Deformation Failure Mechanism Research Articles

Deformation failure mechanism and stability-control technology of deep layered clastic-rock roadway under dynamic disturbance

The deep layered clastic-rock roadways (LCRRs) of the gold mines in southwestern Guizhou, China, are adversely affected by dynamic disturbances such as blasting and mechanical operations, yielding poor roadway stability and unsatisfactory control effectiveness. This study investigates the deformation failure mechanism of a deep LCRR under dynamic disturbance and proposes and validates an optimised roadway stability-control scheme. Through on-site investigation and theoretical analysis, the main roadway stability-control factors are determined; that is, the mudstone-layer thickness, roadway buried depth, and dynamic-load amplitude. Similar simulation experiments reveal the deformation failure characteristics and strain-field evolution laws of similar models. Numerical analysis shows that increasing buried depth most severely affects the two sides of the roadway, whereas the dynamic-load amplitude determines the disturbance duration. Moreover, with increasing mudstone-layer thickness, the overall impact of the dynamic disturbance on the surrounding rock first intensifies and then diminishes. The results of the similar simulation experiment and numerical analyses are highly consistent, indicating a danger zone on the roadway roof. The roadway deformation and failure mechanisms are revealed, and a more rational technical solution for roadway stability control is proposed and implemented on-site. Analysis and monitoring results reveal a relative reduction in roadway surface displacement exceeding 30 %, and improvement of the overall roadway stability. The findings constitute a valuable reference and guide for roadway stability control under such geological conditions.

Deformation evolution and failure mechanism of rainfall-induced granite residual soil landsliding event in Northern Guangdong, China

Deformation evolution and failure mechanism of rainfall-induced granite residual soil landsliding event in Northern Guangdong, China

In-Plane Cyclic Mechanical Properties of CF/PEEK/TPU Flexible Composite with Zero Poisson Ratio.

This paper presents the in-plane deformation and cyclic mechanical properties of CF/PEEK (Carbon Fiber-Reinforced Polyetheretherketone)-reinforced TPU (thermoplastic polyurethanes) flexible composites with a zero Poisson ratio. A novel CF/PEEK honeycomb reinforcement with a zero Poisson ratio was fabricated by using 3D-printing technology. Then, TPU was bonded in the two sides of the CF/PEEK honeycomb reinforcement. The in-plane deformation ability and cyclic mechanical properties were evaluated. The results show that the zero Poisson ratio flexible composite can achieve a large in-plane plastic deformation of more than 50% and can better maintain the zero Poisson ratio superstructure. By collecting and comparing the mechanical characteristic values of the CF/PEEK flexible composite under a cyclic load, the CF/PEEK flexible composite MH22-t0.6-CT has the best structural stability. The length of the structure was increased by about 12.53%. By studying the deformation mechanism and failure mechanisms of the flexible composites, the in-plane recyclability of the flexible composites was evaluated, which provides the basic research basis for large-scale in-plane deformation composites.

Research on Spatiotemporal Continuous Information Perception of Overburden Compression-Tensile Strain Transition Zone during Mining and Integrated Safety Guarantee System.

The mining of deep underground coal seams induces the movement, failure, and collapse of the overlying rock-soil body, and the development of this damaging effect on the surface causes ground fissures and ground subsidence on the surface. To ensure safety throughout the life cycle of the mine, fully distributed, real-time, and continuous sensing and early warning is essential. However, due to mining being a dynamic process with time and space, the overburden movement and collapse induced by mining activities often have a time lag effect. Therefore, how to find a new way to resolve the issue of the existing discontinuous monitoring technology of overburden deformation, obtain the spatiotemporal continuous information of the overlying strata above the coal seam in real time and accurately, and clarify the whole process of deformation in the compression-tensile strain transition zone of overburden has become a key breakthrough in the investigation of overburden deformation mechanism and mining subsidence. On this basis, firstly, the advantages and disadvantages of in situ observation technology of mine rock-soil body were compared and analyzed from the five levels of survey, remote sensing, testing, exploration, and monitoring, and a deformation and failure perception technology based on spatiotemporal continuity was proposed. Secondly, the evolution characteristics and deformation failure mechanism of the compression-tensile strain transition zone of overburden were summarized from three aspects: the typical mode of deformation and collapse of overlying rock-soil body, the key controlling factors of deformation and failure in the overburden compression-tensile strain transition zone, and the stability evaluation of overburden based on reliability theory. Finally, the spatiotemporal continuous perception technology of overburden deformation based on DFOS is introduced in detail, and an integrated coal seam mining overburden safety guarantee system is proposed. The results of the research can provide an important evaluation basis for the design of mining intensity, emergency decisions, and disposal of risks, and they can also give important guidance for the assessment of ground geological and ecological restoration and management caused by underground coal mining.

Analysis of Deformation Characteristics and Failure Mechanism of Interbedded Surrounding Rock Tunnels Based on Principal Stress Difference

Analysis of Deformation Characteristics and Failure Mechanism of Interbedded Surrounding Rock Tunnels Based on Principal Stress Difference

A B-spline material point method for deformation failure mechanism of soft–hard interbedded rock

Geological hazards related to soft–hard interbedded rock are frequent in rock engineering. The material point method (MPM) is a mesh-free numerical approach specifically designed for analyzing large deformations. Notably, significant grid-crossing errors frequently arise when material points traverse the underlying grid. To investigate the failure mechanism of soft–hard interbedded rock, an enhanced MPM incorporating B-spline basis functions and Voronoi polygon discretization is developed and subsequently validated through comparisons with uniaxial compression test data and other numerical methods. The numerical results of soft–hard interbedded rock specimens associated with different soft layer dips (SLD) and confining pressures indicate that the SLD has a great effect on compressive strength and crack extension at low confining pressure. Rocks from SLD-30° to SLD-75° correspond to the “sliding failure along discontinuities” failure mode and have lower compressive strength than rocks with other SLD angles. It is also demonstrated that the propagation of cracks leads to a significant alteration in the internal stress state of the rock, and that stress concentrations at the crack tip exacerbate the development of failure surface. Furthermore, the failure mode of soft–hard interbedded rock can be categorized into four types: (1) sliding failure across multiple discontinuities, (2) tensile fracture across multiple discontinuities, (3) sliding failure along discontinuities, (4) tensile-split along discontinuities.

Failure analysis of Fiber Metal Laminate channel section column under axial compressive pulse loading

The study aims to analyse the dynamic buckling phenomenon and assess the role of the stress tensor components in the failure process of a short Fiber Metal Laminate column under axial compressive dynamic loading. The investigation is focused on a channel-section profile composed of three aluminium layers and two doubled composite plies [Al/0/90/Al/90/0/Al]. The numerical analysis was performed on the finite element model, which was validated by experimental static buckling tests. Employing a progressive failure algorithm, this analysis incorporated the material property degradation method and Hashin’s criterion as the damage initiation criterion. Failure initiation in metal layers was based on the HuberMises-Hencky failure criterion. Based on the conducted analyses, it was concluded that the dominant forms of destruction in the FML structure are yielding in the metal layers due to excessive compressive stresses and the failure of the matrix in composite plies as a result of compressive and shear stresses. Through a thorough examination of the stress tensor components, critical stresses contributing to aluminum plastic deformation and laminate failure mechanisms were identified.

Experimental study on direct shear properties and shear surface morphologies of hydrate-bearing sediments

The safe production of methane gas requires a comprehensive understanding of the geomechanical behavior for hydrate-bearing sediments (HBS). Currently, there is a lack of detailed exploration of the shear surface failure characteristics of specimens. To address this, direct shear tests were performed to observe shear surfaces at the microscopic level. This study mainly focuses on the mechanical parameters of HBS and the morphological characteristics of shear surfaces, aiming to elucidate the deformation modes and failure mechanisms. Results reveal that shear load-displacement curves illustrate three stages: elastic deformation, strain softening, and stability stage. The shear strength increases from 12.65 KPa to 153.86 KPa with hydrate saturation rising from 12% to 72%, while decreases versus shear rate. Shear surfaces exhibit concave, convex, and S-shape patterns with remarkable differences in crack number and orientation. The shear load-displacement curves and shear surface morphology are closely correlated with shear rates, especially shear strength and shear surface roughness. Furthermore, the shear surface roughness varies between 2.02 mm and 3.61 mm with hydrate saturation increasing from 12% to 72%, which are also influenced by the shear rate. Empirical formulas were established based on test data to predict the shear strength and surface roughness. The failure mechanism of the specimens mainly depended on the movement modes of the sediment particles, hydrate strength, and hydrate-sediment cementation strength. Findings of this study provide a theoretical reference for evaluating geo-mechanical stability and predicting the destabilization of natural gas hydrate reservoirs.

Experimental study on the bearing mechanical characteristics and deformation failure mechanism of damaged sandy mudstone

AbstractStudying the mechanical properties and failure mechanisms of damaged rocks holds practical significance in guiding tunnel or roadway support and assessing the stability of engineering rock masses. To uncover the failure mechanisms of sandy mudstone with varying degrees of damage, we conducted cyclic loading‐unloading tests to create specimens at different damage levels. Subsequently, uniaxial loading tests were performed to investigate the fundamental mechanical properties, wave velocity, and acoustic emission (AE) parameter evolution characteristics of the damaged specimens. The classification of damaged rocks was based on the energy evolution characteristics of damaged sandy mudstone. Finally, we discuss the damage and deterioration mechanisms of different types of sandy mudstone. The findings contribute to establishing a theoretical foundation for evaluating the degree of rock damage.

Investigation on uncoordinated deformation and failure mechanism and damage modeling of rock mass with weak interlayer zone

The weak interlayer zone (WIZ) is a high-risk geotechnical system with poor mechanical properties, strong ductility, loose structure, and wide distribution. To comprehensively investigate the uncoordinated deformation characteristics and failure mechanism of rock mass with WIZ, a series of uniaxial loading tests using digital image correlation (DIC) technique, and numerical simulation tests were carried out. Besides, the damage constitutive model of rock mass with WIZ was established, then the damage evolution law was also analyzed. Results show that a high strain localized zone appears in the WIZ from the beginning of loading, which then develops towards the contact surface between the WIZ and the rock mass. As loading proceeds, the WIZ exhibits layered spalling and ultimately forms through-cracks after the initiation of micro-cracks, and vertical tensile cracks to appear in the rock. causing vertical tensile cracks to appear in the rock. With the increase of the WIZ thickness and dip angle, the uniaxial compressive strength and deformation modulus of specimen show a negative exponential decay. When rock mass with WIZ collapse, the bonding of WIZ particles fails and the number of tensile-shear cracks gradually increases, eventually resulting in the plastic squeezing-out of WIZ. Moreover, the particles of the rock masses with smaller WIZ dip angles are mainly displaced vertically, and the failure is mainly caused by tensile splitting. The significant lateral displacement of particles in the rock mass with larger WIZ dip angles leads to the destruction of the rock mass mainly through shear slip, in particular a pronounced sliding down along the WIZ. Furthermore, the damage constitutive model of the rock mass with WIZ was established by distinguishing the total damage of the rock mass with WIZ into the damage of the WIZ and the damage of the rock mass. The model prediction results show that the total damage D increases with the increase of WIZ thickness and dip angle, and develops faster in the early stage and slower in the later stage. The research can provide effective basis and feasible ideas for the uncoordinated deformation and failure evolution, macro–micro failure mechanism, as well as the constitutive model of rock mass with WIZ in underground cavern under high geostress.

Deformation behavior and failure mechanism of AA7075 alloy during the cryogenic temperature-assisted incremental sheet forming process

High-strength aluminum alloys are potential structural materials for thin-walled aerospace and automotive components. However, the limited formability at room temperature (RT) hinders their wide industrial application. In this study, a cryogenic temperature-assisted incremental sheet forming (CT-ISF) process for manufacturing 3D curved thin-walled structures was proposed. An experimental platform for CT-ISF was established to form AA7075 alloys. We found that the formability of the solution-treated AA7075 alloy sheet was greatly improved under the cryogenic environment without sacrificing its strength. In combination with double pass forming process, the formability of the sheet can be further improved. The stable deformation of the sheet is promoted due to the suppression of the Portevin-Le Chatelier (PLC) effect at CT, which reduces axial force fluctuations during the forming process. The line roughness value of the meridional direction was reduced by 36.8% at CT due to the enhanced work-hardening and the utilization of MoS2 lubricant. In terms of microstructural evolution, we found that the fracture morphology of the formed parts changed from tensile fracture at RT to shear fracture at CT. The improved formability was attributed to increased Goss and E texture contents, delay in dislocation evolution, and suppression of the PLC effect. This work introduces a novel CT-ISF process that significantly enhances the formability of high-strength Al alloy. In particular, it unravels the enhancement mechanism of formability in the CT-ISF process, providing theoretical support for further research.

Three-dimensional numerical simulation on failure mechanical characteristics of fissured sandstone specimens under true triaxial conditions

Understanding intermediate principal stress influences on deformation characteristics and failure mechanism of fractured rock from deep engineering often necessitates long term on-site detection and complex experimental research, although very limited efficacy can be obtained. With presently available experimental data on conventional triaxial cuboid noncoplanar fissured sandstones, this study further investigated the effects of differential stress (σ2 − σ3) and rock bridge inclination angle (β30°, β60°, β90°, β120°, and β150°) on their damage evolution processes and failure modes based on 3D discrete element methods (PFC3D). Numerical simulation results indicated that the peak strength of the fissured sandstone under the same state of horizontal principal stress shows an overall increasing pattern with the increase of the inclination angle of the rock bridge, while its peak strain displays a decreasing and then increasing trend. Besides, in this work, five failure modes, nine crack types and two kinds of stress–strain curves are summarized which are significantly affected by the horizontal principal stress, rock bridge inclinations or cooperative interaction. Differential stress value of 15 MPa is an important threshold for determining the residual strength of the stress–strain curve from present to absent. The cracking and force chain evolution processes of five failure modes were analyzed in order to discover the corresponding failure mechanisms. Finally, differential stress and flaw inclination influences on rock mechanical parameters and failure behavior have significant implications for strategies of the design, operation, and maintenance of rock engineering under severe conditions in the underground.

Shaking table tests on deformation pattern and failure mechanism of fault-crossing tunnels in non-rupture scenario

Tunnels, as critical underground infrastructures, often intersect with faults. Field investigations have underscored the susceptibility of fault-crossing tunnels to extensive damages during earthquakes. Hence, large-scale shaking table tests are conducted to investigate the deformation pattern and failure mechanism of fault-crossing tunnels under transverse excitation, particularly in non-rupture scenarios. The dynamic behavior of the tunnel, as expected, is dominated by the surrounding strata. Acceleration responses vary notably across different regions of the fault site. The disparity increases with the increments of seismic intensity and input frequency. The tunnel section at the interface between the fault and the hanging wall manifest the strongest acceleration, where the largest strains of the tunnel and most of the lining cracks also occur, highlighting its vulnerability to seismic vibrations. The damage-induced non-linearity of the tunnel is then identified by the decreasing dominant frequency thereof. The fault-crossing tunnel exhibits unique three-dimensional shearing-torsional deformations, elucidated through the test data and an analytical model. This deformation pattern provides a better understanding of the seismic responses of fault-crossing tunnels under seismic vibrations.

Deformation Patterns and Failure Mechanisms of Soft-Hard-Interbedded Anti-Inclined Layered Rock Slope in Wolong Open-Pit Coal Mine

Since the beginning of spring 2022, successive landslides have occurred in the eastern pit slope of the Wolong Coal Mine in Qipanjing Town, Otog Banner, Inner Mongolia, which has adversely affected the mine’s production safety. This study aims to reveal the deformation patterns and failure mechanisms of landslides. Firstly, this study establishes the stratigraphic structure of the eastern pit slope of the Wolong Coal Mine using extensive field geological surveys combined with unmanned aerial vehicle photography, drilling, and comprehensive physical exploration techniques. Indoor geotechnical tests and microscopic experiments reveal that rock mass typically exhibits the characteristics of expansibility and water sensitivity. Moreover, the mechanical parameters of the rock mass were determined using a combination of the window sampling method, the Geological Strength Index, and the Hoek–Brown strength criterion estimation theory. Finally, this study consolidates the previously mentioned insights and employs FLAC3D (7.0) software to assess the stress–strain characteristics of the excavated slope. The results indicate that the deformation mode of the Wolong open pit coal mine is the toppling failure of soft-hard-interbedded anti-inclined layered rock slopes. The unloading effect and rock expansion-induced softening lead to stress concentration at the slope corners and more substantial deformation, thereby accelerating upper slope deformation. The deformation and destabilization process of landslides is categorized into four stages: the initial deformation stage, the development stage of lateral shear misalignment, the development stage of horizontal tensile-shear damage, and the slip surface development to the preslip stage. This research offers valuable references and engineering insights for future scientific investigations and the prevention of similar slope-related geological hazards.

Experimental and simulation investigation for prismatic lithium-ion battery cells under impact loading

In the current work, prismatic lithium-ion battery (LIB) cells were impacted in various rigid cylinder loading speeds (v = 1, 5, 10, 2000 and 5000 mm/s), which provided the data basis for establishing a practical and reasonable LIB cell damage assessment method. Based on thermal-runaway cell safety borders (TCSB) and undamaged cell safe borders (UCSB), the deformed cells can be classified into safe, risk and failure regions. With the increment of the v values, the UCSB and TCSB of cells decreased linearly along a logarithm axis. Moreover, the relationships between key cell parameters (cell thickness, separator thickness and separator fracture strain) and the cell deformation limits (DL) under rigid cylinder impact loads were also revealed. A DL prediction method was newly introduced for the prismatic LIB cells with different sizes. Finally, the tensile mechanical data of cell components (anodes, cathodes and separators) were also measured for cell local detailed simulation models. By the simulations, the effect of the frictional behaviors between cell components on the deformation processes and failure mechanisms of LIB cells were deeply discussed.

Failure mechanism and treatment of mine landslide with gently-inclined weak interlayer: a case study of Laoyingzui landslide in Emei, Sichuan, China

The landslide of mine is of great harm and wide influence, which can easily cause huge economic losses and endanger the life safety of workers. Therefore, landslide failure mechanism and more efficient landslide treatment methods have been the focus of landslide research. Laoyinzui landslide with a volume of 250,000 m3 occurred along the gently inclined weak interlayer at 6:00 (UTC + 8) on 5 January 2019 in Huangshan Limestone Mine, Emei City, Sichuan Province, China. The deformation history and failure mechanism of the landslide were analyzed based on the field investigation and geological conditions of landslide area. The treatment method of using excavators to remove all sliding body within the arm length by excavating the small-bench in the bedrock was proposed. The slope stability after treatment was analyzed based on the monitoring data. The results showed that the landslide was triggered by rainfall and earthquake after long-term creep deformation under the action of various factors. Weak interlayer was the potential sliding surface of landslide. The tensile cracks at the back edge of the landslide and the joint fissures and karst caves of the upper limestone provided convenient conditions for rainwater infiltration. Mining activities, including excavation and blasting, resulted in deterioration of mechanical properties of rock mass. Rainfall was the main trigger for the landslide. Water accumulated in weak interlayer, leading to increase of pore water pressure and decrease of anti-sliding force. Earthquake was the trigger for the landslide, which resulted in the reduction of rock mass structural strength. The Laoyingzui landslide consisted of two stages. First, a traction landslide of + 825 m–915 m occurred, and then a push landslide of + 725 m–+ 825 m occurred under the compression of the upper rock mass. The slope displacement was small and the deformation tended to be stable. The treatment method was safe and efficient. This paper can provide reference for the failure mechanism research and treatment of similar landslides.

Study on Coordinated Deformation Failure Mechanism and Strength Prediction Model of Rock-lining Concrete

Shotcrete has been widely used in the excavation of caverns and tunnels as a key load-bearing element in the support system. However, the interfacial stresses and bond strengths within the composite structures formed by the interaction of geologic bodies and tectonic formations are not well understood, which can lead to safety accidents and excessive wastage of support materials in engineering. To address this gap, rock-concrete composite specimens were created using six distinct types of surrounding rocks. The strength law of composite specimens was analyzed, and the uniaxial compressive strength prediction model of composite specimens was derived based on Mohr−Coulomb strength yield criterion. The results show that the uniaxial compressive strength of the composite specimen changes with the change of rock type, which is between the strength of rock and concrete. The uniaxial peak strength and elastic modulus of composite specimens are linearly positively correlated with the ratio (Y) of concrete-rock elastic modulus, which is easily affected by concrete properties. However, the peak strain is linearly and negatively correlated with Y, which is greatly influenced by rock. The rock-concrete interface of the composite specimen plays an important role in the failure of the specimen, which changes the stress transfer state of the composite specimen, produces uncoordinated deformation, and finally causes the failure of the specimen. The theoretical and test value error of the derived composite specimen uniaxial compressive strength prediction model are –1.19%~12.20%, and the theoretical calculation model can be used to predict the uniaxial compressive strength of rock-concrete composite specimens.

Multiaxial low cycle fatigue behavior and life prediction of wire arc additive manufactured 308L stainless steel

Wire arc additive manufacturing (WAAM) is a technique that has gained popularity in various industrial sectors due to its high productivity and flexibility. However, the comprehension of cyclic deformation and fatigue behaviors in WAAM austenitic stainless steel (SS), particularly under complex multiaxial loading conditions, is much less advanced compared to conventional manufacturing methods. This study aims to fill some of these gaps by performing fatigue tests of WAAM 308L SS under axial, torsional and axial–torsional multiaxial loadings. Similar tests were carried out on the hot-rolled 308L SS as a basis for comparison. WAAM 308L SS exhibits notable distinctions in cyclic deformation, fatigue life, cracking mode and fatigue failure mechanisms compared to its hot-rolled counterparts as a result of its distinct manufacturing technologies and resulting microstructures. To assess all fatigue life data, three critical plane criteria, namely FS, SWT and CXH criteria, were employed. The CXH model, which considers the effects of both tensile and shear damage on fatigue properties, has the ability to predict the fatigue life of both hot-rolled and WAAM 308L SS.

Shear deformation characteristics and failure mechanisms of tunnel segment inter-ring joints: Numerical and experimental study

The dislocation of inter-ring joints in tunnel segments poses a significant risk to tunnel structural safety. Therefore, gaining insights into the shear deformation and failure behavior of these inter-ring joints is paramount. In this study, we developed a robust three-dimensional numerical simulation model grounded in the concrete damaged plasticity (CDP) constitutive model. Complementing this, full-scale experiments were conducted on circumferential joints, subjecting them to both positive and negative shear loads. To enhance our understanding, we employed distributed optical fiber sensing (DOFS) and acoustic emission (AE) detection technologies. Our investigation delved into the deformation process, mechanical behavior of bolts, and failure characteristics of inter-ring joints featuring double bolt-tenon and mortise structures. Various parameters were explored, including longitudinal force, bolt preload, and the height-to-thickness ratio of the tenon and mortise (h/t). Notably, our results unveiled distinct stages in the shear deformation process of the joints. In the final failure stage, the tenon exhibited crushing failure, while the mortise underwent shear failure. As the h/t ratio increased, the mortise's failure mode transitioned from overall failure at the root to localized failure at the contact area. Analyzing the mechanical behavior of bolts, we observed more favorable outcomes in positive shear than in negative shear. Bolt preload emerged as a modest factor for enhancing the load-carrying capacity of the joint in positive shear, with minimal impact in negative shear. Furthermore, an increase in longitudinal force was found to positively enhance the joint's load-carrying capacity in both shear conditions. Our findings contribute valuable insights for optimizing the design and safety considerations of tunnel structures.

Molecular Dynamics Investigation of Shock-Induced Deformation Behavior and Failure Mechanism in Metallic Materials

Molecular Dynamics Investigation of Shock-Induced Deformation Behavior and Failure Mechanism in Metallic Materials