Surface Displacement Vector Research Articles

The failure mechanism of the Baishi landslide in Beichuan County, Sichuan, China

The Baishi landslide was located in the western part of Beichuan County, Sichuan Province, China. The landslide experienced multiple minor collapses at the front part, accompanying with numerous tensile cracks. To comprehensively grasp the stability conditions and predict the moment of failure of the landslide, deformation monitoring of the landslide has been carried out from the moment that the landslide was reported until it failed. This study analyzed the different phases of landslide deformation and its failure mechanism through the analysis of monitoring data. The result showed that the failure manifests both the retrogressive and advancing features. The landslide was divided into several zones based on the spatial variation of the deformation characteristics. Moreover, the improved tangential angle criterion is applied to categorize the deformation phases of a landslide. Investigating the surface displacement vectors and vector angles of landslides plays a significant role for ascertaining the failure and sliding mechanism. The monitoring results revealed that the front part of the landslide played a key role in the stability of the landslide. Therefore, the monitoring data from this zone were crucial for predicting the moment of complete landslide failure.

A model that predicts a real-time tumour surface using intra-treatment skin surface and end-of-expiration and end-of-inhalation planning CT images.

To develop a mapping model between skin surface motion and internal tumour motion and deformation using end-of-exhalation (EOE) and end-of-inhalation (EOI) 3D CT images for tracking lung tumours during respiration. Before treatment, skin and tumour surfaces were segmented and reconstructed from the EOE and the EOI 3D CT images. A non-rigid registration algorithm was used to register the EOE skin and tumour surfaces to the EOI, resulting in a displacement vector field that was then used to construct a mapping model. During treatment, the EOE skin surface was registered to the real-time, yielding a real-time skin surface displacement vector field. Using the mapping model generated, the input of a real-time skin surface can be used to calculate the real-time tumour surface. The proposed method was validated with and without simulated noise on 4D CT images from 15 patients at Léon Bérard Cancer Center and the 4D-lung dataset. The average centre position error, dice similarity coefficient (DSC), 95%-Hausdorff distance and mean distance to agreement of the tumour surfaces were 1.29 mm, 0.924, 2.76 mm, and 1.13 mm without simulated noise, respectively. With simulated noise, these values were 1.33 mm, 0.920, 2.79 mm, and 1.15 mm, respectively. A patient-specific model was proposed and validated that was constructed using only EOE and EOI 3D CT images and real-time skin surface images to predict internal tumour motion and deformation during respiratory motion. The proposed method achieves comparable accuracy to state-of-the-art methods with fewer pre-treatment planning CT images, which holds potential for application in precise image-guided radiation therapy.

Bedrock Fractures Control Groundwater‐Driven Mountain Slope Deformations

AbstractSeasonal deformation of mountain rock slopes can be driven by groundwater infiltration and depletion. Such processes could explain our field observation in the Aletsch Valley, Switzerland, where GNSS‐derived 3D annual displacement amplitudes reach 3.4 cm. However, the physical mechanisms behind such groundwater‐driven surface displacements are not well understood. Here, we develop a fully coupled hydromechanical model to simulate the relevant processes in a valley slope embedded with numerous fractures of variable sizes. The magnitude and orientation of transient annual slope surface displacement obtained from our model are in overall agreement with the field observations. The key geological factors controlling the type and magnitude of reversible mountain slope deformations are fracture network geometry, fracture aperture, and regional stress field. We show that the heterogeneity and anisotropy of bedrock hydromechanical responses, originating from depth‐dependent variations of fracture properties, play a critical role in groundwater recharge and valley slope deformation. During recharge events, pore pressure perturbations migrate downward from the groundwater table and toward the receiving stream and the deep subsurface. This process driven by pressure diffusion and poroelastic stressing develops in the subsurface with a great reach of up to a few kilometers, called critical hydromechanical response zone, and controls surface deformation patterns. During groundwater recession, this hydromechanical response zone expands downward and ground surface displacement vectors rotate upwards. Our results suggest that slope surface deformation can inform about subsurface permeability structures and pore pressure fluctuations, which have important implications for understanding groundwater flow in fractured bedrock slopes.

Combination of InSAR with a Depression Angle Model for 3D Deformation Monitoring in Mining Areas

The current three-dimensional (3D) deformation monitoring methods, based on the single line-of-sight (LOS) interferometric synthetic aperture radar (InSAR) technology, are constructed by combining the deformation characteristics of mining subsidence basins, which are incompletely suitable in the edge area of the subsidence basin and some large deformation gradient mines with surface uplift in the LOS direction.The 3D deformation monitoring method of InSAR combined with the surface displacement vector depression angle model (InSAR+ depression angle model) is proposed to obtain more detailed and accurate deformation information of the entire basin. This method first establishes a surface displacement vector depression angle model based on the probability integral method (PIM). The magnitude of the surface displacement vector—owing to the spatial relationship between the LOS direction and the surface displacement vector—is obtained because the horizontal movement direction field and the displacement vector depression angle field of the mining area determine the 3D directions of the surface displacement vector. Then, the PIM model is used to obtain the settlement information of the central area with a large deformation gradient. A complete subsidence basin of the mining area is received by combining the proposed method and the PIM. A total of 35 Sentinel-1A data from 31 March 2018 to 13 May 2019 and the leveling data were used to apply and analyze the accuracy of this method. The experimental results show that this method can obtain more accurate information on surface subsidence around the mining area. Moreover, the overall settlement is more consistent with the actual situation, and the monitoring ability is significantly improved compared with the InSAR and PIM.

Monitoring the changing seismic site response of a fast-moving rockslide (Brienz/Brinzauls, Switzerland)

SUMMARYSeismic measurements on unstable rock slopes are a complementary tool to surface displacement surveys to characterize and monitor landslides. A key parameter is seismic amplification, which tends to scale with the degree of rock mass degradation. Amplification also provides a direct measure of how the wavefield is intensified during seismic loading, eventually leading to coseismic failure. Here we present the dynamic response of the fast-moving Brienz/Brinzauls rock slope instability in Switzerland (10 $ \times $ 106 to 25 $ \times $ 106 m3), which threatens settlements and infrastructure in the area. The rockslide shows strong seismic amplification at two resonant frequencies with factors of up to 11 and wavefield polarization influenced by the local fracture network orientation. We monitored the dynamic response over a period of 30 months using ambient vibrations and regional earthquake recordings. We observed a change in wavefield polarization of up to 50°, coinciding with a rotation of the relative surface displacement vector field measured by geodetic systems, highlighting the linkage between wavefield polarization and stress field (i.e. rock mass kinematics). For the analysis of secondary, relative surface displacements, we propose a singular value filtering of the displacement field to remove the principal component of landslide motion. In addition, we found increased seismic amplification values after periods of strong precipitation, providing empirical field evidence that the local precipitation history is a key parameter for assessing the hazard of earthquake-induced slope failure.

Modelling asymmetric deformation along a curved strike-slip basement-fault system

Large-scale curved strike-slip fault systems along which significant amounts of displacement have taken place are common in nature. Scaled analogue experiments were used in this study to investigate strike-slip deformation in cover units above a curved basement-fault system simulated by a rigid plate with an in-built curvature depicting a half-circular fault. The model results show that en-echelon, right-stepping Riedel shears and low-angle synthetic shears (Y-shears) always form at the beginning of deformation, and grow outwards with splay faults, most of which evolve into thrusts at later stages of deformation. Digital image correlation (DIC) analyses of the surface displacement vectors show that a diffuse zone of deformation progressively changes into en-echelon shears, which gradually develop into throughgoing shear zones with further deformation. The geometries of Riedel shears along two sides of the basement fault (i.e. concave and convex sides) show significant differences in fault shape and intersection angles between the faults and the curved basement fault, indicating an asymmetry in deformation with a much wider deformation zone occurring on the concave side. As a result, en-echelon and/or overlapping flower structures develop along the curved basement strike-slip fault system. In particular, Riedel shears with a upward-convex geometry are localised in both sides of the curved basement fault and a continuous reverse oblique-slip fault forms at the concave side. When compared with the geometry of curved strike-slip faults in nature (e.g. the Daliangshan shear zone in Xichang basin and the Red River shear zone in the Yinggehai basin, China) the model results depict the asymmetric evolution pattern of the faults on either side of curved basement faults.

Monitoring and analysis of active rockslide-glacier interactions (Moosfluh, Switzerland)

Valley glaciers have traditionally been expected to significantly influence the stability and movement rates of adjacent paraglacial landslides. However, detailed studies related to the mechanical and displacement interactions between glacier ice and unstable rock slopes are very rare. Here we present a detailed in-situ investigation of the spatial variations of the displacement field of the Great Aletsch Glacier in the surroundings of a large active instability, i.e., the Moosfluh Landslide, a Deep-Seated Gravitational Slope Deformation, with superimposed large (1–5 million m3) secondary rockslides formed during fall 2016. We performed repeat UAV-based photogrammetric surveys during ~3 days (74 h) and applied Digital Image Correlation techniques to record high-resolution surface displacement vector fields of the landslide, stable slopes and adjacent glacier. Our results show that the secondary rockslide adjacent to the glacier is composed of two parts of 1.5 and 2.8 million m3 volume respectively, showing significant differences in mean displacement velocities (0.4 and 0.9 m in 74 h respectively, excluding rapid movements from detached blocks). Both rockslide compartments induce clear deflections of the glacier flow field, moving with a maximum velocity of about 0.3 to 0.4 m in 74 h. This influence is highest near the ice-contact boundary and decreases within a distance of about 100–200 m from the rock slope instability. We investigate the viscous forces at the landslide/glacier contact using a straightforward analytical model for an incompressible rockslide block sliding along a planar, cohesionless surface into ice. These forces are then applied to a slope stability model based on the limit equilibrium concept, representing the real geometry at the interface boundary to quantitatively explore the true buttressing effects of valley glaciers on an already moving slope instability. We show that the viscous ice deformation plays an important role in mediating the displacement velocities of landslides in unstable conditions, while, on the other hand, the slope support from the valley glacier has very little influence on the stability of the investigated rockslides.As most valley glaciers are currently strongly retreating due to global warming, uncovering significant numbers of pre-LIA slope instabilities, this detailed investigation provides important hints on their potential displacement behavior. Understanding the factors controlling landslide velocity is of great importance for hazard analyses and early warning. Hence, this study has implications beyond academic interest, e.g., for the planning and operation of alpine infrastructure, such as cable cars or hydropower systems.

Is it possible to estimate surface displacement vector via distance measurement in two directions? : A case of distance measurement at a lava dome of Mt. Unzen-Fugen-Dake

Is it possible to estimate surface displacement vector via distance measurement in two directions? : A case of distance measurement at a lava dome of Mt. Unzen-Fugen-Dake

The posterior temporal supraSMAS minimally invasive lifting technique using soft-tissue fillers.

To investigate the effectiveness of the posterior temporal supraSMAS minimally invasive lifting technique and compared it to experiments performed in fresh human body donors by applying skin vector displacement measurement technology. A total of 15 patients (14 females/1 male) with a mean age of 37.1±9.4years and a mean body mass index of 21.4±3.3kg/m2 were included into this observational analysis. The injection procedure was additionally performed in 2 male and 1 female fresh body donors with a mean age of 85.67±9.7years and a mean body mass index of 23.83±4.7kg/m2 . Different grades of skin laxity, variable amounts of product, and the application with and without subcision were tested and measured via three-dimensional reconstructions and surface displacement vectors using Vectra software with VAM module. Esthetic outcome was rated by an independent professional observer and by the patient immediately after the treatment (76.67%±17.6% vs 66.67%±18.1%) (P=0.001) and after 1month (80.00%±14.0% vs 75.00%±21.1%) (P=0.19). Skin laxity, subcision, and the application of more than 1.0cc per side resulted in our experimental setting in a smaller magnitude of skin displacement vectors indicating a reduced lifting effect. The posterior temporal supraSMAS minimally invasive lifting procedure seems to be a valid technique to treat temporal volume loss and to reduce the signs of age-related changes in the middle and lower face, ie "marionett line" and jowl deformity.

Displacement of a landslide retaining wall and application of an enhanced failure forecasting approach

The 10-mile Slide is contained within an ancient earthflow located in British Columbia, Canada. The landslide has been moving slowly for over 40 years, requiring regular maintenance work along where a highway and a railway track cross the sliding mass. Since 2013, the landslide has shown signs of retrogression. Monitoring prisms were installed on a retaining wall immediately downslope from the railway alignment to monitor the evolution of the retrogression. As of September 2016, cumulative displacements in the horizontal direction approached 4.5 m in the central section of the railway retaining wall. After an initial phase of acceleration, horizontal velocities showed a steadier trend between 3 and 9 mm/day, which was then followed by a second acceleration phase. This paper presents an analysis of the characteristics of the surface displacement vectors measured at the monitoring prisms. Critical insight on the behavior and kinematics of the 10-mile Slide retrogression was gained. An advanced analysis of the trends of inverse velocity plots was also performed to assess the potential for a slope collapse at the 10-mile Slide and to obtain further knowledge on the nature of the sliding surface.

Sensitivity of tumor motion simulation accuracy to lung biomechanical modeling approaches and parameters

Finite element analysis (FEA)-based biomechanical modeling can be used to predict lung respiratory motion. In this technique, elastic models and biomechanical parameters are two important factors that determine modeling accuracy. We systematically evaluated the effects of lung and lung tumor biomechanical modeling approaches and related parameters to improve the accuracy of motion simulation of lung tumor center of mass (TCM) displacements. Experiments were conducted with four-dimensional computed tomography (4D-CT). A Quasi-Newton FEA was performed to simulate lung and related tumor displacements between end-expiration (phase 50%) and other respiration phases (0%, 10%, 20%, 30%, and 40%). Both linear isotropic and non-linear hyperelastic materials, including the neo-Hookean compressible and uncoupled Mooney–Rivlin models, were used to create a finite element model (FEM) of lung and tumors. Lung surface displacement vector fields (SDVFs) were obtained by registering the 50% phase CT to other respiration phases, using the non-rigid demons registration algorithm. The obtained SDVFs were used as lung surface displacement boundary conditions in FEM. The sensitivity of TCM displacement to lung and tumor biomechanical parameters was assessed in eight patients for all three models. Patient-specific optimal parameters were estimated by minimizing the TCM motion simulation errors between phase 50% and phase 0%. The uncoupled Mooney–Rivlin material model showed the highest TCM motion simulation accuracy. The average TCM motion simulation absolute errors for the Mooney–Rivlin material model along left-right, anterior–posterior, and superior–inferior directions were 0.80 mm, 0.86 mm, and 1.51 mm, respectively. The proposed strategy provides a reliable method to estimate patient-specific biomechanical parameters in FEM for lung tumor motion simulation.

Recent geodynamics of fault zones: faulting in real time scale

Recent deformation processes taking place in real time are analyzed on the basis of data on fault zones which were collected by long-term detailed geodetic survey studies with application of field methods and satellite monitoring. A new category of recent crustal movements is described and termed as parametrically induced tectonic strain in fault zones. It is shown that in the fault zones located in seismically active and aseismic regions, super intensive displacements of the crust (5 to 7 cm per year, i.e. (5 to 7)·10–5 per year) occur due to very small external impacts of natural or technogenic / industrial origin. The spatial discreteness of anomalous deformation processes is established along the strike of the regional Rechitsky fault in the Pripyat basin. It is concluded that recent anomalous activity of the fault zones needs to be taken into account in defining regional regularities of geodynamic processes on the basis of real-time measurements. The paper presents results of analyses of data collected by long-term (20 to 50 years) geodetic surveys in highly seismically active regions of Kopetdag, Kamchatka and California. It is evidenced by instrumental geodetic measurements of recent vertical and horizontal displacements in fault zones that deformations are ‘paradoxically’ deviating from the inherited movements of the past geological periods. In terms of the recent geodynamics, the ‘paradoxes’ of high and low strain velocities are related to a reliable empirical fact of the presence of extremely high local velocities of deformations in the fault zones (about 10–5 per year and above), which take place at the background of slow regional deformations which velocities are lower by the order of 2 to 3. Very low average annual velocities of horizontal deformation are recorded in the seismic regions of Kopetdag and Kamchatka and in the San Andreas fault zone; they amount to only 3 to 5 amplitudes of the earth tidal deformations per year. A ‘fault-block’ dilemma is stated for the recent geodynamics of faults in view of interpretations of monitoring results. The matter is that either a block is an active element generating anomalous recent deformation and a fault is a ‘passive’ element, or a fault zone itself is a source of anomalous displacements and blocks are passive elements, i.e. host medium. ‘Paradoxes’ of high and low strain velocities are explainable under the concept that the anomalous recent geodynamics is caused by parametric excitation of deformation processes in fault zones in conditions of a quasi-static regime of loading. Based on empirical data, it is revealed that recent deformation processes migrate in fault zones both in space and time. Two types of waves, ‘inter-fault’ and ‘intra-fault’, are described. A phenomenological model of auto-wave deformation processes is proposed; the model is consistent with monitoring data. A definition of ‘pseudo-wave’ is introduced. Arrangements to establish a system for monitoring deformation auto-waves are described. When applied to geological deformation monitoring, new measurement technologies are associated with result identification problems, including ‘ratios of uncertainty’ such as ‘anomaly’s dimensions – density of monitoring stations’ and ‘anomaly’s duration – details of measurements in time’. It is shown that the RSA interferometry method does not provide for an unambiguous determination of ground surface displacement vectors.

Model-based autosegmentation of the central brain of the honeybee, Apis mellifera, using active shape models

Event Abstract Back to Event Model-based autosegmentation of the central brain of the honeybee, Apis mellifera, using active shape models Jochen Singer1*, Matthias Lienhard1, Heiko Seim2, Dagmar Kainmüller2, Anja Kuss2, Hans Lamecker2, Stefan Zachow2, Randolf Menzel1 and Jürgen Rybak1 1 Free University of Berlin, Germany 2 Zuse Institute Berlin (ZIB), Germany The Honeybee Brain Atlas serves as 3D database and communicative platform to accumulate structural data, i.e. reconstructed neurons, derived from confocal scans (Brandt et al., 2005) (www.neurobiologie.fu-berlin.de/beebrain/) (1). Transforming neurons into the atlas requires manual segmentation of neuropils within confocal images, a time-consuming task requiring expertise in identifying biological structures which can result in different outcomes from various segmenters. Recently we investigated a method to build a statistical 3D shape model of a substructure of the honeybee brain, the median calyx, which can be used for automatic image segmentation using a-priori knowledge about the shape that is to be segmented (3). The shape model is generated from a set of segmented calyces, representing an average shape including shape variations within the training data. The statistical modeling is based on a principal component analysis (PCA). Correspondence between the individual structures is established via a common patch decomposition of the surfaces of anatomical regions (2). For automatic segmentation, the shape model integrates characteristic image information at the boundaries. Surface displacement vectors were computed by analyzing grey value profiles within the image data and fitting the shape model to the data (4). A newly developed procedure for enhancing contrast in wholemounts of the brain based on Lucifer Yellow (LY) added to the fixative helps us to improve signal to noise in the confocal images. Contrary to the original antibody method used for the BeeBrain Atlas (1) the LY method is less time consuming (2 h versus 1 week incubation time of staining agents). Volume and shape of brain neuropil which will be included in the shape model are roughly the same for both methods. We are aiming to expand the current statistical 3d shape model of the median calyx to the whole protocerebrum (central brain), including eight brain neuropils. The advantage will be to develop a displacement algorithm with a more efficient pattern recognition based on more a-priori knowledge of the bee brain. Currently the collection contains 25 LY datasets. Additionally an expanded 3d shape model of the bee brain needs a hierarchical strategy, which is able to separate sub-elements of the model, thus allowing the autosegmentation of single brain structures based on high-resolution confocal scans.

Analysis of Internal Clearance of Oil-Free Screw Compressor and Its Application to Performance Simulation.

Clearance between male and female rotors and that between the rotors and casing of an oil-free screw compressor in operation are calculated. Surface displacement vectors of both rotors due to, for example, thermal deformation, profile errors, and deviation of the center distance, are converted to such that the clearance between the rotors changes assuming that the rotor surface is approximated by a plane in the vicinity of the calculating point and that the normal line of the plane does not change direction before or after the displacements. The calculation is applied to a computer simulation for predicting air compressor performance. Change in volumetric efficiency related to suction air temperature was calculated and the results agreed well with experimental ones.

A Whole-Field Interferometric Scheme for Measuring strain and Flow Rates of Glacier and Other Natural Surfaces

AbstractThe flow of glacier ice is mapped using high-resolution photography and non-coherent-light speckle interferometry. Young’s fringe patterns result when a double-exposed photoplate image of the straining surface is illuminated by a narrow beam of coherent light. Geometry gives a relationship between the ice surface displacement vector and the interference fringe patterns. This displacement vector is corrected for rigid-body (camera) movement and projected onto the ice surface using topological maps. The strain during the time-lapse interval is thus known. Comparison with data acquired by surveying techniques at Nisqually Glacier, Washington, U.S.A., is limited because of small overlap of the surface studied. In the areas for which results can be compared, our experiments yield a flow of 0.6 m/d where conventional methods yield about 0.4 m/d.

A Whole-Field Interferometric Scheme for Measuring strain and Flow Rates of Glacier and Other Natural Surfaces

AbstractThe flow of glacier ice is mapped using high-resolution photography and non-coherent-light speckle interferometry. Young’s fringe patterns result when a double-exposed photoplate image of the straining surface is illuminated by a narrow beam of coherent light. Geometry gives a relationship between the ice surface displacement vector and the interference fringe patterns. This displacement vector is corrected for rigid-body (camera) movement and projected onto the ice surface using topological maps. The strain during the time-lapse interval is thus known. Comparison with data acquired by surveying techniques at Nisqually Glacier, Washington, U.S.A., is limited because of small overlap of the surface studied. In the areas for which results can be compared, our experiments yield a flow of 0.6 m/d where conventional methods yield about 0.4 m/d.

On perturbation problems associated with finite boundaries

The methods of a previous paper (9) are improved and extended. It is assumed that the eigenfunctions and eigenvalues of an eigenvalue problem given by an elliptic differential equation are known subject to given boundary conditions on a finite boundary. It is shown how the corresponding quantities can be obtained for a similar problem in which the original differential equation, boundary and boundary conditions are simultaneously perturbed. The introduction of a surface displacement vector allows of a Taylor expansion of all quantities and a subsequent separation of orders. The problem of finding the perturbed eigenfunctions for each order then reduces to the solution of an inhomogeneous differential equation subject to known boundary conditions. These equations are solved by a variational method. An application of Green's theorem at each stage enables us to find the perturbed eigenvalues. The method is applied to a problem of which an exact solution is known and good agreement is obtained.The author is greatly indebted to Dr H. Fröhlich for many interesting discussions and some valuable suggestions.