Slip Displacement Research Articles

3D Finite Element Analysis of Fault Displacements in the Nobi Fault Zone, Japan

The Nobi fault zone, which generated the 1891 Nobi Earthquake (M8.0), includes five or six faults distributed in and around Gifu and Aichi prefectures, Japan. Because large cities are located near the fault zone (e.g., Gifu and Nagoya), and because the zone will likely be reactivated in the future, relatively thorough surveys have been conducted on the 1891 Nobi earthquake event, examining the fault geometry, house collapse rate, and the magnitude and distribution of earthquake intensity and fault displacement. In this study, we calculated the earthquake slip along faults in the Nobi fault zone by applying a 3D numerical analysis. The analysis shows that a zone with slip displacements of up to 100 mm included all areas with house collapse rates of 100%. In addition, the maximum vertical displacement was approximately ± 1700 mm, which is in agreement with the ± 1400 mm or greater vertical displacements obtained in previous studies. The analysis yielded a fault zone with slip displacements of > 30 mm that is coincident with areas in which house collapse rates were 60% of more. The analysis shows that the regional slip sense was coincident with areas of uplift and subsidence caused by the Nobi earthquake.

3D modeling of earthquake cycles of the Xianshuihe fault, southwestern China

We perform 3D modeling of earthquake generation of the Xianshuihe fault, southwestern China, which is a highly active strike-slip fault with a length of about 350km, in order to understand earthquake cycles and segmentations for a long-term forecasting and earthquake nucleation process for a short-term forecasting. Historical earthquake data over the last 300years indicates repeated periods of seismic activity, and migration of large earthquake along the fault during active seismic periods. To develop the 3D model of earthquake cycles along the Xianshuihe fault, we use a rate- and state-dependent friction law. After analyzing the result, we find that the earthquakes occur in the reoccurrence intervals of 400–500years. Simulation result of slip velocity distribution along the fault at the depth of 10km during 2694years along the Xianshuihe fault indicates that since the third earthquake cycle, the fault has been divided into 3 parts. Some earthquake ruptures terminate at the bending part of the fault line, which may means the shape of the fault line controls how earthquake ruptures. The change of slip velocity and displacement at 10km depth is more tremendous than the change of the shallow and deep part of the fault and the largest slip velocity occurs at the depth of 10km which is the exact depth of the seismic zone where fast rupture occurs.

An unload-induced direct-shear model for granular gouge friction in rock discontinuities.

The experimental study introduces an unload-induced direct-shear model to investigate the frictional slip of a layer of simulated granular gouges induced by the combination of a decreasing normal stress and a constant shear stress. A frictional equilibrium state of the gouge layer is initially established under fixed normal and shear stresses. The normal stress is proposed to decrease at a constant unloading rate to induce the frictional slip of the gouge layer, and the shear stress is proposed to keep a constant value during the test. A displacement meter and load cells synchronously measure the slip displacement and the applied normal and shear stresses, respectively. The normal and shear stresses sharply decrease with the frictional slip, owing to damage of gouge contacts. The frictional slip is then gradually arrested with new formation of gouge contacts. A greater initial shear stress induces larger normal and shear stress reductions and a smaller slip displacement. The strain energy stored in the discontinuous system before the frictional slip is found to affect the slip displacement. The advantages and the limitations of this model are discussed at the end.

Determination of the shakedown limit for large, discrete frictional systems

It has been shown that complete frictional contacts subjected to cyclic loads can shake down such that the interface becomes fully stuck after some number of cycles (even if partial-slip occurs at the onset of loading). However, if the amplitude of the cyclic load is greater than a particular value (the shakedown limit), it is impossible for shakedown to occur. In this paper, we examine a numerical approach for determining the shakedown limit for elastic frictional systems subjected to quasi-static loads using a discrete formulation. We then use this technique to determine the shakedown limit for a finite element model of a (coupled) complete contact with ∼50,000 total degrees of freedom and ∼250 along the contact interface. Finally, we compare the calculated value of the shakedown limit to a series of over 1000 transient simulations and investigate the influence of initial conditions on steady state frictional energy dissipation. The results demonstrate that the dissipative properties of complete contacts can be highly dependent on the initial residual slip displacement state.

Existence and uniqueness of attractors in frictional systems with uncoupled tangential displacements and normal tractions

We consider the class of two or three-dimensional discrete contact problems in which a set of contact nodes can make frictional contact with a corresponding set of rigid obstacles. Such a system might result from a finite element discretization of an elastic contact problem after the application of standard static reduction operations. The Coulomb friction law requires that the tractions at any point on the contact boundary must lie within or on the surface of a ‘friction cone’, but the exact position of any ‘stuck’ node (i.e., a node where the tractions are strictly within the cone) depends on the initial conditions and/or the previous history of loading. If the long-term loading is periodic in time, we anticipate that the system will eventually approach a steady periodic cycle.Here we prove that if the elastic system is ‘uncoupled’, meaning that changes in slip displacements alone have no effect on the instantaneous normal contact reactions, the time-varying terms in this steady cycle are independent of initial conditions. In particular, we establish the existence of a unique ‘permanent stick zone’ T comprising the set of all nodes that do not slip after some finite number of cycles. We also prove that the tractions and slip velocities at all nodes not contained in T approach unique periodic functions of time, whereas the (time-invariant) slip displacements in T may depend on initial conditions.Typical examples of uncoupled systems include those where the contact surface is a plane of symmetry, or where the contacting bodies can be approximated locally as half spaces and Dundurs’ mismatch parameter β=0. An important consequence of these results is that systems of this kind will exhibit damping characteristics that are independent of initial conditions. Also, the energy dissipated at each slipping node in the steady state is independent of initial conditions, so wear patterns and the incidence of fretting fatigue failure should also be so independent.

The Fethiye–Burdur Fault Zone: A component of upper plate extension of the subduction transform edge propagator fault linking Hellenic and Cyprus Arcs, Eastern Mediterranean

The Hellenic and Cyprus Arcs, that mark the convergent boundary of the African and Aegean–Anatolian plates, are offset along a subduction transform edge propagator (‘STEP’) fault running NE–SW along the Pliny and Strabo Trenches. The continuation of the fault to the northeast through the Rhodes Basin and into SW Anatolia is assessed. Seismic reflection profiles show that the structural architecture of the northern sector of the Rhodes Basin includes a large crustal-scale fold–thrust belt which is overprinted by numerous faults with small extensional stratigraphic separations. A protracted episode of convergence in the Miocene resulted in the development of a prominent NE–SW-striking and NW-verging fold–thrust belt in the Rhodes Basin. The absence of evaporites in the Rhodes Basin and several seaward prograded vertically stacked Quaternary delta successions resting at 2500–3500m water depth collectively suggest that the Rhodes Basin must have remained above the depositional base of marine evaporite environment during the Messinian and that the region must have subsided very rapidly during the Pliocene-Quaternary. During the Pliocene-Quaternary, a NE–SW-trending belt developed across the Rhodes Basin: while the structural framework of this belt was characterised by reactivated thrusts in the central portion of the basin, a prominent zone of NE–SW-striking and NW- and SE-dipping faults with extensional separations developed in the northern portion of the basin. Two seismic profiles running parallel to the present-day coastline provide the much needed linkage between the Fethiye–Burdur Fault Zone onland and the reactivated thrusts in central Rhodes Basin, and show that the Pliocene-Quaternary zone of high-angle faults with extensional separations clearly link with the similarly trending and dipping strike–slip faults onland in the Eşen Valley, thus providing the continuity between the Pliny–Strabo Trenches in the southwest and the Fethiye–Burdur Fault Zone in the northeast. Mapping of many faults in parts of the Fethiye–Burdur Fault Zone shows evidence for sinistral strike–slip but total displacement across the fault zone is at maximum a few tens of kilometres. The STEP fault thus appears to have diminishing displacement associated with it as it propagates upwards into the upper plate from its originating tear in the subducting plate.

Source study of the Jan Mayen transform fault strike-slip earthquakes

Seismic source parameters of oceanic transform zone earthquakes have been relatively poorly studied. Previous studies showed that this type of earthquakes has unique characteristics such as not only the relatively common occurrence of slow events with weak seismic radiation at high frequencies but also the occurrence of some events that have high apparent stress indicating strong high frequency radiation. We studied 5 strike-slip earthquakes in the Jan Mayen fracture zone with magnitudes in the range of 5.9<Mw<6.7. We determined finite-fault slip distributions with the iterative deconvolution method from teleseismic data. The slip models were characterized by determining source parameters on the asperities and background areas. We found that the areas of the asperities represent about 23–28% of the total rupture area with two different criteria based on average slip and maximum displacement. Sensitivity tests were carried out to estimate the variability of slip patterns and source parameters. We observed robust solutions and reliable source parameter estimates from the models. We also determined the radiated seismic energy and apparent stress in order to identify possible slow events. Our results suggest that the analyzed events in Jan Mayen have a regular nature in terms of apparent stress, seismic energy and centroid time delay compared to other oceanic transform fault earthquakes.

Lumbar Facet Joint Orientation in Degenerative Spondylolisthesis: The Role of Ethnic Variation in Asia Pacific—A Study from the AOSAP Research Collaboration

Introduction Degenerative spondylolisthesis (dSpl) can lead to various symptoms, including low back pain. Lumbar facet joint orientation has been reported to be associated with the development of dSpl. The role of ethnicity regarding facet joint orientation remains uncertain. As such, the following study was performed across a wide-ranging population base to assess the role of ethnicity in facet joint orientation in patients with dSpl in the Asia Pacific region. Materials and Methods A multinational, multiethnic cross-sectional image-based study was performed in 34 institutions in Asia Pacific, identifying 448 cases. Lateral standing X-rays and axial MRIs and/or CT scans were obtained for patients with lumbar dSpl. Magnitude of slip displacement, level of dSpl, and left/right facet joint angulation, width-curvature ratio, and gap width were noted on image assessment. Facet joint measurements were performed at each level from L3-S1. Gender, age, BMI, and ethnicity were also noted. Results The study included 389 patients with known ethnic origin (mean age: 61.4 years; 36.7% males, 63.3% females). The mean BMI was 25.6 kg/m2. The level of dSpl was most prevalent at L4/L5 (72.4%). There were 28.8% Indian, 28.5% Japanese, 17.5% Chinese, 8.2% Korean, 6.2% Thai, 4.6% Caucasian, 2.3% Filipino, 2.3% Malay, and 1.3 were of mixed Asian origin. Accounting for patient demographics and displacement, there was a statistically significant difference between ethnicity to that of left/right facet joint angulations, width-curvature ratios, and gap widths from L3-S1 between specific ethnic groups ( p &lt; 0.05). Conclusion This is the largest study to address the role of ethnicity upon lumbar facet joint orientation in dSpl. Ethnicity plays a role in facet joint orientation and may influence the occurrence and severity of dSpl or be a potential consequence. An understanding of ethnic variability may be one factor which assists in identifying those patients at risk of postsurgical development or progression of dSpl. Acknowledgments This study was funded by AOSpine Asia Pacific. Disclosure of Interest None declared

Facet Joint Tropism and Degenerative Spondylolisthesis—A Study from the AOSAP Research Collaboration

Introduction Degenerative spondylolisthesis (dSpl) is translation of the vertebral body in relation to adjacent levels, mainly attributed to degenerative changes of the intervertebral disc and facet joint complexes, and primarily occurs at L4-L5. Studies have suggested that more sagittal oriented facet joints at L4-L5 are associated with dSpl. However, the role of facet joint tropism (i.e., asymmetry between facet joint orientations) in L4-L5 dSpl remains inconclusive, in particular, in an Asian population and possibly attributed to nonstandardized definitions of tropism. As such, the following study addressed the role of facet joint tropism in relation to L4-L5 dSpl in the Asia Pacific region. Materials and Methods A multinational, multiethnic cross-sectional image-based study was performed in 34 institutions in the Asia Pacific region. Lateral standing radiographs and axial MRIs and/or CT scans were obtained for patients diagnosed with lumbar dSpl. Imaging assessment consisted of the following: magnitude of slip displacement, level of spondylolisthesis, and left/right L4-L5 facet joint angulations were noted on image assessment. Patients with single level dSpl were included. Patients were further stratified into those presenting with (Group A) or without (Group B) L4-L5 dSpl. Facet joint tropism was defined as 7 degrees difference (Grogan et al 1997) between left and right facet joints and also assessed on receiver operating characteristics (ROC) curve analysis to identify critical values for multivariate analysis. Gender, age, weight/height (body mass index [BMI]), and ethnicity were also noted. Results The study included 351 patients (36.9% males and 63.1% females) with a mean age of 61.8 years (range: 24-90 years). The mean BMI was 25.6 kg/m2 (range: 15.4-43.9 kg/m2). There were 267 patients (76.1%) in Group A and 84 individuals (23.9%) in Group B (control). Sex type ( p = 0.295) and BMI ( p = 0.227) did not significantly differ between groups, but elevated age was more pronounced with L4-L5 dSpl ( p = 0.001). There was a statistically significant difference between right and left L4-L5 facet joint angulations between Group A (right mean: 57.5 degrees; left mean: 55.4 degrees) and Group B (right mean: 48.4 degrees; left mean: 46.5 degrees) ( p &lt; 0.001). Based on facet joint tropism of 7 degrees difference between facet angulations, there was no statistically significant difference between groups. ROC analysis identified high sensitivity and specificity of facet joint angulation difference of 15 degrees or greater associated with dSpl. Based on age-adjusted multivariate analysis, facet joint tropism with a critical value of 15 degrees or greater angulation difference noted an odds ratio of 2.34 (95% CI: 1.17-4.67; p = 0.016) associated with dSpl. Slippage was noted with increased facet joint tropism, but the effects could not be discerned. Conclusion Greater sagittal FJ orientation was associated with dSpl, as was joint tropism. A critical value of 15 degrees FJ angle difference produced a twofold increased likelihood of dSpl. Our study broadens the understanding of FJ morphology and its role in degenerative sagittal plane instability. Acknowledgments This study was funded by AOSpine Asia Pacific. Disclosure of Interest None declared

Fretting fatigue tests and crack initiation analysis on zircaloy tube specimens

Grid-to-rod fretting damage remains as a significant cause of nuclear fuel failure in pressurized water reactors (PWRs). By using a self-designed apparatus, fretting fatigue tests directly on thin-wall tube specimens were carried out. The S–N curve of the Zr-4 tube under some given fretting contact pressure is obtained, which is substantially lower than its life without fretting. And the initial crack occurs at the edge of the contact area where the amplitude of stress is confirmed to reach the maximum by FEM simulation. The position can be predicted by half-length of the initial contact region and the slip displacement.

미끄럼방지 노인화에 대한 생체역학적 분석

Fall is very fatal accident causes death to older people. Shoe may affect to fall. Shoe influences risk of slips, trips, and falls by altering somatosensory feedback to the foot. The purpose of this study was to investigate the analysis of non-slip shoes for older people and influence on older people's lower extremity. For this study twenty three healthy older people were recruited. Each subjects walked over slippery surfaces (COF 0.08). Four pairs of non-slip shoes (shoe A had the greatest COF, 0.23 while shoe B, C, and D had smaller COF relatively) for older people were selected and tested mechanical and biomechanical experiment. For data collection motion capture and ground reaction forces were synchronized. There were statistically significant differences for slip-displacement, coefficient of friction, braking force, propulsion force, knee range of motion and knee joint stiffness by shoes. It was concluded that shoe A was the best for non-slip function because of the lowest slip displacement, the highest braking and propulsion forces, and the highest mechanical and biomechanical coefficient of friction where as shoe B, C, D were identified as a negative effect on the knee joint than shoe A. To prevent fall and slip, older people have to take a appropriate non-slip shoes such as shoe A.

Numerical Investigations of the Dynamic Shear Behavior of Rough Rock Joints

The dynamic shear behavior of rock joints is significant to both rock engineering and earthquake dynamics. With the discrete element method (DEM), the dynamic direct-shear tests on the rough rock joints with 3D (sinusoidal or random) surface morphologies are simulated and discussed. Evolution of the friction coefficient with the slip displacement shows that the 3D DEM joint model can accurately reproduce the initial strengthening, slip-weakening, and steady-sliding responses of real rock joints. Energy analyses show that the strengthening and weakening behavior of the rock joint are mainly attributed to the rapid accumulation and release of the elastic energy in the joint. Then, effects of the surface roughness and the normal stress on the friction coefficient and the micro shear deformation mechanisms, mainly volume change and asperity damage, of the rock joint are investigated. The results show that the peak friction coefficient increases logarithmically with the increasing surface roughness, but decreases exponentially with the increasing normal stress. In addition, the rougher rock joint exhibits both higher joint dilation and asperity degradation. However, high normal stress constrains the joint dilation, but promotes the degree of asperity degradation significantly. Lastly, the effects of the 3D surface morphology on the shear behavior of the rock joint are investigated with a directional roughness parameter. It is observed that the anisotropy of the surface roughness consequently results in the variation of the peak friction coefficient of the joint corresponding to different shearing directions as well as the micro shear deformation mechanisms, e.g., the extent of joint dilation.

Testing and modelling of friction characteristics between concrete slab and subbase layers

This paper presents the results of an analysis of the interlayer friction characteristics between a concrete slab and various types of subbases, which are commonly used in concrete pavement construction. The interlayer friction characteristics were examined by conducting push-off tests on concrete slabs placed on top of lean concrete, crushed stone, or asphalt subbase, with and without separation membranes, under a range of saturated conditions. Throughout the tests, the friction resistance force and horizontal displacement, along with different types of subbases, were measured during the first application of a load, steady conditions, and saturated conditions. The measured interlayer friction resistance force and horizontal displacement after applying the first load showed results similar to other studies. To incorporate the test results into an analysis, a simple method was developed to estimate the maximum friction resistance force, initial slip displacement, and friction stiffness based on bilinearisation from the field-measured nonlinear friction resistance force, displacement relationship using the energy method. The finite element programs, ABAQUS and EverFE, were incorporated to analyse a concrete pavement. The interlayer friction behaviour was considered both with nonlinear and bilinear models in finite element programs and the interlayer friction characteristics were modelled with connector elements. The maximum tensile stress and horizontal displacement under temperature loading conditions were calculated using analytical models and the results were compared with field data. The results of the bilinear model based on the energy method matched the field data.

Insights into the damage zones in fault-bend folds from geomechanical models and field data

Abstract Understanding the rock mass deformation and stress states, the fracture development and distribution are critical to a range of endeavors including oil and gas exploration and development, and geothermal reservoir characterization and management. Geomechanical modeling can be used to simulate the forming processes of faults and folds, and predict the onset of failure and the type and abundance of deformation features along with the orientations and magnitudes of stresses. This approach enables the development of forward models that incorporate realistic mechanical stratigraphy (e.g., the bed thickness, bedding planes and competence contrasts), include faults and bedding-slip surfaces as frictional sliding interfaces, reproduce the geometry of the fold structures, and allow tracking strain and stress through the whole deformation process. In this present study, we combine field observations and finite element models to calibrate the development and distribution of fractures in the fault-bend folds, and discuss the mechanical controls (e.g., the slip displacement, ramp cutoff angle, frictional coefficient of interlayers and faults) that are able to influence the development and distribution of fractures during fault-bend folding. A linear relationship between the slip displacement and the fracture damage zone, the ramp cutoff angle and the fracture damage zone, and the frictional coefficient of interlayers and faults and the fracture damage zone was established respectively based on the geomechanical modeling results. These mechanical controls mentioned above altogether contribute to influence and control the development and distribution of fractures in the fault-bend folds.

Applicability of adhesive–embossing hybrid joining process to glass-fiber-reinforced plastic and metallic thin sheets

Adhesive–embossing hybrid joining process was applied to A2017P and three types of glass-fiber-reinforced plastic (GFRP) thin sheets. Optical microscopy shows that a sound A2017P–thermosetting GFRP hybrid joint without crack/delamination in the composite or adhesive failure can be produced by optimizing adhesive thickness, embossing stroke and embossing temperature. The results of tensile shear test indicate that the optimally hybrid-bonded A2017P–GFRP joint exhibits improved load carrying capability, slip displacement and better energy absorbing characteristics than the adhesively bonded joint when subjected to tensile loading. This investigation shows that the adhesive–embossing hybrid joining process is a competitive alternative joining method for the fabrication of ultra lightweight thermosetting GFRP-metal hybrid structures and has great potential for wider applications, which is attributed to its benefits in terms of joining properties, operation simplicity, weight-cost effectiveness and recyclability.

A Dynamic-induced Direct-shear Model for Dynamic Triggering of Frictional Slip on Simulated Granular Gouges

This study presents a dynamic-induced direct-shear model to investigate the dynamic triggering of frictional slip on simulated granular gouges. An incident P-wave is generated as a shear load and a normal stress is constantly applied on the gouge layer. The shear stress accumulates in the incident stage and the frictional slip occurs in the slip stage without the effect of the reflected wave. The experimental results show a non-uniform shear stress distribution along the gouge layer, which may be induced by a shear load induced torque and by normal stress vibration along the layer. The shear stress at the trailing edge strongly affects the frictional slip along the P-wave loading direction, while the rebound stress at the leading edge propagates along the opposite direction. The frictional slip is triggered when the maximum shear stress at the trailing edge reaches a critical value. The normal stress influences the maximum shear stress at the trailing edge, the maximum slip displacement and the slip velocity. The advantages and the limitations of this model are discussed at the end.

Earthquake parameters affecting the performance of an RC frame with friction damper

In this paper, correlation between the ground motion parameters and the peak displacement demand of a reinforced concrete single degree of freedom system retrofitted by friction dampers is investigated. The aim is to reveal the best parameters that are used in selecting earthquake records for nonlinear dynamic analysis of the system. Performing numerous nonlinear time history analyses, it is observed that different earthquake parameters play role in peak displacement demand related to the ranges formed by the different periods of a reinforced concrete frame, the strength ratio of total system at slip displacement and the stiff/soft soil profiles. For the both soil types, out of sixteen ground motion parameters, the eight, Spectral Response Acceleration, Peak Ground Acceleration, Effective Peak Acceleration, Maximum Incremental Velocity, Peak Ground Velocity, Arias Intensity, Arias Intensity-based Parameter and Effective Peak Velocity correlate better with peak displacement demand.

A Method for the Calculation of Dynamic Response Considering Joint Dry Friction

A method for computing dynamic response considering joint dry friction has been developed based on equivalent linearization and micro-slip model. Computational simulation model was established by linking corresponding contact nodes with Matrix27 elements which simulate additional stiffness and damping effects on structure caused by dry friction nonlinear force. Equivalent stiffness and damping coefficient formula was deduced to calculate real constants of Matrix27 elements. An iterative program was created to compute maximum slip displacements of Coulomb contact nodes on interface and dynamic response and vibration stress were calculated then. An experimental verification has also been carried out which testified the accuracy of the method. Evidently attenuation of vibration is revealed which certifies the effectiveness of joint dry friction damper. Better attenuation effect occurs when exciting frequency is nearer natural frequency.

Estimation of longitudinal hoof slip displacement at the canter on two different track surfaces using accelerometric and kinematic methods: a preliminary comparative study with one horse

Estimation of longitudinal hoof slip displacement at the canter on two different track surfaces using accelerometric and kinematic methods: a preliminary comparative study with one horse

Fault‐Growth Pattern of the South Margin Normal Fault of the Yuguang Basin in Northwest Beijing and its Influencing Factors

Abstract:Based on high‐resolution remote sensing image interpretation, digital elevation model 3‐D analysis, field geologic field investigation, trenching engineering, and ground‐penetrating radar, synthetic research on the evolution of the Yuguang Basin South Margin Fault (YBSMF) in northwest Beijing was carried out. We found that the propagation and growth of faults most often occurred often at two locations: the fault overlapping zone and the uneven or rough fault segment. Through detailed observation and analysis of all cropouts of faults along the YBSMF from zone a to zone i, we identified three major factors that dominate or affect fault propagation and growth. First, the irregularity of fault geometry determine the propagation and growth of the fault, and therefore, the faults always propagate and grow at such irregular fault segments. The fault finally cuts off and eliminates its irregularity, making the fault geometry and fault plane smoother than before, which contributes to the slipping movement of the half‐graben block in the basin. Second, the scale of the irregularity of the fault geometry affects the result of fault propagation and growth, that is, the degree of the cutting off of fault irregularity. The degree of cutting off decreases as irregularity scale increases. Third, the maximum possible slip displacement of the fault segment influences the duration of fault propagation and growth. The duration at the central segments with a large slip displacement is longer than that at the end segments with a smaller slippage value.