Vertical Displacement Profile Research Articles

Experimental study of precast concrete walls with replaceable corner components

AbstractTo improve the seismic resiliency of precast concrete (PC) wall, a type of emulative PC wall with replaceable corner components (RCCs) was developed in this study. The damage of the PC wall was deliberately concentrated in the RCCs, which can be replaced after an earthquake. Four large‐aspect‐ratio specimens (including three PC walls with different tensile strength RCCs, and one monolithic cast‐in‐place reinforced concrete (RC) wall) were tested to investigate the seismic behavior of the PC wall, the replaceability of the RCCs, and comparability of the PC wall with the RC wall. Although flexural failure occurred for the three PC walls, the locations of damage were different. For PC walls with low and moderate tensile strength RCCs, the damage was successfully concentrated in RCCs, while for PC wall with high tensile strength RCCs, the damage was expanded from RCCs to the non‐replaced part of the PC wall. When RCCs had approximately identical tensile strength to the boundary element of RC wall, the performance of the PC wall emulated that of the RC wall. The ultimate drift ratio of the PC walls ranged from 1.7% to 2.2% which is lower than that of 2.7% for the RC wall. The PC wall, before and after replacing RCCs, exhibited approximately identical lateral load, while slight lower initial stiffness. The vertical displacement profiles of wall bottom section were almost linear, and the yielding and peak strength of the PC walls could be reasonably estimated by assuming the wall bottom section remain plane after deformation.

Monitoring of a landmark bridge using SAR interferometry coupled with engineering data and forensics

ABSTRACT Infrastructure monitoring can facilitate the evaluation of capacity and functionality loss and therefore provide valuable data and evidence for reliable, lifetime and automated risk assessments. Terrestrial monitoring systems can provide information about assets and their condition. Yet, they fall short of engineering requirements related to the history of the asset loading, deterioration and potential damage, which is of paramount importance in risk-based decision-making by infrastructure operators. This capability gap can be filled by Persistent Scatterer Interferometry (PSI) Monitoring in conjunction with engineering forensics and judgment. This paper puts forward this hybrid approach to assess the structural condition of a landmark bridge by coupling advanced Differential SAR Tomography (D-TomoSAR) techniques with an adaptive deformation model, environmental measurements and engineering evidence and evaluations. A dataset of 360 Sentinel A &B images covering the period between 10/2014 and 2/2020 and temperature records to account for seasonal deformation were deployed. Displacement products, such as the development of annual displacement and time series were calculated demonstrating a strong correlation with temperature variation and resulting deformations of the asset. The spatiotemporally evolving deformation trends of the bridge superstructure were derived, and vulnerable deck locations were identified on the basis of engineering forensics, judgment and progressive displacements calculated from the D-TomoSAR technique. The vertical displacement profile at the critical deck location was developed reaching a displacement velocity of 1.8 mm/year and potential deterioration issues are manifested as potential causes of the observed geometric alterations. Based on the D-TomoSAR results matched with engineering evidence and on-site visual inspections and judgment, this study contributed to the decision-making process. This research is a pilot showcase of D-TomoSAR for the bridge monitoring, not only providing mm-level quantitative measurements of the bridge in a 6-year observation span using medium resolution Sentinel-1 SAR images alone but also indirectly identifying potential structural defects in the north section of the bridge. This research is a primer example of how we can deploy diverse evidence to facilitate targeted adaptation measures and prioritize restoration strategies to facilitate asset owners in better decision making.

Improvement of metrological measurements of bridge crossings at waterworks when studying non-destructive testing methods

The article considers the main parameters of applying the modern methods of metrological measurements of bridge crossings on water channels during research with non-destructive testing methods. Instrumental surveys of water supply facilities in Russia showed that in some cases their effectiveness, operational quality and reliability are insufficient, which is associated with violations of normal water supply systems functioning. In modern conditions, with limited public resources allocated for the reconstruction of water facilities, problems of optimizing the requirements for metrological support of the developed non-destructive testing measuring instruments and the unification of observation technologies are of particular importance. The most common are defects of an internal nature, leading to the disruption of waterworks normal functioning. We can conclude that violations of the butt joints of prefabricated elements, breaking and breaching of walls in various zones, cracks, sliding and subsidence of elements relative to each other lead to disruption of the normal operation of bridge crossings. This raises problems such as the loss of scarce irrigation water, rising groundwater levels, waterlogging and salinization of irrigated lands. The solution to these problems should be based on the mandatory consideration of reliability requirements in design, construction and operation. The purpose of research with non-destructive testing instruments was to detect possible defects in concrete bridge crossings and determine the condition of reinforcing bars. These field studies were carried out using the OKO-2 GPR and the electronic concrete strength measurer IPS-MG4.01. Comparison of the vertical displacement profiles of bridge crossing bearing components through the waterworks horizontally along and across the bearing elements revealed insignificant internal changes. A metrological support system for research by non-destructive methods for monitoring bridge crossings at waterworks is necessary to achieve unity and the required accuracy, completeness, timeliness and efficiency of measurements.

Spatiotemporal behavior of a large-scale landslide at Mt. Onnebetsu-dake, Japan, detected by three L-band SAR satellites

We applied differential InSAR analysis to the Shiretoko Peninsula, northeastern Hokkaido, Japan. All the interferograms of long temporal baseline (~ 3 years) processed from SAR data of three L-band satellites (JERS-1, ALOS, ALOS-2) commonly indicate remarkable phase changes due to the landslide movement at the southeastern flank of Mt. Onnebetsu-dake, a Quaternary stratovolcano. The area of interferometric phase change matches to known landslide morphologies. Judging from the timing of the SAR image acquisitions, this landslide has been moving at least from 1993 to the present. Successive interferograms of 1-year temporal baseline indicate the temporal fluctuation of the landslide velocity. Especially for the descending interferograms, the positive line-of-sight (LOS) length change, which indicates large subsidence relative to the horizontal movement, is observed in the upslope section of the landslide during 1993–1998, while the negative LOS change is observed in the middle and the downslope section after 2007 indicating less subsidence. The landslide activity culminates from 2014 to 2017: the eastward and the vertical displacement rates reach ~ 6 and ~ 2 cm/yr, respectively. Utilizing high spatial resolution of ALOS and ALOS-2 data, we investigated velocity distribution inside the landslide. During 2007–2010, the eastward component of surface displacement increases toward the east, implying that the landslide extends toward the east. During 2014–2017, the vertical displacement profile exhibits spatially periodic uplift and subsidence consistent with surface gradient, which indicates the ongoing deformation driven by gravitational force. Heavy rainfall associated with three typhoons in August 2016 might have brought about an increase in the landslide velocity, possibly due to elevated pore-fluid pressure within and/or at the base of the landslide material. Also, annual rainfall would be an important factor that prescribes the landslide velocity averaged over 3 years.

Analysis of mechanics of fault reactivation in depleting reservoirs

Pressure depletion of hydrocarbon reservoirs can cause re-activation along fault planes of weakness, resulting in geomechanical hazards such as seismicity. The article presents analytical solutions of conditions leading to mechanical fault reactivation. The developed methodology starts by defining various fault categories present in the Dutch subsurface based on reservoir setting and fault properties, such as throw, dip, strike and transmissibility. For all fault categories initiation criteria for fault re-activation have been developed based on a new Coulomb stability relationship. The depletion-induced poro-elastic stress changes depend on the reservoir geometry and the fault transmissibility while the induced shear stresses are determined from differential vertical displacement profiles. The induced shear stress is either caused by the fault throw or by the pressure difference caused by the (partly) sealing fault or at the boundary fault. Analysis of the Coulomb stability function allows determination of the relative importance of poro-elastic stressing relative to differential compaction. The critical reservoir pressure depletion for fault re-activation to occur has been determined for open, intra-reservoir faults with or without a throw, (partly) sealing intra-reservoir faults and boundary faults. Satisfying this Coulomb criterion is the first necessary mechanical condition for seismicity to occur. These results can be used to determine the initiation pressures for seismicity to occur in depleting gas reservoirs in The Netherlands and can in addition explain why the observed seismicity has been attributed to steeply dipping fault planes.

A Cautionary Tale of Topography and Tilt from Kīlauea Caldera

AbstractWe conduct finite element analysis to investigate the effect of sharp topography on surface ground deformation caused by pressure changes in a magma reservoir. Tilt data express the horizontal gradient of vertical displacement and therefore can emphasize small variations in deformation that go unnoticed using other methods. We find that the vertical displacement profile at a surface with a cliff can be thought of as the superposition of the deformation from shallow and deeper sources. This combination can create a small peak in vertical displacement that acts as a pseudo‐source, creating a reversal of the deformation gradient and therefore anomalous tilt magnitude and a rotation of up to 180°. We apply these models to Kīlauea Caldera and find that surface geometry creates a tilt rotation of ∼10°, partially explaining anomalous tilt that has been observed. Our analysis highlights the importance of considering topography when assessing tilt measurements at active volcanoes.

In Situ Acoustic Diagnostics of Particle-Binder Interactions in Battery Electrodes

Summary The high phase-transformation strain developed upon intercalation in the host particles of a composite battery electrode affects the polymeric binder network mechanically, deteriorating the electrode cycling performance. Here, electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) is used to demonstrate a new strain-accommodation mechanism, in high-strain NaFePO 4 /PVdF electrodes, via relaxation of the binder network surrounding the intercalation particles. Complete mechanical degradation of the polymer network occurs during long-term cycling of NaFePO 4 electrodes in aqueous solutions (hard and tough behavior). In contrast, in aprotic solutions, a softened binder easily accommodates the high transformation strain, ensuring excellent electrode cycling performance (soft and tough behavior). Quantification of the high-frequency viscoelastic properties of an operating composite electrode linked to the binder's fracture toughness ensures fast and facile screening of the optimal polymeric binder/electrolyte solution combinations. This methodology should be extremely important for optimization of cycling performance of Li-Si anodes undergoing huge volume changes during cycling.

The effects of pre-existing discontinuities on the surface expression of normal faults: Insights from wet-clay analog modeling

We use wet-clay analog models to investigate how pre-existing discontinuities (i.e. structures inherited from previous tectonic phases) affect the evolution of a normal fault at the Earth's surface. To this end we first perform a series of three reference experiments driven by a 45° dipping master fault unaffected by pre-existing discontinuities to generate a mechanically isotropic learning set of models. We then replicate the experiment six times introducing a 60°-dipping precut in the clay cake, each time with a different attitude and orientation with respect to an initially-blind, 45°-dipping, master normal fault. In all experiments the precut intersects the vertical projection of the master fault halfway between the center and the right-hand lateral tip. All other conditions are identical for all seven models. By comparing the results obtained from the mechanically isotropic experiments with results from experiments with precuts we find that the surface evolution of the normal fault varies depending on the precut orientation. In most cases the parameters of newly-forming faults are strongly influenced. The largest influence is exerted by synthetic and antithetic discontinuities trending respectively at 30° and 45° from the strike of the master fault, whereas a synthetic discontinuity at 60° and an antithetic discontinuity at 30° show moderate influence. Little influence is exerted by a synthetic discontinuity at 45° and an antithetic discontinuity at 60° from the strike of the master fault. We provide a ranking chart to assess fault-to-discontinuity interactions with respect to essential surface fault descriptors, such as segmentation, vertical-displacement profile, maximum displacement, and length, often used as proxies to infer fault properties at depth. Considering a single descriptor, the amount of deviation induced by different precuts varies from case to case in a rather unpredictable fashion. Multiple observables should be taken into consideration when analyzing normal faults evolving next to pre-existing discontinuities.

Effect of daily temperature variations on the continuous deflection profiles of airfield jointed concrete pavements

Compared with highway roads primarily damaged by repeated vehicle loads, airfield pavements suffer more from heavier aircraft loading, along with environmental factors. In particular, a pavement temperature is one of the critical factors affecting the behavior and response of airfield jointed concrete pavements (JCP). Temperature variations cause curling and expansion/contraction of a slab, which may ultimately influence the in-situ deflection measurements. Along with the pavement temperature, it is well known that other parameters such as subsurface conditions (i.e. stiffness of base/subbase layers), setting temperature of concrete, slab dimensions, and joint/crack width also affect the behavior and response of JCP. The main objectives of this paper are to characterize: (1) the behavior of airfield JCP due to temperature variations in terms of pavement “deflections” (defined as the dynamic movements of a pavement induced by dynamic loading); and (2) the effects of various affecting parameters on the vertical displacement profile of JCP slabs. The primary research means include in-situ pavement deflection measurements at different times of a day. For this purpose, a rolling dynamic deflectometer (RDD) which measures the continuous deflection profiles along a selected pavement section (100% coverage of a tested path) was employed. Also, extensive two-dimensional numerical simulations were performed to provide supporting evidence for the behavior trends generated by RDD.

Strain profiles in thin films: influence of a coherently diffracting substrate and thickness fluctuations

A simple least-squares fitting-based method is described for the determination of strain profiles in epitaxial films using high-resolution X-ray diffraction. The method is model-independent,i.e.it does not require any `guess' model for the shape of the strain profile. The shape of the vertical displacement profile is modelled using the versatile cubicB-spline functions, which puts smoothness and curvature constraints on the fitting procedure. The effect of a coherently diffracting substrate is taken into account as well as the effects of film thickness fluctuations. The model is applied to the determination of strain profiles in SmNiO3films epitaxically grown on SrTiO3(001) substrates. The shape of the retrieved strain profile is discussed in terms of oxygen vacancies.

Simplified approach for design of raft foundations against fault rupture. Part II: soil-structure interaction

This is the second paper of two, which describe the results of an integrated research effort to develop a four-step simplified approach for design of raft foundations against dip-slip (normal and thrust) fault rupture. The first two steps dealing with fault rupture propagation in the free-field were presented in the companion paper. This paper develops an approximate analytical method to analyze soil-foundation-structure interaction (SFSI), involving two additional phenomena: (i) fault rupture diversion (Step 3); and (ii) modification of the vertical displacement profile (Step 4). For the first phenomenon (Step 3), an approximate energy-based approach is developed to estimate the diversion of a fault rupture due to presence of a raft foundation. The normalized critical load for complete diversion is shown to be a function of soil strength, coefficient of earth pressure at rest, bedrock depth, and the horizontal position of the foundation relative to the outcropping fault rupture. For the second phenomenon (Step 4), a heuristic approach is proposed, which “scans” through possible equilibrium positions to detect the one that best satisfies force and moment equilibrium. Thus, we account for the strong geometric nonlinearities that govern this interaction, such as uplifting and second order (P-Δ) effects. Comparisons with centrifuge-validated finite element analyses demonstrate the efficacy of the method. Its simplicity makes possible its utilization for preliminary design.

3D seismic characterisation of an array of blind normal faults in the Levant Basin, Eastern Mediterranean

The geometry, throw distribution and kinematics of an array of blind normal faults were investigated using a high resolution 3D seismic dataset located in the Levant Basin, offshore Israel, to establish criteria allowing true blind faults to be distinguished from minor synsedimentary faults. A detailed analysis of throw distribution on the fault planes shows that the displacement exhibits a crudely concentric pattern about a maximum region located centrally on a fault plane, as expected for ideal blind faults. However, vertical displacement profiles do not exhibit classical linear or triangular profiles but are mostly flat-topped or hybrid in type. Comparison of unrestricted blind faults to those that interacted with a mechanical boundary or another structure suggests that such interactions significantly modify the throw spatial distribution on a fault plane. To distinguish small synsedimentary faults from blind faults, we use a combination of three criteria to assess whether a fault grew by blind propagation: (1) plunging upper-tip region and complementary pattern in the throw contours, (2) presence of upper-tip propagation fold, and (3) absence of stratigraphic evidence that the fault interacted with the free surface.

Fault Rupture Propagation through Sand: Finite-Element Analysis and Validation through Centrifuge Experiments

The three notorious earthquakes of 1999 in Turkey (Kocaeli and Duzce) and Taiwan (Chi-Chi), having offered numerous examples of surface fault rupturing underneath civil engineering structures, prompted increased interest in the subject. This paper develops a nonlinear finite-element methodology to study dip–slip (“normal” and “reverse”) fault rupture propagation through sand. The procedure is verified through successful Class A predictions of four centrifuge model tests. The validated methodology is then utilized in a parametric study of fault rupture propagation through sand. Emphasis is given to results of engineering significance, such as: (1) the location of fault outcropping; (2) the vertical displacement profile of the ground surface; and (3) the minimum fault offset at bedrock necessary for the rupture to reach the ground surface. The analysis shows that dip–slip faults refract at the soil–rock interface, initially increasing in dip. Normal faults may keep increasing their dip as they approach the ...

The 1923 Kanto earthquake reevaluated using a newly augmented geodetic data set

This study revisits the mechanism of the 1923 Ms = 7.9 Kanto earthquake in Japan. We derive a new source model and use it to assess quantitative and qualitative aspects of the accommodation of plate motion in the Kanto region. We use a new geodetic data set that consists of displacements from leveling and angle changes from triangulation measurements obtained in surveys between 1883 and 1927. Two unique aspects of our analysis are the inclusion of a large number of second‐order triangulation measurements and the application of a correction to remove interseismic deformation. The geometry of the fault planes is adopted from a recent seismic reflection study of the Kanto region. We evaluate the minimum complexity necessary in the model to fit the data optimally. Our final uniform‐slip elastic dislocation model consists of two adjacent ≈20° dipping low‐angle planes accommodating reverse dextral slip of 6.0 m on the larger, eastern plane and 9.5 m on the smaller, western plane with azimuths of 163° and 121°, respectively. The earthquake was located in the Sagami trough, where the Philippine Sea plate subducts under Honshu. Compared to the highly oblique angle of plate convergence, the coseismic slip on the large fault plane has a more orthogonal orientation to the strike of the plate boundary, suggesting that slip partitioning plays a role in accommodation of plate motion. What other structure is involved in the partitioning is unclear. Uplift records of marine coastal terraces in Sagami Bay document 7500 years of earthquake activity and predict average recurrence intervals of 400 years for events with vertical displacement profiles similar to those of the 1923 earthquake. This means that the average slip deficit per recurrence interval is ∼50% of the relative plate convergence. These findings of plate motion partitioning and slip deficit lead us to suggest that instead of a simple recurrence model with characteristic earthquakes, additional mechanisms are necessary to describe the accommodation of deformation in the Kanto region. So far, obvious candidates for these alternative mechanisms have not been discovered.

Normal fault thermal regimes: conductive and hydrothermal heat transfer surrounding the Wasatch fault, Utah

The thermal regime across an active normal fault is affected by tectonic processes of exhumation and erosion of the footwall and burial and sedimentation on the hanging wall. An enhanced thermal regime in the footwall is juxtaposed against a thermally depressed regime in the hanging wall causing significant two-dimensional (2D) heat flow. These thermal processes have been simulated with 2D numerical models and applied to the Wasatch fault of central Utah. Simulations included variable fault angles of 90°, 60°, and 45° and a vertical displacement profile accounting for hanging wall and footwall tilt. After 20 m.y. of fault movement, 60° fault, isotherms are displaced ∼1 km on the footwall and hanging wall. Furthermore, model surface heat flow is enhanced by 25% above the footwall and depressed by 15% above the hanging wall 10 km from the fault trace; the heat flow transition has a half width of 10 km. Present-day surface heat flow was compiled for 23 sites along the Wasatch Front. Heat flow has a mean value of 92 mW/m 2 (standard deviation 25 mW/m 2) but, unlike model predictions, does not show a discernible variation in heat flow across the fault. Part of the discrepancy between predicted and observed conductive heat flow may be caused by groundwater which recharges in the uplifted footwall, is heated in the subsurface, and discharges as thermal water along the range bounding fault or into the hanging wall valley. Flow rates and water temperatures from 29 tectonic hot springs along the Wasatch Front indicate a minimum hydrothermal thermal power loss of 90 MW or 0.24 MW per kilometer of strike along the fault. This thermal power is equivalent to a heat flow of 21 mW/m 2 captured uniformly between the range crest and range front, and discharged in hot springs.

Vertical fine structure observations in the eastern equatorial Pacific

Measurements of vertical displacement and horizontal velocity finestructure near the equator at 110°W in the eastern Pacific Ocean are reported. Profiles were scaled to a constant Brünt‐Väisälä frequency ocean (No = 1 cph) in accordance with a WKBJ approximation. A total of 57 CTD casts between 3°N and 3°S taken during five cruises in 1979 were analyzed. Results show an equatorial enhancement of vertical displacement variance for vertical wavelengths longer than 50 sdbar (stretched decibars). This enhancement is similar to that which has been reported at 125°W and 179°E. Differences between locations can be accounted for by the observed temporal variability at 110°W. Coherence between vertical displacement profiles separated in time by delays of 2 hour to 120 hour indicate that the high wave number structures were largely associated with time scales of 4 days and less. Meridionally, vertical structures longer than 300 sdbar were coherent within 50 km of the equator. We interpret this vertical displacement fine structure enhancement as high wave number equatorially trapped inertial‐gravity waves. The velocity fine structure measurements in July 1979 also indicate equatorially enhanced horizontal kinetic energy for vertical wave lengths longer than 100 sdbar. The velocity structures persisted over the 56 hour of measurement and appeared to have longer time scales than the vertical displacements. Meridional energy exceeded zonal energy; however, the two components were coherent. We interpret these velocity structures as inertial‐gravity waves which were produced off the equator and are propagating through the equatorial region.

Migrating Thermal Structure in a Freshwater Thermocline

Abstract The vertical migration of thermal structure in freshwater thermoclines is investigated with theory and observations. The theory is for the wind-forced internal oscillations of a viscous, nonrotating, long narrow lake of constant stratification. The introduction of viscosity results in a smooth phase change with depth near the nodes of the vertical displacement profiles, The gradual change of phase enables the theory to model the observed vertical migration of the temperature structure created by the internal oscillations. The theory is compared to data obtained from a vertical army of thermistors moored in a stratified freshwater lake. Vertical phase profiles calculated from the thermistor chain data agree well with the theoretical profiles for values of kinematic viscosity of about 10.0 × 10−6 m2s−1. The amplitudes of the vertical displacement away from the nodes agree reasonably well with values predicted by the theory. The agreement is sufficient to warrant the description of the migrating str...