Cumulative Plastic Deformation Research Articles

Experimental and Numerical Simulation Investigation of Cement Sheath Integrity during Multi-Stage Fracturing in Offshore Tight Oil Reservoir

The integrity of the cement sheath is susceptible to failure during multi-stage fracturing. In this study, the failure mechanisms of cement sheath integrity during multi-stage fracturing in the A offshore tight oil reservoir wells were investigated. The cement samples were subject to triaxial compression test (TCT), triaxial cyclic loading test (TCLT), and permeability test. A full-scale device was constructed for cement sheath integrity experiments. Additionally, a 3-D finite element model was developed to simulate the interface debonding and the subsequent growth of micro-annuli throughout multi-stage fracturing. The results revealed that TCLT induced cumulative plastic deformation in the cement samples, resulting in a 10.7% decrease in triaxial compressive strength, an 8.3% decrease in elastic modulus, and a 150% increase in permeability. Despite these significant variations, no serious damage was caused to the cement sheath matrix. It was observed that gas leakage occurred at the 8th, 10th, and 14th cycles under cyclic loading with upper limits of 70 MPa, 80 MPa, and 90 MPa, respectively. After 15 cycles, the experimentally measured widths of micro-annuli were 117 μm, 178 μm, and 212 μm, which were in good agreement with simulation results of 130 μm, 165 μm, and 205 μm, respectively. These findings elucidate the causes of cement sheath integrity failure, providing insights into the failure mechanisms of cement sheath integrity during multi-stage fracturing.

Failure evaluation mechanism of cement sheath sealing integrity under casing eccentricity during multistage fracturing

A microannulus (MA) is the primary reason for sustained casing pressure in multi-stage fractured-shale gas wells. However, the effect of the casing eccentricity on the long horizontal section has not been considered. In this study, a full-scale integrity tester for cement sheaths is adopted to measure the cumulative plastic deformation. Numerical models are applied to evaluate the development of the cumulative plastic deformation and quantify the MA width considering casing centralization and eccentricity in the context of multiple loading and unloading cycles. Subsequently, the influences of the eccentricity distance and angle, cement-sheath mechanical variables, and different well depths on the cumulative sheath plastic deformation and sheath MA development are explored. The research results demonstrate that casing eccentricity significantly increases the cumulative sheath plastic deformation compared with that of the casing-centered condition. Consequently, the risk of sealing integrity failure increases. The accumulated plastic deformation increases when the eccentricity distance increases. In contrast, the initial plastic deformation increases as the eccentricity angle increases. However, the cumulative plastic deformation decreases after a specific loading and unloading cycle count. Affected by the coupled influence of the internal casing pressure and fracturing stages, the width of the MA in the horizontal section increased from the toe to the heel, and the casing eccentricity significantly increased the MA width at each stage, thus increasing the risk of gas channeling. Finally, an engineering case is considered to study the influence of casing eccentricity. The results show that cement slurries that form low and high elastic moduli can be applied to form a cement sheath when the fracturing stage is lower or higher than a specific value, respectively. The results of this study offer theoretical references and engineering support for the integrity control of cement sheath sealing.

Nonlocal fretting fatigue assessment for dovetail joints

In fretting fatigue, the local stress concept leads to a significant underestimation of fatigue life. Conventional fatigue models lack conservatism in dovetail structures due to mesh dependency and cumulative plastic deformations. The present study aims to develop a nonlocal life model for fretting fatigue of dovetail joints based on extensive experimental and computational analyses. Frictional work was analytically derived and utilized to describe fretting damage, combined with a multiaxial fatigue model. The developed model aligns well with experimental results under various loading conditions, with deviations falling within a double-error band.

Study on dynamic response and long-term settlement of silty soil around Shanghai metro tunnel

At present, the method for calculating long-term tunnel settlement predictions under metro loading considers only one working condition of passenger loading, which is inconsistent with actual working conditions. To establish a tunnel settlement model that accounts for variations in passenger flow, this study uses data mining methods to categorize metro operation into three working conditions: "peak period, secondary period, and low period." The impact of these passenger flow conditions on the dynamic response of the soil around the tunnel is analyzed. Then, based on the principles of calculus, a calculus-based prediction model is established to consider the changing patterns of metro passenger flow. The model is applied to analyze the long-term settlement characteristics of Shanghai Metro Line 10. The results indicate that, under identical conditions, soil displacement and dynamic deviatoric stress around the tunnel increase with passenger capacity. The calculus prediction model aligns more closely with actual working conditions than the conventional model. The predicted tunnel settlement of Shanghai Metro Line 10 after 20 years of operation is approximately 37.07 mm, with most settlement occurring in the early stages, primarily due to cumulative plastic deformation of the soil.

Experimental study on seismic performance of stainless steel full-scale frames: Global response

This paper presents an experimental study of the seismic performance of austenitic stainless steel full-scale frames using the pseudo-static test method. The bottom single-span, two-storey substructure of the designed prototype frame was chosen as the test frame. Two full-scale frames were tested, one with a bolt-welded joint and the other with an extended end-plate joint. This paper is the first of two accompanying papers to this experimental study and focuses on the specimen design, testing details and global response of the stainless steel frame under cyclic loading. The test results were utilized to analyse the global response of the frames, encompassing failure mode, bearing capacity, deformation capacity, energy dissipation capacity, the overstrength factor, ductility factor and seismic response modification factor. The experimental findings suggest that the stainless steel frames with two joint types demonstrate consistent ability to dissipate energy during cyclic loading. The structure also performs well in terms of deformation, with uniform inter-storey deformation and no soft-storey detected. The maximum storey drift ratio of the frame is 7%. Prior to reaching a storey drift ratio of 2%, the frames with both joint types exhibit similar cumulative plastic deformation, stiffness degradation, and cumulative energy dissipation.

An undrained dynamic strain-pore pressure model for deep-water soft clays from the South China Sea

With the increasing use of oceans for engineering purposes, such as the installation of suction anchors and pipelines, the stability of seabed structures has become a pivotal concern and is intricately linked to the characteristics of seabed soils. This study focuses specifically on deep-sea soft clay, a predominant seabed soil type distinguished by its high water content, thixotropy, and low permeability. These clays are vulnerable to destabilization and damage when disturbed, thereby posing threats to seabed installations. While the existing literature extensively examines the cyclic behavior of clay, considering factors such as the pore pressure response and strain and deformation characteristics, there is a notable gap in research addressing the behavior of deep-sea soft clay under comprehensive stress levels and prolonged cyclic loading. In this study, cyclic shear tests of the natural marine clay of the South China Sea were conducted, and the cyclic stress ratio (CSR), overpressure consolidation ratio (OCR), consolidation ratio (Kc), and loading frequency were varied. It was found that the CSR, OCR, and Kc significantly impact the cumulative dynamic strain in deep-sea soft clay during undrained cyclic dynamic tests. Higher CSR values lead to increased dynamic strain and structural failure risk. Subsequently, a dynamic strain-dynamic pore pressure development model was proposed. This model effectively captures the cumulative plastic deformation and dynamic pore pressure development, showing correlations with the CSR, OCR, and Kc, thus providing insights into the deformation and pore pressure trends in deep-sea clay under high cyclic dynamic loading conditions. This research not only furnishes essential background information but also addresses a critical gap in understanding the behavior of deep-sea soft clay under cyclic loading, thereby enhancing the safety and stability of seabed structures.

Experimental tests and numerical simulations of miniature buckling-restrained braces using iron-shape memory alloy bar

Miniature buckling-restrained braces (BRBs) have a concise configuration and clear working mechanism. Owing to stable and full hysteresis, miniature BRBs are emerging as favorable energy-dissipating fuse elements in seismic applications. This paper proposes using iron-shape memory alloy (FeSMA) in lieu of conventional steel as the yielding core and focuses on the cyclic behavior. Four specimens, corresponding to four loading protocols, were fabricated and tested. According to experimental data, the miniature FeSMA BRBs exhibited full hysteresis, which is characterized by large damping, noticeable isotropic and kinematic hardening behavior and appreciable post-yield stiffness ratio. The cumulative plastic deformations meet the requirement by ANSI/AISC 341-16. Further, high fidelity finite element models, which explicitly considered damage and fracture rules, were established for numerical simulations. Good agreement can be found between the experimental data and numerical simulations, in terms of failure modes, fracture locations and global hysteresis.

Experimental Study on Mechanical Characteristics of Prefabricated Fractured Sandstone Samples under Uniaxial Cyclic Compression

The loading-unloading physical and mechanical characteristics of fractured coal-bearing strata are greatly affected by fracture occurrence. In order to study the physical and mechanical response characteristics of fractured rock under cyclic compression, this paper takes prefabricated fractured sandstone samples with different dip angles as the object, and uses uniaxial cyclic loading and unloading test to study the influence of crack dip angle on sample strength, failure mode and crack propagation law. The results show that with the increase of crack inclination angle, the cyclic loading and unloading peak strength and elastic modulus of the sample increase significantly, and the peak strain decreases first and then increases. During the cyclic loading process, the area of the hysteresis loop gradually decreases, the slope gradually increases, the energy con-sumed by the hysteresis loop gradually decreases, the cumulative plastic deformation increases, and the curve shape presents a “concave” type; when it is 15 ° and 30 °, the cracks at the crack tip are wing cracks. When it is 45 °, the cracks at the crack tip are secondary inclined cracks and wing cracks. When it is 60 °, 75 ° and 90 °, the cracks at the crack tip are secondary coplanar cracks and wing cracks. With the increase of fracture dip angle, the number of cycles and peak strength at failure are increasing.

Microscale analysis of geogrid–aggregate interface cyclic shear behavior using DEM

The performance of a geogrid-stabilized structure affected by dynamic loadings is significant. This study investigates the microscale deformation mechanism of the geogrid–aggregate interface cyclic shear behavior using the discrete element method (DEM). Spheres and nonspherical clumps are generated to form aggregate samples. The DEM models are able to capture the macroscopic dynamic shear laws of the aggregate layers stabilized with a geogrid in a similar way to those tested experimentally. The microscale mechanical responses of the cyclic shear tests (e.g., shear strain, fabric evolution, and confined zone), which vary with the particle shape as well as the measurement volume, are analyzed. The rib flexural rigidity has a minor influence on the peak shear strength of the geogrid–aggregate interface cyclic shear test, but is a key factor influencing the shape of the hysteretic loop, which is closely related to the micromechanical responses at the geogrid–aggregate interface. The particles in the upper and lower shear boxes show different motion patterns in response to the aperture ratio. In the case of A/D50 = 2.53, the cumulative plastic deformation of the soil layers extending beyond the interface during the loading and reversal loading process is effectively restrained.

Experimental study on effects of cyclic loading paths on cracking behavior and fracture characteristics of granite

To investigate the impact of cyclic loading paths on the Mode I fracture characteristics of granite, a series of fracture tests were conducted on semi-circular bend (SCB) specimens using acoustic emission (AE), digital image correlation (DIC) and 3D scanning. The tests included monotonic loading, variable amplitude (VA) cyclic loading, and tiered constant amplitude (TCA) cyclic loading. The results demonstrated that VA cyclic loading leads to an average enhancement of 5.6% in fracture toughness, whereas TCA cyclic loading results in an average reduction of 3.7% in fracture toughness. During cyclic loading and unloading, the TCA loading path exhibits a higher rate of cumulative plastic deformation growth and greater magnitude cumulative plastic deformation compared to the VA loading path. Additionally, detailed observations from 3D scanning revealed that under cyclic loading, the fracture trajectories and surface morphology exhibit more tortuosity and roughness compared to monotonic loading, particularly in the case of TCA cyclic loading. Furthermore, according to the AE and DIC analysis, the proportion of microcrack initiation and stable propagation stage, cumulative AE counts and fracture process zone (FPZ) size generated under VA cyclic loading are greater than those generated under TCA cyclic loading, displaying a consistent variation pattern with fracture toughness. The changes of fracture properties can be attributed to a competition between the compaction-induced hardening effect and the cracking-induced damage effect. A higher cyclic upper limit and incomplete unloading are more likely to accelerate the growth of the irreversible crack damage and rapid crack extension, resulting in weakened rock fracture properties. These findings provide important references for rock instability control in underground rock engineering.

New Technology of Multidirectional Loading Rotary Extrusion

To satisfy the requirements for the precise formation of large-scale high-performance lightweight components with inner ring reinforcement, a new multidirectional loading rotary extrusion forming technology is developed to match the linear motion with the rotary motion and actively increases the strong shear force. Its principle is that the radial force and rotating torque increase when the blank is axially extruded and loaded. Through the synergistic action of axial, radial, and rotating motions, the orderly flow of metal is controlled, and the cumulative severe plastic deformation (SPD) of an “uplift-trowel” micro-area is generated. Consequently, materials are uniformly strengthened and toughened. Simultaneously, through the continuous deformation of a punch “ellipse-circle,” a high reinforcement component is grown on the cylinder wall to achieve the high-quality formation of cylindrical parts or the inner-ring-reinforcement components. Additionally, the effective strain increases with rotation speed, and the maximum intensity on the basal plane decreases as the number of revolutions increase. The punch structure also affects the axial extrusion loading and equivalent plastic strain. Thus, the proposed technology enriches the plastic forming theory and widens the application field of plastic forming. Furthermore, the formed large-scale high-performance inner-ring-stiffened magnesium components have been successfully verified in aerospace equipment, thereby solving the problems of integral forming and severe deformation strengthening and toughening. The developed technology has good prospects for mass production and application.

Hysteretic energy dissipation capacity of dual-steel welded-plate preloaded bolted T-stubs

With the high- and ultrahigh-strength steels applied in the construction industry, the seismic safety of their structural components is very concerned due to the inferior material ductility of those steels. The current studies on bolted high-strength steel T-stubs mainly focus on their monotonic loading behavior. There is limited research work conducted to study their cyclic loading behavior. In this study, cyclic tests of bolted dual-steel T-stubs were conducted. Their T-elements were produced by Q690 high-strength steel flanges and Q355 normal-strength steel webs, and class 10.9 high-strength bolts with pretension were used to connect the groove-welded T-elements. Failure modes, force-deformation hysteretic and backbone curves, cumulative plastic deformation and energy dissipation capacities were tested and analyzed. The test results indicated that an optimal β ratio between the plastic resistances of Mode 1 (neglecting the influence of bolt action on a finite contact area) and Mode 3 in Eurocode 3 Part 1–8, could be 0.3 for those bolted T-stubs to maximize hysteretic energy dissipation. Accordingly, predictive formulas with good precision were proposed for the low-cycle fatigue failure criterion and hysteretic energy dissipation capacity of those bolted T-stubs, respectively.

Effect of Repeated Processing Passes during Ultrasonic Rolling on Fatigue Performance and Corrosion Resistance of Ti6Al4V Alloy

Ultrasonic surface rolling processing (USRP) is a new method to improve the fatigue performance of titanium alloy, and repeated processing pass is an important factor that affects its strengthening effect. The effect of USRP passes on the surface microstructure, residual stress, fatigue performance and corrosion resistance of titanium alloy is researched via SEM, X-ray diffractometer, rotating–bending fatigue test and electrochemical impedance spectroscopy. The results show that Ti6Al4V alloy undergoes cumulative plastic deformation during USRP process, the surface grains are refined and a residual compressive stress field with a thickness of 500 μm is introduced, which together improve the fatigue performance of the Ti6Al4V alloy. Increasing the repeated processing passes will deepen the grain refinement layer and increase the surface hardening effect, but the fatigue life of the Ti6Al4V alloy does not increase with an increase in processing passes. A five-passes processing under a static force of 550 N can result in a greater gain for the fatigue resistance of the Ti6Al4V alloy; the fatigue life of a five-passes-processed sample under 600 MPa is 8 times higher than that of an untreated sample, and its fatigue crack source initiates at the subsurface away from the surface of 180 μm. Furthermore, Ti6Al4V alloys treated by USRP show a better corrosion resistance in both neutral and acidic solutions, especially for the five-passes-processed sample.

Impact of ground motion duration on seismic performance of buckling restrained braced frames

Buckling restrained braced frames (BRBFs) are commonly employed as seismic lateral force resisting system due to their high stiffness and energy dissipation capacity. However, under long-duration strong earthquakes, buckling-constrained braces are susceptible to fracture due to low-cycle fatigue. Previous studies evaluating their seismic performance have not considered the impact of earthquake duration on the results. This study evaluates the impact of ground motion duration on the seismic performance of BRBFs. By employing 44 pairs of spectrally equivalent ground motions with varying durations, the impact of ground motion duration is studied independently from other effects arising from ground motion amplitude and acceleration spectral shape. Nonlinear numerical models considering low-cycle fracture of buckling restrained braces are developed for 4-, 8-, and 12-story archetypes. The effects of ground motion duration on the seismic performance of BRBFs are examined using standard performance and collapse-assessment procedures. The results indicate that under seismic excitations not exceeding the maximum considered earthquake level, ground motion duration does not significantly affect the structural maximum interstory drift, but longer duration generally results in larger cumulative plastic deformation for the buckling restrained brace. Meanwhile, ground motion duration has a significant impact on the results of collapse risk evaluation. In addition, using combined duration- and spectrum-related intensity measure can better evaluate the damage potential of ground motion.

Experimental study on seismic performance of low-yield point steel plate shear walls

This paper studies the seismic performance of the low-yield point steel plate shear wall (LSPSW) by conducting cyclic loading tests on three single-story single-span steel plate shear wall (SPSW) specimens, including a non-stiffened LSPSW (LYP) and a non-stiffened normal strength SPSW (NW). A new LSPSW with steel tube stiffeners (HSS) is then proposed to restrain the out-of-plane deformation of the infill panel. The failure modes, strain development, bearing capacity, stiffness, ductility, energy dissipation capacity, degradation characteristics, and deformation performance of the above three SPSWs are compared and analyzed. Afterwards, the corresponding numerical modeling approaches are developed and verified by the test results. Furthermore, supplementary analyses of the plate-frame interaction in terms of the shear distribution, energy dissipation behavior, and plastic damage performance are performed, and relevant suggestions are provided for the design of SPSW. The experimental and numerical results show that compared with the NW specimen, the use of low-yield point steel in the LYP specimen significantly improves the ductility and energy dissipation capacity of the SPSW, delays the tearing of the infill panels, reduces the residual deformation of the infill panels with higher ability of recovery, and achieves a more uniform distribution of cumulative plastic deformation. The application of steel tube stiffeners in the HSS specimen further enhances the energy dissipation capacity of LSPSW, effectively restrains the out-of-plane deformation of the infill panels, and reduces the impact of the tension strips on the edge columns. The analyses of the plate-frame interaction show that the boundary frame has more contribution to the shear resistance and energy dissipation after using the low-yield point steels for the infill panel. The proportion of shear force borne by the boundary frame is up to 65%–70%, which should be considered in the design procedure to optimize the geometrical dimensions of the infill panel and the boundary frame, allowing to optimize the structural performance and material utilization.

Fretting fatigue behavior and damage mechanism of cast Al-Si-Cu-T6 alloy under two surface roughness conditions

This paper experimentally evaluates the fretting fatigue properties of cast Al-Si-Cu-T6 alloys against nodular cast irons with two surface roughnesses. A softening phenomenon contrary to the cyclic response behavior of plain cyclic loading is pointed out and discovered to be affected by persistent damage and cumulative plastic deformation. Two considerably different roughness conditions produce two entirely distinct damage mechanisms, and a schematic diagram is drawn to illustrate the discrepancy. The initiation and propagation of cracks are not only affected by fretting wear damage but also significantly depend on the microstructure, especially the α-Fe and (β + ω) phases play key roles. The realization of this research comprehensively reveals the fretting damage mechanism of Al-Si cast alloys under two characteristic contact surface states, which serves the fretting failure analysis of aluminum castings in the automotive industry.

Analysis of the Effects of an Unconventional Rolling Process under Cumulative Plastic Deformation Conditions.

This article presents the results of research carried out on an experimental rolling mill with axial, cyclic movement of rolls (RCMR). The device was made on the basis of an unconventional technical solution for the movement of shaping tools and equipped with a complete measuring system recording all the parameters of the process. The research was conducted on selected copper alloys CuFe2 and CuCr0.6. Rolling tests in the RCMR process were carried out for rolling speeds vr = 3.1 × 10-3, 6.3 × 10-3 and 9.4 × 10-3 m/s, which correspond to the rotational speed of the rollers at ω = 1, 2 and 3 rpm for an active diameter of the rollers = 60 mm. In testing the thermal effects of the process, the rolling speed ω = 0.7 rpm was also used. A constant value of the frequency of axial movement of the rollers f = 1 Hz and the amplitude of the displacement of the rollers A = 0.8 mm were assumed. The rolling process for the strands was carried out in six culverts using the average relative crush in the passage of Δh = 15%. Conventional rolling tests were carried out to compare rolling processes, and the obtained data formed the basis for assessing the strain intensity and identifying local deformation zones in the RCMR rolling process. The waveforms of rolling pressures, intensity and non-uniformity of deformation, and increase in the temperature of the strip surface in subsequent culverts were compared with the results obtained in the conventional rolling process.

EVALUATION METHOD FOR CUMULATIVE PLASTIC DEFORMATION OF HYSTERETIC DAMPERS INSTALLED IN SMRF

By yielding under small inter-story deformation, hysteretic dampers installed to a response control structure absorb seismic energy and effectively control the damage to the frame. When designing such a structure, it is important to estimate the maximum deformation and the cumulative plastic deformation of the dampers against ground motions. Especially in the early stage of design, simple methods are useful for the preliminary study of determining the characteristics of the dampers. In this research, the shortcomings of the existing simple methods are discussed and a new method is proposed. Its accuracy and applicability are investigated using numerical examples.

Development and testing of knife-plate connected steel panel dampers

Steel panel dampers (SPDs), consisting of the inelastic panel and elastic connecting segments, have been widely used in steel building structures commonly with brace- or stub-column-type configurations, especially in high seismic regions. The elastic connecting segments of stub-column-type SPDs were usually significantly enlarged to ensure their elasticity under the associated extreme loads of the inelastic panel. With the aim of improving the structural efficiency and ductility capability of SPDs, a novel design, named as knife-plate-connected SPD (KSPD), was proposed in the study. The proposed KSPD consisted of one steel panel and two boundary-columns on the horizontal sides with pinned column ends, which were achieved by knife-plate details, connecting to the framing systems. The designed configuration of KSPDs potentially reduced the aspect ratio of the steel panels for easily achieving shear yielding while remaining the stud-column appearance, and mitigated the deformation amplification of the steel panels usually occurred in conventional stub-column-type SPDs. Five full-scale KSPD specimens with various configurations of the panel stiffeners have been experimentally examined and compared under cyclic loadings including fatigue cycles. The feasibility of the KSPD design was experimentally validated, and the developed KSPDs were verified to achieve stable energy dissipation and significant ductility of approximate ten and cumulative plastic deformation (CPD) value up to 796. For the design purpose of the members, the width-to-thickness limits of the steel panel were established to prevent panel buckling and the sub-panel edge fracture upon the test results, respectively, and a design inequality of the knife plates upon strengths was developed to prevent the fracture of the knife plate. Finally, the design suggestions of the proposed KSPD were summarized upon the experimental results and findings of the study.

Critical Dynamic Stress and Cumulative Plastic Deformation of Calcareous Sand Filler Based on Shakedown Theory

Calcareous sand is a special marine soil rich in calcium carbonate minerals, characterized by brittle particles. It is, therefore, widely used as a filling material in the construction of islands and reefs. In this study, a series of cyclic tri-axial tests were conducted on calcareous sand taken from a reef in the South China Sea under different confining pressures and cyclic stress ratio (CSR). Then, applying the shakedown theory, the cumulative deformation of calcareous sand under a long-term cyclic load of aircraft was evaluated. Results showed that with the increase in the effective confining pressure, the stress–strain curves of calcareous sand showed a change from the strain-softening to the strain-hardening state; the volumetric strain of calcareous sand showed a change from shear shrinkage and then shear expansion to continuous shear shrinkage. Calcareous sand showed three different response behaviors under cyclic load: plastic shakedown, plastic creep and incremental plastic failure. With the plastic strain rate as the defining index, this study determined the critical CSR of calcareous sand under different shakedown response statuses and found them to increase with the effective confining pressure. The empirical formula for critical stress was established based on the fitting analysis of critical CSR under different confining pressures, taking the confining pressure as the variable. At the early stage of the cyclic load, calcareous sand samples were under compression. When the resilient modulus grew rapidly and the number of loading cycles continued to increase, the particles of calcareous sand samples were crushed, causing the fine particles to fill the voids among coarse particles, further compacting the samples and increasing the resilient modulus of calcareous sand samples. Hardin’s breakage potential model was adopted to quantitatively describe the particle breakage of calcareous sand samples before and after tests. The results indicated that calcareous sand samples produced obvious particle breakage when the CSR was small. As the CSR increased, the extent of the breakage of the sample particles first increased and thereafter stabilized. This study provides a theoretical reference for the assessment of the dynamic stability of calcareous sand subgrade subjected to traffic loads.