Pre-existing Fissures Research Articles

Experimental evaluation on rock failure mechanism with combined flaws in a connected geometry under coupled static-dynamic loads

Flaws in different geometries are widely existed in rock masses and play a significant role in the stability of rock engineering structures. To investigate the failure mechanisms of rock block with combined flaws under coupled static and dynamic loads, a series of experiments were conducted on granite containing pre-existing fissures in the vicinity of a circular opening by using a modified split Hopkinson pressure bar (SHPB) device. Digital image correlation (DIC) method was applied to record the real-time cracking processes. The results show that the fissure inclination angle and the number of fissure are important factors affecting the mechanical properties and cracking processes. The strength of specimens shows a decrease trend with fissure inclination angle increasing, and the localized strain of fissure tip can be used to identify and reveal the crack initiation in the experiments. Based on the temporal and spatial evolution rules of principal strain field obtained by DIC technique, the crack sequences and crack paths of typical specimens are summarized in the paper, especially the crack initiation position. The roof, floor of the opening and the fissure tip are the critical zones where the new cracks usually initiate from. The crack types of the specimens can be categorized as wing crack, coplanar secondary crack, oblique secondary crack, tensile crack and shear crack based on the observation of the failure processes.

Peridynamic simulation on fracture mechanical behavior of granite containing a single fissure after thermal cycling treatment

Abstract In this study, the thermal-mechanical fracturing behaviors of granite after thermal cycling treatment are investigated using the fully coupled ordinary state-based peridynamic method. First, two benchmark examples: transient heat conduction and crack propagation, are conducted to test the numerical convergence and calibrate the simulation parameters. Then, a new method for accurately reflecting the mineral compositions and the corresponding characteristics is proposed to simulate the heterogeneity property of rock materials. Based on the latter, the thermal microcracking behaviors of granite induced by the incompatible expansion between different minerals under thermal cycling treatment (infrared-radiation-heating stage, constant-temperature stage and natural-cooling stage) are simulated. Finally, the numerical specimens of a granite material containing a single pre-existing fissure with various fissure inclination angles under uniaxial compression after thermal cycling treatment are modeled. Correspondingly, the methods for reducing the unexpected failure caused by a thermal shock are discussed. The combination effect of the temperature and fissure inclination angle on the stress-strain response as well as the crack evolution processes is also systematically investigated, and the corresponding characteristics of crack initiation, propagation, and coalescence modes are discussed and summarized.

Experimental Study of the Mechanical Characteristics of a Rock‐Like Material Containing a Preexisting Fissure under Loading and Unloading Triaxial Compression

An experimental study of a rock‐like material containing a preexisting fissure subjected to loading and unloading triaxial compression is carried out, and the results show that the mechanical characteristics of the rock‐like specimen depend heavily on the loading paths and the inclination of the fissure. The triaxial loading experiment results show that the failure strength linearly increases, while the residual strength linearly decreases with increasing inclination. Furthermore, specimens subjected to triaxial compression show an “X”‐type shear failure mode. The triaxial unloading compression experimental results show that specimens with different inclination angles have various failure modes. Specimens with gentle inclinations show a tensile‐shear mix failure mode, specimens with middle inclinations show a shear‐sliding failure mode, and specimens with steep inclinations show a tensile failure mode. These findings can be used to forecast excavation‐induced instabilities in deep underground engineering rock structures.

Real-time experiment investigations on the coupled thermomechanical and cracking behaviors in granite containing three pre-existing fissures

This paper investigates the coupled thermomechanical (TM) behavior, in real time, of granite containing three pre-existing fissures under uniaxial compression. The ligament angle spans from 75° to 120° with an interval of 15°, and the testing temperature varies from 25 °C to 700 °C. The strength and deformation of the granite are first considered as functions of the temperature and the ligament angle. The elastic modulus of the granite greatly decreases at 400 °C, and uniaxial compression strength of the granite substantially decreases at 600 °C. The fracturing behavior of the granite specimens depends on not only the temperature but also the fissure array. For relatively small ligament angles, the crack coalescence pattern only depends on the ligament angle, while for relatively large ligament angles, the crack coalescence pattern depends on both the ligament angle and the temperature. The granite specimens mainly exhibit tensile failure modes at 25–300 °C, the brittle-ductile transition occurs at 300 °C, the granite specimens experience a mixed tensile-shear failure mode at 300–400 °C, and they experience a shear failure mode at T = 400–700 °C. Moreover, the thermal damage of the granite is analyzed by thin section observation and electron microscopy scanning (SEM). Thermally induced micro-cracks in the granite mainly include intercrystalline cracks and intracrystalline cracks, which occur dramatically at T = 400–700 °C. Electron probe micro analyzer (EPMA) experimental results show that the physical properties of the granite are considerably affected by temperature, while the chemical composition of the minerals remains unchanged at T = 25–700 °C. The damage to the microstructure of the granite at high temperatures is caused by physical changes rather than chemical changes.

Effects of pre-existing fissures on surface macro-crack characteristics of granite subjected to elevated temperatures

Effects of pre-existing fissures on surface macro-crack characteristics of granite subjected to elevated temperatures

Experimental study on failure characteristics of jointed rock mass under staged unloading conditions

Strength and deformability characteristics of rock with pre-existing fissure are governed by cracking behavior. To further research the effects of pre-existing fissures on the mechanical properties and crack coalescence process under staged unloading conditions, a series of uniaxial compression tests were carried out. In this study, cement, fine sand, and water were used to fabricate a kind of brittle rock-like material rectangular model specimen. The mechanical properties of rock-like material specimen used in this research were all in good agreement with the brittle rock materials. The pre-existing fissure was created by mica sheets and the unloading zone was created by pre-filling Polylactic acid (PLA) resin material during the molding processes the model specimen. And the staged unloading test was conducted based on polylactic acid’s hot-melt characteristics. In order to investigate the crack initiation, propagation and coalescence process, inclination angle of pre-existing fissure was set to change from 0° to 90°. The mechanism of crack propagation and coalescence under photographic monitoring was discussed. And these experimental results indicate that the failure modes in the zone above unloading zone mainly consist of four modes: separation failure, shear-slip failure, mixed shear-separation failure and compression-shear failure. The experimental results are also expected to increase the understanding of the strength failure behavior and the cracking mechanism of rock under staged unloading.

Effect of High Temperature on Deformation Failure Behavior of Granite Specimen Containing a Single Fissure Under Uniaxial Compression

To investigate the role of fissure angle and heat treatment temperature on the mechanical properties and deformation failure behavior, uniaxial compression tests were carried out on granite specimens containing a single fissure. Using stress–strain curves, the peak strength, peak strain, and elastic modulus of the one-fissured granite specimens were analyzed in detail. The mechanical parameters are closely related to the fissure angle and the high temperature. As the fissure angle increases from 0° to 90°, the peak strength and elastic modulus first decrease and then increase, while the peak strain increases slowly. However, the peak strength and elastic modulus first increase and then decrease, while the peak strain first decreases and then increases with increasing treatment temperature. During the experiments, the crack evolution process and acoustic emission (AE) counts were obtained using real-time photography and the AE monitoring technique. In the granite specimens containing a pre-existing fissure, large AE counts are clearly observed before the peak strength, which indicates crack initiation and propagation. The accumulated AE count first increases slowly, but is followed by a sharp increase, with increasing deformation. The AE events in the one-fissured specimen also depend on the heat treatment temperature. As the temperature increases, the rate of increase of the accumulated AE count curve is reduced. Finally, using a digital image correlation method, the full fields of surface deformation were obtained for the entire testing process. In addition, the local strain around the pre-existing fissure was measured using strain gauges. The full strain field and local strain concentration are discussed to describe the fracture mechanism of brittle granite.

Creep Investigation on Shale‐Like Material with Preexisting Fissure under Coupling Temperatures and Confining Pressures

In order to investigate the influence of temperature, confining pressure, and preexisting fissure on creep characteristics of rock mass, multistage creep experiments were performed on shale‐like material, with preexisting fissure under different temperatures and confining pressures. The results showed that new microcracks generated and propagated with the increase of temperature in both uniaxial and triaxial creep experiments, and the generation and propagation were most pronounced at 60°C and least at 20∼50°C in uniaxial creep experiments. The generation and propagation were restricted by confining pressure. Temperature had less influence on the creep strain rate in triaxial creep experiment, whereas it had a significant influence on the steady‐state creep rate in uniaxial creep experiment. The influence of confining pressure on the steady‐state creep rate was slight when confining pressure was 1 MPa, whereas it was obvious when confining pressure was 3∼7 MPa. The closure of preexisting fissure promoted the creep strain rate, and the closure was incomplete when confining pressure was below 3 MPa, whereas it was complete when confining pressure at 5 and 7 MPa.

Acoustic‐Mechanical Responses of Intact and Flaw‐Contained Rock Deformation under Uniaxial Compression: A Comparison

The study of the mechanical properties and cracking behaviors of jointed rock masses is important in rock engineering projects. In the present study, a series of uniaxial compression experiments were conducted on intact rock, and rock masses with single or double preexisting flaws, and then the strength, deformability, and fracture behavior of samples are investigated. Moreover, photographic monitoring technique and emission monitoring technique are introduced to explore the fracturing mode and the acoustic emission (AE) evolution characteristic of fractured rock during the whole loading process. The obtained results show that the preexisting flaw has a strong influence on the mechanical properties, fracture behavior, and AE characteristic of sandstone specimens. In detail, the stress‐strain curves show that no significant stress jump occurs at prepeak and postpeak points for intact sandstone specimens; however, the flaw‐contained sandstone specimens exhibit distinct stress jump during the entire loading process. Meanwhile, the strength parameters of the the rock specimen is obviously weakened by the preexisting fissures, and the uniaxial compression strength of rock specimens generally decreases with the increase in the number of preexisting fissure as well as the peak strain and the elastic modulus. The failure modes of intact and flaw‐contained sandstone specimens exhibit the splitting failure and the mixed failure modes of shear and tension, respectively. Similarly, the maximum AE counts and AE energy both decrease with the increasing number of preexisting flaw. The present research can enhance the understanding of mechanical properties, cracking behaviors, and failure mechanism of jointed rock mass.

Influence of fissure inclination and confining pressure on the local behaviour of natural clays

In this experimental study the influence of fissuring orientation and confinement pressure on the mechanical behaviour of natural clays is investigated. The tested material, the scaly clay from Santa Croce di Magliano (south of Italy), is characterised by an intense network of pre-existing fissures of single orientation. Several plane strain compression tests have been conducted, under different confinement pressures (i.e., from 50 to 600 kPa), on specimens having fissures with vertical, medium and horizontal inclination. Digital Image Correlation has been used to follow the deformation processes of the specimens throughout the tests by measuring incremental shear and volumetric strain maps. The results showed a strong coupling between the total confinement and the fissure inclination, that is controlling both the onset and the development of the patterns of the localisation processes. The new results have been compared with previous ones carried out on the same material without confinement. The comparison shed light on the role of total confinement that becomes particularly relevant from certain levels of pressures and fissuring inclination.

Mechanical behaviors of rock-like specimens with two non-coplanar fissures subjected to coupled static-dynamic loads

Fissured rocks, widely existing in underground engineering structures, are quite sensitive to coupled static-dynamic loading conditions. Understanding the mechanical properties of fissured rocks under coupled loads is significant for the rational design and stability analysis of underground rock engineering projects. This study experimentally investigated the effect of coupled static-dynamic strain rates on the mechanical behaviors of synthetic rock models containing two non-coplanar fissures. Our results revealed that the mechanical properties of fissured specimens are highly dependent on the dynamic strain rate under same static pre-stress. Nevertheless, under same dynamic strain rate, the variation of the mechanical behavior of fissured specimens is not monotonous with increasing static pre-stress; the coupled strength and elastic modulus of fissured specimens feature an increase as the static pre-stress increases from 0 to 50% uniaxial compression strength (σc), and then decrease when the static pre-stress ranging from 50% to 80% σc. In view of energy principles, the fissured specimen with higher dynamic strain rate is characterized by more dissipated energy during the loading process and more released elastic energy at the end of loading under same dynamic strain rate. However, the greatest released elastic energy of fissured specimen occurs under the static pre-stress of 50% σc. The splitting tensile failure is prominent in all recovered fissured specimens under coupled static-dynamic loads, and the two inner tips of preexisting fissures are coalesced with a typical tensile wing crack.

The length of pre-existing fissure effects on the dilatancy behavior, acoustic emission, and strength characteristics of cracked sandstone under different confining pressures

It is significant to study the dilatancy behavior and strength characteristic of cracked rock to ensure the stability and safety of engineering rock mass. Consequently, the effects of the length of pre-existing fissures and confining pressure on the strength characteristic of sandstone specimens were analyzed, and the dilatancy and acoustic emission (AE) behaviors of sandstone specimens with different lengths of pre-existing fissures under different confining pressures were discussed. The rationality of the stress of dilatancy onset can be as the strength parameter of rock is explained from the cohesion and internal friction characteristics of rock material and its dilatancy behavior. The results show that the strength parameters of sandstone specimens are negative related to the length of pre-existing fissures, but positive related to the confining pressure. The difference between the stress of dilatancy onset and peak strength decreases with the increase of length of pre-existing fissures, but increases with confining pressure, which is related to the internal friction characteristic of rock material. Under the condition of uniaxial compression or low confining pressure, the obvious stress drop easily occurs after the dilatancy onset, and the frequency of this phenomenon is positive related to the length of pre-existing fissures. However, this phenomenon gradually decreases with the increase of confining pressure, it correspondingly transforms to the emergence of yield platform. No matter what occurrence of stress drop or yield platform, all the cracked rock specimens show the special characteristics of drastic increase of volume dilatancy, active AE signals, and full evolution of cracks. After the dilatancy onset, it seems to be more insecure from the way to obtain the higher strength parameters by the frequent occurrence of cohesive particles fracture in rock, and the rock material can still rely on crack friction to load. In addition, from the dilatancy behavior of rock material, it seems that the large deformations always appear after the dilatancy onset, which is more likely to cause the potential engineering danger.

Experimental study on mechanical properties and failure modes of low-strength rock samples containing different fissures under uniaxial compression

Uniaxial compressive tests (UCS) were carried out to investigate the influence of pre-existing fissure geometry parameters (various dip angles, lengths, widths, and numbers) on the mechanical properties and deformation failure modes of low-strength rock samples. The results suggested that UCS, elastic modulus and axial peak strain were reduced by pre-existing fissures, but the reduction degree was strongly associated with the pre-existing fissure geometry. In addition, the UCS and elastic modulus of the low-strength rock samples were very sensitive to fissure dip angle and number, while the fissure number had the greatest effect on both of them. The axial peak strain was mainly influenced by the fissure dip angle. Moreover, due to the influence by the pre-existing fissures, the stress-strain curves of low-strength rock specimens usually changed from rapid drop to multistage decline, and even to horizontal extension slow decline. This indicated that low-strength specimens usually can change from brittle failure to ductile failure, and even had ductile flow deformation damage occurring under the influence of the pre-existing fissures. This change did not occur in high-strength rock mass. The fracture morphology of low-strength rock specimens was primarily affected by the fissure dip angle, and the influence of the fissure number on the fracture morphology was constrained by the fissure dip conditions, while the fissure length and width had fairly little effects on the fracture morphology of low-strength rock samples. This paper may provide new insights into the principle features of rock failure under uniaxial compression for future studies.

Effects of coupled static and dynamic strain rates on mechanical behaviors of rock-like specimens containing pre-existing fissures under uniaxial compression

Rocks containing pre-existing fissures in underground engineering are likely to be subjected to static pre-stress and dynamic loads simultaneously. Understanding the deformation and failure mechanism of fissured rocks under coupled static and dynamic strain rates is beneficial for the stability assessment of rock engineering structures. This study experimentally investigates the mechanical behaviors of fissured specimens under coupled static and dynamic loads with different loading parameters. Our experiments reveal that the coupled static–dynamic strain rates significantly affect the strength, deformation, energy characteristics, and failure mode of fissured specimens. For each dynamic strain rate, the strength and elastic modulus of specimens feature an increase first as the static pre-stress increases up to half of the uniaxial compression strength, and then a decrease. However, for each static pre-stress of coupled loads, the strength and elastic modulus increase noticeably with increasing dynamic strain rate. From the perspective of energy partition, for each static pre-stress, the higher dynamic strain rate induces greater energy dissipation of the specimens during the coupled loading, and more elastic energy is released at the end of loading. Moreover, for each dynamic strain rate, the pre-stress of half uniaxial compression strength induces the highest released elastic energy.

Effect of the Preexisting Fissure with Different Fillings in PMMA on Blast‐Induced Crack Propagation

In order to study the dynamic crack propagation law in fissured rock under the different fillings, a borehole with 7 mm diameter was processed in the center of a polymethyl methacrylate (PMMA) specimen. The preexisting fissure with different angles (θ = 0°, 45°, and 90°) and different distances (L = 20, 30, 40, 50, and 60 mm) was prefabricated around the borehole. Air, soil, and water were employed as fillings in the fissure, respectively. The experiment of explosive loading was carried out by a single detonator, and the dynamic crack propagation process of the experimental specimens was simulated by nonlinear dynamics software AUTODYN. The results show that the blast‐induced cracks are the most favorable and unfavorable to propagate when θ = 0° and θ = 45°, respectively. The length of the far‐end wing crack decreases with the increase of the distance L, and the length of the far‐end wing crack in the air‐filled specimens is larger than those in soil‐filled and water‐filled specimens. The damage‐pressure curve of the far‐end wing crack initiation point shows “S”‐type change, and the damage‐pressure curve shows two obvious damage evolution processes of initial nonlinear and later linear stages. With the increase of the angle, the distance from the borehole to the crack initiation point decreases and the compressive stress wave peak value should increase, but the tensile force peak value decreases. Meanwhile, the relationships between pressure and average velocity of the initiation point and L, θ, and fillings are established, respectively. The numerical simulation agrees with the experimental results well. It can be seen that the fillings types, angle, and distance have a mutual restraint relationship with the reflected and absorbed stress wave energy. The phenomenon of crack propagation under different fillings can be explained well from the viewpoint of discontinuity degree and stress wave energy, which reveals the general law of blast‐induced crack propagation.

The length of pre-existing fissures effects on the mechanical properties of cracked red sandstone and strength design in engineering

It is important to study the mechanical properties of cracked rock to understand the engineering behavior of cracked rock mass. Consequently, the influence of the length of pre-existing fissures on the strength, deformation, acoustic emission (AE) and failure characteristics of cracked rock specimen was analyzed, and the optimal selection of strength parameter in engineering design was discussed. The results show that the strength parameters (stress of dilatancy onset and uniaxial compressive strength) and deformation parameters (axial strain and circumferential strain at dilatancy onset and peak point) of cracked rock specimen decrease with the increase of the number of pre-existing fissures, and the relations which can use the negative exponential function to fit. Compared with the intact rock specimens, the different degrees of stress drop phenomena were produced in the process of cracked rock specimens when the stress exceeds the dilatancy onset. At this moment, the cracked rock specimens with the existence of stress drop are not instantaneous failure, but the circumferential strain, volumetric strain and AE signals increase burstingly. And the yield platform was presented in the cracked rock specimen with the length of pre-existing fissure more than 23mm, the yield failure was gradually conducted around the inner tip of pre-existing fissure, the development of original fissures and new cracks was evolved fully in rock. However, the time of dilatancy onset is always ahead of the the time of that point with the existence of stress drop. It indicates that the stress of dilatancy onset can be as the parameter of strength design in rock engineering, which can effectively prevent the large deformation of rock.

Experimental study on cracking behaviour of moulded gypsum containing two non-parallel overlapping flaws under uniaxial compression

Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour.

The observation of AE events under uniaxial compression and the quantitative relationship between the anisotropy index and the main failure plane

In this paper, the P-wave velocities in different directions of sandstone samples under uniaxial compression are measured. The results indicate that the changes in the P-wave velocity in different directions are almost the same. In the initial stage of loading, the P-wave velocity exhibits a rising trend due to compaction and closure of preexisting fissures. As the stress increase, preexisting fissures are closed but induced fractures are not yet generated. The sandstone samples become denser and more uniform. The P-wave velocity remains in a steady state at a high level. In the late stage of loading, the P-wave velocity drops significantly due to the expansion and breakthrough of induced fractures. The P-wave velocity anisotropy index ε is analyzed during the process of loading. It can be observed that the change in the degree of wave velocity anisotropy can be divided into three stages: the AB stage, the BC stage and the CD stage, with a changing trend from decline to incline. In the initial stage of loading, the preexisting fissures have a randomized distribution, and the change is large-scale and uniform. The difference in each spatial point decreases gradually, and synchronization increases gradually. Thus, the P-wave velocity anisotropy declines. As the stress increases gradually, with the expansion and breakthrough of induced fractures, the difference in each spatial point increases. Before failure of rock samples, the violent change region of the rock samples' internal structure is focused on a narrow two-dimensional zone, and the rock samples' structural change is obviously local. Therefore, the degree of velocity anisotropy rises after declining, and it also has good corresponding relation among the AE count, the location of AE events and the degree of wave velocity anisotropy. The projection plane of the main fracture plane on the axis plane is recorded as M plane. Based on the AFF equation, for the CD stage, we analyze the quantitative relationship between the velocity anisotropy index ε and angle θ, which is the difference between the angle of the M plane and the X plane and the angle of the M plane and the Y plane from the theoretical point. The results indicate that 1ε and cotθ2 have good negative linear relationship that can be expressed as cotθ2=a∗1ε+b. According to experimental data, the linear fit of 1ε and cotθ2 is found, obtaining cotθ2=−0.04721ε+0.03, with a linear fit index of 0.908. From an experimental point of view, the linear relationship between 1ε and cotθ2 is verified. Through this research, we propose a new method for quantitatively predicting the main fracture occurrence position by P-wave velocity anisotropy. This work has an important significance for understanding buckling failure of rocks.

Mechanical behavior and failure analysis of granite specimens containing two orthogonal fissures under uniaxial compression

The mechanical behavior, crack initiation stress, cracking modes, and crack coalescence process due to uniaxial compressive loading for brittle granite specimens (70 × 140 × 29 mm in size) containing two orthogonal fissures with different “virtual ligament length” were first modeled experimentally. Intact granite specimens present typical axial splitting failure, and the ultimate failure of specimens containing a single fissure results mainly from tensile cracks initiated from the fissure tips. Basically, mechanical parameters of granite specimens containing two orthogonal fissures are lower than the values for intact specimens, and the reduction extent is distinctly related to the virtual ligament length. The uniaxial compressive strength, peak axial strain, Young’s modulus, secant Young’s modulus, and crack initiation stress of granite specimens containing two orthogonal fissures present the same trend with the increasing virtual ligament length, i.e., first decrease and then increase, finally once again decrease. The effect of virtual ligament length on the crack initiation type and ultimate failure modes of granite specimens containing two orthogonal fissures is analyzed. Crack types based on the fissure geometry and crack propagation mechanism are identified, and three different crack initiation types are summarized. The crack coalescence is observed and characterized from tips of pre-existing fissures. Relation between the real-time cracking process and axial stress–strain curves of granite specimens containing two orthogonal fissures for the entire deformation process is captured, and the corresponding axial stress for crack coalescence is also obtained. Each sharp stress drop in axial stress–strain curves indicates an obvious crack coalescence.

Modelling ground rupture due to groundwater withdrawal: applications to test cases in China and Mexico

Abstract. The stress variation induced by aquifer overdraft in sedimentary basins with shallow bedrock may cause rupture in the form of pre-existing fault activation or earth fissure generation. The process is causing major detrimental effects on a many areas in China and Mexico. Ruptures yield discontinuity in both displacement and stress field that classic continuous finite element (FE) models cannot address. Interface finite elements (IE), typically used in contact mechanics, may be of great help and are implemented herein to simulate the fault geomechanical behaviour. Two main approaches, i.e. Penalty and Lagrangian, are developed to enforce the contact condition on the element interface. The incorporation of IE incorporation into a three-dimensional (3-D) FE geomechanical simulator shows that the Lagrangian approach is numerically more robust and stable than the Penalty, thus providing more reliable solutions. Furthermore, the use of a Newton-Raphson scheme to deal with the non-linear elasto-plastic fault behaviour allows for quadratic convergence. The FE – IE model is applied to investigate the likely ground rupture in realistic 3-D geologic settings. The case studies are representative of the City of Wuxi in the Jiangsu Province (China), and of the City of Queretaro, Mexico, where significant land subsidence has been accompanied by the generation of several earth fissures jeopardizing the stability and integrity of the overland structures and infrastructure.