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Based on the measured data of sandstone mudstone interbedded rock mass in the Three Gorges Reservoir area, the soft-hard interbedded rock samples were made. Under uniaxial compression, the effects of different static loading rates on the mechanical and acoustic emission characteristics of rock samples with different thickness ratios and different rock formation combinations were explored. The results show that the loading rate and the volume ratio of hard and soft rock are the main factors affecting the peak strength, while the loading rate and the thickness ratio of hard and soft rock are the main factors affecting the final failure characteristics. On the one hand, with the increase of loading rate, the peak strength of the soft-hard interbedded rocks decreases first and then increases; The proportion of hard rock is positively correlated with the compressive strength of rock samples. On the other hand, the ultimate failure mode of rock samples at low loading rate is complete failure of materials, and at high loading rate, 1～2 main fracture surfaces penetrating soft and hard rock layers are finally formed. The less the volume proportion of soft rock, the more severe the damage to soft rock. In addition, the sudden increase of AF value and the sudden decrease of b value can be taken as early warning signals of large-scale damage of the soft-hard interbedded rock mass. [ABSTRACT FROM AUTHOR]

Failure characteristics of the coal seam floor above-confined aquifer are key to evaluating the water inrush risk from the floor in the deep mining. At present, based on the analysis of water inrush impact indicators, mathematical evaluation methods are often used to evaluate the water inrush risk of a mining floor. This study proposes a theoretical risk assessment method for water inrush from the floor considering the failure characteristics of the coal seam floor above-confined aquifer. The 11301# coalface in the Wanglou colliery, Shandong Province, is considered as a case study. The mechanical model of the mining floor stress along the coalface inclination direction was established, and the analytical solutions of the vertical, horizontal, and shear stress and floor failure depth were derived. The floor failure mode along the coalface inclination direction is similar to the letter "lying flat-B" and the maximum and minimum failure depth is around 13 and 6 m. Furthermore, the dynamic failure characteristics of the floor during coal mining were simulated. Subsequently, the thickness of the floor key aquiclude was determined and the water inrush coefficient exhibits a certain trend from increasing to becoming stable in the mining process, that is, from 0.05 to 0.08 MPa/m. The analytical solution of the critical water pressure for floor aquiclude failure was derived based on the limit equilibrium theory. That is, the ultimate water pressure 3.9 MPa is greater than the actual water pressure 2 MPa, and there is no floor water inrush risk. Taking these into account, the water inrush risk of the mining floor above-confined aquifer was comprehensively analyzed and evaluated. The findings were deemed to be consistent with the actual mining case. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Joined fractures are an important factor affecting natural rock masses’ mechanical and deformation properties. In this paper, indoor uniaxial compression experiments reproduce prefabricated cracks’ generation, extension, and coalescence in rock-like specimens. For the fractured specimens, a single crack with an inclination of α = 45° was placed on the left and right sides, and a third crack with an angle of β = 30°, 45°, 60°, and 90° to the single crack on the right side was placed in groups III–VI, respectively. All cracks extended in the thickness direction. Vertical pressure was applied at a constant loading rate of v = 0.1 mm/min until the stress dropped dramatically. In addition, numerical calculations were performed on the rock specimens using PFC2D, a sub-module of the Discrete Element Method (DEM). The experimental results agree with the numerical simulations in that the strength of the specimens containing a conjugate crack is significantly reduced, and the mechanical and deformation properties of the specimens are related to the internal angle of the conjugate crack, with the lowest peak strength and lowest percentage energy dissipation at β = 45°.

In order to investigate the energy evolution and failure characteristics of carbonaceous shale containing single fissure under drying−wetting cycles, the intact carbonaceous shale samples and the carbonaceous shale samples with fissure angles of 30°, 45° and 60° were prepared. MTS815 rock mechanics test system was used to conduct triaxial compression tests under different drying−wetting cycles. The influence of drying−wetting cycles on the strength, failure mode and energy evolution of single fissure carbonaceous shale were studied. The results show that the elastic energy and dissipated energy at crack initiation stress, damage stress and peak stress present exponential relationships with drying-wetting cycles. The elastic energy and dissipated energy at crack initiation stress and dissipated energy at damage stress are less sensitive to drying−wetting cycle, while the sensitivities of elastic energy at damage stress, and elastic energy and dissipated energy at peak stress are relatively high. The failure mode of carbonaceous shale is dominated by drying−wetting cycle and fissure angle, in which the drying-wetting cycle is the main controlling factor, and the fissure angle is the secondary controlling factor. It is found that tensile shear failure occurs in dry rock sample with fissure angle of 30°, while the dry rock sample with fissure angle of 45°and 60° are subjected to shear failure. With the increase of the number of drying−wetting cycles, the macroscopic length of the main crack increases, the density of secondary cracks increases, and the failure mode transforms to shear-tension composite failure. With the increase of the number of drying−wetting cycles, the energy storage level at crack initiation stress Kci and the energy storage level at damage stress Kcd increase gradually. The higher the energy storage level at crack initiation and damage stress, the more likely the crack initiation and rock damage occur. Kcd can be used as a warning indicator of rock failure. A larger Kcd indicates that the rock is more vulnerable to failure.

In deep rock engineering, evaluating the likelihood of rock burst is imperative to ensure safety. This study proposes a new metric, the post-peak dissipated energy index, which accounts for strain rate and size effects in assessment of the rock burst proneness of a rock mass. To investigate rock burst proneness, conventional compression tests were conducted on limestone and slate samples with different length to diameter (L/D) ratios (ranging from 0.3 to 1.5) at four different strain rates (0.005, 0.01, 0.5, and 1.0 s−1). Based on the testing observations, the actual rock burst proneness was classified into three categories (no risk, low risk, and high risk). A new criterion was also established using the post-peak dissipated energy index, which is the ratio of elastic energy to total dissipated energy. The impact of the strain rate and L/D ratio on rock burst proneness was analyzed. The results indicated that increased strain rates cause a strong hardening effect, leading to staged growth of rock burst proneness. However, the rock burst proneness decreases non-linearly with the increasing L/D ratio. The accuracy of the proposed criterion was validated by comparison with existing criteria, demonstrating that the energy-based index ensures a reliable evaluation of the rock burst proneness of a rock mass. The proposed method has excellent potential for practical application in deep rock engineering.

Under the action of dissolution, rock masses form solution fissure leading to changes in their internal structure, which in turn affect their engineering mechanical properties and failure characteristics. Karst rock masses usually have a significant impact on the stability of tunnel surrounding rocks in karst stratum. This article utilizes digital image processing technology and particle flow discrete element method to numerically reconstruct calculation models of limestone with different degree of dissolution. A series of uniaxial compression discrete element numerical experiments were conducted on karst limestone with different degree of dissolution, analyzing the stress-strain relationship, mechanical parameters, failure modes, and energy changes of limestone with different degree of dissolution. Research results indicated the following: (1) The karst limestone model constructed based on digital image processing technology can effectively characterize the dissolution features of karst limestone, and numerical simulation experiments can effectively characterize the mechanical behavior of karst limestone. (2) As the degree of dissolution increases, the stress-strain curve of karst limestone gradually exhibits bimodal or multimodal characteristics, and the uniaxial compressive strength of karst limestone shows an exponential decrease trend, while the elastic modulus shows a linear decrease trend. (3) Under high degree of dissolution, the existence of pore structure causes the stress skeleton inside the karst limestone to be damaged, and the number of shear and tensile cracks is continuously decreasing. The distribution of internal force chains is dispersed, making the karst limestone more prone to failure. (4) During the process of karst limestone failure, most of the input total strain energy is first converted into elastic strain energy, and only a small portion is converted into dissipative strain energy. The increase in the degree of dissolution significantly reduces the total energy input and the storage limit of elastic strain energy during the uniaxial compression failure process of karst limestone, and increases the degree of strain energy dissipation.

Rocks are a typical kind of heterogeneous material composed of differences in size, shape, type, and mineral particle distribution. The strength and deformation characteristics of rocks are controlled by their internal heterogeneous structures. A numerical model was built to analyse the strength and failure characteristics of sandstone samples with randomly distributed heterogeneous. The results revealed that heterogeneous structures induce local stress concentrations and accelerate sample failure. At a loading rate of 0.01 mm/s, the mechanical properties of sandstone samples with soft heterogeneous particles are uniformly smaller than those of standard sandstone samples, while those of sandstone samples with hard heterogeneous particles follow different variation rules, depending on the specific heterogeneous particle content. With the differences between heterogeneous particles and sandstone particles in properties, an increase is observed in the mechanical properties of samples with different heterogeneous particle contents. Soft heterogeneous structures determine the crack initiation position of the main crack and the development and propagation space of cracks through their distribution pattern, while hard heterogeneous structures are load-bearing and change crack propagation paths. When there are multiple structures with different properties in rocks, micro-cracks occur first between soft heterogeneous particles, and the distribution pattern of soft heterogeneous particles determines the ultimate failure mode of samples as well as the propagation paths and development space of cracks. [ABSTRACT FROM AUTHOR]

Most of the previous studies focused on the mechanical characteristics before the stress peak of solid waste cemented backfill, but in the compression process of a solid waste cemented body, the phenomenon of post-peak stress rebound often occurs. Through the uniaxial compression experiment of a solid waste cemented body composed of coal gangue, fly ash, desulfurization gypsum, gasification slag, and furnace bottom slag, this paper analyzed the compression deformation characteristics of a solid waste cemented body with different mix proportions before and after the stress peak, established the stress–strain curve model of rebound stress in the rising and descending section after the stress peak, and revealed the reasons for the rebound stress and secondary unloading of the cemented body after the stress peak. The results showed that the maximum rebound stress accounts for 40%–80% of the compressive strength, and the changes in the two are positively correlated. The stress–strain curve model is a cubic function in the post-peak stress rising section and a quadratic rational function in the descending section. With the increase in the maximum compressive strength of the cemented body, its maximum rebound stress also increases, but its corresponding compressive strain generally shows a downward trend. There is a positive correlation between the rebound stress increment and strain increment of the cemented body. The change in the supporting structure and the evolution of the failure form of the cemented body before and after the maximum rebound stress indicate that the compression failure of the residual supporting structure caused by the main crack is the main reason for the rebound of the stress after the peak value of the cemented body to the complete unloading. [ABSTRACT FROM AUTHOR]

In the process of geothermal energy exploitation, granites undergo cyclic heating and water cooling due to the heat conduction from distant rock mass to the cooled rock. The mechanical response, deformation and acoustic emission (AE) characteristics of granite treated by cyclic heating (150–300 °C) and water cooling (1–15) under the coupling action of compressive and shear stress were analyzed by preset angle shear tests in three preset angles (45°, 55°, 65°) at macroscopic level. Given that the peak strength of granite shows an accelerating downward trend with the increase of heating temperature and cycle times. The cohesion of granite declines, and the internal friction angle increases in general. AE activities are active throughout the loading process, which shows ductile failure characteristics of granite obviously. The accumulative AE events decrease by 69.3% with increasing heating temperature (150–600 °C), and 82.4% with increasing cycle times (1–15). The crack initiation area gradually shifts from the two ends of sample to the middle area with the increasing thermal damage. Shear behaviors inside the granite start earlier and last for a longer period, which results in the complex fracture network distribution of turtle shape and the shearing failure of "Z" shape on the surface of 600-1 sample. Scanning electron microscopy (SEM) was conducted to reveal the microscopic mechanism of thermal damage. Given that the intergranular and transgranular cracks induced by the uneven expansion of particles connect with each other and form a complex crack network as the thermal damage increasing. The continuous heating with high temperature causes minerals to melt and deform, resulting in the decrease of bonding strength between particles. All above results can provide references for the analysis and prediction of rock stability of granite in Enhanced Geothermal Systems (EGS) project. [ABSTRACT FROM AUTHOR]

On October 5, 2021, a small-scale catastrophic loess landslide occurred in Niangniangba town, Tianshui City, Gansu Province in China. The landslide with a volume of approximately 15,360 m3 buried 2 houses and damaged another 2 houses. On the basis of field investigation, unmanned aerial vehicle photography, and numerical simulation, the characteristics and dynamic processes of the Zhongzhai landslide are analyzed, and the potential destructive zone of the unstable loess mass is preliminarily assessed. The Zhongzhai landslide is a typical rainfall–reactivated flow-type loess landslide, and its failure mode is creep-tensile type. The upper sliding mass is the typical retrogressive failure, and the lower sliding mass shows thrust load caused failure. The runout simulation results show that the entire sliding process of Zhongzhai landslide lasted for approximately 35 s, with a maximum velocity of 12 m/s. The maximum travel distance of the sliding mass is 130 m. In addition, the presence of masonry buildings has a great influence on the sliding distance. Simulation results of potential destructive zone of the unstable loess mass show that the travel distance of the unstable loess mass is approximately 250–295 m, the thickness of the deposited mass is approximately 2.7–3.3 m in the potential destructive zone, and the maximum velocity is 28 m/s. This work contributes to improving the understanding of evolution law, dynamic processes, and risk prevention of this kind of landslide in loess plateau areas. [ABSTRACT FROM AUTHOR]

Blasting tests on iron ore specimens with different stemming structures were carried out to quantify the internal fracture and damage characteristics of the specimens by means of computed tomography (CT) scanning, digital image processing and three-dimensional (3D) model reconstruction techniques. The results showed that the blasting load produced radial and circumferential cracks in the iron ore, mainly along the blast hole. Using the fractal theory to analyze the damage characteristics of the samples, the stemmed structure under blasting load produced more fractures than the unstemmed structure, with a maximum increase of 33.6% in internal damage. As the stemming material changed from weak (yellow clay) to strong (fine sand), the fractal dimension of the specimen spatial tended to increase after blasting, and the degree of damage increased, with the stemming of fine sand increasing the maximum damage to the three-dimensional spatial by 12.1% compared to yellow clay stemming. This further suggested that the strength of the stemming material was positively correlated with the size of the damage to the specimen. The damage characteristics of the different layers of iron ore specimens (surface, stemmed section, charged section) were consistent with those of the 3D spatial as a whole, with the smallest difference in damage to the charged section and the larger difference in damage to the stemmed section. In practical blasting projects, the findings of this paper are used to make full use of the explosive energy using a reasonable stemming structure to achieve better breakage results for iron ore. The research result is of great significance to engineering practice. Highlights: The experimental study on the damage characteristics of iron ore (real rock collected in the field) under blasting load with different stemming structures was successfully carried out by using special devices and advanced technologies such as CT scanning, 3D digital image processing, and 3D model reconstruction, revealing the crack expansion and breakage distribution law of iron ore under blasting load, laying the theoretical foundation for improving the blasting efficiency of metal mines. The 3D spatial reconstruction structure and 3D damage evaluation of the specimen revealed that the 3D spatial damage of the structure without stemming was at most 33.6% lower than that of the stemming structure; when the stemming length was the same, the fractal dimension and damage degree of the strong stemming material was larger than that of the weak stemming material. The resistance of stemming can improve the utilization rate of the energy released by the explosives, and give full play to the effect of the successive superposition of the explosive blast stress wave and the blast-generated gas on the expansion of the internal rock fissures, which make the internal rock crushing more adequate and more favorable to the distribution of breakage. After blasting iron ore specimens with different stemming structures, the damage and destruction characteristics of the specimens at different levels (surface, stemmed section, charged section) and the 3D spatial structure as a whole were the same, showing a small difference in the degree of damage and destruction of the charged section and a large difference in the degree of damage and destruction of the stemmed section. [ABSTRACT FROM AUTHOR]

In this study, the uniaxial compression test and the numerical simulation of the twodimensional particle flow code (PFC2D) were used to study the mechanical properties and failure laws of rock masses with parallel cracks. The experiment considers the influences of crack length (��º, crack angle (��1, ��2), and numerical changes in the rock bridge length (ℎ) and bridge angle (��) on failures of rock-like specimens. The results indicate that the uniaxial compressive strength (UCS) of the rock-like specimens with parallel cracks decreases with increasing �� under different �� values. The smaller angle between the preset crack and the loadinging direction (��) resulting in higher UCS. In addition, a larger ℎ results in higher UCS in the specimen. When ��1 or ��2 is fixed, the UCS and elastic modulus of the specimen show an ‘M’ shape with an increase in ��. Moreover, the crack growth or failure mode of samples with different �� values is similar. When ��1 or ��2 is small, the failure of the specimen is affected by the development and expansion of wing cracks. If one of ��1 and ��2 is large, the failure of the specimen is dominated by the expansion and development of the secondary cracks which is generated at the tip of the prefabricated crack. Furthermore, when the angle between the prefabricated crack and the loading direction is ��1 = 0°, the rock bridge is less likely to reach penetration failure as ℎ increases. Secondary crack connections between the prefabricated cracks occur only when �� is small. When �� ¡ 30°, the failure mode of the specimen is crack tip cracking which leads to penetration failure of the specimen, or the overall splitting failure.

Rockburst hazards exhibit different spatiotemporal characteristics in deep tunnel excavation. Failure characteristics and energy evolution process of delayed and instantaneous rockburst of basalt rock were investigated based on single-sided unloading experiments under true triaxial conditions. High-speed photography and acoustic emission (AE) monitoring were used, and computed tomography (CT) scanning, fractal theory, and crack classification were employed for failure analysis. A three-dimensional damage model considering variable stiffness of testing machine was established to calculate the energy evolution of rock-machine system during the entire process of rockbursts. Results show that delayed rockburst includes three stages of small particles ejection, rock slab buckling, and violent mixed ejection, while instantaneous rockburst is characterized by rock slab spalling accompanied with slight particles ejection. Delayed rockburst exhibits a progressive failure mode of large-scale expansion of tensile cracks (before failure) to small-scale penetration of shear cracks (upon failure), while instantaneous rockburst shows a large-scale shear failure and abrupt penetration of shear planes upon failure. Delayed rockburst consumes less energy, and most of dissipated energy is converted into kinetic energy of ejected rock fragments, causing a higher intensity level of rockburst; instantaneous rockburst consumes more energy, but almost all dissipated energy comes from internal friction energy of shear failure, causing a higher scale of rock damage. Before rockburst failure, elastic strain energy stored in rock remains basically unchanged, while the energy stored in testing machine continuously decreases, indicating that rockburst is triggered by energy release of loading system. Energy dissipation rate (EDR) can be used as a precursory index for rock failure induced by quasi-static loading such as delayed rockburst. High EDR means damage intensification, stress drop, active AE events, and acceleration of shear crack expansion inside the rock. The findings of this study can provide new perspectives for the mechanisms and early warning of rockbursts. • Delayed rockburst and instantaneous rockburst were reproduced in laboratory. • Basalt rockburst characteristics and its energy evolution process were revealed. • A damage model considering variable rigidness was used to calculate energy. • Energy dissipation rate can be used as a precursory index of delayed rockburst. [ABSTRACT FROM AUTHOR]

Dry–wet cycling has a significant impact on the mechanical properties of rocks, and a series of problems such as rock collapse can occur in rock masses under long-term dry–wet cycling. Based on this, some mechanical tests were carried out on sandstone under different dry–wet cycles to analyze the evolution law of its physical and mechanical parameters. The results show that the internal connection of the mineral becomes looser, the drying quality of the sample decreases, and the water absorption quality increases gradually under different dry–wet cycles. The peak strength of the sample decreases first and then increases with increasing dry–wet cycles. The change trend of the elastic modulus and deformation modulus with the increase in dry–wet cycles are similar to the peak strength, which is mainly related to the change in the connection between particles. Furthermore, the specimens showed axial tensile failure under uniaxial action. With the increase in dry–wet cycles, the tensile crack on the surface of the specimen increased, and the fracture of the specimen became looser. The specimen exhibited block spalling when the number of dry–wet cycles was eight times.

The mechanical properties of fractured rock have always been a focal point in the rock mechanics field. Based on previous research, this paper proposes improvements to the SPH method and applies it to the study of crack propagation in fractured rocks. By conducting uniaxial compression tests and simulating crack propagation on various specimens with different crack shapes, the characteristics of crack propagation were obtained. The comparison between the simulated results in this study and existing experimental and numerical simulation results confirms the validity of the SPH method employed in this paper. The present study utilizes the proposed methodology to analyze the influence of the crack angle, width, and orientation on crack propagation. The SPH method employed in this study effectively demonstrates the expansion process of fractured rock under uniaxial compression, providing valuable insights for the engineering applications of SPH.

For the sake of solving sustainability issues and analyzing the complicated service force states, eccentric compression experiments on self-compacting concrete-filled thin-walled medium-length steel tube columns with a circular cross-section were carried out in the present study. Thereafter, the influence of the eccentric ratios and the wall thickness factors on the mechanical behavior and failure characteristics of both the eccentrically loaded and axially loaded columns was comprehensively analyzed. Finally, prediction formulas for the ultimate load of the columns under eccentric compression were proposed, and a comprehensive comparison of the ultimate loads between the predicted values and experimental values was also conducted. The results indicated that the typical failure characteristics of the eccentrically loaded columns presented lateral deflection together with buckling, while the axially compressed columns displayed expansion and rupture at local positions. Moreover, the ultimate loads of the eccentrically loaded columns decreased by 43.0% and 34.5% in comparison to the columns under axial compression, with the wall thickness factor decreasing from 116.7 to 46.7, respectively. Meanwhile, the ratios of the ultimate loads calculated using design codes to the tested values were in the range of 0.70~0.90, which demonstrated that the design codes could predict the ultimate loads conservatively. Additionally, the ratios of the ultimate loads calculated using the proposed formulas to the tested values were within the range of 0.99~1.08, implying that the proposed formulas were more accurate than the design codes. At the same time, the initial stiffness of the columns under eccentric compression was correspondingly lower than that of the columns undergoing axial compression. The lateral deflections along the height of the columns were almost symmetrical at different loading levels. This study could provide a meaningful approach for designing columns and facilitate their application in civil industry.

This paper aims to study the influence of the goaf in the upper coal seam on the overlying ultra-thick coal seam and determine the dislocation distance in the roadway layout of the lower coal seam. Based on finite difference method, this research, takig Tashan Coal Mine as the engineering background, established Mohr-Coulomb and double yield constitutive models to invert the rock strata and the rock mass in the caving zone. The failure law of the ultra-thick coal seam under the influence of the overlying close goaf was studied on the basis of goaf and the residual coal pillar. In addition, the distribution law of stress field and the failure range in the coal seam under the goaf were clarified. With the theoretical analysis and the field borehole peep results, the reliability of the numerical method in this paper was verified, and the inner interlocked distance in the roadway layout of the lower coal seam was determined. The results show that the residual coal pillar has the greatest influence on the mining of the lower coal seam. The stress field under the residual coal pillar forms an approximate “normal trapezoid” influence range in the lower coal seam, with the width of the upper and lower being 32 m and 56 m respectively. The plastic zone under the residual coal pillar is distributed in an “inverted trapezoid” in the lower coal seam, and the width of the upper and lower is 81.36 m and 61.47 m, respectively. The inner interlocked distance of the roadways of the lower seam should be 13.5 m.

Frozen fractured rock mass is often encountered during the implementation of geotechnical engineering in cold regions. The tensile strength parameters of frozen rock play an important role in the construction of rock slopes involving tensile failure. In order to study the tensile characteristics of a frozen fractured rock mass in a cold region, original rock specimens were mined and processed in the Yulong Copper Mine, and artificial, frozen fractured marble specimens were made. The effects of different ice-filled crack angles, lengths, and widths on the force–displacement curve and the tensile strength of frozen rock were studied by laboratory Brazilian splitting experiments and RFPA3D, and the evolution law of the tensile strength of frozen rock was revealed. At the same time, wing crack initiation and cracking mode after tensile failure were analyzed by high-speed camera; the whole process of the Brazilian splitting of frozen rock was reconstructed, and the development of microcrack initiation in frozen rock was analyzed. The following conclusions were drawn from the test results: the frozen rock specimens have typical brittle-failure characteristics. The tensile strength of frozen rock decreases gradually with the increase in the width and length of ice-filled cracks, and decreases first and then increases with the increase in the angle of the ice-filled crack. The ice-filled crack incurs damage first, and then the wing cracks start from the tip of the ice-filled crack and extend continuously. The tensile strength of frozen rock is significantly affected by the angle and length of ice-filled cracks. [ABSTRACT FROM AUTHOR]

Many research results show that under any stress state the rock mass is most likely to crack, swell, bifurcate, and infiltrate from the fissure tip, resulting in rock engineering instability and failure. In order to study the influence of double fissure angles on rock mechanical characteristics, five rock numerical models with different fissure angles were established by numerical simulation software. Uniaxial compression tests were carried out, and the variation characteristics of rock stress, strain, failure, microcrack, and acoustic emission (AE) were recorded. The test results show that: With increases in the fissure angles, the elastic modulus of rock increased, while the peak strength decreased first and then increased. The number of microcracks in rock was greater at 15° and 75° than at other angles. The microcracks in rock were mainly tensile cracks, and relatively few were shear cracks. The angles of microcracks were mostly concentrated between 0 and 180°, most of which were between 60 and 110°. The failure of rock was relatively light when the fissure angle was15° or 75°, but it produced more and smaller fragments, and the failure was the most serious when the fissure angle was 30°. The angles of the fissures affected the maximum number of AE events, the strain values for the initial AE event, and the maximal AE event. This research can provide some reference for disasters caused by rocks with pre-existing fissures. [ABSTRACT FROM AUTHOR]

The civil light and small UAVs industry which brings convenience presents an explosive development, while its security problems increasingly prominent. In order to study the dynamic response characteristics, the possible internal short circuit, thermal runaway and fire laws of the lithium-ion batteries of light and small UAVs under strong impact, the tests of lithium-ion batteries of light and small UAVs under the drop-weight impact were carried out, and the impact loads, response modes, voltage and temperature changes under different impact energy were studied. Combined with the mechanical. comresponses and electrochemical performances of the batteries, the safety of the batteries for light and small UAVs were comprehensively analyzed. The results show that the battery cells mainly show three response modes after the impact. low energy impact mode; medium energy impact mode and high energy impact mode. There is a significant correlation between the changes of battery stiffness, battery voltage and impact energy. The battery voltage and impact energy influence each other and have strong coupling characteristics. There are no obvious coupling relationships between the state of charge(SOC) and the electrochemical performances of the batteries such as voltage drop law, trend and amplitude during the impact processes, but it has an important impact on the safety consequences such as fire and explosion of the battery after impact. [ABSTRACT FROM AUTHOR]

The present study explores the failure and surface characteristics of Glass Fiber-Reinforced Polymers (GFRP). Stepwise loading was applied in this study to understand the multi-static loading effect on the laminates before final failure. The loading was set three times to reach 10 kN with loading–unloading movement before final load until failure. The results showed that the angle of the GFRP UD laminates' position significantly impacts the system's failure. The results were analyzed using theoretical calculation experiment analysis, and then the failure sample was identified using ASTM D3039 standard failure. The laminates with 0° layer on edge ([0/90]S laminates) underwent preliminary failure before final failure. The mechanism of stepwise loading can be used to detect the effect of preliminary failure on the laminates. The [0/90]S laminates are subjected to stress concentration on the edge due to fiber alignment and discontinued fibers in the 0-degree direction. This fiber then fails due to debonding between the fiber and the matrix. The laminates' strength showed that [90/0]S specimens have an average higher strength with 334.45 MPa than the [0/90]S laminates with 227.8 MPa. For surface roughness, the value of Ra increases more than six times in the 0° direction and three times in the 90° direction. Moreover, shore D hardness showed that the hardness was decreased from 85.6 SD then decreased to 70.4 SD for [0/90]S and 65.9 SD for [90/0]S. The matrix debonding, layer delamination and fiber breakage were reported as the failure mode behavior of the laminates. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Stem cutting is the main process of broccoli harvesting, and the structure and mechanical properties of the stem significantly affect the cutting efficiency. In the current research, the structural characteristics and component contents of the broccoli stem are analyzed. Through different processing methods of stretching, compressing and bending, the aim is to obtain the parameters for mechanical properties of broccoli stem, and to provide basic data and reference for establishing visual models of broccoli stem. The test results show: The content of rind is highest in the middle of the stem, the content of xylem is highest in the bottom of the stem, and the content of pith is highest in the top of the stem. The densities of rind, xylem and pith of broccoli stem were 1056.1, 938.9 and 1009.9 kg·m−3, respectively. The elastic modulus of the rind of broccoli stem was 27.2~47.5 MPa, the elastic modulus of the xylem was 19.2~110.7 MPa, and the elastic modulus of the pith was 6.5~7.5 MPa. The compressive elastic modulus of the stem was 1.3~2 MPa. The bending strength of the broccoli stem was 6.9 MPa, and the bending modulus was 3.1 MPa. The mechanical model of broccoli stem established in this study provides a theoretical basis for cutting and other processes. [ABSTRACT FROM AUTHOR]

The size effect has a significant effect on the mechanical behavior of rock, thereby fundamentally influencing the stability of rock excavations. The main challenge associated with the experimental research on the size effect of fractured rock mass lies in the difficulty of specimen preparation to represent the influence of size and fracture on the mechanical behavior of the rock material. In order to preliminarily explore the feasibility of 3D printing technology in the field of rock mechanics, fractured rock specimens of different sizes and different fracture characteristics were produced using sand powder 3D printing technology. The uniaxial compression test was combined with the digital image correlation method (DIC) technology to study the influence of the size effect on the mechanical properties and deformation and failure of different fractured specimens. The research finds that: (1) The elastoplastic mechanical characteristics of the sand powder 3D printed specimens are similar to soft rock. Specimen size and fracture angle have significant effects on the mechanical properties of specimens. Under different fracture conditions, the uniaxial compressive strength (UCS) and Elasticity Modulus of sand powder 3D specimens should be decreased with the increase of the specimen size, and the size effect has different influences on the specimens with different fracture characteristics. (2) Under different fracture conditions, the crack initiation position and failure mode of specimens of various sizes are affected by the fracture inclination to varying degrees. (3) The size effect of fractured rock mass is closely related to the defect level inside the rock mass. The size effect originates from the heterogeneity inside the material. The research results verify the feasibility of applying sand powder 3D printing technology to study the size effect of fractured rock masses and provide an innovative test method for the size effect test study. Preliminary exploration of the size effect of fractured rock masses provides a powerful reference for related research in this field. The study proves the feasibility of applying sand powder 3D printing technology in similar rock mechanics tests and contributes to understanding the size effect of a fractured rock mass. [ABSTRACT FROM AUTHOR]

Conventional borehole pressure relief can meet the requirements for preventing rock bursts, but it can also easily destroy the roadway, resulting in system support failure. Taking coal-like samples with boreholes as the research object, the pressure relief effects of the same-diameter boreholes and variable-diameter boreholes are compared and analyzed by a uniaxial compression test. The joint pressure relief mechanism of the variable-diameter drilling hole is discussed. The experimental results show that the stress–strain curve of variable-diameter drilling sample occurred the phenomenon of pre-peak stress drop and post-peak stress plateau, which indicates that the variable-diameter drilling hole can enhance the plastic characteristics of coal-like samples. The borehole size dramatically influences the variation of various pressure relief indexes. The evolution law of AE counting the pre-peak and post-peak of borehole samples verified the abovementioned law. Variable-diameter drilling can enhance the plasticity of samples, weaken the brittleness and reduce the impact tendency. Under the maximum size of the variable-diameter drilling hole and the same-diameter drilling hole is same, the pressure relief effect is more significant. The results obtained in this paper can provide a new theoretical basis and technical guidance for borehole pressure relief and roadway support. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the extreme water sensitivity of shale, the excavation of shale underground engineering is prone to major disaster accidents such as roof falls and collapses. However, current investigations have failed to fully explain the mechanisms by which water content affects shale damage behaviors. In this study, the acousto-mechanical properties and failure behaviors of laminated shale under different confining pressures σ3 are investigated with the aid of AE monitoring for three different water content states. The results show that the shale strength decreases with the increase of the water content, but it increases as the confining pressure σ3 increases. For the shale, the change in the wetting angle and the distance between the centroids of the two adjacent particles inside the bedding plane is more prominent than the surrounding shale matrix, and the swelling pressure is generated among the clay minerals, which are the two main mechanisms for the bedding-participating failure and the shale softening after immersion. Moreover, with the increase of the water content and σ3, the damage mode of shale specimens gradually changes from tension damage to shear damage. Controlled by bedding, shale failure shows significant suddenness without clear acoustical precursors. This study provides experimental and theoretical bases for the stability analysis of shale underground engineering.

In the Loess Plateau region, loess, as a widely distributed building material, is often used as a filling material for dams. When the water level reaches a certain height, the body of a dam is prone to shear failure due to the penetration of water. The change in the shear performance of local loess filler can affect the overall strength of loess dams. Therefore, the filler of a loess dam is selected to study the shear performance. The progressive failure process of a loess dam is simulated. The shear failure characteristics of loess filler under the influence of water content, confining pressure, and dry density were explored. The characteristics of the shear failure of a loess dam were analyzed. The remolded loess is prone to shear expansion failure under low confining pressure, low water content, and high dry density, and is prone to shear shrinkage failure under high confining pressure, high water content, and low dry density. When the water content is constant, the cohesion increases with the increase in dry density. When the dry density is constant, the internal friction angle generally increases with the increase in water content. However, when the dry density is high, the permeability of the remolded loess is weakened, resulting in uneven water distribution under a low water content, which affects the test results. The failure process of the loess dam is a progressive shear failure, which is affected by the water level and water pressure, and is destroyed under the action of pore water pressure and water body lateral pressure.

Efforts to meet regulations ensuring the safety of lithium-ion battery (LIB) modules in electric vehicles are currently limited in their ability to provide sufficient safe escape times in the event of thermal runaway (TR). Thermal runaway occurs when the heat generation of a battery module exceeds its heat removal capacity, leading to a rapid increase in temperature and uncontrolled heat release. To address this issue, this study focuses on evaluating the cascading thermal failure characteristics of six-cell LIB modules under an air environment in an experimental combustion chamber. Sensors are strategically placed at advantageous locations to capture changes in various characteristic parameters, including LIB temperature, module voltage, module mass, and the concentrations of venting gases in the combustion chamber. Analysis of the variations in these characteristic parameters over time aims to identify effective signals that can predict thermal failure conditions with a maximum warning time. The results demonstrate that monitoring LIB temperature provides the shortest advance warning of TR propagation within the module. However, module voltage measurements offer a warning that is approximately 2% earlier on average. On the other hand, measurements of the module mass and concentrations of venting gases in the combustion chamber allow for warnings of thermal failure that are, on average, approximately 2 min earlier than those based solely on LIB temperature. These findings can serve as guidance for improving the safety of LIBs, enhancing the reliability of fault detection systems, and exceeding the safe escape time requirements set by current global regulations.

CFRP composites with the advantages of enhanced mechanical properties and lightweight are recognized as an ideal material in repairing cracked structures. This paper aims to comprehensively investigate whole‐field strain distribution and fracture characteristics of central inclined titanium plates repaired with CFRP laminates, with consideration of various overlap length and repair type. Results indicated that the initial central cracks significantly deteriorated mechanical performance, while inclined direction of it exhibited limited influence on repair behavior. Repairs with increased overlap length possessed superior mechanical performance and repair effectiveness. When increasing the overlap length to 80 mm, strength recovery rate for four types of repairs reached above 80.0%. Digital image correlation (DIC) results indicated that central hole was the highly strained zone for all repairs, and hole repairs presented relatively higher strain values compared with cracked repairs. Progressive failure analysis showed that repairs with initial cracks presented premature fracture of titanium plates, while hole repairs were capable to sustain load until adhesive layer fractured. Adhesive failure, cohesive failure and substrate fracture predominated on fractured surfaces irrespective of repair type and overlap length. With the increase of overlap length, cohesive failure was enhanced and light‐fiber‐tear/fiber‐tear could be found, which corresponded to relatively higher repair effectiveness. [ABSTRACT FROM AUTHOR]

To explore the fatigue evolution characterizing the surrounding rock of a compressed air energy storage tunnel, discontinuous cyclic loading tests were conducted on sandstone collected from a coal mine in Henan, China. The experimental results show that the presence of low-stress time intervals accelerates the accumulation of residual deformation. The fatigue life of sandstone in the discontinuous fatigue test is much shorter than that in the traditional fatigue test. The time intervals could influence the residual strain of each cycle when the stress is at a very low level (10 MPa), and the effect increases with the duration of the time intervals. The proportion of the residual strain from cycle A to that from cycle B is defined as the accelerant rate and is a negative exponential function of the time interval duration. A mechanical model was developed to reveal the mechanical mechanism of the internal residual stress generation. The mechanical response of the sandstone microstructure in one loading–unloading cycle was simulated using the finite element method. The results show that the partial internal residual stress around the inclusion remains during the unloading process due to the difference in states between the inclusions and the interstitial materials. The sustained damage effect of the internal residual stress during intervals may be the main reason for the reduction in fatigue life and the acceleration of plastic deformation. [ABSTRACT FROM AUTHOR]

In order to study the failure characteristics of hard rock with nonlinear velocity variety in unloading phase, three unloading rate variety modes of cosine, linear and exponent were used to study the damage and failure of the hard rock by using the indoor triaxial compression tests and particle flow numerical simulation. The results show that the hard rock with exponential unloading rate first fails to stabilize, while the hard rock with cosine unloading rate is less likely to fail. The faster unloading rate in the early stage has a greater impact on the damage accumulation in the whole unloading process. The bearing strength of hard rock in unloading process is affected by both initial confining pressures and unloading modes, and the higher the confining pressure is, the more significant the influence of unloading mode is. According to the Mogi-Coulomb strength criterion, exponential unloading affects hard rock strength through internal friction angle, while the strength of hard rock under linear and cosine unloading mode is mainly affected by cohesion. Exponential unloading is easy to cause partial breakage at the end due to rapid unloading at the early stage. With the increase of confining pressure, linear unloading leads to multiple "V-shaped" shear failures from the steep dip shear fracture zone. Cosine unloading presents a plastic failure characteristic trend with the increase of confining pressure. [ABSTRACT FROM AUTHOR]

Compaction degree is an important factor affecting the stability of loess fill slope. At present, few scholars combine macro (model test), micro (triaxial test) and micro (SEM test) methods to study compacted loess. For this reason, model tests, isobaric consolidation undrained (ICU) test and scanning electron microscope (SEM) test under different compactness were carried out. The saturation strength, critical state and Pore water pressure and peak strength(u-qmax ) relationship of compacted loess under different compactness were analyzed. The micro pore structure characteristics under different compactness were also analyzed. The number and area of different pore types, the average area, porosity and probability entropy of pores were counted. The results show that the saturation strength, the slope M of the critical state line and u-qmax relationship increase with the increase of compactness. With the increase of compactness, the number of pores increases, but the pore area decreases, and the micro pores determine the pore structure of compacted loess. The average pore area and porosity decrease with the increase of compactness, while the probability entropy increases with the increase of compactness. In loess fill slope, increasing the compactness of filling material can improve the strength of soil and slow down the infiltration rate of water. In the case of rainfall, increasing soil compaction can improve the stability of loess fill slope to a certain extent [ABSTRACT FROM AUTHOR]

In this study, taking the Sheng'an coal mine as an engineering background, the failure characteristics of the surrounding rock of a roadway under repeated mining in a close-distance coal seam is comprehensively illustrated through field measurements (e.g., drilling imaging), theory analysis and numerical simulation (finite difference method (FDM)). The results show that although the return airway 10905 remains intact, the apparent failure of the roadway's roof and the coal pillar can be observed. In addition, the expression of floor failure depth caused by upper coal seam mining is obtained through elastic-plastic theory. Meanwhile, the deformation of the surrounding rock of the roadway increases with the increase of repeated mining times, especially for the horizontal displacement of the roadway on the coal pillar side. Moreover, the cracks' evolution of surrounding rock in the roadway can be observed as asymmetric characteristics. Finally, the stability control technology of "asymmetric anchor net cable + I-steel" is proposed to prevent potential mining disasters, and the feasibility of this support scheme is verified by numerical simulation and field practices. It can meet the requirement of safe mining and provide guidelines to effectively solve the failure of a roadway in close-distance coal seam mining. [ABSTRACT FROM AUTHOR]

To study the mechanical properties of rocks with cracks of different angles around the hole, the particle flow discrete element software PFC2D and laboratory experiments were used to conduct uniaxial compression tests on rocks with cracks of different angles around the hole. The failure behaviour and mechanical properties of rock samples with cracks of different angles were analysed, the failure modes of rocks with defects of different angles were revealed, and the crack propagation and stress evolution of rocks with cracks of different angles were studied. The results show that compared with the intact rocks, the peak stress, elastic modulus, peak strain, initiation stress, damage stress, and other properties of fissure rocks with different angles around the hole are lower; the defect combination of different fissure angles around the hole has a substantial impact on the failure characteristics of rock samples—different fissure angles in rock samples produce different failure modes, resulting in different crack development and propagation processes. Through the comparative study of indoor experiments, the results of indoor real rock and numerical simulation experiments are verified, and the macroscopic failure characteristics of rocks are similar. This study can correctly understand the mechanical properties of fissure rocks with different angles around the hole and provide theoretical guidance for practical rock engineering. [ABSTRACT FROM AUTHOR]

Earthquakes are one of the main factors inducing large-scale loess bedrock and especially loess-mudstone landslides in Western China, and these types of landslides are often closely related to fault zones. To study the influence of high anti-dip angle fault zones (HADAFZs) on loess-mudstone slopes (LMSs) during earthquakes, a scaled model with an HADAFZ of 80° using a shaking table test and numerical calculation, subjected to earthquake waves, was applied to reveal the rules of seismic response and failure characteristics. The acceleration dynamic response had a top surface amplification effect on the slope surface, an accelerated increase effect on the slope-surface hanging wall, an amplification effect away from the free slope face in the loess stratum, and a combination of elevation and lithology effects in the vertical section. At the loess–weathered mudstone (L–W) and weathered mudstone–mudstone (W–M) interfaces, the amplification response of a hanging wall was the largest, fault zone was the second, and foot wall was the smallest. Furthermore, the key value of input peak ground acceleration (PGA) for the dynamic response was a = 0.3 g. The hanging wall amplification effect became apparent while a > 0.3 g, and cracks appeared on the surface of the slope. The dynamic response of the soil pressure was influenced by the hanging wall amplification effect and had a positive correlation with the thickness of the overlying layers, both in the loess stratum and at the L–W interface. However, the dynamic soil pressure maximum variation (DSPMV) on both sides of the fault zone was larger than that in the fault zone. The development of an HADAFZ in the LMS hindered the integral connection of the potential sliding surface and restricted the overall sliding failure of the slope during the earthquakes. [ABSTRACT FROM AUTHOR]

Based on the indoor conventional triaxial compression test and the principle of energy dissipation, the effects of mass concentration and confining pressure on the mechanical properties and energy evolution characteristics of cemented backfill were studied systematically. The results show that the deformation and failure of cemented backfill experienced micro pore, fracture compaction stage (OA), linear elastic deformation stage (AB), yield stage (BC) and strain hardening stage (CD). The peak stress of backfill increases with the increase of mass concentration or confining pressure, and the first-order function can well express the relationship between confining pressure and peak stress. With the increase of confining pressure, the residual stress and elastic modulus of backfill basically follow the increasing law of primary function and exponential function, and the increase of mass concentration is also conducive to improve the residual stress and elastic modulus of backfill. The crack distribution density of the backfill decreases with the increase of mass concentration or confining pressure, indicating that the increase of confining pressure or mass concentration can enhance the anti deformation ability of the backfill. The total energy, elastic strain energy and dissipation energy of the backfill are positively correlated with the confining pressure and mass concentration, and the relationship between confining pressure and each energy conforms to the quadratic function model. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgy (10057854) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The single-lap joints with different overlap lengths were bonded by carbon fiber reinforced plastics (CFRP) laminate, and their failure load, fracture process and strain fields were characterized by digital image correlation (DIC) and universal testing machine. The effects of overlap length on the tensile properties, fracture process, strain distribution and failure characteristics of single lap joints were studied. The results show that with the development of overlap length, the average shear strength of joints is decreased firstly and then tends to be stable. The secondary bending effect of joints caused by the eccentric load during the stretching process becomes more significant with the increase of overlap length, the end deformation of the lap area is increased, and the initial failure position of joints changes from one end to both ends of the lap area. The strain concentration area at the end of the front and side of joints transitions from asymmetric to symmetric. The peeling stress of joints gradually is increased, and the main failure mode between layers is changed from shear to peeling failure. The failure mode of joints go through the process from interface and slight fiber tearing to mixed failure and then to delamination.

The recycling of waste tire rubber resources and its application in the field of civil engineering materials have the importance of the economy, environmental protection, and promoting the development of civil engineering materials. In this work, rubber cement mortar short-column was used as the research object, and the cyclic loading-unloading tests with finite cycles were carried out under three different loading modes (I, II, and III). A series of basic characteristics of rubber cement mortar under three different cyclic loading-unloading modes were further discussed and analysed, such as energy, deformation, damping ratio, failure mode mechanism, and crack development mechanism. The results showed that when the rubber content was 30%, the energy damage was reduced by 13.7 ~ 45.7%, and the cumulative damping ratio was increased by 57.0%. The evolution characteristics of the hysteresis loops in the loading-unloading curves in the form of ''non-closed crescent'' were explained. The development mechanism of cracks based on the principle of minimum energy was revealed, and the evolution characteristics of cracks were confirmed. The crack resistance effect of rubber cement mortar was explained by the property of damping energy dissipation of rubber particles. The purpose is to better apply rubber-cement composites to seismic structures, underground structures, and road engineering.

The deformation and failure characteristics and mechanism of granite under different water content are of great significance to the stability evaluation of this kind of engineering rock mass. The uniaxial compression tests of biotite monzogranite under different water content were carried out to analyze the failure characteristics and stress-strain curve characteristics. The fracture scanning electron microscope test was carried out to analyze the micro morphology characteristics, and study the failure mechanism of granite. The test results show that: biotite monzogranite has obvious strain softening characteristics. With the increase of water content, the length of the microfracture compaction stage increases, while the length of the stable fracture stage and the unstable fracture stage gradually shortens, but the proportion increases, and the fluctuation alternation in the pre-peak stage of the curve intensifies. Compared with dry samples, the uniaxial compressive strength and elasticity modulus of saturated sample decreased by 40.68% and 20.3% respectively. The deformation and failure process can be roughly divided into five stages: quiescent stage, crack initiation stage, crack growth with particle ejection stage, flaky debris peeling with particle ejection stage and caving failure stage. With the increase of water content, the intensity, sound and brittleness of granite failure gradually decrease. In general, the failure mechanism of granite is tension-shear composite failure. When the granite with low water content, the dominant failure mechanism is tensile failure induced by compression; with the increase of water content, the tensile failure decreases and the shear failure increases; and while the granite is in saturation, the dominant failure mechanism is shear failure. The research results can provide theoretical support for the construction of coupling model between biotite monzogranite and water, and have important scientific significance for the stability analysis of engineering rock mass under water-rock coupling environment.

With an increase in urban construction waste, and in order to find an effective method of microwave-assisted mechanical RC regeneration, thermal damage characteristics of the interfacial bond between steel rebar and concrete after different microwave irradiations are analysed in this paper. The results show that, with an increase in microwave power, the overall failure mode of the specimen changes from splitting failure to pull-out failure. Bond slip curves and the corresponding fitting equations were obtained at various levels of microwave irradiation. By analysing characteristic points of the curve, 3500W was determined as a reasonable irradiation power.

• The similarities and differences in the mechanical properties of yellow sandstone under the influence of tailings water and distilled water were investigated. • The variation patterns of acoustic emission parameters in sandstone under the influence of tailings water were analysed. • The immersion height determines the failure mode of intact samples, while the failure mode of fissured samples after water immersion is still dominated by fissures. • The acoustic emission waveform signals from sandstone samples predominantly exhibit characteristics of abrupt signals. To investigate the influence of tailings water immersion height on the failure process of rocks, intact yellow sandstone samples and yellow sandstone samples with prefabricated fissures were prepared. Uniaxial compression tests were conducted on these sandstone samples with varying immersion heights, and the failure processes were simultaneously monitored using a camera and an acoustic emission monitoring system. Based on the test results, the crack propagation and failure characteristics of the yellow sandstone samples under uniaxial loading at different immersion heights were determined. The relationships between the immersion height and peak strength and between the immersion height and elastic modulus were characterized. Additionally, the intrinsic connection between sandstone damage and acoustic emission signal parameters was revealed. The experimental results indicate that the uniaxial compressive strength and elastic modulus of the sandstone samples decrease continuously with increasing immersion height, but the rate of decrease gradually slows. The presence of water is the primary reason for the deterioration of mechanical properties, and the chemical components in the tailings water are significant factors that cannot be ignored. The initiation location and propagation of cracks in intact samples depend on the immersion height, while the fracture behaviour of fissured samples after immersion is mainly influenced by the prefabricated fissures. As the immersion height increases, the longitudinal wave velocity increases, while the number of acoustic emission events, peak frequency, and amplitude exhibit a decreasing trend that is initially rapid and then slows. A damage evolution model based on acoustic emission ringing counts at different immersion heights was established. It was also found that the acoustic emission signals of these yellow sandstone samples mainly show the characteristics of abrupt signals under any immersion water height. [ABSTRACT FROM AUTHOR]