sandstone varies significantly, with increasing moisture content promoting the development of tensile cracks and thereby inhibiting the development of shear cracks. The research results can provide a reference for the stability evaluation and monitoring of fissured rock under the effect of water.

Conventional explosions are accompanied by significant electromagnetic effects, which can interfere with explosion testing and also serve as a non-contact means of testing explosion shock waves. The study of explosive electromagnetic effects has important engineering application value. A measurement system composed of an oscilloscope, antennas, and a high-speed camera was used to conduct 5 sets of electromagnetic radiation measurement experiments, whose testing object is 100 or 200 g RDX. The experiment recorded electromagnetic radiation signals with 2 ms, and analyzed the electromagnetic radiation generated by RDX explosion. The experimental results showed that the RDX explosive electromagnetic radiation signal mainly consists of three periods: a typical peak at 30 μs with strong repeatability, subsequent peaks with strong repeatability in the same group but poor repeatability in different groups during 30−200 μs, and a pulse signal without obvious repeatability after 200 μs. Combined with high-speed imaging of the explosion, it’s found that there has been a strong correlation between the explosive electromagnetic radiation and the state of detonation products. The typical peak and subsequent peaks are mainly signals generated by the ionization of the explosive products during the violent reaction in the pre-explosion stage. By using the antenna factor to invert the electric field strength curve, the relationship between the explosive equivalent, distance, and electric field strength was analyzed. It’s found that at the same explosive equivalent, the electric field intensity of typical peak decreases exponentially with distance. At the same distance, the electric field intensity of typical peak generated by a 200 g explosion is greater than that of a 100 g explosion.

The uniaxial compressive strength of cemented paste backfill (CPB), as an important indicator of their mechanical properties, is usually determined by traditional mechanical tests. In the proposed model, the whale optimization algorithm (WOA) with global optimization capacity was used to tune the hyperparameters of the extreme gradient boosting (XGBoost) model. Taking the 80 sets of data obtained from the filling slurry ratio test of a lead-zinc mine as the database, the solid mass fraction, cement content, tailings content as well as curing age, were selected as input variables and the uniaxial compressive strength of the filling body as an output variable. XGBoost, random forest (RF) and WOA-RF models were constructed to compare with the WOA-XGBoost model. The results indicates that the hybrid WOA-XGBoost model (Its determination coefficient is 0.965 0, the root mean square error is 0.207 4, and the mean absolute error is 0.170 3) performs rather better than the individual XGBoost model (Its determination coefficient is 0.897 1, the root mean square error is 0.408 4, and the mean absolute error is 0.246 7). Compared with other models, the WOA-XGBoost model exhibits the highest prediction accuracy, contributing to the design and ratio optimization of cemented paste backfill materials.

To investigate the alumina ceramics’ crack evolution process under impact loading, a numerical simulation of dynamic Brazilian splitting for platform disc ceramics was carried out by the discrete element method. The discrete element particle flow software was adopted to establish the numerical simulation model of ceramic specimens in impact loading experiments. The crack evolution process and failure mode of specimens with different inclination angles (the angle between the prefabricated crack and the loading direction) under impact loading were analyzed. Combined with the stress field distribution at the tip of mixed mode crack, the initiation and propagation laws of wing crack were analyzed. The results show that the cracks in the platform disc specimen are produced in the center firstly, then the secondary cracks sprouted and expanded from the disc edge. The specimen finally shows a tensile damage pattern. The results of the discrete element simulations are consistent with the experimental phenomena of dynamic Brazilian splitting based on the SHPB device. When the inclination angle of the prefabricated crack is 0°～60°, changing the inclination angle can produce a mixed crack mode between type Ⅰ crack and type Ⅱ crack. And the main crack on the specimen is nucleated from the tip of the prefabricated crack and exhibits a winged crack extension type (the curvature of the extension tapers to zero). With the increase of the inclination angle of the prefabricated crack, the crack initiation angle increases, and the crack initiation stress shows a trend of decreasing firstly and then increasing. The specimens are most susceptible to cracking when the prefabricated crack inclination is 30°.

Through numerical simulation, the relation between the crack propagation during deep rock blasting and the decoupling charge coefficient under the conditions of in-situ stress or not was studied. The simulation results showed that the initial ground stress has a great influence on the generation and the propagation of blasting cracks. The radius of the crushing zone, the radius of the crack zone, the maximum length of radial crack propagation, and the peak stress of the blast hole wall all decrease with the increase of the decoupling coefficient. According to the radial crack propagation lengths under different decoupling coefficients obtained by dynamic caustic similarity test, a relation between the radial crack propagation length and the decoupling coefficient was established, and the degree of fit reaches 0.974. During the process of deep rock blasting excavation, the blasting parameters can be designed according to the relation between the radial crack propagation length and the decoupling coefficient, so as to realize high efficiency blasting mining. This study provides some reference for the background of deep mining.

To investigate the effect of hexamethylenetetramine content on the performance of ammonium-amine explosives, five groups of ammonium-amine explosives were prepared using hexamethylenetetramine with mass fractions of 5.5%, 6.5%, 7.5%, 8.5% and 9.5%. The cross-linking time, detonation velocity and thermal decomposition process of ammonium-amine explosives were studied by means of viscosity analyzer, chronograph, detonation velocity tester and thermal analysis techniques. The results show that when the mass fraction of hexamethylenetetramine increases from 5.5% to 9.5%, the cross-linking speed of ammonium-amine explosive gradually slows down and the cross-linking time gradually increases from 7 h to 13 h, and the detonation velocity of explosive increases firstly from 3552 m/s to 4070 m/s and then decreases to 3663 m/s. The content of hexamethylenetetramine has insignificant effect on the thermal decomposition process of ammonium-amine explosives. With increasing content of hexamethylenetetramine, the apparent activation energy of ammonium-amine explosive increases from 93.71 kJ/mol to 124.71 kJ/mol, and the thermal stability is improved.

In this paper, the interaction between 2H₂+O₂+nAr gas-phase detonation waves with different reactivities and cylindrical obstacles was investigated by experiments. Piezoelectric pressure sensors were flushed-mounted on the top wall of the channel to record pressure time histories, from which the detonation wave velocities were calculated. The schlieren technology and smoked foil technique were used to record the wave system and cellular structure of the whole process from detonation failure to re-initiation. The results show that the detonation wave will be reflected when it touches the obstacle, and diffraction will occur downstream of the obstacle after crossing the obstacle. When the detonation wave crosses the obstacle, it is attenuated and decoupled by the expansion wave at the tail of the obstacle, but Mach reflection occurs as the diffraction shock wave bypassing both sides of the cylindrical obstacle collides at the rear axis of the obstacle and the central axis of the channel, and Mach reflection occurs when the incident shock collides with the downstream channel wall, completing the re-initiation process. The obstacles with smaller diameters cause less energy loss of the detonation wave, and the re-initiation distances of the cell detonation wave shorten with the decrease of the diameters of the obstacles. The experimental results of obstacles of different diameters show that with the increase of initial pressure, the reactivity of the premixed gas increases and the stability of self-sustaining detonation increases, thereby weakening the influence of the geometric size of the obstacles, which is conducive to weakening the attenuation of detonation and shortening the re-initiation distance. Under the geometric dimensions of the obstacles experimented in this paper, the detonation re-initiation distance was measured, and the relationship of re-initiation distance of 2H₂+O₂ after the cylindrical obstacle under different dilution ratios of Ar was established with the cylindrical vertical spacing and cell size.

In order to ensure the safety and stability of sand-mudstone interbedded rock slope under blasting vibration, it is necessary to clarify the attenuation law of blasting vibration in sand-mudstone interbedded rock slope. Based on the first-stage project of Pinglu Canal Youth Hub, through the field blasting test, the fitting results of the blasting vibration attenuation model before and after the elevation effect correction were compared and analyzed, and the blasting vibration attenuation law of the sand-mudstone interbedded rock slope was deeply studied. The results show that the maximum displacement of slope rock mass under blasting vibration produces elevation amplification effect, and the final displacement may not be zero. The fitting accuracy of a blasting vibration attenuation model considering the elevation effect is higher than that of the unmodified Sadoevsky formula, and the elevation effect should be considered in the blasting vibration attenuation law of rock slope. There are differences in the attenuation law of blasting vibration for the sand-mudstone interbedded rock slope with different tendency and dip angles of beddings. It is an important research direction to establish the attenuation law of blasting vibration for different beddings.

The blasting load generated by the blasting excavation of the tunnel has an impact on the adjacent building structure. In order to study the influence of the blasting excavation of the post-construction tunnel on the adjacent tunnel, this paper takes the E60 highway tunnel in Georgia as the engineering background. Through the numerical simulation of the blasting excavation of the large-section shallow-buried double-track tunnel, the influence of the blasting load on the vibration velocity of the adjacent tunnel with different tunnel spacing, tunnel buried depths and surrounding rock grades was explored. The results showed that the blasting load propagated from the tunnel face of the later construction tunnel to the surrounding rock, and the vibration velocity of the surrounding rock reaches the maximum value at the 5 m section in front of the adjacent tunnel from the blasting source. The vibration velocity in front of the adjacent tunnel from the blasting source is greater than that behind it. In addition, the vibration velocity of the facing-blasting side of the adjacent tunnel is much larger than that of the back-blasting side, and the attenuation rate of the vibration velocity of the facing-blasting side is greater than that of the back-blasting side, in which the arch waist of the adjacent tunnel is most obviously affected by the blasting load. The maximum vibration velocity of the surrounding rock of the adjacent tunnel is in the x-direction, followed by the z-direction and the minimum in the y-direction. Under different conditions, the tunnel spacing, tunnel burial depth and surrounding rock grade are inversely proportional to the vibration velocity of the surrounding rock and initial support of the adjacent tunnel, in which different rock level on the adjacent tunnel blasting effect is the most significant.

Tunnel structures in service usually have initial cracking damage, which can affect the tunnel structure when exposed to explosive. In this paper, the secondary damage and response law of the subway tunnel with crack under explosion were simulated by using the material point method with multistage background grid. Under the explosion, the initial crack damage causes a decrease of the stiffness of the lining structure, and increases the damage range of the tunnel floor by 34.2% at the track zone. Besides, the initial crack accelerates the damage speed of the tunnel structure. The depth and length of the initial crack damage significantly alter the dynamic response of the tunnel structure and surrounding rock. The secondary damage area of the track floor increases linearly with the crack depth. When the crack depth reaches half of the lining thickness, the equivalent plastic strain peak increases the fastest. Moreover, the secondary damage area at the track floor, the peak plastic strain, and the peak displacement of the surrounding rock, all increase with the lining crack length, but the growth rate slows down gradually.