Vertical Ground Displacements Research Articles

On the joint use of SAR and meteo-climatological information to monitor the Po River under nominal and drought conditions

This study addresses the drought phenomenon that affected the Po River, north of Italy, by jointly exploiting methods based on measurements remotely sensed by the European Sentinel-1 C-band Synthetic Aperture Radar (SAR) and meteo-climatological information derived from both in situ and satellite datasets. The SAR methods consist of a baseline approach, which estimates the water-covered area from dual-polarized SAR imagery using a constant false alarm rate (CFAR) approach, augmented with ancillary vertical ground displacement information derived from SAR interferometry (InSAR). The meteo-climatological information includes hydrometric water level, rainfall data, and the Standard Precipitation Evapotranspiration Index (SPEI). Experimental results, obtained using a seven-year time series of SAR scenes collected over the Po River close to the city of Piacenza and contrasted with ancillary external information, demonstrate the soundness of the proposed SAR-based added-value products and their satisfactory accuracy in emphasizing both seasonal trends and the drought phenomena occurred in the area. This paves the way for an operational use of SAR measurements to monitor the water-covered area of the Po River and potentially other similar environments.

Drought‐Induced Vertical Displacements and Water Loss in the Po River Basin (Northern Italy) From GNSS Measurements

AbstractWe study vertical ground displacement time series from Global Navigation Satellite System (GNSS) stations to measure deformation associated with hydrological drought in the Po river basin. Focusing on interannual trend changes, rather than seasonal (annual) components, we found a clear spatially correlated deformation signal that is temporally (anti)correlated with changes in the Po river level and the SPEI‐12 drought index, with stations moving upward during periods of river/index level decrease and vice versa. In the 2021–2022 time span, which culminated in the most severe drought of the last two centuries, we estimate the amount and spatial distribution of water loss in the basin and its surroundings. Excluding the seasonal signals, between January 2021 and August 2022, the GNSS stations underwent uplift, up to 7 mm, which corresponds to ∼70 Gtons of water loss. Compared to Global Land Data Assimilation System and Gravity Recovery and Climate Experiment estimates, GNSS results show a similar temporal evolution of water content but a more heterogeneous distribution of values. We show that continuous GNSS networks provide an effective way to monitor multiannual trend changes in water storage even in small water basins and serve as a reliable indicator of drought severity.

A unified empirical method for predicting both vertical and horizontal ground displacements induced by tunnel excavation

An empirical model for describing the soil movements induced by tunneling is proposed, then the mathematical relationship between horizontal displacement and vertical displacement is obtained. By analyzing 25 sets of data from field engineering and 35 sets of data from model tests, the formula for the maximum settlement Sv, max( z) is optimized to adapt to different ground conditions. The Modified Gaussian function is developed by introducing the existing width coefficient of the settlement trough i( z) and the optimized Sv, max( z) to describe the surface and subsurface vertical displacement. Subsequently, the formula for the horizontal displacement is derived based on the Modified Gaussian function. H( z) representing the position of the oriented point of the soil movement is a variable in the formula for horizontal displacement. Based on measured results, a logarithmic function and a quadratic polynomial function are proposed to describe the variation of H( z) with depth in the clay stratum and sand stratum, respectively. Then, the rationality of the proposed method is validated by 4 sets of in-situ data and 4 sets of test data. Finally, the implementation process of the proposed method is illustrated, and the inversion results of the ground displacement field in Beijing Metro Line 12 are presented.

Seismic Fragility Analysis of Retaining Walls Dependent on Initial Conditions

Fragility curves of retaining walls constitute an efficient tool for the estimation of seismic risk and can be utilized for prevention from potential damage or for immediate decision-making. In this work, fragility curves for cantilever retaining walls of three different heights are proposed, considering cohesionless soil materials. The seismic response of the soil-wall system, in terms of permanent vertical ground displacement of the backfill soil and permanent horizontal displacement of the wall’s base, is estimated by conducting non-linear time history analyses, through the 2D finite element simulation method. Five initial conditions are investigated regarding the value of the global factor of safety (FS) under static conditions. An initial value of FS equal to 1.5 is considered for dry conditions. If the presence of the water table is taken into account, the corresponding FS drops to values ranging from 1.4 to 1.1. Parameters that characterize seismic intensity are evaluated based on criteria, in order to identify the intensity measures that best correlate with the system’s response. Three damage states are adopted, corresponding to minor, moderate, and extensive damage. The approach of combined damage criteria is also investigated. Finally, fragility curves are derived demonstrating the degree of dependency on initial conditions.

A Comprehensive Review on Mining Subsidence and its Geo-environmental Impact

Over the course of several decades, subsidence has exerted a notable impact on the mining sector. The preponderance of subsidence occurrences is evident within coal mines. Remote sensing and Geographic Information Systems (GIS) have emerged as principal instruments for the evaluation and characterization of subsidence phenomena. The manifestation of mininginduced subsidence engenders concerns encompassing roof collapse, infrastructural damage, and the formidable challenge of preserving human lives. The repercussions of mining-related subsidence extend to indigenous flora and subterranean water reservoirs. This phenomenon critically impedes the sustainable advancement of mining zones, precipitates the depletion of natural reservoirs, and engenders a host of ecological and environmental predicaments that cast an adverse influence on socio-economic dynamics. Within mining contexts, subsidence manifests as both vertical and horizontal ground displacement, presenting as fissures, depressions, troughs, and sinkholes. The present article furnishes a comparative discourse on diverse methodologies harnessed for the assessment of mining-induced subsidence. The scholarly community has employed a repertoire of eight predominant techniques, as delineated in the conclusive remarks of this study. Over the bygone two decades, considerable strides have been taken, enabling the deployment of sophisticated paradigms, such as remote sensing and GIS, Light Detection and Ranging (LiDAR), and Differential Interferometric Synthetic Aperture Radar (DiNSAR), for the identification and quantification of land subsidence phenomena.

Analytical solutions for the restraint effect of isolation piles against tunneling-induced vertical ground displacements

Analytical solutions for the restraint effect of isolation piles against tunneling-induced vertical ground displacements

Deformations caused by subsurface heat islands: a study on the Chicago Loop

Deformations caused by subsurface heat islands: a study on the Chicago Loop

Underground Gas Storage Monitoring Using Free and Open Source InSAR Data: A Case Study from Yela (Spain)

Gas consumption is subject to large seasonal fluctuations between the summer season (period with lower request) and the winter season (time with increased consumer demand). Underground gas storage applications (UGS) help to ensure a steady and reliable supply of natural gas, even during periods of peak demand, smoothing price fluctuations and providing a means of balancing the supply and demand of natural gas on a daily, weekly, or seasonal basis. However, UGS activities can induce vertical ground displacement, which is usually strictly associated with the injection and withdrawal of gas into/from the reservoir. It is necessary to carefully monitor and manage the potential impact of UGS activities on the subsurface and surface to ensure the stability and safety of the local environment. The Interferometric Synthetic Aperture Radar (InSAR) technique can provide a wide range of high-precision information on seasonal surface deformation associated with UGS activities useful for increasing the amount of information on ground deformation monitoring. This study introduces a unique and replicable approach to investigating freely available ground movement data for a fractured aquifer reservoir located in the Madrid Basin (Guadalajara, Spain), which is currently employed for seasonal underground gas storage applications. Notably, this study gives a comprehensive comparison of InSAR results of UGS activity in a deep aquifer, leveraging data that are entirely open-source and easily accessible. The Yela UGS project exploits a carbonate reservoir (dolomite) managed, since 2012, by Enagás, the Spanish main Transmission System Operator (TSO). InSAR data from 2015 to 2021 provided a full and coherent ground deformation pattern of the area. Based on this data, a fully integrated volumetric variation model was developed, elucidating the effects of gas storage activity. A significant correlation between the periodic injection/withdrawal rates of natural gas and InSAR ground deformation over time was identified.

Bearing behavior of rock socketed pile in limestone stratum embedded with a karst cavity beneath pile tip

This paper investigates the bearing behavior of axially loaded rock socketed piles in limestone stratum embedded with a karst cavity beneath the pile. The pile foundation supporting a cross-river bridge located in a karst area in China is considered. Based on this project, three-dimensional finite element analyses are performed to capture the effects of pile length, pile diameter, limestone cohesion, and cavity roof thickness. Their impact on the bearing characteristics of the pile is comprehensively outlined through analysis of load-settlement curves, variations in pile bearing capacity, distributions of axial pile force and pile side friction, as well as contours of vertical ground and cavity roof displacement. It is found that the load-settlement curves exhibit the saltation type, based on which the pile-bearing capacity can be conveniently obtained. The pile bearing capacity increases nonlinearly with increasing the pile length, whereas almost linearly with an increase in the pile diameter, limestone cohesion, and cavity roof thickness. For the considered conditions, larger magnitudes of vertical ground displacements occur primarily surrounding the pile side in the pebble layer and at the pile bottom. This is attributed to the weakening effect of the karst cavity on the bearing capacity of the cavity roof. The achievements from this study are beneficial for the design optimization of rock socketed piles in karst areas.

Ground Surface Deformation Analysis Integrating InSAR and GPS Data in the Karstic Terrain of Cheria Basin, Algeria

Karstic terrains are usually dominated by aquifer systems and/or underground cavities. Overexploitation of groundwater in such areas often induces land subsidence and sometimes causes sinkholes. The Cheria basin in Algeria suffers from severe land subsidence issues, and this phenomenon has been increasing in recent years due to population expansion and uncontrolled groundwater exploitation. This work uses GPS data and persistent scatterer interferometry synthetic aperture radar (PS-InSAR) techniques to monitor the land subsidence rate by employing Sentinel-1 satellite data for the period from 2016 to 2022. Our results demonstrate that the Cheria basin experiences both uplift and subsidence in places, with an overall substantial change in the land surface. The total cumulative subsidence over 6 years reached a maximum of 500 mm. Comparison of land deformation between PSI and GPS showed root mean square error (RMSE) values of about 2.83 mm/year, indicating that our analyzed results are satisfactorily reproducing the actual changes. Nonetheless, these results can be used to extract the susceptible zones for vertical ground displacement and evaluate the surface deformation inventory map of the region for reducing damages (e.g., human losses, economic impact, and environmental degradation) that may occur in the future (e.g., sinkholes) and can be further utilized in perspective for a sinkhole early warning system.

Ground behaviour and settlements analysis on tunnelling of shallow-buried metro in Tashkent city

This paper proposed a calculation method that reflects the process of deformations of the soil mass and subsidence of the ground's surface around the shallow subway tunnels and their study, taking into account the engineering and geological conditions of the construction site on the third line of Tashkent metro. The vertical ground displacements of soil mass and zone of destruction (instability) around the hole of the running tunnel of the metro located at different depths were determined. As a result of the numerical calculations performed, the settlements of the ground's surface were determined during tunneling by the shield method. It was found that the maximum value of the trough of the ground's surface decreases with an increase in the depth of the tunnel. This is because with deep tunneling, settlements are largely determined by the decrease in the vertical pressure of the soil on the tunnel due to the formation of a limited disturbed zone around the tunnel hole.

Assessment of ground deformation and seismicity in two areas of intense hydrocarbon production in the Argentinian Patagonia

The exploitation of both conventional and unconventional hydrocarbons may lead to still not well-known environmental consequences such as ground deformation and induced/triggered seismicity. Identifying and characterizing these effects is fundamental for prevention or mitigation purposes, especially when they impact populated areas. Two case studies of such effects on hydrocarbon-producing basins in Argentina, the Neuquén and the Golfo de San Jorge, are presented in this work. The intense hydrocarbon production activities in recent years and their potential link with the occurrence of two earthquakes of magnitude 4.9 and 5 near the operating well fields is assessed. A joint analysis of satellite radar interferometry and records of fluid injection and extraction demonstrate that, between 2017 and 2020, vertical ground displacements occurred in both study areas over active well fields that might indicate a correlation to hydrocarbon production activities. Coseismic deformation models of the two earthquakes constrain source depths to less than 2 km. The absence of seismicity before the beginning of the hydrocarbon activities in both areas, and the occurrence of the two largest and shallow earthquakes in the vicinity of the active well fields just after intensive production periods, points towards the potential association between both phenomena.

Common-mode signals and vertical velocities in the greater Alpine area from GNSS data

Abstract. We study the time series of vertical ground displacements from continuous global navigation satellite system (GNSS) stations located in the European Alps. Our goal is to improve the accuracy and precision of vertical ground velocities and spatial gradients across an actively deforming orogen, investigating the spatial and temporal features of the displacements caused by non-tectonic geophysical processes. We apply a multivariate statistics-based blind source separation algorithm to both GNSS displacement time series and ground displacements modeled from atmospheric and hydrological loading, as obtained from global reanalysis models. This allows us to show that the retrieved geodetic vertical deformation signals are influenced by environment-related processes and to identify their spatial patterns. Atmospheric loading is the most important process, reaching amplitudes larger than 2 cm, but hydrological loading is also important, with amplitudes of about 1 cm, causing the peculiar spatial features of GNSS ground displacements: while the displacements caused by atmospheric and hydrological loading are apparently spatially uniform, our statistical analysis shows the presence of N–S and E–W displacement gradients. We filter out signals associated with non-tectonic deformation from the GNSS time series to study their impact on both the estimated noise and linear rates in the vertical direction. Taking into account the long time span of the time series considered in this work, while the impact of filtering on rates appears rather limited, the uncertainties estimated from filtered time series assuming a power law plus white noise model are significantly reduced, with an important increase in white noise contributions to the total noise budget. Finally, we present the filtered velocity field and show how vertical ground velocity spatial gradients are positively correlated with topographic features of the Alps.

Ground movement induced by triple stacked tunneling with different construction sequences

This study tried to explore the ground movement induced by triple stacked tunneling (TST) with different construction sequences. A case study in Tianjin, China was used to investigate the ground movement during the TST (upper tunneling (UT)). For this, a modified Peck formula was proposed to predict the surface settlement induced by TST. Next, three sets of finite element analyses (FEA) were used to compare the effects of construction sequences (i.e. UT, middle tunneling (MT), and lower tunneling (LT)) on vertical and lateral ground displacements. The results of Tianjin case and UT reveal that compared to a Gaussian distribution for a single tunnel, the surface settlement curve of triple stacked tunnels is a bimodal distribution. It seems that the proposed modified Peck formula can effectively predict the surface settlement induced by TST. The results of the three sets of FEA demonstrate that the construction sequence has a significant influence on the ground movement. Among the three construction sequences, the largest lateral displacement is observed in the MT and the smallest one in UT. The existing tunnel has an inhibitory effect on the vertical displacement. The maximum value of the lateral displacement occurs at the depth of the new tunnel in each construction sequence.

Ground Stress Analysis and Automation of Workface in Continuous Mining Continuous Backfill Operation

The cost, complexity, lack of filling space and time create challenges in the longwall backfill operation, resulting in poor subsidence control and reduced productivity. This paper proposes an automated continuous mining and continuous backfill (CMCB) method by examining its key requirements and investigates the optimum sequence of coal panel (such as drifts) excavation to ensure ground strata control at relatively high productivity. The automated CMCB adopts the highwall mining technique underground, which enables easier automation at the workface. A numerical simulation of the Changxing coal mine in China was undertaken, and five different sequences of coal excavation were investigated, using the automated CMCB excavation parameters (assuming a 4 m width cut, 5 m mining height for a 200 m long coal slice) to determine the optimum sequence of resource excavation. The plastic zones and vertical displacement across the five models were analyzed. Simulation results of the 5 m high coal seam excavation show that the odd-even slice (OES) mining sequence, which has a vertical ground displacement of 74 mm, is the most efficient excavation method, due to its effective stress redistribution and lower induced ground displacement.

Coastal Quarries as Relative Sea-Level Markers: A Methodological Approach Applied in the Apulia Region (Southern Italy)

The assessment of past sea-level positions requires a multidisciplinary approach that involves both scientific and historical humanistic fields. The use of a multidisciplinary approach allows us to obtain reliable information on the relative sea-level position, the determination of which requires the evaluation of the eustatic and steric components as well as an assessment of the vertical ground displacements, such as the isostatic adjustments and tectonic movements. In this context, coastal geoarchaeological markers play a fundamental role since their architectural height (generally defined as functional height) was relative to the sea level at the time of their construction. Thus, a comparison between the current elevation of geoarchaeological structures (or depth in the case they are currently submerged) with their estimated functional height allows us to obtain the relative sea-level variation. In this study, we applied a methodological procedure for the evaluation of the functional height of architectural elements using modern technologies (Terrestrial Laser Scanner and GPS-Real Time Kinematic) and detailed sea-level analysis. The proposed methodology was applied to coastal quarries located along the coast of Bari (Apulia region, southern Italy). The results allowed us to confirm the functional height of the detachment surface reported in the literature and to assess the sea-level position in the fifth and fourth centuries before Christ.

Vertical Ground Displacements and Its Impact on Erosion along the Karachi Coastline, Pakistan

This study employed remote sensing (optical and synthetic aperture radar) and data analysis techniques to quantify vertical ground displacements and assess their contribution to coastline erosion. To provide evidence from Pakistan, we selected the coast of Karachi—a mega-city located along the dynamic coastline of the Indus River Delta—which has been experiencing severe coastal erosion during the last few decades. Observations from the C-band Envisat/ASAR and Sentinel-1A sensors over the 2004–2010 and 2014–2016 periods, respectively, enabled us to study vertical ground displacements in the study area, providing a long-term assessment during 2004–2016. Results suggest that some areas along the Karachi coastline are subsiding at comparable rates to or even much higher than the relative sea-level rise (SLR, ~1.9 mm/yr), which may amplify the rates of relative SLR in coming years, along with accelerating coastal erosion. Various parts of the study area along the coast are unstable and undergoing displacement. Landsat images from 1989 to 2018 (10-year temporal resolution) were further used to examine the state of coastline erosion using three statistical approaches (i.e., End Point Rate (EPR), Linear Regression Rate (LRR), and Least Median of Squares (LMS)). While the erosion underlaid the majority of the eastern sections of the study area, the ground displacements were spatially heterogeneous across the study area and along the coastline. Erosion rates of ~2.4 m/yr spatially corresponded with ground displacement rates of up to ~−1.4 cm/yr, but not all the coastline segments with high annual mean erosion rates were associated with local mean subsidence. The causes of ground displacements and coastline erosion were analyzed, and results were interpreted by integrating spatial ancillary information. Results indicate that rapid urbanization, construction on reclaimed land, coastline erosion favoring seawater intrusion, failed drainage/sewerage networks, and soil liquefaction are contributing to the site-specific variations in the land displacement in Karachi.

Ground Displacements Estimation through GNSS and Geometric Leveling: A Geological Interpretation of the 2016–2017 Seismic Sequence in Central Italy

Between August 2016 and January 2017, a very energetic seismic sequence induced substantial horizontal and vertical ground displacements in the Central Italian Apennines. After this event, the Italian Military Geographical Institute (IGM), owner and manager of the Italian geodetic networks, executed several topographic surveys in the earthquake area in order to update the coordinates of vertices belonging to the IGM95 geodetic network. The measurements began in the areas where the most significant deformation occurred: the localities of Amatrice and Accumoli, in the Rieti Province, and the area covering Norcia and Castelluccio, in the Province of Perugia, all the way to Visso (Province of Macerata). The activities described in this paper focused on the updated measurement of the IGM95 network points through GNSS and the restatement of extensive parts of the high precision geometric lines that were levelled until reaching stable zones. This unprecedented amount of data was used for a new geological interpretation of the seismic sequence, which confirms some of the previous hypotheses of the scientific community. In the analyzed territory, the latest estimate of the geodetic position points has allowed for an accurate determination of the east and the north and of the altitude components of the displacement induced by the earthquake through a comparison with the previous coordinates. The results confirm that the seismicity was induced by normal faults system activity. Still, they also indicate the possible influence of a significant regional thrust that conditioned the propagation of the seismicity in the area. The obtained maps of the displacement are coherent with other geodetic works and with a rupture propagation driven by the documented geotectonic structure.

Theoretical analysis of the barrier effect of embedded isolation piles on tunneling-induced vertical ground displacements

This paper proposes an elastic solution for evaluating tunneling-induced vertical ground displacements due to the restraint of embedded isolation piles. Based on the modified Loganathan-Poulos (L&P) formula and the general form of the Melan/Mindlin solution, the restrained tunneling-induced vertical ground displacements can be calculated according to the displacement compatibility condition at the pile-soil interface. The solution can consider the relative vertical slip between the pile shaft and the surrounding soil and the embedding of the pile tip into the supported soil. The method is verified through comparisons with existing analytical solutions, boundary element program and field-measured data. Parametric analysis indicates that the parameters associated with the isolation pile (the distance of the tunnel axis from the pile axis, the pile length and the relative pile axis stiffness) and the soil (Poisson's ratio, the friction angle and the ground volume loss) have important influences on the ground surface settlement troughs and the barrier efficiency. The results also show that the pile skin-soil shear stiffness, which characterizes the relative slip between the pile shaft and the surrounding soil, determines the barrier efficiency. When the pile-soil interface is completely bonded, the contact state of the pile tip with the supported soil also has a nonnegligible impact on the barrier efficiency.

Mindlin solution on ground deformation caused by the trench excavation during installation of concrete diaphragm wall panels

Concrete diaphragm walls (CDWs) are widely used as support of deep excavation in soft ground in urban areas. Ground deformation occurs during the excavation of trenches for the installation of the CDW panels due to ground stress release. This paper investigates the ground deformation during slurry trenching using Mindlin solution. The pressure of slurry used to protect the trench stability during excavation is simulated as a triangularly distributed load on the trench walls, the soil stress state is solved using Mindlin solution, and the horizontal and vertical ground displacement are obtained through integral transformation of ground strain. The rationality of the solution is verified through comparison between the analytical solution and field measurement. Sensitivity analyses are performed on soil elastic modulus, Poisson's ratio, trench excavation depth and panel length. Simplified formulation is proposed for the prediction of horizontal ground deformation. The impact of excavation stages and adjacent panels on the ground deformation is explored. The study finds that the Mindlin solution is able to provide an approximate solution on the ground deformation during slurry trenching, and the simplified formulation can be used to provide a fast estimate of the horizontal ground movement in engineering practice.