Ground Deformation Characteristics Research Articles

Evaluation Method of the Impact of Twin Shield Tunneling Construction on Elevated Bridges: Case Study

In urban metro construction, shield tunneling often needs to pass through building and bridge pile foundations, potentially affecting the stability of existing structures. Therefore, accurately assessing the impact of shield tunneling on bridges and buildings is crucial. This study presents a comprehensive prediction method combining numerical simulation and empirical formulas, taking the underpass project of the Shijiazhuang–Wuhan High-Speed Railway Bridge by Zhengzhou Metro Line 5 as a case study. Three-dimensional numerical model calculations were performed using finite element software to analyze the displacement and stress changes of buildings and tunnel structures at different construction stages, revealing the deformation patterns of buildings adjacent to the tunnel during shield tunneling. In particular, the ground settlement caused by twin-tunnel excavation was compared with Peck’s empirical formula to verify the reliability of the numerical simulation. The results show that twin-tunnel excavation exacerbates the horizontal displacement, uplift, and settlement of the ground, with maximum deformation rates increasing by 7.10%, 20%, and 11.4%, respectively. Comparing the ground deformation results of Peck’s empirical formulas with numerical calculations revealed similar trends in the settlement curves, with a maximum deviation of 6.67%. It can be concluded that using Peck’s empirical formula to calculate ground deformation characteristics complements the limitations of numerical simulations, making the assessment results more reliable. The findings of this study demonstrate that integrating numerical simulation with empirical formulas significantly enhances the reliability of deformation predictions in complex tunneling scenarios. This research not only offers a comprehensive safety assessment method for shield tunneling construction but also provides valuable guidance for the design and construction of similar projects, serving as a theoretical reference for future engineering endeavors.

Detection Ground Deformation Characteristics of Reclamation Land with Time-Series Interferometric Synthetic Aperture Radar in Tianjin Binhai New Area, China

In order to alleviate the conflict between populations and land resource, Tianjin adopted multi-phase reclamation projects to the formed large-scale artificial reclamation land. The reclamation areas, however, are prone to subsidence, which poses a significant threat to infrastructure as well as the safety and assets of the residents. The SBAS-InSAR was used to acquire surface deformation of Tianjin Binhai New Area from January 2017 to December 2022, analyze in depth the response relationship between land subsidence, reclamation project time, and land-use type. There is a strong correlation between surface deformation and reclamation time. Severe land subsidence occurred over newly reclaimed areas. In the offshore direction, the deformation values of the Nangang Industrial Zone, the Lingang Industrial Zone, and Hangu Harbor were −98 mm to −890 mm, 45 mm to −580 mm, and −140 mm to −290 mm, respectively. Significant differences in deformation were detected among different land-use types where reclamation projects were completed in the same time. Subsidence was positively correlated with surface load; in areas with higher surface loads, the surface settlement was also more severe. The average surface settlement for the heavy shipyard, with 67 grain storage tanks and 27 grain storage tanks, road, and bare land were −201 mm, −166 mm, −107 mm, −64 mm, and −43 mm, respectively. This study reveals significant differences of surface deformation in the reclamation completed at different times, and determines that the load is the main driving factor of settlement difference in the reclamation land completed at the same time. This has important guiding significance for preventing and controlling geological disasters in the reclamation area and later development planning.

Multi-Scale Ground Deformation Analysis and Investigation of Driver Factors Based on Remote Sensing Data: A Case Study of Zhuhai City

Ground deformation poses an imminent threat to urban development. This study uses the multiscale geographically weighted regression (MGWR) model to investigate the spatial heterogeneity in factors influencing ground deformation, thereby elucidating the drivers behind regional variations in ground deformation patterns. To gain insights into the characteristics of ground deformation in Zhuhai, China, and its spatial relationship with natural and anthropogenic features, we initially utilized the small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method to collect data on ground deformation and its distribution across the entire area. Concurrently, remote sensing imagery was used to identify the various mechanisms affecting ground deformation during the same period, including geotectonic conditions, geographic environment, and human activities. Subsequently, we used the MGWR model to quantitatively estimate the effects of these driving force factors on ground deformation in Zhuhai. Our findings reveal significant ground deformation in specific areas, including Baijiao Town (Doumen District), Hongqi Town (Jinwan District), the Gaolan Port Economic Zone, and the northern part of Hengqin Town, with peak deformation rates reaching 117 mm/y. Key drivers of ground deformation in Zhuhai include NDVI, groundwater extraction intensity, and soft soil thickness. The application of the MGWR model, with an R-sq value of 0.910, outperformed both the global regression model ordinary least squares (OLS), with an R-sq value of 0.722, and the local regression model geographically weighted regression (GWR), with an R-sq value of 0.770, in identifying driving forces. This study can provide valuable insights for government policies aimed at mitigating the disaster risks associated with urban ground deformation.

The simulation of urban development with the consideration of ground deformation threats in Sidoarjo Regency, East Java Province of Indonesia

Sidoarjo plays a role as buffer zone for the expanding urban growth of Surabaya City, which results in the rapid development of built areas. After the Lapindo mudflow in 2006, subsidence occurred in the surrounding area of Porong District. Land subsidence is a slow-onset disaster that impact people's lives due to vertical displacement. Urban development in areas that are geologically prone to subsidence may have long-term impacts, both on settlements and infrastructure. Therefore, it is necessary to acknowledge its ground deformation trait and how it interacts with urban spatial development. The characteristics of ground deformation were identified utilizing Interferometric Synthetic Aperture Radar (InSAR) processing with Small Baseline Subset (SBAS) method which resulted in 10 levels of ground deformations. The map of ground deformation level was overlaid with the map of future land use of 2041 which was generated from Cellular Automata (CA) based land use simulation. Areas with alarming ground deformation level, that are “at-risk”, are found around the Lapindo area, and extends to Sidoarjo's north side. Meanwhile, the built area is estimated to grow around the major roads, in the central side from north to south, and in the middle-south part of Sidoarjo. The interaction between urban development and ground deformation provides an overview of areas that may encounter ground deformation threats, such as land subsidence and uplift movement, in the future. The results of this study can be used for spatial planning decisions with consideration of ground deformation threats by directing urban development to the “safe” areas.

Identification of Ground Deformation Patterns in Coal Mining Areas via Rapid Topographical Analysis

Coal mining inevitably brings some negative impacts, such as surface subsidence, aquifer breakage, and land degradation, to the eco-geological environment in the mining area. Among these impacts, coal mining-induced ground deformation is the most serious and has threatened the geological, ecological, and human settlement securities of mining areas. Efforts existing in the literature apply to ground deformation identification in mined-out areas at the meso-/micro and short-time scales. However, when looking back at coal mining history, there are few ways to quickly and accurately quantify ground deformation at the regional and long-time scales. In this context, we propose a method for identifying ground deformation patterns in coal mining areas using historical high-precision digital elevation models (DEMs), including data preprocessing, DEM subtraction operations, interpretation, and fitting correction. This method was applied to the Yulin National Energy and Chemical Base and successfully identified the ground deformation characteristics of the Yulin coal mining area from 2015 to 2019. By determining surface subsidence displacement, excavation depth, stacking height, and the position of the goaf suspended roof area, the objective situation of ground deformation in Yulin mining area was obtained, and the mining methods and distribution characteristics of different surface deformations were analyzed and determined. The research results are of great significance for the development of mineral resources in mining areas, reducing geological disaster risks, protecting the ecological environment, and achieving the goal of coordinated development in mining areas.

Geomechanical Modeling of Ground Surface Deformation Associated with Thrust and Reverse-Fault Earthquakes: A Distinct Element Approach

ABSTRACTWe seek to improve our understanding of the physical processes that control the style, distribution, and intensity of ground surface ruptures on thrust and reverse faults during large earthquakes. Our study combines insights from coseismic ground surface ruptures in historic earthquakes and patterns of deformation in analog sandbox fault experiments to inform the development of a suite of geomechanical models based on the distinct element method (DEM). We explore how model parameters related to fault geometry and sediment properties control ground deformation characteristics such as scarp height, width, dip, and patterns of secondary folding and fracturing. DEM is well suited to this investigation because it can effectively model the geologic processes of faulting at depth in cohesive rocks, as well as the granular mechanics of soil and sediment deformation in the shallow subsurface. Our results show that localized fault scarps are most prominent in cases with strong sediment on steeply dipping faults, whereas broader deformation is prominent in weaker sediment on shallowly dipping faults. Based on insights from 45 experiments, the key parameters that influence scarp morphology include the amount of accumulated slip on a fault, the fault dip, and the sediment strength. We propose a fault scarp classification system that describes the general patterns of surface deformation observed in natural settings and reproduced in our models, including monoclinal, pressure ridge, and simple scarps. Each fault scarp type is often modified by hanging-wall collapse. These results can help to guide both deterministic and probabilistic assessment in fault displacement hazard analysis.

Normal fault rupture propagation in overburdened rock and its impact on the ground deformation profile based on a model experimental approach

Rupture propagation and ground deformation are two major issues encountered during fault propagation. However, few studies have investigated the rupture propagation and ground deformation of a crossing fault field. In this study, three large-scale experimental tests for simulating normal faulting in crossing fault field were conducted to investigate the propagation characteristics and patterns of fault ruptures. In the conducted tests, different factors were considered, such as the fault dip Df, fault width Wf and amount of normal faulting h. The result revealed that the fault rupture pattern was mainly affected by Df, while Wf could affect the initial rupture length and ground tensioned cracks. Three fault rupture patterns can be distinguished under different Df values. In the former two patterns, the main fault rupture trace is in the form of a nonlinear logarithmic spiral line with an outcropping direction of 45°-ψp/2. Although the ground deformation profiles can be fitted roughly by empirical equation, the local deformations at fault fracture zone are not usually predicted well. The Gompertz function can describe the growth of ground settlement in a fault-crossing rock mass field. Therefore, Gompertz was introduced to characterize the growth and geometrical features of ground settlement due to normal faulting. Finally, bell-shaped ground slope curves were identified mathematically according to the first derivation of the Gompertz function. Based on the geometrical parameters, the ground deformation characteristics were furtherly revealed. This research would assist engineers in selecting sites and designing facilities in regions with weak fault fracture zones.

InSAR-derived surface deformation of Chaoshan Plain, China: Exploring the role of human activities in the evolution of coastal landscapes

Understanding the characteristics of different human-induced coastal surface deformation will improve our understanding of recent temporal-spatial evolution trends of the coastal terrain, and help better predict the risks of coastal disasters. However, few surface deformation studies have focused on the distinction between different types of anthropogenic ground deformation. Based on Sentinel-1 Synthetic Aperture Radar (SAR) data, this study employs the hybrid multi-temporal Interferometric Synthetic Aperture Radar (InSAR) method to extract the surface deformation of Chaoshan Plain from 2015 to 2020, with a spatial resolution of 30 m × 30 m. A series of historical optical satellite images and groundwater extraction data are used to help distinguish different types of human activities that have induced surface deformation. The characteristics of ground deformation induced by different types of anthropogenic activities are explored in the space and time dimensions. Results show that InSAR ground deformation in the study area is mainly caused by three types of human activities: groundwater extraction, land reclamation, and construction. Groundwater extraction has impacted >50% of the regional surface deformation by area. The interannual variability of the surface deformation rate corresponds well to that of groundwater extraction, and the subsidence effect can last for more than five years with seasonal variability. The maximum surface subsidence rate in land reclamation areas reaches ~100 mm/year, with a linear decreasing trend against time. Without extra compaction, the reclamation area can continue to deform almost at the same rate for several years. The rapid increase of overlying loads caused by construction in the reclamation area has led to a sharp decrease in the deformation rate within 2–3 years after the completion of the construction. In areas absent of other human-induced deformation, construction activities are shown to cause surface subsidence of 10–20 mm/year in a relatively short period. In areas experiencing a combination of construction and groundwater extraction, land subsidence rates of >50 mm/year are observed. This study shows that the spatial and temporal analysis of the correlations between human activities and InSAR surface deformation is an effective way to attribute the driven factors of coastal plain deformation.

Large-Scale Land Deformation Monitoring over Southern California with Multi-Path SAR Data

Southern California, USA, has been suffering severe surface deformation due to its active crustal movement under the north–south compression of the Pacific Plate and North American Plate. Meanwhile, affected by groundwater extraction and recharge, oil exploitation, surface subsidence, uplift, and seasonal deformation occur commonly in this region. In this paper, multi-path SAR datasets were collected to investigate and monitor surface deformation in Southern California. The unified simultaneous least squares (USLS) approach is applied to remove the deformation discontinuity between adjacent SAR image paths. Multiple deformation patterns of structural faults, groundwater withdrawal, and oil exploitation are observed with the interferometric synthetic aperture radar (InSAR) technique. The InSAR-derived results were validated with GPS monitoring data. The correlations between land deformation and groundwater withdrawal, faults, and precipitation were intensively analyzed, finding out and mastering the magnitude and characteristics of ground deformation in Southern California.

Analysis of Shield Tunnel Ground Deformation Characteristics and Affecting Factors in Water-Rich Soft Stratum: A Case Study on the Section Tunnel of Tianjin Metro Line 6

With the increasing intensity of underground development, the planned metro lines will inevitably pass through water-rich soft stratum. The existing research results show that shield tunneling in water-rich stratum is prone to ground settlement and segment cracking due to the large moisture content and the low soil strength, which will pose risks to the safety of construction. The prediction of ground deformation characteristics and influencing ranges caused by shield tunneling in water-rich soft stratum has been a topical issue among the tunnel research community. Based on the shield tunnel project of Tianjin Metro Line 6, supported by the monitoring data, this paper analyses the ground deformation characteristics caused by shield tunneling in water-rich soft stratum. The results suggest that the surface settlement ranges from −14.20 mm to −28.00 mm in Tianjin’s water-rich soft stratum, which is at an acceptable level of engineering. A refined 3D model addressing fluid–structure interactions is developed to consider the construction process in water-rich soft stratum. Based on this technique, this article focuses on the effect of the support pressure at the excavation surface, the friction between the shield skin and the soil, and synchronous grouting quantity on the ground settlement and structural deformation. The results show that the friction between the shield skin and the soil is the most detrimental to deformation control, whereas the synchronous grouting quantity is the most advantageous to ground and segment deformation control. In practice, timely injection of bentonite slurry reduces friction between the shield skin and the soil, and effective synchronous grouting reduces shield tunneling disruption. This technique can provide calculation support in the optimization of shield tunneling schemes in water-rich soft stratum.

Monitoring of Land Subsidence and Ground Fissure Activity within the Su-Xi-Chang Area Based on Time-Series InSAR

Serious land subsidence and ground fissure (GF) disasters have brought huge economic losses to the Su-Xi-Chang area (China) and threatened the safety of its residents. To better understand the development of these disasters, it is urgent to carry out long-term and large-scale deformation monitoring in this region. In this study, based on time-series interferometric synthetic aperture radar (InSAR) technology, ground deformation characteristics were obtained at different periods. Meanwhile, Fast Lagrangian Analysis of Continua in Three Dimensions (FLAC3D) version 5.00 was used to study the stress, seepage field, and displacement changes in the soil layers caused by pumping activities at the bedrock bulge. The results showed that three subsidence centers were located in Suzhou, Wuxi, and Changzhou from 2007 to 2010. The ground fissures in Guangming village had obvious differential settlements and intense activities. The land subsidence in the Su-Xi-Chang area was under control from 2018 to 2021, while there was a relative rebound in most areas. Combined with numerical simulation and geological data, we demonstrated that pumping activities would accelerate and intensify the land subsidence process, and differential subsidence was prone to occur at the buried hill, which in turn led to the formation of ground fissures. By comparing the characteristics of ground deformation in different periods, it was proven that banning groundwater exploitation is an effective measure for preventing and controlling such disasters.

Ground Deformation Pattern Analysis and Evolution Prediction of Shanghai Pudong International Airport Based on PSI Long Time Series Observations

Being built on the reclamation area, Shanghai Pudong International Airport (SPIA) has been undergoing uneven subsidence since the beginning of its operation in 1999. In order to explore the evolution characteristics of ground deformation in the SPIA reclamation area and further provide assurance for the airport’s safe operation, 141 Sentinel-1A images from October 2016 to September 2021 were selected to acquire time-series ground deformation observations by the StaMPS PSI processing procedure. We subsequently built a ground deformation prediction model using the Long Short Term Memory (LSTM) neural network for the short-term prediction of the SPIA deformation severity area. On this basis, the spatial-temporal evolution trends of SPIA ground deformation in the reclamation area were revealed concerning the influence and mode of action of geological conditions and environmental factors. Finally, we proposed targeted recommendations and strategies for the comprehensive ground deformation prevention and control needs of SPIA. The results indicated that the SPIA exhibits overall subsidence in the eastern part, with the maximum deformation rate reaching −57.29 mm/a. Meanwhile, the central and western part has a local uplift with the maximum deformation rate reaching 32.76 mm/a. The proposed LSTM ground deformation prediction model demonstrated excellent robustness in the region of uneven deformation, and the prediction results were in high agreement with the StaMPS PSI monitoring results. The time-series observations and prediction results are expected to provide references for the expansion project of SPIA and help the research of ground deformation and prevention in related fields.

Characteristics of ground deformation induced by pre-excavation dewatering considering blocking effect of adjacent structure

Characteristics of ground deformation induced by pre-excavation dewatering considering blocking effect of adjacent structure

Ground Deformation Characteristics Induced by Mechanized Shield Twin Tunnelling along Curved Alignments

This paper investigates the ground deformation characteristics induced by mechanized shield twin tunnelling along curved alignments by adopting the nonlinear three-dimensional (3D) finite element method (FEM). The performance of the adopted FEM is demonstrated to be satisfactory by comparing the numerical analysis results with the field monitoring data in a typical case history and with the predicted results generated by a modified version of the Peck’s empirical Gaussian formula. It has been found that the tunnelling-induced transverse ground surface settlement troughs and the distributions of the subsurface horizontal and vertical ground displacements are mostly similar in both form and magnitude for the considered various radii of curvature of tunnel alignment including 50 m, 100 m, 150 m, 200 m, 250 m, 300 m, 400 m, and infinity (i.e., straight-line tunnel). Considering the variational characteristics of the ground deformations with the magnitude of the radius of curvature, the radius of curvature of 100 m can be regarded as a critical tunnel alignment radius of curvature controlling the transformation of the curved tunnelling-induced ground deformational behaviors. For the benefit of geotechnical engineers interested in curved tunnelling with a small radius of curvature, a discussion of the technologies for reducing the overexcavation and improving the accuracy of tunnel lining segment installation is also presented.

Study on Tire Noise and Grip Performance Based on Tread Ground Deformation Characteristics

Study on Tire Noise and Grip Performance Based on Tread Ground Deformation Characteristics

A case study on the characteristics of footwall ground deformation and movement and their mechanisms

The characteristics of ground deformation induced by the excavation of underground orebodies are summarized based on an analysis of over 10 years of deformation data recorded in the eastern mining area of the Chengchao mine in China. These data are combined with laws governing the development of ground-surface cracking and collapse to study the corresponding failure mechanism. The results indicate that the ground deformation in most mining-affected areas increases at a low rate of acceleration. Furthermore, the displacement–time curves are exponential in nature (that is, the relationship between displacement and time can be expressed using an exponent). Curves representing the ratio of the horizontal: vertical displacement over time show different behaviors including convergence, fluctuation, increase, fall-back, exponential, and linear trends. The originally designed scope of the ground movement is significantly smaller than the scope of the actual ground movement suggested by the in situ deformation data (the difference in movement angle amounts to 18°; the difference in break angle to 20°). After rapidly decreasing in the initial mining stage, the break angle remained constant (~ 50°) for a long period of time. The surrounding rock mass conformed to a failure model in which the rock mass topples toward the mined-out area leading to failure surfaces being formed in the deep parts of the rock mass. The inclination angles of these failure surfaces are different in different excavation-affected areas. The excavation-affected area in which the failure surfaces occur can be viewed as a large-scale surface-cracking zone. Outside this zone, small-scale surface cracking can be observed and this area can be viewed as a small-scale surface-cracking zone. In the area investigated, the occurrence of ground movement that is significantly larger than predicted is attributed to the combined effect of engineering-geological conditions, hydrogeological conditions, and the burial depth and geometric configuration of the underground orebodies of the mine. More specifically, the surrounding rock mass is continuously subjected to large-scale unloading during the process of karst collapse (during the construction stage) and ground collapse (during the mining stage) of the mine. Then, the surrounding rock mass progressively undergoes toppling failure and becomes unstable, making the region subjected to ground movement progressively extend outwards.

Numerical simulation on ground deformation characteristics during double-line shield tunnel crossing airport runway

Using Peck empirical formula and superposition method, the variation of ground settlement, uneven settlement and ground curvature caused by single-line and double-line shield tunnel are obtained. The finite element numerical simulation method is used to analyze the construction process of shield tunnel below the airport runway. Considering the existence of the runway structure and the successive excavation effects of the left and right line, the comparison of simulation and empirical formula is analyzed. Based on this, the deformation Characteristics of the runway is derived under different buried depths and different ground loss ratios.

Ground Deformation Analysis Using InSAR and Backpropagation Prediction with Influencing Factors in Erhai Region, China

The long continuity of Interferometric Synthetic Aperture Radar (InSAR) can provide high space and resolution data for ground deformation investigations. The ground deformation in this paper appeared in the city’s development, although it is close to the Erhai region, which is different from a water-deficient city. Therefore, the analysis and prediction of ground deformation using a new method is required. In this study, Sentinel-1 Synthetic Aperture Radar (SAR) images from 2015 to 2018 were used to study the characteristics of ground deformation in the Erhai region using the Small Baseline Subset Interferometric SAR (SBAS-InSAR) technique. The results were cross-validated using ascending and descending direction images to ensure the accuracy. In addition, the results showed that there was little ground deformation in the northern part of the Erhai region, while there was obvious ground deformation in the southern part. Four influencing factors—including the building area, water level, cumulative precipitation, and cumulative temperature of the southern Erhai region—were used together to predict the cumulative ground deformation using back-propagation (BP). The R of all the involved data was 0.966, and the root mean square errors (RMSEs) between the simulated values using BP and the true measured values were 3.063, 1.003, and 1.119, respectively. The results showed that BP has great potential in predicting the change tendency of ground deformation with high precision. The main reason for ground deformation is the continuous increase of building area; the water level followed. The cumulative precipitation and cumulative temperature are the reasons for the seasonal ground deformation. Some countermeasures and suggestions are given to face the challenge of serious ground deformation.

Thoughts on the criteria to determine the origin of volcanic unrest as magmatic or non-magmatic.

As our ability to detect volcanic unrest improves, we are increasingly confronted with the question of whether the unrest has a magmatic origin (magma on the move) or a non-magmatic origin from a change in the hydrothermal system (fluids that are not magma on the move) or tectonic processes. The cause of unrest has critical implications for the potential eruptive hazard (e.g. used in constructing Bayesian Event Trees), but is frequently the subject of debate, even at well-studied systems. Here, we propose a set of multi-disciplinary observations and numerical models that could be used to evaluate conceptual models about the cause of unrest. These include measurements of gas fluxes and compositions and the isotopic signature of some components (e.g. H2, He, C, SO2, H2 O, CH4 and CO2), the spatial and temporal characteristics of ground deformation, thermal output, seismicity, changes in gravity, and whether there is topographic uplift or subsidence spanning hundreds to thousands of years. In several volcanic systems, both magmatic and non-magmatic unrest is occurring at the same time. While none of these observations or models is diagnostic on its own, we illustrate several examples where they have been used together to make a plausible conceptual model of one or more episodes of unrest and whether eruptions did or did not follow the unrest. This article is part of the Theo Murphy meeting issue 'Magma reservoir architecture and dynamics'.

ANALYSIS OF MINING-INDUCED SUBSIDENCE PREDICTION BY EXPONENT KNOTHE MODEL COMBINED WITH INSAR AND LEVELING

Abstract. The principle of exponent Knothe model was introduced in detail and the variation process of mining subsidence with time was analysed based on the formulas of subsidence, subsidence velocity and subsidence acceleration in the paper. Five scenes of radar images and six levelling measurements were collected to extract ground deformation characteristics in one coal mining area in this study. Then the unknown parameters of exponent Knothe model were estimated by combined levelling data with deformation information along the line of sight obtained by InSAR technique. By compared the fitting and prediction results obtained by InSAR and levelling with that obtained only by levelling, it was shown that the accuracy of fitting and prediction combined with InSAR and levelling was obviously better than the other that. Therefore, the InSAR measurements can significantly improve the fitting and prediction accuracy of exponent Knothe model.