Significant Horizontal Displacements Research Articles

Numerical Simulation Study on the Impact of Excavation on Existing Subway Stations Based on BIM-FEM Framework

Building information modeling (BIM) and finite element method (FEM) models have a wide range of applications in underground engineering design, construction, and operation and maintenance. This study employs a BIM-FEM framework to numerically simulate the impact of excavation on existing subway stations, using the Yanjiang New City Station TOD project as a case study. This framework simplifies the smooth integration of BIM and FEM models, automating functions such as assigning material properties, conducting construction simulations, and generating high-quality meshes. Simulation results reveal significant horizontal and vertical displacements in diaphragm walls, support structures, and subway station structures, with the greatest impacts occurring closest to the excavation site. The BIM-FEM framework is validated as an effective tool for designing foundation pit support structures, enhancing numerical modeling accuracy and efficiency in underground engineering. The findings contribute to a better understanding of the dynamic interactions between excavation and underground structures, informing the development of construction strategies and protective measures to ensure structural safety.

Pressure-relief joints of initial support structural system used in tunnels with high-stress surrounding rock.

To address the problem of large deformations in weak surrounding rock tunnels under high ground stress, which cause damage to initial support structures, this study proposes a novel type of circumferential pressure-relief joint based on the concept of relieving deformation pressure of the surrounding rock. Key parameters of the pressure-relief joint, such as initial bearing capacity peak, constant bearing capacity, and allowable pressure-relief displacement, were obtained through numerical simulations and laboratory experiments. A comparison was made between the mechanical characteristics of rigid joints and the new type of pressure-relief joint. The applicability of the pressure-relief joint was verified through field tests, monitoring the surrounding rock pressure, internal forces in the steel frames, and the convergence displacement of the support structure. The results show that: (1) In the elastic stage, the stiffness of the new pressure-relief joint is similar to that of rigid joints. In the plastic stage, rigid joints fail directly, whereas the pressure-relief joint can control deformation and effectively release the deformation pressure of the surrounding rock while providing a constant bearing capacity. (2) The right arch foot in the experiment had poor rock quality, leading to high stress in the steel frame and significant horizontal displacement. After the deformation of the pressure-relief joint, the stress in the surrounding rock and steel frame significantly reduced, and the rate of horizontal deformation of the support structure slowed down. (3) The vertical and horizontal final displacements of the pressure-relief joint in the experiment were 61mm and 15mm, respectively, which did not exceed the allowable deformation values. The components of the support structure remained intact, ensuring safety. However, this study has limitations: the design of the new pressure-relief joint only allows for a vertical deformation of 150mm and a horizontal deformation of 50mm, limiting the range of pressure-relief deformation.

Mechanics of the Kalabagh Fault, northwest Himalayan fold and thrust belt (convergence zone of India and Eurasia), using SAR interferometry and CFS

The Kalabagh strike–slip fault, which is characterized by right-lateral movement, is part of the northwestern Himalayan foreland fold and thrust belt in Pakistan. This structure marks the western and eastern terminations of the Salt Range and Surghar Ranges, respectively. No significant (>M6) earthquakes have been reported along the Kalabagh Fault in recent decades. Here, we take advantage of space-borne Sentinel-1A SAR interferometry to gain insight into the mechanics of faulting, aseismic creeping, and stress loading of the seismic cycle on the Kalabagh Fault spanning over approximately 7 years. In this study, we also removed the tropospheric effects using the Generic Atmospheric Correction Online Service data from the rate map. We further resolved the LOS deformation into both horizontal and vertical deformations. Our Bayesian inversion indicates that the fault experiences significant horizontal and vertical displacements. The fault’s southern and northern segments exhibit a creeping rate of approximately ∼4.2 ± 1.3 to 4.8 ± 1.6 mm/year, respectively, while the central section does not display any horizontal creeping. We found that the creeping is confined between 0 and ∼2.7 ± 1.1 km depth at the northern section and 0 and ∼3.9 ± 1.1 km on the southern section of the faults. Nevertheless, we found that the vertical creeping of ∼10 mm/year is confined between 0.5 and 6 km depth in the central segment of the fault. Moreover, our model does not resolve the interseismic slip at depth on the Kalabagh Fault. Our results affirm that Kalabagh Fault is creeping, and the internal deformation due to the presence of a thick salt layer over the decollement facilitates the creeping on this fault. In addition, Coulomb stress modeling depicts that the creeping on the Kalabagh Fault increases the Coulomb stress changes in the northern section of the KBF.

Simulation analysis on seismic dynamic response of pile supported tunnels in deep backfill area of soil-rock mixture

To reveal the seismic dynamic response of the pile-supported tunnel group in the soil-rock mixture deep backfill region, a three-dimensional finite element model was established based on the engineering conditions of the subway section and three tunnels with close access lines. Subsequently, the seismic dynamic response of the tunnel lining structure was studied. The results show that: Under the action of seismic, the soil-rock mixture stratum presents nonlinear characteristics with shear failure and plastic deformation. In addition, the acceleration and earth pressure of the soil-rock mixture stratum is in a “saturated” state; The seismic dynamic response of the three tunnels influences each other. The bending moments in the X and Y directions of the tunnel lining cross-section are distributed in “X” and inverted “V” shapes, respectively. Meanwhile, the tensile stress and shear stress are distributed in an “X” shape; Under the action of seismic, the main failure form of tunnel lining is tension shear failure, and the most vulnerable position is the left and right arch foot, followed by the left and right arch shoulder; The bending moment of the pile body changes nonlinearly in the height direction. The most significant bending moment value appears at the top 1/5 of the pile length and the junction of different strata. Furthermore, the most significant horizontal displacement of the lining structure occurs at the tunnel vault.

Deformation Behavior of Grouted Sleeve Wall Connector Under Shear Load in Precast Process of Concrete Wall

This study investigated the behaviour of grouted sleeve connectors under shear loads. Tapered Head Sleeve (THS) connectors were fabricated from mild steel pipes. Five test specimens and a control specimen were produced. Each test specimen comprised two walls, which were connected by THS. An incremental shear load was applied at the joint until the specimen failed. The behaviour of the specimens was analyzed based on the load-displacement response. The feasibility of THS as a wall connection was determined based on ductility ratio, failure mode, performance ratio, and serviceability ratio. THS required an embedded length of 8 times the bar diameter to generate sufficient bond strength. The specimens experienced bar dowel action, which led to a significant horizontal displacement with a ductility ratio of 27.5 to 55.9. The test specimens offered shear capacities comparable to the control specimen, with performance ratios close to 1.0. The service load was only 1/3 of the ultimate capacity, and thus THS was ineffective in resisting shear load. Shear keys would be required to strengthen the joint of the specimen.

Cyclic behavior of alkali-silica reaction-damaged reinforced concrete beam-column joints strengthened with FRP composites

The research investigates the effect of using external fiber-reinforced polymer (FRP) –composites to strengthen the alkali-silica reaction (ASR)-damaged reinforced concrete (RC) beam-column joints. The nonlinear finite element analysis (NLFEA) method has been used to achieve the aims of this paper. Before experimenting, the B-C beam model has been verified following accredited previous experimental. Afterward, the experiment was extended to include the impact of the column’s axial load level and the ASR damage stage. For these purposes, the levels of the axial load were set at 0%, 25%, 50%, and 75%, while the stages of the ASR damage were: stage 0 (un-damaged), stage 1 (45 days), stage 2 (80 days), and stage 3 (120 days). Some of the models were strengthened with FRP, while the others were not. The evaluation of the models' structural performance was conducted by monitoring: the failure mode, distribution of stresses, degradation of stiffness, dissipation of energy, displacement ductility, pulling-pushing ultimate load capacity, and correspondent displacements, in addition to the horizontal load-displacement hysteretic loops and envelopes. The achieved results from this work indicated that the strengthened-with-FRP of ASR damaged RC B-C joint models showed an enhancement in their cyclic performance, as they showed: higher load capacity, more significant horizontal displacement, more displacement ductility, more dissipation of energy, and less secant stiffness degradation. It was also noticed that the higher the stage of the ASR damage, the better the efficiency of FRP composites. Further, strengthening the joint models with FRP transformed their failure mode from brittle mode to ductile, by forming a plastic hinge in the beam side at a column axial load exceeding 25%. On the other side, applying a column axial load below 25% only improved the ultimate deflection and corresponding axial load capacity.

Displacement evolution of reverse-dip rock slope considering the change of the reservoir level

The fluctuation and periodic change of reservoir level are the important incentives that affect the stability of the reverse-dip rock slope. Based on the field monitoring data, this paper investigates the topping deformation evolution characteristics of a typical reverse-dip slope containing different geological partitions considering the fluctuation of reservoir level. A typical reverse-dip rock slope was taken as an engineering case, whose geological factors including elevation, slope angle, and aspect were first obtained by a field survey. Subsequently, the factors were superimposed through ArcGIS to obtain the geological partitions. Afterwards, a spatiotemporal evolution nephogram of the topping displacement was obtained by discrete monitoring data of surface displacement of the slope. Finally, the deformation characteristic of the prone zone was analyzed by superposing the nephogram of the displacement and the geometrical partition, considering the change of the reservoir level. The results show that the largest geological and geometric characteristic zone is at the bottom elevation, medium slope, and north aspect. The zone with significant horizontal displacement is distributed in the front and middle edges of the slope, which increases with the increase of the reservoir level and vice versa. The vertical displacement mainly occurs in the trailing of the slope. The area of superimposed displacement in strong deformation zones increases as either the reservoir level rises or falls. After the superposition, zones with strong deformation increase with the variation of the reservoir level, and the area with the largest displacement is distributed at the medium gradient, low elevation, and north aspect zones.

ГЕОДИНАМІКА

The second part of the article studies the tectonic conditions and natural mechanisms of tectonic inversion of the Dnieper-Donets Basin and the Western Donets Graben. Method. The research uses the original method of reconstruction of fields of tectonic stresses and deformations. It also makes tectonophysical analysis of geostructures was used. The analytical base of the research consisted of the latest materials of geo-mapping, numerical modeling of deformations of the southern edge of the Eastern European platform and comparison of model and reconstructed stress fields. Results. In the geodynamic environment of the interference of the intraplate submeridional collision compression with the regional strike-slip stress field, the inversion deformations of the rift-like geostructure took place in the uplift-thrust and strike-slip modes. This led to significant horizontal movements of geomass of sedimentary rocks, deformation folding with the formation of three inversion floors - Late Hercynian (Saal-Pfalz), Early Alpine (Laramian) and Late Alpine (Attic). They formed structural ensembles of scaly tectonic covers of transverse displacement of geomass a from axial to onboard zones, folded covers of longitudinal approach from the Donbas Foldbelt and long linear anti- and synforms, the axes of which are oriented orthogonally to the direction of geomass advancement. Together they form the body of the Segment of Tectonic Wedging of geomass, which is distinguished as part of the Cover-Folded System of Tectonic Thrusting of regional scale. A feature of the tectonic framework of the Segment is the curvature of the planes of the main thrusts, which limit it, and smaller plumage thrusts, which control the folded covers of the thrust. It is associated with a change in the extension of the thrusts from the north-west in the territory of the Western Donets Graben to the western direction in the extreme south-east of the Basin. This causes the corresponding bending of the axes of the fracture anti- and synforms. Structural patterns of folding with a tendency to adapt the axes of folds to the extension of thrusts indicate significant horizontal displacements of geomas of the sedimentary stratum, which in conditions of limited geological space cause secondary deformations of linear folded forms. Due to the displacement of geomas from the zones of maximum compression in the axial part of the Graben to the zones of geodynamic shadow - in the direction of the Oryl depression and Graben boards, the West Donets Cover-Folded Tectonic Region was formed within the transition zone. Scientific novelty. The study completed an original kinematic model of tectonic inversion of the Western Donets Graben was completed. The mechanism of inversion, due to which the riftogenic structure is completely destroyed by folded deformations of platform orogeneses, is caused by the pressure of the "tectonic stamp" of the Donbas Foldbelt. Under its influence, a segment of tectonic wedge was formed in the Graben, which was diagnosed with oroclin of transverse extension of the sliding type. The body of the Oroclin is formed by echeloned, rock-articulated ensembles of anticlinal uplift -folds, synclines and scaly plates-covers of pushing. A geodynamic injection band was formed in the foreland of the Tectonic Orocline extension, where folded zones of geomas displacement were formed, which consist of coulisse articulated uplift-anticlines. At the top of the Orocline, at the ends of dynamically conjugate main thrusts, an advanced tectonic compression fan is formed. In the rear of the Oroclin – hinterland are tectonic sutures – the roots of the folding covers of the approach. Practical significance. Development of a structural-kinematic model of tectonic inversion of the Western Donets Graben will allow to improve the geodynamic model of tectonic inversion of the Dnieper-Donets paleorift, on the basis of which regional schemes of tectonic and oil-gas-geological zoning will be adjusted.

An Alternative Approach for Constraining 3D‐Displacements With InSAR, Applied to a Fault‐Bounded Groundwater Entrainment Field in California

AbstractWe explore the use of elastic Green’s functions in inversions of one‐dimensional Interferometric Synthetic Aperture Radar (InSAR) observations to recover three‐dimensional displacement fields. This approach enforces coupling of the horizontal displacements and limits the need for prior assumptions about the subsurface sources, driving the deformation or explicit damping of a given dimension of the full 3D deformation field. We apply these methods to data from the Coachella Valley, California, where artificial groundwater recharge in 2017 and the associated increases in pore pressure resulted in ground displacements of up to 12 cm. This area is covered by Sentinel‐1a/b data for two overlapping paths from both ascending and descending orbits, as well as an east‐west flight line from the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), providing five unique line‐of‐sight geometries. The regularization approaches applied to the Sentinel data alone agree in most respects, with the elastically coupled approach producing a slightly better fit to the independent UAVSAR observations. Our results suggest that the 2017 groundwater entrainment in the Coachella Valley is likely associated with significant horizontal displacements that led to contraction across the fault bounding the northern side of the basin, as well as increases in right‐lateral sense of strain in some areas along the fault.

Аналіз стійкості русла річки Свіча в місцях переходу об’єктів паливно-енергетичної інфраструктури

The aim of the work is to study the horizontal displacements of the Svicha riverbed, as well as to analyze the locations of the transitions of the fuel and energy complex across the river. The research methodology involves the use of archival topographic maps, in particular the Austrian period (1874), the Polish period (1933) and the Soviet period (1989), as well as satellite images. To determine the horizontal displacements of the Svicha riverbed, the archival maps are tied to reference points and brought to a single coordinate system with images. The root mean square error of determining the planned coordinates for archival maps is up to 20 m, for a topographic map of the Soviet period – up to 10 m. Digitalization of the riverbed was performed for each data set. Results. As a result of measurements, the maximum displacements in the studied areas were determined. Horizontal displacements in four sections of the Svicha river at the transition points of fuel and energy infrastructure were analyzed. It has been established that in two sections the river is unstable and changes its horizontal position, which leads to periodic accidents at facilities. In particular, significant horizontal displacements of the riverbed, up to 450 m, were established in the sections of the crossing near the villages of Shevchenkove and Pidberezh. Scientific novelty and practical significance. The method of geoinformation monitoring of horizontal displacements for the Svicha riverbed was applied in order to determine the suitability of the existing transition points of the fuel and energy complex.

Kibi Plateau: A stable-coherent tectonic unit in the active Japanese Islands

The Kibi Plateau in the active Japanese Islands consists of mainly Permian to Cretaceous rocks that have been deeply weathered into a red soil, comprising a peneplain with U-shaped valley. Systematic geological analyses of the Eocene fluvial deposits revealed the paleo-rivers that existed in the eastern Asian continent and streamed out to the paleo-Pacific Ocean. Each paleo-river is traced in a flow line shape without any significant vertical and horizontal displacement. The Eocene shallow marine sediments in a possible coastal region have no relevant inclination. These geological data strongly suggest that the Kibi Plateau has been a stable-coherent tectonic unit since the Eocene through the opening of the Japan Sea and the associated quick rotation of SW Japan in the Middle Miocene. The Kibi Plateau region with a thick crust over 30 km existed as a stable eastern segment of the Asian continent in the Eocene. The Kibi Plateau tectonic unit drifted to the south without any destruction due to the peripheral successive tectonic events such as the Philippine Sea plate subduction and the reactivation of Median Tectonic Line. No subduction related arc volcanism since the Eocene has also influenced to preserve the stable tectonic unit.

Monitoring the deformation of a concrete dam: a case study on the Deriner Dam, Artvin, Turkey

This paper investigates the behaviour of the double-curvature Deriner dam, which is in the operation phase and also one of the highest dams in the world. In order to determine the displacements, a geodetic network consisting of twelve reference and seven object points was measured in four periods by means of the Global Navigation Satellite Systems (GNSS) data. The -Criteria method was used to determine the extent of the deformation. The deformation analysis results based on the GNSS measurements revealed significant horizontal and vertical displacements on the object points on the dam crest. Hence, the vertical displacements found based on the GNSS measurements can be considered erroneous, because they are greater than expected. This may be due to the narrow topography of the valley. Another conclusion drawn from the results is that there is a strong relationship between the change in the reservoir water level and horizontal deformations, as can be seen from the horizontal deformation vectors.

Ground Surface Deformations of Klyuchevskoi Volcano, Kamchatka in 1978‒2014 Based on Geodetic Data

This paper gives measured quantities, inclined distances, and elevations between geodetic monuments on the northeastern slope of Klyuchevskoi Volcano for the period from 1978 through 2014. Parasitic and summit eruptions were generally preceded by uplifts of the slope, while the termination of an eruption was accompanied by subsidence. The data from the longest series of observations of vertical displacements on the Kirgurich radial line during the period from 1979 to 2014 were used to determine an uplift of the slope that was increasing nearer to the crater. The maximum displacements occurred 2 years before the start of the 1983 parasitic eruption on the Predskazannyi vent and before the 2003–2004 and 2007 summit eruptions. A ground uplift of 12.5 microradians measured on a 17.8-km baseline was recorded in 2007. Farther from the crater, at a distance of 27 km from it, the vertical displacements were insignificant. We show that the measurement stations at heights of 2000 m to 3000 m were subject to deep creep, i.e., a sliding movement. The rates of movement at these stations reached 5–20 cm/yr. Significant horizontal displacements of geodetic monuments occurred near the parasitic eruptions of March 6, 1980 and March 8, 1983. All lines of measurements were observed to shrink by 5 to 20 mm in 1989‒1993 to 2014, indicating a compression for the northeastern slope of Klyuchevskoi Volcano.

Geodesic monitoring of ground deformations at Klyuchevskoy Volcano in 1978–2014, Kamchatka

Measured values are given - slant distances and elevations between geodetic marks on the northeast slope of Klyuchevskaya volcano for 1978–2014. As a rule, a rise was observed before the secondary and summit eruptions, and the end of the eruptions was accompanied by the lowering of the volcano slope. According to the longest series of observations of vertical displacements from 1979 to 2014. on the “Kirgurich” radial profile, the rise of the volcano slope is determined to increase as it approaches its crater. The maximum displacements occurred two years before the start of the “Predskazannuy” side breakthrough in 1983, and before the summit eruptions of 2003–2004 and 2007. At a distance of 27 km from the crater of the volcano, the vertical displacements become insignificant. It is shown that points located at altitudes from 2000 meters to 3000 meters are subject to deep creep, i.e. sliding down. The displacement rates of such points reached 5–20 cm/year. Significant horizontal displacements of geodetic points occurred near incidental breaks on March 6, 1980 and March 8, 1983. From 1989–1993. until 2014, reductions of all lengths of lines from 5 to 20 mm were observed, which indicated compression of the northeast slope of Klyuchevskaya volcano.

Landscape Response to Lateral Advection in Convergent Orogens Over Geologic Time Scales

AbstractConvergent orogens exhibit high elevations and relief, features characteristic of active rock uplift, the latter influencing normalized channel steepness (Ksn). In systems with significant horizontal displacement, Ksn values and interfluves are elevated over a region of tens of kilometers and gradually decline in the direction of rock advection. To evaluate potential relationships between elevated Ksn, a gradual decline in interfluve elevation (i.e., tapered topography), and lateral advection, we integrated kinematic models that simulate advection over a midcrustal ramp with a 2‐D surface processes model. Varying convergence rate, bedrock erodibility, and ramp angle, we tracked topographic evolution over time. The process of advection through the region of active rock uplift above a midcrustal ramp is preserved in the geomorphic record through transient legacy landscapes characterized by (i) high‐relief, advection‐parallel interfluves, (ii) tapered topography, (iii) elevated and gradually declining Ksn values, and (iv) higher Ksn in trunk relative to tributary streams likely reflecting the influence of increased sediment flux, elevated interfluves, and changes in drainage area. The width of legacy landscapes provides a minimum constraint on the total lateral displacement, controlled by the duration of ramp activity and the rates of advection and erosion. The development of legacy landscapes is facilitated by spatial variations in flow convergence that occur in a 2‐D setting but are not captured in idealized 1‐D approaches. The presence of elevated Ksn and high relief, advection‐parallel interfluves beyond the region of active rock uplift likely reflects the horizontal advection component inherent to convergent orogenic systems.

Arthro-Biomechanical Investigation of the Tarsal Joint of One-Humped Camel (Camelus dromedarius) during gait: Forensic Biomechanics Evidence

It is expected that dromedary camel’s tarsus plays a crucial role in survivals in the arid and semiarid regions. These regions are open and the dromedary camel is tall with long legs. Thus, databases of biomechanical variables are needed to investigate the changes of velocity, displacement, angular changes as well as anatomical consideration of tarsal joint during walking and stance phase. Nine healthy camels of three different sizes and ages were selected for gait analysis using motion track program. Moreover, five tarsal joints cadavers obtained for 3D reconstruction computed tomography. The present study stated that, tarsal joint is a hinge biaxial joint, primarily allowing flexion, extension and small amount of rotation and gliding movement. The gait analysis during walking revealed some data of hind limb velocity, angular change and displacement of tarsal joint. Different sizes of camel had no significant effect on average and minimum value of velocity of hind limb during walking. Medium sized camel showed higher degree of extension of tarsal joint than small and large one. Medium and large camel showed significant higher vertical (p=0.01) and horizontal (p=0.05) displacement of right tarsal joint than small camel during walking. We anticipate our findings can be a useful tool in lameness investigation to discriminate between the normal and diseased gait as expecting the nature of the inhabitant environment as well as add promising evidence in the field of forensic biomechanics to avoid legal violations in racing camels.

Surface deformation and source modeling of Ayaz-Akhtarma mud volcano, Azerbaijan, as detected by ALOS/ALOS-2 InSAR

Azerbaijan, located on the western edge of the Caspian Sea in Central Asia, has one of the highest populations of mud volcanoes in the world. We used satellite-based synthetic aperture radar (SAR) images derived from two L-band SAR satellites, ALOS/PALSAR along an ascending track from 2006 to 2011, and its successor ALOS-2/PALSAR-2 along both ascending and descending tracks from 2014 to 2017. First, we applied interferometric SAR (InSAR) technique to detect surface displacements at the Ayaz-Akhtarma mud volcano in Azerbaijan. The 35 derived interferograms indicate that the deformation of the mud volcano is largely characterized by horizontal displacement. Besides the InSAR technique, we also used multiple-aperture interferometry (MAI) to derive the surface displacements parallel to the satellite flight direction to complement the InSAR data. Using the InSAR and MAI data, we obtained 3D displacements, which indicate that the horizontal displacement is dominant relative to subsidence and possible uplift. To explain the displacements, we performed source modeling, based on the assumption of elastic dislocation theory in a half space. The derived model consists of a convex surface on which normal-fault-type slips are semi-radially distributed, causing the significant horizontal displacements with minor subsidence. The convex source surface suggests that a steady overpressure system would be maintained by constantly intruding mud and gas.

Comparative clinical efficacy evaluation of three gingival displacement systems.

Aim:We compared the clinical efficacy of three gingival displacement systems to accurately record intra-crevicular margins of tooth preparation.Materials and Methods:One mechanical (magic foam cord) and two chemico-mechanical (expasyl paste and retraction cord impregnated with 15% aluminum chloride) gingival displacement systems were used. This study was conducted on the maxillary central incisors of 20 patients (20-60 years old) requiring full coverage restoration. All the three gingival displacement systems were tested in three sessions at an interval of 14 days in same order. The casts were sectioned and viewed under an optical microscope, followed by quantitative measurements of the width of the pre and postretracted sulci.Results:All the three displacement systems produced highly significant horizontal gingival displacement. Retraction cord soaked in 15% aluminum chloride produced maximum displacement (0.74 mm), followed by expasyl paste (0.48 mm) whereas magic foam cord produced the least displacement (0.41 mm).Conclusions:Gingival displacement shown by each displacement system was found to be more than the accepted value necessary for elastomeric impression accuracy (0.2 mm) to record intra-crevicular margins of tooth preparation.

Modification of fault slip models of the Mw 9.0 Tohoku Earthquake by far field GPS observations

GPS data from Crustal Movement Observation Network of China (CMONOC) are used to derive far-field co-seismic displacements induced by the Mw 9.0 Tohoku Earthquake. Significant horizontal displacements about 30mm, 10mm, and 20mm were caused by this large event in northeast China, north China, and on the Korean peninsula respectively. Vectors of relatively large horizontal displacements with dominant east components pointed to the epicenter of this earthquake. The east components show an exponential decay with the longitude, which is characteristic of the decay of the co-seismic horizontal displacements associated with earthquakes of thrust rupture. The exponential fit of the east components shows that the influence of the co-seismic displacements can be detected by GPS at a distance of about 3200km from the epicenter of the earthquake. By considering the capability of the far field displacements for constraining the inversion of the fault slip model of the earthquake, we use spherically stratified Earth models to simulate the co-seismic displacements induced by this event. Using computations and comparisons, we discuss the effects of parameters of layered Earth models on the results of dislocation modeling. Comparisons of the modeled and observed displacements show that far field GPS observations are effective for constraining the fault slip model. The far field horizontal displacements observed by GPS are used to modify the slips and seismic moments of fault slip models. The result of this work is applicable as a reference for other researchers to study seismic source rupture and crustal deformation.

Precision of jaw‐closing movements for different jaw gaps

Jaw-closing movements are basic components of physiological motor actions precisely achieving intercuspation without significant interference. The main purpose of this study was to test the hypothesis that, despite an imperfect intercuspal position, the precision of jaw-closing movements fluctuates within the range of physiological closing movements indispensable for meeting intercuspation without significant interference. For 35 healthy subjects, condylar and incisal point positions for fast and slow jaw-closing, interrupted at different jaw gaps by the use of frontal occlusal plateaus, were compared with uninterrupted physiological jaw closing, with identical jaw gaps, using a telemetric system for measuring jaw position. Examiner-guided centric relation served as a clinically relevant reference position. For jaw gaps ≤4mm, no significant horizontal or vertical displacement differences were observed for the incisal or condylar points among physiological, fast, and slow jaw-closing. However, the jaw positions under these three closing conditions differed significantly from guided centric relation for nearly all experimental jaw gaps. The findings provide evidence of stringent neuromuscular control of jaw-closing movements in the vicinity of intercuspation. These results might be of clinical relevance to occlusal intervention with different objectives.